JabRef References output

BibTeX-Key	Author / Editor / Organization	Title	Year	Journal / Proceedings / Book	BibTeX type	Keywords
Able1982761	Able, K.P.	Field studies of avian nocturnal migratory orientation I. interaction of sun, wind and stars as directional cues [Abstract] [BibTeX] [URL]	1982	Animal Behaviour Vol. 30 (3) , pp. 761 - 767	article	animal navigation
Abstract: Tracking radar and visual observation techniques were used to observe the orientation of free-flying passerine nocturnal migrants in situations in which potentially usable directional cues were absent or gave conflicting information. When migrants had seen the sun near the time of sunset and/or the stars, they oriented in appropriate migratory directions even when winds were opposed. Under solid overcast skies that prevented a view of both sun and stars, the birds headed downwind in opposing winds and thus moved in seasonally inappropriate directions. The data point to the primacy of visual cues over wind direction, with either sun or stars being sufficient to allow the birds to determine the appropriate migration direction.
BibTeX: @article{Able1982761, author = {Kenneth P. Able}, title = {Field studies of avian nocturnal migratory orientation I. interaction of sun, wind and stars as directional cues}, journal = {Animal Behaviour}, year = {1982}, volume = {30}, number = {3}, pages = {761 - 767}, url = {http://www.sciencedirect.com/science/article/B6W9W-4JTYB02-J/2/dda6af2153564f59c6671264aed05f83}, doi = {DOI: 10.1016/S0003-3472(82)80148-6} }
Able1990905	Able, K.P. & Able, M.A.	Ontogeny of migratory orientation in the savannah sparrow, Passerculus sandwichensis: calibration of the magnetic compass [Abstract] [BibTeX] [URL]	1990	Animal Behaviour Vol. 39 (5) , pp. 905 - 913	article	animal navigation
Abstract: The ontogeny of magnetic orientation was examined in the savannah sparrow by manipulating the early experience of hand-raised birds with visual and magnetic cues. Tests of magnetic orientation were performed indoors in orientation cages covered by translucent sheets so that the birds could see nothing outside the cages. Control birds, raised entirely indoors, oriented in a magnetic north-northwest to south-southeast axis during autumn migration. Birds raised outdoors, exposed to clear daytime skies in a normal magnetic field, showed north-south magnetic orientation. Three groups were given experience with the natural sky only within a set of coils that shifted magnetic north clockwise to geographical east-southeast: one group saw only the daytime sky, one group saw only the clear night sky, and the third saw both day and night skies. The birds of all three groups oriented magnetic northeast-southwest, significantly different from the controls. Magnetic northeast-southwest corresponded approximately to geographical northwest-southeast within the magnetic coils in which the birds obtained their visual experience. The differences in the orientation directions chosen by the groups show that the primary magnetic compass may be calibrated early in life by some reference to geographical directions. Experience with either the clear daytime or night sky was sufficient to effect this modification. Celestial rotation, which provides a source of geographical directions both day and night, is proposed to be that geographical reference. At night the birds presumably used the stars to assess celestial rotation. In the daytime sky, both the sun itself and patterns of polarized skylight provide a means of determining geographical north. Experiments designed to determine which of these two visual cues was the relevant stimulus in the calibration of the magnetic compass were inconclusive.
BibTeX: @article{Able1990905, author = {Kenneth P. Able and Mary A. Able}, title = {Ontogeny of migratory orientation in the savannah sparrow, Passerculus sandwichensis: calibration of the magnetic compass}, journal = {Animal Behaviour}, year = {1990}, volume = {39}, number = {5}, pages = {905 - 913}, url = {http://www.sciencedirect.com/science/article/B6W9W-4K3KBK8-C/2/eb911b4300ef8f29fc2ab9af1f62d9f3}, doi = {DOI: 10.1016/S0003-3472(05)80955-8} }
Able1994449	Able, K.P.	Magnetic orientation and magnetoreception in birds [BibTeX] [URL]	1994	Progress in Neurobiology Vol. 42 (4) , pp. 449 - 473	article	animal navigation
BibTeX: @article{Able1994449, author = {Kenneth P. Able}, title = {Magnetic orientation and magnetoreception in birds}, journal = {Progress in Neurobiology}, year = {1994}, volume = {42}, number = {4}, pages = {449 - 473}, url = {http://www.sciencedirect.com/science/article/B6T0R-483SKHB-3W/2/6b2e77148ec7c9033c41954f82c4cc3d}, doi = {DOI: 10.1016/0301-0082(94)90047-7} }
Abraçado2008e204	Abraçado, L.; Esquivel, D. & Wajnberg, E.	Oriented magnetic material in head and antennae of Solenopsis interrupta ant [Abstract] [BibTeX] [URL] [NOTE]	2008	Journal of Magnetism and Magnetic Materials Vol. 320 (14) , pp. e204 - e206	article	animal navigation; fire ant; fmr; magnetoreception; magnetic sensor; nanoparticle
Abstract: Ferromagnetic resonance (FMR) has been used to study the magnetic material in the antennae, head, thorax and abdomen of Solenopsis interrupta ants. The measurements were performed at room temperature (RT). The ferrimagnetic broad lines associated to magnetite/maghemite isolated nanoparticles (high field, HF) and to large nanoparticles or aggregates (low field, LF) in insect spectra are present in the S. interrupta body part spectra, although they slightly differ in resonant fields and lineshapes. The spectral absorption areas show (32±3)%, (24±2)%, (21±2)% and (23±1)% of magnetic material average fractions in antennae, head, abdomen and thorax, respectively. Only the resonance field of the head and antennae showed angular dependence. This work shows that head and antenna of S. interrupta ant present organized magnetic material, indicating a biomineralization process.
BibTeX: @article{Abraçado2008e204, author = {L.G. Abraçado and D.M.S. Esquivel and E. Wajnberg}, title = {Oriented magnetic material in head and antennae of Solenopsis interrupta ant}, journal = {Journal of Magnetism and Magnetic Materials}, year = {2008}, volume = {320}, number = {14}, pages = {e204 - e206}, note = {VIII Latin American Workshop on Magnetism, Magnetic Materials and their Applications}, url = {http://www.sciencedirect.com/science/article/B6TJJ-4RWH8FD-8/2/94617e3d8f6a279764da5874b6110e50}, doi = {DOI: 10.1016/j.jmmm.2008.02.048} }
AkeMorMuhOtt2002	Åkesson, S.; Morin, J.; Muheim, R. & Ottosson, U.	Avian orientation: effects of cue-conflict experiments with young migratory songbirds in the high Arctic [Abstract] [BibTeX] [URL]	2002	Animal Behaviour Vol. 64 (3) , pp. 469 - 475	article	animal navigation
Abstract: The migratory orientation of juvenile white-crowned sparrows, Zonotrichia leucophrys gambelli, was investigated by orientation cage experiments in manipulated magnetic fields performed during the evening twilight period in northwestern Canada in autumn. We did the experiments under natural clear skies in three magnetic treatments: (1) in the local geomagnetic field; (2) in a deflected magnetic field (mN shifted -90°); and (3) after exposure to a deflected magnetic field (mN -90°) for 1 h before the cage experiment performed in the local geomagnetic field at dusk. Subjects showed a mean orientation towards geographical east in the local geomagnetic field, north of the expected migratory direction towards southeast. The sparrows responded consistently to the shifted magnetic field, demonstrating the use of a magnetic compass during their first autumn migration. Birds exposed to a cue conflict for 1 h on the same day before the experiment, and tested in the local geomagnetic field at sunset, showed the same northerly orientation as birds exposed to a shifted magnetic field during the experiment. This result indicates that information transfer occurred between magnetic and celestial cues. Thus, the birds' orientation shifted relative to available sunset and geomagnetic cues during the experimental hour. The mean orientation of birds exposed to deflected magnetic fields prior to and during testing was recorded up to two more times in the local geomagnetic field under natural clear and overcast skies before release, resulting in scattered mean orientations.Copyright 2002 The Association for the Study of Animal Behaviour. Published by Elsevier Science Ltd. All rights reserved .
BibTeX: @article{AkeMorMuhOtt2002, author = {Åkesson, Susanne and Morin, Jens and Muheim, Rachel and Ottosson, Ulf}, title = {Avian orientation: effects of cue-conflict experiments with young migratory songbirds in the high Arctic}, journal = {Animal Behaviour}, year = {2002}, volume = {64}, number = {3}, pages = {469 - 475}, url = {http://www.sciencedirect.com/science/article/B6W9W-46W187P-H/2/b08eac926653b251a9abc6a67d75a832}, doi = {DOI: 10.1006/anbe.2002.3077} }
BatKayMcLauShk1993	Batchelor, S.N.; Kay, C.W.M.; McLauchlan, K.A. & Shkrob, I.A.	Time-resolved and modulation methods in the study of the effects of magnetic fields on the yields of free-radical reactions [Abstract] [BibTeX] [URL]	1993	The Journal of Physical Chemistry Vol. 97 (50) , pp. 13250-13258	article	darpa
Abstract: In an attempt to understand the apparently disparate results reported in magnetic field effect studies on the same reaction system from different experimental groups, two different techniques, time-resolved methods and field-modulated ones, have been applied to systems comprising pyrene and either dicyanobenzene or dimethylaniline. It is shown that these yield different results whose origin lies less in the detection method than in the light sources which produce the radicals. The results from the time-resolved experiments, in which the effects of spin relaxation in a singlet-correlated pair are apparent, have been analyzed using a novel approach applicable to more complex reaction systems than have been studied in the past. An original experiment is introduced to observe the effects of relaxation at field strengths where the hyperfine-driven spin mixing has reached its asymptotic rate. The discrepancy between the results originates in a much shortened radical pair lifetime, resulting from a very low radical concentration under the conditions used in the modulation experiment as opposed to the time-resolved one. This lifetime effect has been confirmed by using degenerate electronexchange reactions to affect the chemistry in the period of observation in each technique. Low-field minima in the field effect curves observed using the modulation method are shown to originate in hyperfine and degeneracy effects and not to be due to J-resonances.
BibTeX: @article{BatKayMcLauShk1993, author = {Batchelor, S. N. and Kay, C. W. M. and McLauchlan, K. A. and Shkrob, I. A.}, title = {Time-resolved and modulation methods in the study of the effects of magnetic fields on the yields of free-radical reactions}, journal = {The Journal of Physical Chemistry}, year = {1993}, volume = {97}, number = {50}, pages = {13250-13258}, url = {http://pubs.acs.org/doi/abs/10.1021/j100152a032}, doi = {http://dx.doi.org/10.1021/j100152a032} }
Beason1987229	Beason, R.C. & Semm, P.	Magnetic responses of the trigeminal nerve system of the bobolink (Dolichonyx oryzivorus) [Abstract] [BibTeX] [URL]	1987	Neuroscience Letters Vol. 80 (2) , pp. 229 - 234	article	animal navigation; extracellular recording; trigeminal nerve; magnetic field; optic tectum; pineal gland; bobolink; magnetite
Abstract: Extracellular recordings using glass microelectrodes were made from the ophthalmic and supraorbital nerves of a transequatorial migratory bird, the bobolink. The rate of electrical activity was modified in 15% of the spontaneously active units by earth-strength alterations of the horizontal or vertical component of the ambient magnetic field using box coils. Responses to magnetic stimulation included augmentation or inhibition of spontaneous activity, or an ON-OFF or OFF response. Responses to magnetic stimulation were also recorded from the optic tectum and the pineal gland. The responses of the trigeminal system are probably independent of the visual system and indicate the presence of two separate magnetic receptor systems in one avian species. The responses from the trigeminal receptor may involve magnetite for transduction of magnetic field information.
BibTeX: @article{Beason1987229, author = {Robert C. Beason and Peter Semm}, title = {Magnetic responses of the trigeminal nerve system of the bobolink (Dolichonyx oryzivorus)}, journal = {Neuroscience Letters}, year = {1987}, volume = {80}, number = {2}, pages = {229 - 234}, url = {http://www.sciencedirect.com/science/article/B6T0G-482YKSR-4H/2/94d80f6ea95b8e7dbb6a966089e893d6}, doi = {DOI: 10.1016/0304-3940(87)90659-8} }
BegCerNeeVojBur2008	Begall, S.; Červený, J.; Neef, J.; Vojtěch, O. & Burda, H.	Magnetic alignment in grazing and resting cattle and deer [Abstract] [BibTeX] [URL]	2008	Proceedings of the National Academy of Sciences Vol. 105 (36) , pp. 13451-55	article	animal navigation
Abstract: We demonstrate by means of simple, noninvasive methods (analysis of satellite images, field observations, and measuring “deer beds” in snow) that domestic cattle (n = 8,510 in 308 pastures) across the globe, and grazing and resting red and roe deer (n = 2,974 at 241 localities), align their body axes in roughly a north–south direction. Direct observations of roe deer revealed that animals orient their heads northward when grazing or resting. Amazingly, this ubiquitous phenomenon does not seem to have been noticed by herdsmen, ranchers, or hunters. Because wind and light conditions could be excluded as a common denominator determining the body axis orientation, magnetic alignment is the most parsimonious explanation. To test the hypothesis that cattle orient their body axes along the field lines of the Earth's magnetic field, we analyzed the body orientation of cattle from localities with high magnetic declination. Here, magnetic north was a better predictor than geographic north. This study reveals the magnetic alignment in large mammals based on statistically sufficient sample sizes. Our findings open horizons for the study of magnetoreception in general and are of potential significance for applied ethology (husbandry, animal welfare). They challenge neuroscientists and biophysics to explain the proximate mechanisms.
BibTeX: @article{BegCerNeeVojBur2008, author = {Begall, Sabine and Červený, Jaroslav and Neef, Julia and Vojtěch, Oldřich and Burda, Hynek}, title = {Magnetic alignment in grazing and resting cattle and deer}, journal = {Proceedings of the National Academy of Sciences}, year = {2008}, volume = {105}, number = {36}, pages = {13451-55}, url = {http://www.pnas.org/content/early/2008/08/22/0803650105.abstract}, doi = {http://dx.doi.org/10.1073/pnas.0803650105} }
Bingman1981962	Bingman, V.P.	Savannah sparrows have a magnetic compass [BibTeX] [URL]	1981	Animal Behaviour Vol. 29 (3) , pp. 962 - 963	article	animal navigation
BibTeX: @article{Bingman1981962, author = {Verner P. Bingman}, title = {Savannah sparrows have a magnetic compass}, journal = {Animal Behaviour}, year = {1981}, volume = {29}, number = {3}, pages = {962 - 963}, url = {http://www.sciencedirect.com/science/article/B6W9W-4JN731R-1D/2/bb23e183c3ee7bd3607951a105e851e7}, doi = {DOI: 10.1016/S0003-3472(81)80040-1} }
BisSchOkaLinHitGetWeb2009	Biskup, T.; Schleicher, E.; Okafuji, A.; Link, G.; Hitomi, K.; Getzoff, E. & Weber, S.	Direct Observation of a Photoinduced Radical Pair in a Cryptochrome Blue-Light Photoreceptor [Abstract] [BibTeX] [URL]	2009	Angewandte Chemie International Edition Vol. 48 (2) , pp. 404-407	article	animal navigation
Abstract: Compass component: Blue-light excitation of the photoreceptor cryptochrome generates a transient radical pair by electron transfer from a tryptophan (Trp) at the surface to the flavin cofactor in the center of the protein (see picture; FAD=flavin adenine dinucleotide). Simulated EPR spectra show that the electronic coupling parameters of these radical pairs are suitable for animal magnetoreception.
BibTeX: @article{BisSchOkaLinHitGetWeb2009, author = {Biskup , Till and Schleicher , Erik and Okafuji , Asako and Link, Gerhard and Hitomi, Kenichi and Getzoff, Elizabeth D. and Weber, Stefan}, title = {Direct Observation of a Photoinduced Radical Pair in a Cryptochrome Blue-Light Photoreceptor}, journal = {Angewandte Chemie International Edition}, year = {2009}, volume = {48}, number = {2}, pages = {404-407}, url = {http://dx.doi.org/10.1002/anie.200803102}, doi = {http://dx.doi.org/10.1002/anie.200803102} }
Bogdanov2000199	Bogdanov, K.	Magnetic Sense [BibTeX] [URL]	2000	Biology in Physics , pp. 199 - 210	incollection	animal navigation
BibTeX: @incollection{Bogdanov2000199, author = {Konstantin Bogdanov}, title = {Magnetic Sense}, booktitle = {Biology in Physics}, publisher = {Academic Press}, year = {2000}, pages = {199 - 210}, url = {http://www.sciencedirect.com/science/article/B859V-4NT3VWG-D/2/de2e5c2290844bd8ff65b8bce2ed3180}, doi = {DOI: 10.1016/B978-012109840-7/50011-4} }
CadMcN2010	Cadiou, H. & McNaughton, P.A.	Avian magnetite-based magnetoreception: a physiologist's perspective [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S193-S205	article	animal navigation
Abstract: It is now well established that animals use the Earth's magnetic field to perform long-distance migration and other navigational tasks. However, the transduction mechanisms that allow the conversion of magnetic field variations into an electric signal by specialized sensory cells remain largely unknown. Among the species that have been shown to sense Earth-strength magnetic fields, birds have been a model of choice since behavioural tests show that their direction-finding abilities are strongly influenced by magnetic fields. Magnetite, a ferromagnetic mineral, has been found in a wide range of organisms, from bacteria to vertebrates. In birds, both superparamagnetic (SPM) and single-domain magnetite have been found to be associated with the trigeminal nerve. Electrophysiological recordings from cells in the trigeminal ganglion have shown an increase in action potential firing in response to magnetic field changes. More recently, histological evidence has demonstrated the presence of SPM magnetite in the subcutis of the pigeon's upper beak. The aims of the present review are to review the evidence for a magnetite-based mechanism in birds and to introduce physiological concepts in order to refine the proposed models.
BibTeX: @article{CadMcN2010, author = {Cadiou, Hervé and McNaughton, Peter A.}, title = {Avian magnetite-based magnetoreception: a physiologist's perspective}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S193-S205}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S193.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0423.focus} }
CaiGueGiaBri2010	Cai, J.; Guerreschi, G.G. & Briegel, H.J.	Quantum Control and Entanglement in a Chemical Compass [Abstract] [BibTeX] [NOTE]	2010	Phys. Rev. Lett. Vol. 104 (22) , pp. 220502	article	animal navigation
Abstract: The radical-pair mechanism is one of the two main hypotheses to explain the navigability of animals in weak magnetic fields, enabling, e.g., birds to see Earth’s magnetic field. It also plays an essential role in spin chemistry. Here, we show how quantum control can be used to either enhance or reduce the performance of such a chemical compass, providing a new route to further study the radical-pair mechanism and its applications. We study the role of radical-pair entanglement in this mechanism, and demonstrate its intriguing connections with the magnetic-field sensitivity of the compass. Beyond their immediate application to the radical-pair mechanism, these results also demonstrate how state-of-the-art quantum technologies could potentially be used to probe and control biological functions.
BibTeX: @article{CaiGueGiaBri2010, author = {Cai, Jianming and Guerreschi, Gian Giacomo and Briegel, Hans J.}, title = {Quantum Control and Entanglement in a Chemical Compass}, journal = {Phys. Rev. Lett.}, publisher = {American Physical Society}, year = {2010}, volume = {104}, number = {22}, pages = {220502}, note = {Could quantum entanglement help a flock of birds fly south for the winter? A team of scientists at the Akademie der Wissenschaften and the Universität Innsbruck, both in Austria, is looking at how concepts central to the field of quantum information—entanglement and coherence—play a role in the chemistry of magnetodetection that animals use for navigation. Writing in Physical Review Letters, Jianming Cai, Gian Giacomo Guerreschi, and Hans Briegel study a model for magnetodetection called radical pair mechanism. Here, light activates two unpaired electrons on a molecule to form a zero-spin singlet state. The interaction between the electrons and nuclei (the hyperfine interaction) mixes the singlet state with the finite-spin triplet state—making the pair sensitive to a particular magnetic field direction and, ultimately, causing decoherence. In contrast to the rule of thumb that coherence is essential to quantum information storage, Cai et al. find that it is not enough to explain the high magnetic field sensitivity of certain radical pair reactions. Entanglement, instead, appears to play a more positive role in some magnetically sensitive molecules—but perhaps not for the specific molecule believed to be important in avian magnetic navigation, where Cai et al. find the entanglement between paired spins lasts for only a fraction of the pair’s lifetime. The study may not affect the flight path of geese in the near future, but it does tie into the ongoing dialogue about quantum versus classical descriptions of what we observe. – Jessica Thomas}, doi = {http://dx.doi.org/10.1103/PhysRevLett.104.220502} }
CanBelDebSch1995	Canfield, J.M.; Belford, R.L.; Debrunner, P.G. & Schulten, K.	A perturbation treatment of oscillating magnetic fields in the radical pair mechanism using the Liouville equation [Abstract] [BibTeX]	1995	Chemical Physics Vol. 195 , pp. 59-69	article	animal navigation
Abstract: This paper describes an application of time-dependent perturbation theory to the calculation of singlet-to-triplet yields in radical pair reactions for oscillating magnetic fields. It outlines an iterative approach, based on the Liouville equation, that holds for any order of perturbation theory. It then compares this method to other methods, namely, numerical integration and the rotating frame treatment as well as methods based on the Schrodinger equation, and gives sample results.
BibTeX: @article{CanBelDebSch1995, author = {Canfield, J M and Belford, R L and Debrunner, P G and Schulten, K}, title = {A perturbation treatment of oscillating magnetic fields in the radical pair mechanism using the Liouville equation}, journal = {Chemical Physics}, year = {1995}, volume = {195}, pages = {59-69} }
CanBelLinDebSch1994	Canfield, J.M.; Belford, R.L.; Debrunner, P.G. & Schulten, K.	A perturbation theory treatment of oscillating magnetic fields in the radical pair mechanism [Abstract] [BibTeX]	1994	Chemical Physics Vol. 182 , pp. 1-18	article	animal navigation
Abstract: This paper describes an application of time-dependent perturbation theory to the calculation of singlet-to-triplet yields in radical pair reactions for oscillating magnetic fields. It outlines an iterative approach, based on the Schrödinger equation, that should hold for any order of perturbation theory and then gives explicit expressions up to second order in the oscillating field strength for the dependence of the singlet-to-triplet yield on the frequency of the oscillating field. It then compares this method to other methods, namely, numerical integration and the rotating frame treatment, and gives sample results for exponential and Noyes time-dependences. Finally, assuming the radical pair mechanism can explain certain magnetic field effects in biology, this paper discusses several counterintuitive behaviors of the singlet-to-triplet yields that may account for conflicts in the magnetic field bioeffects literature.
BibTeX: @article{CanBelLinDebSch1994, author = {Canfield, Jeff M. and Belford, R. Linn and Debrunner, Peter G. and Schulten, Klaus}, title = {A perturbation theory treatment of oscillating magnetic fields in the radical pair mechanism}, journal = {Chemical Physics}, year = {1994}, volume = {182}, pages = {1-18} }
CerBegKouNovBur2010	Červený, J.; Begall, S.; Koubek, P.; Nováková, P. & Burda, H.	Directional preference may enhance hunting accuracy in foraging foxes [Abstract] [BibTeX] [URL]		Biology Letters	article	animal navigation
Abstract: Red foxes hunting small animals show a specific behaviour known as ‘mousing’. The fox jumps high, so that it surprises its prey from above. Hearing seems to be the primary sense for precise prey location in high vegetation or under snow where it cannot be detected with visual cues. A fox preparing for the jump displays a high degree of auditory attention. Foxes on the prowl tend to direct their jumps in a roughly north-eastern compass direction. When foxes are hunting in high vegetation and under snow cover, successful attacks are tightly clustered to the north, while attacks in other directions are largely unsuccessful. The direction of attacks was independent of time of day, season of the year, cloud cover and wind direction. We suggest that this directional preference represents a case of magnetic alignment and enhances the precision of hunting attacks.
BibTeX: @article{CerBegKouNovBur2010, author = {Červený, Jaroslav and Begall, Sabine and Koubek, Petr and Nováková, Petra and Burda, Hynek}, title = {Directional preference may enhance hunting accuracy in foraging foxes}, journal = {Biology Letters}, url = {http://rsbl.royalsocietypublishing.org/content/early/2011/01/06/rsbl.2010.1145.abstract}, doi = {http://dx.doi.org/10.1098/rsbl.2010.1145} }
ClaKyrRep2001	Clayton, J.D.; Kyriacou, C.P. & Reppert, S.M.	Keeping time with the human genome [Abstract] [BibTeX]	2001	Nature Vol. 409 , pp. 829-831	article	animal navigation
Abstract: The cloning and characterization of 'clock gene' families has advanced our understanding of the molecular control of the mammalian circadian clock. We have analysed the human genome for additional relatives, and identified new candidate genes that may expand our knowledge of the molecular workings of the circadian clock. This knowledge could lead to the development of therapies for treating jet lag and sleep disorders, and add to our understanding of the genetic contribution of clock gene alterations to sleep and neuropsychiatric disorders. The human genome will also aid in the identification of output genes that ultimately control circadian behaviours.
BibTeX: @article{ClaKyrRep2001, author = {Clayton, Jonathan D and Kyriacou, Charalambos P and Reppert, Steven M}, title = {Keeping time with the human genome}, journal = {Nature}, year = {2001}, volume = {409}, pages = {829-831}, doi = {http://dx.doi.org/10.1038/35057006} }
CocMouWik2004	Cochran, W.W.; Mouritsen, H. & Wikelski, M.	Migrating Songbirds Recalibrate Their Magnetic Compass Daily from Twilight Cues [Abstract] [BibTeX] [URL]	2004	Science Vol. 304 (5669) , pp. 405-408	article	animal navigation
Abstract: Night migratory songbirds can use stars, sun, geomagnetic field, and polarized light for orientation when tested in captivity. We studied the interaction of magnetic, stellar, and twilight orientation cues in free-flying songbirds. We exposed Catharus thrushes to eastward-turned magnetic fields during the twilight period before takeoff and then followed them for up to 1100 kilometers. Instead of heading north, experimental birds flew westward. On subsequent nights, the same individuals migrated northward again. We suggest that birds orient with a magnetic compass calibrated daily from twilight cues. This could explain how birds cross the magnetic equator and deal with declination.
BibTeX: @article{CocMouWik2004, author = {Cochran, William W. and Mouritsen, Henrik and Wikelski, Martin}, title = {Migrating Songbirds Recalibrate Their Magnetic Compass Daily from Twilight Cues}, journal = {Science}, year = {2004}, volume = {304}, number = {5669}, pages = {405-408}, url = {http://www.sciencemag.org/content/304/5669/405.abstract}, doi = {http://dx.doi.org/10.1126/science.1095844} }
Davila200556	Davila, A.F.; Winklhofer, M.; Shcherbakov, V.P. & Petersen, N.	Magnetic Pulse Affects a Putative Magnetoreceptor Mechanism [Abstract] [BibTeX] [URL]	2005	Biophysical Journal Vol. 89 (1) , pp. 56 - 63	article	animal navigation
Abstract: Clusters of superparamagnetic (SP) magnetite crystals have recently been identified in free nerve endings in the upper-beak skin of homing pigeons and are interpreted as being part of a putative magnetoreceptor system. Motivated by these findings, we developed a physical model that accurately predicts the dynamics of interacting SP clusters in a magnetic field. The main predictions are: 1), under a magnetic field, a group of SP clusters self-assembles into a chain-like structure that behaves like a compass needle under slowly rotating fields; 2), in a frequently changing field as encountered by a moving bird, a stacked chain is a structurally more stable configuration than a single chain; 3), chain-like structures of SP clusters disrupt under strong fields applied at oblique angles; and 4), reassemble on a timescale of hours to days (assuming a viscosity of the cell plasma [eta] ~ 1 P). Our results offer a novel mechanism for magnetic field perception and are in agreement with the response of birds observed after magnetic-pulse treatments, which have been conducted in the past to specifically test if ferrimagnetic material is involved in magnetoreception, but which have defied explanation so far. Our theoretical results are supported by experiments on a technical SP model system using a high-speed camera. We also offer new predictions that can be tested experimentally.
BibTeX: @article{Davila200556, author = {Alfonso F. Davila and Michael Winklhofer and Valera P. Shcherbakov and Nikolai Petersen}, title = {Magnetic Pulse Affects a Putative Magnetoreceptor Mechanism}, journal = {Biophysical Journal}, year = {2005}, volume = {89}, number = {1}, pages = {56 - 63}, url = {http://www.sciencedirect.com/science/article/B94RW-4V40XN1-B/2/82a7b91f170fa44f431e636774bcd98b}, doi = {DOI: 10.1529/biophysj.104.049346} }
DeBWeaRep2007	DeBruyne, J.P.; Weaver, D.R. & Reppert, S.M.	CLOCK and NPAS2 have overlapping roles in the suprachiasmatic circadian clock [Abstract] [BibTeX] [URL]	2007	Nature Neuroscience Vol. 10 (5) , pp. 543-545	article	animal navigation
Abstract: Heterodimers of CLOCK and BMAL1, bHLH-PAS transcription factors, are believed to be the major transcriptional regulators of the circadian clock mechanism in mammals. However, a recent study shows that CLOCK-deficient mice continue to exhibit robust behavioral and molecular rhythms. Here we report that the transcription factor NPAS2 (MOP4) is able to functionally substitute for CLOCK in the master brain clock in mice to regulate circadian rhythmicity.
BibTeX: @article{DeBWeaRep2007, author = {DeBruyne, Jason P and Weaver, David R and Reppert, Steven M}, title = {CLOCK and NPAS2 have overlapping roles in the suprachiasmatic circadian clock}, journal = {Nature Neuroscience}, year = {2007}, volume = {10}, number = {5}, pages = {543-545}, url = {http://dx.doi.org/10.1038/nn1884} }
Deutschlander2003779	Deutschlander, M.E.; Freake, M.J.; Borland, S.C.; Phillips, J.B.; Madden, R.C.; Anderson, L.E. & Wilson, B.W.	Learned magnetic compass orientation by the Siberian hamster, Phodopus sungorus [Abstract] [BibTeX] [URL]	2003	Animal Behaviour Vol. 65 (4) , pp. 779 - 786	article	animal navigation
Abstract: Magnetic orientation in mammals has been demonstrated convincingly in only two genera of subterranean mole-rats (Spalax and Cryptomys sp.) by examining the directional placement of nests in radially symmetrical indoor arenas. Mole-rats show a spontaneous directional preference to place their nests to the south or southeast of magnetic north. Using a similar nest-building assay, we show that laboratory-raised Siberian hamsters also use directional information from the magnetic field to position their nests. In contrast to mole-rats, however, the directional preference for nest position shown by Siberian hamsters appears to be learned. Hamsters were housed in rectangular cages aligned along perpendicular axes before testing. When subsequently tested in a radially symmetric arena, the hamsters positioned their nests in a bimodal distribution that coincided with the magnetic direction of the long axis of the holding cages. We also present results from an earlier set of experiments in which hamsters showed consistent orientation only in the ambient magnetic field, and not in experimentally rotated magnetic fields. The conditions under which these earlier experiments were carried out suggest that holding conditions prior to testing and the presence of nonmagnetic cues may influence the expression of magnetic orientation in the Siberian hamster. Failure to consider these and other factors may help to explain why previous attempts to demonstrate magnetic orientation in a number of rodent species have failed or, when positive results have been obtained, have been difficult to replicate. Copyright 2003 Published by Elsevier Science Ltd on behalf of The Association for the Study of Animal Behaviour.
BibTeX: @article{Deutschlander2003779, author = {Mark E. Deutschlander and Michael J. Freake and S. Christopher Borland and John B. Phillips and Robert C. Madden and Larry E. Anderson and Bary W. Wilson}, title = {Learned magnetic compass orientation by the Siberian hamster, Phodopus sungorus}, journal = {Animal Behaviour}, year = {2003}, volume = {65}, number = {4}, pages = {779 - 786}, url = {http://www.sciencedirect.com/science/article/B6W9W-484V9CJ-H/2/55dbef931b8b952e1e8295e1b794a940}, doi = {DOI: 10.1006/anbe.2003.2111} }
DiValCeoSalAgaCar2008	Di Valentin, M.; Ceola, S.; Salvadori, E.; Agostin, G. & Carbonera, D.	Identification by time-resolved EPR of the peridinins directly involved in chlorophyll triplet quenching in the peridinin-chlorophyll a-protein from Amphidinium carterae [Abstract] [BibTeX] [URL]	2008	Biochimica et Biophysica Acta (BBA) - Bioenergetics Vol. 1777 (2) , pp. 186 - 195	article	pcp, carotenoid, triplet, tr-epr, darpa
Abstract: The mechanism of triplet-triplet energy transfer in the peridinin-chlorophyll-protein (PCP) from Amphidinium carterae was investigated by time-resolved EPR (TR-EPR). The approach exploits the concept of spin conservation during triplet-triplet energy transfer, which leads to spin polarization conservation in the observed TR-EPR spectra. The acceptor (peridinin) inherits the polarization of the donor (chlorophyll) in a way which depends on the relative geometrical arrangement of the donor-acceptor couple. Starting from the initially populated chlorophyll triplet state and taking the relative positions among Chls and peridinins from the X-ray structure of PCP, we calculated the expected triplet state polarization of any peridinin in the complex. Comparison with the experimental data allowed us to propose a path for triplet quenching in the protein. The peridinin-chlorophyll pair directly involved in the triplet-triplet energy transfer coincides with the one having the shortest center to center distance. A water molecule, which is coordinated to the central Mg atom of the Chl, is also placed in close contact with the peridinin. The results support the concept of localization of the triplet state mainly in one specific peridinin in each of the two pigment subclusters related by a pseudo C2 symmetry.
BibTeX: @article{DiValCeoSalAgaCar2008, author = {Di Valentin, Marilena and Ceola, Stefano and Salvadori, Enrico and Agostin, Giancarloi and Carbonera, Donatella}, title = {Identification by time-resolved EPR of the peridinins directly involved in chlorophyll triplet quenching in the peridinin-chlorophyll a-protein from Amphidinium carterae}, journal = {Biochimica et Biophysica Acta (BBA) - Bioenergetics}, year = {2008}, volume = {1777}, number = {2}, pages = {186 - 195}, url = {http://www.sciencedirect.com/science/article/pii/S0005272807002034}, doi = {DOI: 10.1016/j.bbabio.2007.09.002} }
DiValKayGiaMob1996	Di Valentin, M.; Kay, C.W.M.; Giacometti, G. & Möbius, K.	A time-resolved electron nuclear double resonance study of the photoexcited triplet state of P680 in isolated reaction centers of photosystem II [Abstract] [BibTeX] [URL]	1996	Chemical Physics Letters Vol. 248 (5-6) , pp. 434 - 441	article	darpa
Abstract: A time-resolved ENDOR spectrum of the triplet state of the primary donor of photosystem II in isolated reaction centers has been obtained at cryogenic temperatures. Selective excitation of donor molecules, which have their z triplet axes parallel to the magnetic field, has permitted the measurement of the $A_zz$ component of the hyperfine coupling tensor of protons, in the reference frame of the zero field splitting tensor. For comparison, measurements have also been made on the photoexcited triplet state of monomeric chlorophyll a in vitro. The results indicate that in the temperature range 10-20 K the triplet state of the primary donor of photosystem II is largely located on a monomeric chlorophyll a molecule.
BibTeX: @article{DiValKayGiaMob1996, author = {Di Valentin, M and Kay, C W M and Giacometti, G and Möbius, K}, title = {A time-resolved electron nuclear double resonance study of the photoexcited triplet state of P680 in isolated reaction centers of photosystem II}, journal = {Chemical Physics Letters}, year = {1996}, volume = {248}, number = {5-6}, pages = {434 - 441}, url = {http://www.sciencedirect.com/science/article/pii/0009261495013474}, doi = {DOI: 10.1016/0009-2614(95)01347-4} }
Dommer2008719	Dommer, D.H.; Gazzolo, P.J.; Painter, M.S. & Phillips, J.B.	Magnetic compass orientation by larval Drosophila melanogaster [Abstract] [BibTeX] [URL]	2008	Journal of Insect Physiology Vol. 54 (4) , pp. 719 - 726	article	drosophila; magnetoreception; larvae; magnetic compass; animal navigation
Abstract: We report evidence for magnetic compass orientation by larval Drosophila melanogaster. Groups of larvae were exposed from the time of hatching to directional ultraviolet (365 nm) light emanating from one of four magnetic directions. Larvae were then tested individually on a circular agar plate under diffuse light in one of four magnetic field alignments. The larvae exhibited magnetic compass orientation in a direction opposite that of the light source in training. Evidence for a well-developed magnetic compass in a larval insect that moves over distances of at most a few tens of centimeters has important implications for understanding the adaptive significance of orientation mechanisms like the magnetic compass. Moreover, the development of an assay for studying magnetic compass orientation in larval D. melanogaster will make it possible to use a wide range of molecular genetic techniques to investigate the neurophysiological, biophysical, and molecular mechanisms underlying the magnetic compass.
BibTeX: @article{Dommer2008719, author = {David H. Dommer and Patrick J. Gazzolo and Michael S. Painter and John B. Phillips}, title = {Magnetic compass orientation by larval Drosophila melanogaster}, journal = {Journal of Insect Physiology}, year = {2008}, volume = {54}, number = {4}, pages = {719 - 726}, url = {http://www.sciencedirect.com/science/article/B6T3F-4RV7YNG-3/2/6412fe78534ba47df654aaa43383ff97}, doi = {DOI: 10.1016/j.jinsphys.2008.02.001} }
Efimova20081565	Efimova, O. & Hore, P.	Role of Exchange and Dipolar Interactions in the Radical Pair Model of the Avian Magnetic Compass [Abstract] [BibTeX] [URL]	2008	Biophysical Journal Vol. 94 (5) , pp. 1565 - 1574	article	animal navigation
Abstract: It is not yet understood how migratory birds sense the Earth's magnetic field as a source of compass information. One suggestion is that the magnetoreceptor involves a photochemical reaction whose product yields are sensitive to external magnetic fields. Specifically, a flavin-tryptophan radical pair is supposedly formed by photoinduced sequential electron transfer along a chain of three tryptophan residues in a cryptochrome flavoprotein immobilized in the retina. The electron Zeeman interaction with the Earth's magnetic field (~50 [mu]T), modulated by anisotropic magnetic interactions within the radicals, causes the product yields to depend on the orientation of the receptor. According to well-established theory, the radicals would need to be separated by >3.5 nm in order that interradical spin-spin interactions are weak enough to permit a ~50 [mu]T field to have a significant effect. Using quantum mechanical simulations, it is shown here that substantial changes in product yields can nevertheless be expected at the much smaller separation of 2.0 ± 0.2 nm where the effects of exchange and dipolar interactions partially cancel. The terminal flavin-tryptophan radical pair in cryptochrome has a separation of ~1.9 nm and is thus ideally placed to act as a magnetoreceptor for the compass mechanism.
BibTeX: @article{Efimova20081565, author = {Olga Efimova and P.J. Hore}, title = {Role of Exchange and Dipolar Interactions in the Radical Pair Model of the Avian Magnetic Compass}, journal = {Biophysical Journal}, year = {2008}, volume = {94}, number = {5}, pages = {1565 - 1574}, url = {http://www.sciencedirect.com/science/article/B94RW-4V0KNJF-9/2/04e7f0ea7aa6b9f5709cb0539cbe81ec}, doi = {DOI: 10.1529/biophysj.107.119362} }
EtcLeeWadRep2003	Etchegaray, J.-P.; Lee, C.; Wade, P.A. & Reppert, S.M.	Rhythmic histone acetylation underlies transcription in the mammalian circadian clock [Abstract] [BibTeX]	2003	Nature Vol. 421 , pp. 177-182	article	animal navigation
Abstract: In the mouse circadian clock, a transcriptional feedback loop is at the centre of the clockwork mechanism. Clock and Bmal1 are essential transcription factors that drive the expression of three period genes (Per1–3) and two cryptochrome genes (Cry1 and Cry2). The Cry proteins feedback to inhibit Clock/Bmal1-mediated transcription by a mechanism that does not alter Clock/Bmal1 binding to DNA6. Here we show that transcriptional regulation of the core clock mechanism in mouse liver is accompanied by rhythms in H3 histone acetylation, and that H3 acetylation is a potential target of the inhibitory action of Cry. The promoter regions of the Per1, Per2 and Cry1 genes exhibit circadian rhythms in H3 acetylation and RNA polymerase II binding that are synchronous with the corresponding steady-state messenger RNA rhythms. The histone acetyltransferase p300 precipitates together with Clock in vivo in a time-dependent manner. Moreover, the Cry proteins inhibit a p300-induced increase in Clock/Bmal1-mediated transcription. The delayed timing of the Cry1 mRNA rhythm, relative to the Per rhythms, is due to the coordinated activities of Rev-Erb$ and Clock/Bmal1, and defines a new mechanism for circadian phase control.
BibTeX: @article{EtcLeeWadRep2003, author = {Etchegaray, Jean-Pierre and Lee, Choogon and Wade, Paul A and Reppert, Steven M}, title = {Rhythmic histone acetylation underlies transcription in the mammalian circadian clock}, journal = {Nature}, year = {2003}, volume = {421}, pages = {177-182}, doi = {http://dx.doi.org/10.1038/nature01314} }
FalFleSchKueThaMouHeyWelFle2010	Falkenberg, G.; Fleissner, G.; Schuchardt, K.; Kuehbacher, M.; Thalau, P.; Mouritsen, H.; Heyers, D.; Wellenreuther, G. & Fleissner, G.	Avian Magnetoreception: Elaborate Iron Mineral Containing Dendrites in the Upper Beak Seem to Be a Common Feature of Birds [Abstract] [BibTeX] [URL]	2010	PLoS ONE Vol. 5 (2) , pp. e9231	article	animal navigation
Abstract: The magnetic field sensors enabling birds to extract orientational information from the Earth's magnetic field have remained enigmatic. Our previously published results from homing pigeons have made us suggest that the iron containing sensory dendrites in the inner dermal lining of the upper beak are a candidate structure for such an avian magnetometer system. Here we show that similar structures occur in two species of migratory birds (garden warbler, it Sylvia borin and European robin, it Erithacus rubecula) and a non-migratory bird, the domestic chicken (it Gallus gallus). In all these bird species, histological data have revealed dendrites of similar shape and size, all containing iron minerals within distinct subcellular compartments of nervous terminals of the median branch of the Nervus ophthalmicus. We also used microscopic X-ray absorption spectroscopy analyses to identify the involved iron minerals to be almost completely Fe III-oxides. Magnetite (Fe II/III) may also occur in these structures, but not as a major Fe constituent. Our data suggest that this complex dendritic system in the beak is a common feature of birds, and that it may form an essential sensory basis for the evolution of at least certain types of magnetic field guided behavior.
BibTeX: @article{FalFleSchKueThaMouHeyWelFle2010, author = {Falkenberg, Gerald AND Fleissner, Gerta AND Schuchardt, Kirsten AND Kuehbacher, Markus AND Thalau, Peter AND Mouritsen, Henrik AND Heyers, Dominik AND Wellenreuther, Gerd AND Fleissner, Guenther}, title = {Avian Magnetoreception: Elaborate Iron Mineral Containing Dendrites in the Upper Beak Seem to Be a Common Feature of Birds}, journal = {PLoS ONE}, publisher = {Public Library of Science}, year = {2010}, volume = {5}, number = {2}, pages = {e9231}, url = {http://dx.doi.org/10.1371%2Fjournal.pone.0009231}, doi = {http://dx.doi.org/10.1371/journal.pone.0009231} }
Fischer20011	Fischer, J.H.; Freake, M.J.; Borland, S.C. & Phillips, J.B.	Evidence for the use of magnetic map information by an amphibian [Abstract] [BibTeX] [URL]	2001	Animal Behaviour Vol. 62 (1) , pp. 1 - 10	article	animal navigation
Abstract: The question of whether animals navigate using [`]map' information derived from one or more spatial gradients in the Earth's magnetic field has been debated for half a century. Although there is evidence that certain animals possess the sensory abilities necessary to perceive at least two magnetic components that vary spatially, there previously has been no direct test of the use of magnetic map information by experienced adult migrants. Magnetic information could provide information about an animal's geographic position along a single axis ([`]unicoordinate map') or could be part of a position-fixing system that provides positional information along two nonparallel axes ([`]bicoordinate map') with the second axis being derived from either magnetic or nonmagnetic cues. Here we report that adult eastern red-spotted newts,Notophthalmus viridescens , displaced approximately 45 km NNE of their home ponds oriented in the home direction when exposed either to the ambient magnetic field of the testing site, or to a 2° increase in magnetic inclination (normally found further from the home ponds in the same general direction as the testing site). When exposed to a 2° decrease in inclination resulting in a value that would normally be found on the other side of the home ponds from the testing site, however, newts reversed their direction of orientation. The same changes in magnetic inclination had no effect on shoreward magnetic compass orientation, which does not rely on map information. These findings provide support for two critical predictions of the magnetic map hypothesis, and suggest that information about geographic position along at least one axis relative to home may be derived from the magnetic field.
BibTeX: @article{Fischer20011, author = {J. H. Fischer and M. J. Freake and S. C. Borland and J. B. Phillips}, title = {Evidence for the use of magnetic map information by an amphibian}, journal = {Animal Behaviour}, year = {2001}, volume = {62}, number = {1}, pages = {1 - 10}, url = {http://www.sciencedirect.com/science/article/B6W9W-45BC7N4-3N/2/4f31a7d1892028c9a60b808357abd46d}, doi = {DOI: 10.1006/anbe.2000.1722} }
Frankel2006329	Frankel, R.B. & Bazylinski, D.A.	How magnetotactic bacteria make magnetosomes queue up [Abstract] [BibTeX] [URL]	2006	Trends in Microbiology Vol. 14 (8) , pp. 329 - 331	article	animal navigation
Abstract: Magnetotactic bacteria contain chains of magnetosomes that comprise a permanent magnetic dipole in each cell. In two separate, recent papers, Scheffel et al. and Komeili et al. describe the roles of the proteins MamJ and MamK in magnetosome chain formation. Here, we describe the two studies and highlight questions that must be addressed in future investigations of how magnetotactic bacteria construct their magnetic compass needles.
BibTeX: @article{Frankel2006329, author = {Richard B. Frankel and Dennis A. Bazylinski}, title = {How magnetotactic bacteria make magnetosomes queue up}, journal = {Trends in Microbiology}, year = {2006}, volume = {14}, number = {8}, pages = {329 - 331}, url = {http://www.sciencedirect.com/science/article/B6TD0-4K7164Y-2/2/9254a8cf2143435b671d97b6cbcc2b4f}, doi = {DOI: 10.1016/j.tim.2006.06.004} }
Freire2005R620	Freire, R.; Munro, U.H.; Rogers, L.J.; Wiltschko, R. & Wiltschko, W.	Chickens orient using a magnetic compass [BibTeX] [URL]	2005	Current Biology Vol. 15 (16) , pp. R620 - R621	article	animal navigation
BibTeX: @article{Freire2005R620, author = {Rafael Freire and Ursula H. Munro and Lesley J. Rogers and Roswitha Wiltschko and Wolfgang Wiltschko}, title = {Chickens orient using a magnetic compass}, journal = {Current Biology}, year = {2005}, volume = {15}, number = {16}, pages = {R620 - R621}, url = {http://www.sciencedirect.com/science/article/B6VRT-4GXV66S-7/2/52ddd8bce664846bdb4913bd250abb07}, doi = {DOI: 10.1016/j.cub.2005.08.017} }
Frost2006481	Frost, B.J. & Mouritsen, H.	The neural mechanisms of long distance animal navigation [Abstract] [BibTeX] [URL] [NOTE]	2006	Current Opinion in Neurobiology Vol. 16 (4) , pp. 481 - 488	article	animal navigation
Abstract: Animal navigation is a complex process involving the integration of many sources of specialized sensory information for navigation in near and far space. Our understanding of the neurobiological underpinnings of near-space navigation is well-developed, whereas the neural mechanisms of long-distance navigation are just beginning to be unraveled. One crucial question for future research is whether the near space concepts of place cells, head direction cells, and maps in the entorhinal cortex scale up to animals navigating over very long distances and whether they are related to the map and compass concepts of long-distance navigation.
BibTeX: @article{Frost2006481, author = {Barrie J Frost and Henrik Mouritsen}, title = {The neural mechanisms of long distance animal navigation}, journal = {Current Opinion in Neurobiology}, year = {2006}, volume = {16}, number = {4}, pages = {481 - 488}, note = {Sensory systems}, url = {http://www.sciencedirect.com/science/article/B6VS3-4KCXJ9S-1/2/073f73d56290ceaa2e0ac162b8643089}, doi = {DOI: 10.1016/j.conb.2006.06.005} }
GauRieMorBenVed2011	Gauger, E.M.; Rieper, E.; Morton, J.J.L.; Benjamin, S.C. & Vedral, V.	Sustained Quantum Coherence and Entanglement in the Avian Compass [Abstract] [BibTeX]	2011	Phys. Rev. Lett. Vol. 106 , pp. 040503(1-4)	article	animal navigation
Abstract: In artificial systems, quantum superposition and entanglement typically decay rapidly unless cryogenic temperatures are used. Could life have evolved to exploit such delicate phenomena? Certain migratory birds have the ability to sense very subtle variations in Earth’s magnetic field. Here we apply quantum information theory and the widely accepted ``radical pair'' model to analyze recent experimental observations of the avian compass. We find that superposition and entanglement are sustained in this living system for at least tens of microseconds, exceeding the durations achieved in the best comparable man-made molecular systems. This conclusion is starkly at variance with the view that life is too ‘‘warm and wet’’ for such quantum phenomena to endure.
BibTeX: @article{GauRieMorBenVed2011, author = {Gauger,Erik M. and Rieper, Elisabeth and Morton,John J. L. and Benjamin ,Simon C. and Vedral, Vlatko}, title = {Sustained Quantum Coherence and Entanglement in the Avian Compass}, journal = {Phys. Rev. Lett.}, year = {2011}, volume = {106}, pages = {040503(1-4)} }
GegCasWadRep2008	Gegear, R.J.; Casselman, A.; Waddell, S. & Reppert, S.M.	Cryptochrome mediates light-dependent magnetosensitivity in Drosophila [Abstract] [BibTeX]	2008	Nature Vol. 454 , pp. 1014-1018	article	animal navigation
Abstract: Although many animals use the Earth’s magnetic field for orientation and navigation, the precise biophysical mechanisms underlying magnetic sensing have been elusive. One theoretical model proposes that geomagnetic fields are perceived by chemical reactions involving specialized photoreceptors. However, the specific photoreceptor involved in such magnetoreception has not been demonstrated conclusively in any animal. Here we show that the ultraviolet-A/blue-light photoreceptor cryptochrome (Cry) is necessary for light-dependent magnetosensitive responses in Drosophila melanogaster. In a binary-choice behavioural assay for magnetosensitivity, wild-type flies show significant naive and trained responses to a magnetic field under full-spectrum light ($asymp 300–700nm$) but do not respond to the field when wavelengths in the Cry-sensitive, ultraviolet-A/blue-light part of the spectrum ($<420nm$) are blocked. Notably, Cry-deficient $cry^0$ and $cry^b$ flies do not show either naive or trained responses to a magnetic field under full-spectrum light. Moreover, Cry-dependent magnetosensitivity does not require a functioning circadian clock. Our work provides, to our knowledge, the first genetic evidence for a Cry-based magnetosensitive system in any animal.
BibTeX: @article{GegCasWadRep2008, author = {Gegear, Robert J and Casselman, Amy and Waddell, Scott and Reppert, Steven M}, title = {Cryptochrome mediates light-dependent magnetosensitivity in Drosophila}, journal = {Nature}, year = {2008}, volume = {454}, pages = {1014-1018}, doi = {http://dx.doi.org/10.1038/nature07183} }
GegFolCasRep2008	Gegear, R.J.; Foley, L.E.; Casselman, A. & Reppert, S.M.	Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism [Abstract] [BibTeX]	2008	Nature Vol. 463 , pp. 804-807	article	animal navigation
Abstract: Animals use the Earth's magnetic field for orientation but the biophysical basis of this is unclear. The light-dependent magnetic sense of Drosophila melanogaster was recently shown to be mediated by the cryptochrome (Cry) photoreceptor; here, using a transgenic approach, the type 1 and 2 Cry of the monarch butterfly are shown to both function in the magnetoreception system of Drosophila, and probably use an unconventional photochemical mechanism.
BibTeX: @article{GegFolCasRep2008, author = {Gegear, Robert J and Foley, Lauren E and Casselman, Amy and Reppert, Steven M}, title = {Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism}, journal = {Nature}, year = {2008}, volume = {463}, pages = {804-807}, doi = {http://dx.doi.org/10.1038/nature08719} }
GegFolCasRep2010	Gegear, R.J.; Foley, L.E.; Casselman, A. & Reppert, S.M.	Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism [Abstract] [BibTeX] [URL]	2010	Nature Vol. 463 , pp. 804-807	article	animal navigation
Abstract: Understanding the biophysical basis of animal magnetoreception has been one of the greatest challenges in sensory biology. Recently it was discovered that the light-dependent magnetic sense of Drosophila melanogaster is mediated by the ultraviolet (UV)-A/blue light photoreceptor cryptochrome (Cry). Here we show, using a transgenic approach, that the photoreceptive, Drosophila-like type?1 Cry and the transcriptionally repressive, vertebrate-like type?2 Cry of the monarch butterfly (Danaus plexippus) can both function in the magnetoreception system of Drosophila and require UV-A/blue light (wavelength below 420?nm) to do so. The lack of magnetic responses for both Cry types at wavelengths above 420?nm does not fit the widely held view that tryptophan triad-generated radical pairs mediate the ability of Cry to sense a magnetic field. We bolster this assessment by using a mutant form of Drosophila and monarch type?1 Cry and confirm that the tryptophan triad pathway is not crucial in magnetic transduction. Together, these results suggest that animal Crys mediate light-dependent magnetoreception through an unconventional photochemical mechanism. This work emphasizes the utility of Drosophila transgenesis for elucidating the precise mechanisms of Cry-mediated magnetosensitivity in insects and also in vertebrates such as migrating birds.
BibTeX: @article{GegFolCasRep2010, author = {Gegear, Robert J and Foley, Lauren E and Casselman, Amy and Reppert, Steven M}, title = {Animal cryptochromes mediate magnetoreception by an unconventional photochemical mechanism}, journal = {Nature}, year = {2010}, volume = {463}, pages = {804-807}, url = {http://dx.doi.org/10.1038/nature08719}, doi = {http://dx.doi.org/10.1038/nature08719} }
GofSalLoh1998	Goff, M.; Salmon, M. & Lohmann, K.J.	Hatchling sea turtles use surface waves to establish a magnetic compass direction [Abstract] [BibTeX] [URL]	1998	Animal Behaviour Vol. 55 (1) , pp. 69 - 77	article	animal navigation
Abstract: Hatchling sea turtles emerge from underground nests, crawl to the ocean, and swim away from the land. In shallow water near shore, hatchlings maintain offshore headings by swimming into oceanic waves; in deeper water, however, turtles appear to rely on different mechanisms to maintain their courses. To determine whether loggerhead hatchlings,Caretta carettaL., are able to transfer a course initiated on the basis of waves to a course maintained by a magnetic compass, we studied the orientation behaviour of turtles that had been exposed to waves for either 15 or 30 min before being tested in still water. Hatchlings that swam into waves for 15 min failed to continue swimming on similar courses when the waves were discontinued, but turtles that swam into waves for 30 min maintained similar mean headings after the waves stopped. Inverting the vertical component of the magnetic field during the test period reversed the direction of orientation of this latter group of turtles. Thus, hatchlings can transfer a heading induced by waves to a magnetic compass, and thereby continue to migrate away from land after contact with the coast is lost. Migratory orientation in turtles resembles that of birds in that both rely on multiple cues and an ability to transfer information between various cues and compasses at appropriate times during the journey.
BibTeX: @article{GofSalLoh1998, author = {Goff, Matthew and Salmon, Michael and Lohmann, Kenneth J}, title = {Hatchling sea turtles use surface waves to establish a magnetic compass direction}, journal = {Animal Behaviour}, year = {1998}, volume = {55}, number = {1}, pages = {69 - 77}, url = {http://www.sciencedirect.com/science/article/B6W9W-45KKVHH-5K/2/e9faf50ff38adcda32d88b62c8a7e8c1}, doi = {DOI: 10.1006/anbe.1997.0577} }
GotManWeaKolPosSriMacRep2000	Gotter, A.L.; Manganaro, T.; Weaver, D.R.; Kolakowski, L.F.J.; Possidente, B.; Sriram, S.; MacLaughlin, D.T. & Reppert, S.M.	A time-less function for mouse Timeless [Abstract] [BibTeX]	2000	Nature Neuroscience Vol. 3 , pp. 755 - 756	article	animal navigation
Abstract: The timeless (tim) gene is essential for circadian clock function in Drosophila melanogaster. A putative mouse homolog, mTimeless (mTim), has been difficult to place in the circadian clock of mammals. Here we show that mTim is essential for embryonic development, but does not have substantiated circadian function.
BibTeX: @article{GotManWeaKolPosSriMacRep2000, author = {Gotter, Anthony L and Manganaro, Thomas and Weaver, David R. and Kolakowski, Lee F Jr and Possidente, Bernard and Sriram, Sathyanarayanan and MacLaughlin, David T and Reppert, Steven M}, title = {A time-less function for mouse Timeless}, journal = {Nature Neuroscience}, year = {2000}, volume = {3}, pages = {755 - 756}, doi = {http://dx.doi.org/10.1038/77653} }
Gould1998R731	Gould, J.L.	Sensory bases of navigation [Abstract] [BibTeX] [URL]	1998	Current Biology Vol. 8 (20) , pp. R731 - R738	article	animal navigation
Abstract: Navigating animals need to know both the bearing of their goal (the [`]map' step), and how to determine that direction (the [`]compass' step). Compasses are typically arranged in hierarchies, with magnetic backup as a last resort when celestial information is unavailable. Magnetic information is often essential to calibrating celestial cues, though, and repeated recalibration between celestial and magnetic compasses is important in many species. Most magnetic compasses are based on magnetite crystals, but others make use of induction or paramagnetic interactions between short-wavelength light and visual pigments. Though odors may be used in some cases, most if not all long-range maps probably depend on magnetite. Magnetitebased map senses are used to measure only latitude in some species, but provide the distance and direction of the goal in others.
BibTeX: @article{Gould1998R731, author = {James L Gould}, title = {Sensory bases of navigation}, journal = {Current Biology}, year = {1998}, volume = {8}, number = {20}, pages = {R731 - R738}, url = {http://www.sciencedirect.com/science/article/B6VRT-4CXDGMN-89/2/4b13e400d89e316f97701aa8a3f2f74d}, doi = {DOI: 10.1016/S0960-9822(98)70461-0} }
Gould2010R431	Gould, J.L.	Magnetoreception [Abstract] [BibTeX] [URL]	2010	Current Biology Vol. 20 (10) , pp. R431 - R435	article	animal navigation
Abstract: Summary Few subjects in animal behavior have more exotic mystery than magnetic-field sensitivity. A force we cannot sense, generated by events no one completely understands, creates field lines that pass through our bodies without any evident effect on us or on them. It is an energy felt as much by migrating lobsters on the sea floor as by ocean-crossing birds thousands of meters overhead, transduced in generally poorly understood ways. Despite the blindness of humans, modern life depends on this invisible, ghostlike field. Aside from lights and heaters, nearly every electrical device we own makes use of electromagnetism, and that same magnetism is essential in generating the power these new-found necessities consume. But for many animals, the reliance is far older and more basic: their life-or-death ability to find their way around in the world depends on correctly interpreting the earth's magnetic field.
BibTeX: @article{Gould2010R431, author = {James L. Gould}, title = {Magnetoreception}, journal = {Current Biology}, year = {2010}, volume = {20}, number = {10}, pages = {R431 - R435}, url = {http://www.sciencedirect.com/science/article/B6VRT-5051CHF-B/2/0ef02401728604a3d005bc4b237dca26}, doi = {DOI: 10.1016/j.cub.2010.03.045} }
HeiZapHeyKutSchMou2010	Hein, C.M.; Zapka, M.; Heyers, D.; Kutzschbauch, S.; Schneider, N.-L. & Mouritsen, H.	Night-migratory garden warblers can orient with their magnetic compass using the left, the right or both eyes [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S227-S233	article	animal navigation
Abstract: Several studies have suggested that the magnetic compass of birds is located only in the right eye. However, here we show that night-migrating garden warblers () are able to perform magnetic compass orientation with both eyes open, with only the left eye open and with only the right eye open. We did not observe any clear lateralization of magnetic compass orientation behaviour in this migratory songbird, and, therefore, it seems that the suggested all-or-none lateralization of magnetic compass orientation towards the right eye only cannot be generalized to all birds, and that the answer to the question of whether magnetic compass orientation in birds is lateralized is probably not as simple as suggested previously.
BibTeX: @article{HeiZapHeyKutSchMou2010, author = {Hein, Christine Maira and Zapka, Manuela and Heyers, Dominik and Kutzschbauch, Sandra and Schneider, Nils-Lasse and Mouritsen, Henrik}, title = {Night-migratory garden warblers can orient with their magnetic compass using the left, the right or both eyes}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S227-S233}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S227.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0376.focus} }
Helbig1991313	Helbig, A.J.	Dusk orientation of migratory european robins, Erithacus rubecula: the role of sun-related directional information [Abstract] [BibTeX] [URL]	1991	Animal Behaviour Vol. 41 (2) , pp. 313 - 322	article	animal navigation
Abstract: Within their multiple cue orientation system some nocturnal migratory bird species make use of sun-related directional information (sun azimuth, polarization patterns) during evening take-off. Whether Palearctic migrants have the capacity to use such cues and their relative importance in the orientation system have been controversial. This paper shows that in the absence of meaningful magnetic information European robins are able to use sun-related cues for dusk orientation. They respond to both slow and fast clock-shifts with shifts of directional choices, indicating the use of a time-compensating compass. Their orientation was changed by using polarizers that altered the e-vector direction of incident polarized light and by depolarization of the natural light from clear evening skies. There is no evidence for any fundamental differences between the orientation systems of Nearctic and Palearctic species with respect to the ability to use celestial light cues at sunset.
BibTeX: @article{Helbig1991313, author = {Andreas J. Helbig}, title = {Dusk orientation of migratory european robins, Erithacus rubecula: the role of sun-related directional information}, journal = {Animal Behaviour}, year = {1991}, volume = {41}, number = {2}, pages = {313 - 322}, url = {http://www.sciencedirect.com/science/article/B6W9W-4JSDR0V-G/2/9cfd8f5ecfa81bbfa94c810a8d0ed35c}, doi = {DOI: 10.1016/S0003-3472(05)80483-X} }
HenMaeHorJosBacBitWebTimSch2008	Henbest, K.B.; Maeda, K.; Hore, P.J.; Joshi, M.; Bacher, A.; Bittl, R.; Weber, S.; Timmel, C.R. & Schleicher, E.	Magnetic-field effect on the photoactivation reaction of Escherichia coli DNA photolyase [Abstract] [BibTeX] [URL]	2008	Proceedings of the National Academy of Sciences Vol. 105 (38) , pp. 14395-14399	article	animal navigation
Abstract: One of the two principal hypotheses put forward to explain the primary magnetoreception event underlying the magnetic compass sense of migratory birds is based on a magnetically sensitive chemical reaction. It has been proposed that a spin-correlated radical pair is produced photochemically in a cryptochrome and that the rates and yields of the subsequent chemical reactions depend on the orientation of the protein in the Earth's magnetic field. The suitability of cryptochrome for this purpose has been argued, in part, by analogy with DNA photolyase, although no effects of applied magnetic fields have yet been reported for any member of the cryptochrome/photolyase family. Here, we demonstrate a magnetic-field effect on the photochemical yield of a flavin–tryptophan radical pair in photolyase. This result provides a proof of principle that photolyases, and most likely by extension also cryptochromes, have the fundamental properties needed to form the basis of a magnetic compass.
BibTeX: @article{HenMaeHorJosBacBitWebTimSch2008, author = {Henbest, Kevin B. and Maeda, Kiminori and Hore, P. J. and Joshi, Monika and Bacher, Adelbert and Bittl, Robert and Weber, Stefan and Timmel, Christiane R. and Schleicher, Erik}, title = {Magnetic-field effect on the photoactivation reaction of Escherichia coli DNA photolyase}, journal = {Proceedings of the National Academy of Sciences}, year = {2008}, volume = {105}, number = {38}, pages = {14395-14399}, url = {http://www.pnas.org/content/105/38/14395.abstract}, doi = {http://dx.doi.org/10.1073/pnas.0803620105} }
HeyManLukGunMou2007	Heyers, D.; Manns, M.; Luksch, H.; Güntürkün, O. & Mouritsen, H.	A Visual Pathway Links Brain Structures Active during Magnetic Compass Orientation in Migratory Birds [Abstract] [BibTeX] [URL]	2007	PLoS ONE Vol. 2 (9) , pp. e937	article	animal navigation
Abstract: The magnetic compass of migratory birds has been suggested to be light-dependent. Retinal cryptochrome-expressing neurons and a forebrain region, “Cluster N”, show high neuronal activity when night-migratory songbirds perform magnetic compass orientation. By combining neuronal tracing with behavioral experiments leading to sensory-driven gene expression of the neuronal activity marker ZENK during magnetic compass orientation, we demonstrate a functional neuronal connection between the retinal neurons and Cluster N via the visual thalamus. Thus, the two areas of the central nervous system being most active during magnetic compass orientation are part of an ascending visual processing stream, the thalamofugal pathway. Furthermore, Cluster N seems to be a specialized part of the visual wulst. These findings strongly support the hypothesis that migratory birds use their visual system to perceive the reference compass direction of the geomagnetic field and that migratory birds “see” the reference compass direction provided by the geomagnetic field.
BibTeX: @article{HeyManLukGunMou2007, author = {Heyers, Dominik and Manns, Martina and Luksch, Harald and Güntürkün, Onur and Mouritsen, Henrik}, title = {A Visual Pathway Links Brain Structures Active during Magnetic Compass Orientation in Migratory Birds}, journal = {PLoS ONE}, publisher = {Public Library of Science}, year = {2007}, volume = {2}, number = {9}, pages = {e937}, url = {http://dx.plos.org/10.1371%2Fjournal.pone.0000937}, doi = {http://dx.doi.org/10.1371/journal.pone.0000937} }
HilRit2010	Hill, E. & Ritz, T.	Can disordered radical pair systems provide a basis for a magnetic compass in animals? [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S265-S271	article	animal navigation
Abstract: A proposed mechanism for magnetic compasses in animals is that systems of radical pairs transduce magnetic field information to the nervous system. One can show that perfectly ordered arrays of radical pairs are sensitive to the direction of the external magnetic field and can thus operate, in principle, as a magnetic compass. Here, we investigate how disorder, inherent in biological cells, affects the ability of radical pair systems to provide directional information. We consider biologically inspired geometrical arrangements of ensembles of radical pairs with increasing amounts of disorder and calculate the effect of changing the direction of the external magnetic field on the rate of chemical signal production by radical pair systems. Using a previously established signal transduction model, we estimate the minimum number of receptors necessary to allow for detection of the change in chemical signal owing to changes in magnetic field direction. We quantify the required increase in the number of receptors to compensate for the signal attenuation through increased disorder. We find radical-pair-based compass systems to be relatively robust against disorder, suggesting several scenarios as to how a compass structure can be realized in a biological cell.
BibTeX: @article{HilRit2010, author = {Hill, Erin and Ritz, Thorsten}, title = {Can disordered radical pair systems provide a basis for a magnetic compass in animals?}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S265-S271}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S265.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0378.focus} }
Hogben2009118	Hogben, H.J.; Efimova, O.; Wagner-Rundell, N.; Timmel, C.R. & Hore, P.	Possible involvement of superoxide and dioxygen with cryptochrome in avian magnetoreception: Origin of Zeeman resonances observed by in vivo EPR spectroscopy [Abstract] [BibTeX] [URL]	2009	Chemical Physics Letters Vol. 480 (1-3) , pp. 118 - 122	article	animal navigation
Abstract: The radical pair model of the avian magnetic compass centres around magnetically sensitive chemical reactions in the retina. Recent studies of migratory birds subjected to oscillating magnetic fields found remarkably sensitive disorientation responses when the frequency of the applied field (~1.3 MHz) matched the EPR condition of a radical with g [approximate] 2 in the Earth's magnetic field (~47 [mu]T). The occurrence of such [`]Zeeman resonances' can be understood if one of the radical pair partners is devoid of hyperfine interactions. Here we examine the possibility that this radical is either superoxide or dioxygen and conclude that neither offers a very credible explanation for these in vivo EPR [`]signals'.
BibTeX: @article{Hogben2009118, author = {Hannah J. Hogben and Olga Efimova and Nicola Wagner-Rundell and Christiane R. Timmel and P.J. Hore}, title = {Possible involvement of superoxide and dioxygen with cryptochrome in avian magnetoreception: Origin of Zeeman resonances observed by in vivo EPR spectroscopy}, journal = {Chemical Physics Letters}, year = {2009}, volume = {480}, number = {1-3}, pages = {118 - 122}, url = {http://www.sciencedirect.com/science/article/B6TFN-4X378G3-5/2/308840a061d2e4bab816ecd4c8e0aea1}, doi = {DOI: 10.1016/j.cplett.2009.08.051} }
IoaGagBin2000	Ioalè, P.; Gagliardo, A. & Bingman, V.P.	Further experiments on the relationship between hippocampus and orientation following phase-shift in homing pigeons [Abstract] [BibTeX] [URL]	2000	Behavioural Brain Research Vol. 108 (2) , pp. 157 - 167	article	animal navigation; clock-shift; columba livia; hippocampus; lesions; overcast; sun compass
Abstract: Following a clock- or phase-shift of the light-dark cycle, hippocampal lesioned pigeons (Columba livia) consistently display a larger deviation in vanishing bearings away from the homeward direction compared to intact birds; an effect never seen in unshifted birds. In Experiment 1, control and hippocampal lesioned pigeons oriented similarly after being held 1 week under artificial lighting in the absence of a phase-shift. Housing under artificial light by itself does not result in between group orientation differences. In Experiment 2, control and hippocampal lesioned pigeons oriented equally well under overcast conditions, indicating that both groups had a functional magnetic compass. The between group difference in orientation following phase-shift does not appear to be a consequence of control birds being able to use both the sun and earth's magnetic field for orientation and the hippocampal lesioned pigeons only being able to use the sun. In Experiment 3, lengthening the time held under 6-h clock-shift from 1 to 2 weeks had no effect on the magnitude of the difference in orientation, but fast shifting produced clearer effects than slow shifting. Taken together, the data suggest that hippocampal lesions alter how a pigeon responds to a rapidly changing light-dark cycle, particularly following a fast-shift manipulation, suggesting an as yet unspecified relationship between the avian hippocampus and the circadian rhythm(s) that regulate sun compass orientation.
BibTeX: @article{IoaGagBin2000, author = {Ioalè, Paolo and Gagliardo, Anna and Bingman, Verner P}, title = {Further experiments on the relationship between hippocampus and orientation following phase-shift in homing pigeons}, journal = {Behavioural Brain Research}, year = {2000}, volume = {108}, number = {2}, pages = {157 - 167}, url = {http://www.sciencedirect.com/science/article/B6SYP-3YHG0HG-5/2/5f221598af9e471027f5de52f61815c3}, doi = {DOI: 10.1016/S0166-4328(99)00144-8} }
Irwin2004117	Irwin, W.P.; Horner, A.J. & Lohmann, K.J.	Magnetic field distortions produced by protective cages around sea turtle nests: unintended consequences for orientation and navigation? [Abstract] [BibTeX] [URL]	2004	Biological Conservation Vol. 118 (1) , pp. 117 - 120	article	animal navigation; magnetic orientation; navigation; magnetoreception; sea turtle conservation
Abstract: The Earth's magnetic field plays an important role in the orientation and navigation of sea turtles. Galvanized steel wire cages are often placed over turtle nests to protect them from predators, but the material typically used in cages has a high magnetic permeability and might therefore affect the nearby field. Here we report magnetometer measurements indicating that standard nest cages do indeed significantly alter the local magnetic field in the area where eggs develop. The mean change in total intensity was 26% at a level corresponding to the top of the egg chamber and 5% at a level corresponding to the bottom. Similarly, the mean change in field inclination was 20% for the top level and 4% for the bottom. In principle, the altered magnetic environment might affect subsequent magnetic orientation and navigation behavior in several ways, although whether turtles that develop in an unnatural magnetic field actually suffer navigational impairment has not yet been studied. Constructing protective cages out of magnetically inert materials provides a way to deter predators without risking unintended behavioral consequences of distorting the ambient field.
BibTeX: @article{Irwin2004117, author = {William P. Irwin and Amy J. Horner and Kenneth J. Lohmann}, title = {Magnetic field distortions produced by protective cages around sea turtle nests: unintended consequences for orientation and navigation?}, journal = {Biological Conservation}, year = {2004}, volume = {118}, number = {1}, pages = {117 - 120}, url = {http://www.sciencedirect.com/science/article/B6V5X-4B0X5WV-1/2/ee0e3a8555f179ad14377284f3d64158}, doi = {DOI: 10.1016/j.biocon.2003.07.014} }
Jensen2010129	Jensen, K.K.	Light-dependent orientation responses in animals can be explained by a model of compass cue integration [Abstract] [BibTeX] [URL]	2010	Journal of Theoretical Biology Vol. 262 (1) , pp. 129 - 141	article	magnetoreception; animal navigation
Abstract: The magnetic compass sense of animals is currently thought to be based on light-dependent processes like the proposed radical pair mechanism. In accordance, many animals show orientation responses that depend on light. However, the orientation responses depend on the wavelength and irradiance of monochromatic light in rather complex ways that cannot be explained directly by the radical pair mechanism. Here, a radically different model is presented that can explain a vast majority of the complex observed light-dependent responses. The model put forward an integration process consisting of simple lateral inhibition between a normal functioning, light-independent magnetic compass (e.g. magnetite based) and a vision based skylight color gradient compass that misperceives compass cues in monochromatic light. Integration of the misperceived color compass cue and the normal magnetic compass not only explains most of the categorically different light-dependent orientation responses, but also shows a surprisingly good fit to how well the animals are oriented (r-values) under light of different wavelength and irradiance. The model parsimoniously suggests the existence of a single magnetic sense in birds (probably based on magnetic crystals).
BibTeX: @article{Jensen2010129, author = {Kenneth Kragh Jensen}, title = {Light-dependent orientation responses in animals can be explained by a model of compass cue integration}, journal = {Journal of Theoretical Biology}, year = {2010}, volume = {262}, number = {1}, pages = {129 - 141}, url = {http://www.sciencedirect.com/science/article/B6WMD-4X85FGR-1/2/4b8d895dd16b18470e8694b0d165847a}, doi = {DOI: 10.1016/j.jtbi.2009.09.005} }
JinSheWeaZylDeVRep1999	Jin, X.; Shearman, L.P.; Weaver, D.R.; Zylka, M.J.; De Vries, G.J. & Reppert, S.M.	A Molecular Mechanism Regulating Rhythmic Output from the Suprachiasmatic Circadian Clock [Abstract] [BibTeX] [URL]	1999	Cell Vol. 96 (1) , pp. 57 - 68	article	animal navigation
Abstract: We examined the transcriptional regulation of the clock-controlled arginine vasopressin gene in the suprachiasmatic nuclei (SCN). A core clock mechanism in mouse SCN appears to involve a transcriptional feedback loop in which CLOCK and BMAL1 are positive regulators and three mPeriod (mPer) genes are involved in negative feedback. We show that the RNA rhythm of each mPer gene is severely blunted in Clock/Clock mice. The vasopressin RNA rhythm is abolished in the SCN of Clock/Clock animals, leading to markedly decreased peptide levels. Luciferase reporter gene assays show that CLOCK-BMAL1 heterodimers act through an E box enhancer in the vasopressin gene to activate transcription; this activation can be inhibited by the mPER and mTIM proteins. These data indicate that the transcriptional machinery of the core clockwork directly regulates a clock-controlled output rhythm.
BibTeX: @article{JinSheWeaZylDeVRep1999, author = {Jin, Xiaowei and Shearman, Lauren P and Weaver, David R and Zylka, Mark J and De Vries, Geert J and Reppert, Steven M}, title = {A Molecular Mechanism Regulating Rhythmic Output from the Suprachiasmatic Circadian Clock}, journal = {Cell}, year = {1999}, volume = {96}, number = {1}, pages = {57 - 68}, url = {http://www.sciencedirect.com/science/article/B6WSN-41GP6VJ-8/2/49b5723c7605d0005e362d9b8d6a291f}, doi = {DOI: 10.1016/S0092-8674(00)80959-9} }
Kirschvink1981193	Kirschvink, J.L.	The horizontal magnetic dance of the honeybee is compatible with a single-domain ferromagnetic magnetoreceptor [Abstract] [BibTeX] [URL]	1981	Biosystems Vol. 14 (2) , pp. 193 - 203	article	animal navigation
Abstract: Although honeybees are able to sense the geomagnetic field, very little is known about the method in which they are able to detect it. The recent discovery of biochemically precipitated magnetite (Fe3O4) in bees, however, suggests the possibility that they might use a simple compass organelle for magnetoreception. If so, their orientation accuracy ought to be related to the accuracy of the compass, e.g. it should be poor in weak background fields and enhanced in strong fields. When dancing to the magnetic directions on a horizontal honeycomb, bees clearly show this type of alignment behavior. A least-squares fit between the expected alignment of a compass and this horizontal dance data is consistent with this hypothesis, and implies that the receptors have magnetic moments of 5 × 10-13 emu, or magnetite volumes near 10-15 cm3. Additional considerations suggests that these crystals are slightly sub-spherical and single-domain in size, held symmetrically in their receptors, and have a magnetic orientation energy of approximately to 6 kT in the geomagneticfield. A model of a magnetite-based magnetoreceptor consistent with these constraints is discussed.
BibTeX: @article{Kirschvink1981193, author = {Joseph L. Kirschvink}, title = {The horizontal magnetic dance of the honeybee is compatible with a single-domain ferromagnetic magnetoreceptor}, journal = {Biosystems}, year = {1981}, volume = {14}, number = {2}, pages = {193 - 203}, url = {http://www.sciencedirect.com/science/article/B6T2K-49NY280-6T/2/2aadbaf4e8758b2951d3bfeaf812eb57}, doi = {DOI: 10.1016/0303-2647(81)90068-X} }
Kirschvink2001462	Kirschvink, J.L.; Walker, M.M. & Diebel, C.E.	Magnetite-based magnetoreception [Abstract] [BibTeX] [URL]	2001	Current Opinion in Neurobiology Vol. 11 (4) , pp. 462 - 467	article	animal navigation; magnetoreception; magnetite; elasmobranchs; sensory systems
Abstract: Orientation, navigation, and homing are critical traits expressed by organisms ranging from bacteria through higher vertebrates. Sensory systems that aid such behavior have provided key selective advantages to these groups over the past 4 billion years, and are highly evolved; magnetoreception is no exception. Across many species and groups of organisms, compelling evidence exists that the physical basis of this response is tiny crystals of single-domain magnetite (Fe3O4). It is the opinion of the authors that all magnetic field sensitivity in living organisms, including elasmobranch fishes, is the result of a highly evolved, finely-tuned sensory system based on single-domain, ferromagnetic crystals.
BibTeX: @article{Kirschvink2001462, author = {Joseph L. Kirschvink and Michael M. Walker and Carol E. Diebel}, title = {Magnetite-based magnetoreception}, journal = {Current Opinion in Neurobiology}, year = {2001}, volume = {11}, number = {4}, pages = {462 - 467}, url = {http://www.sciencedirect.com/science/article/B6VS3-43P2CVV-D/2/d1eef4f22e546f378ca97bf0e7347c41}, doi = {DOI: 10.1016/S0959-4388(00)00235-X} }
KirWinWal2010	Kirschvink, J.L.; Winklhofer, M. & Walker, M.M.	Biophysics of magnetic orientation: strengthening the interface between theory and experimental design [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S179-S191	article	animal navigation
Abstract: The first demonstrations of magnetic effects on the behaviour of migratory birds and homing pigeons in laboratory and field experiments, respectively, provided evidence for the longstanding hypothesis that animals such as birds that migrate and home over long distances would benefit from possession of a magnetic sense. Subsequent identification of at least two plausible biophysical mechanisms for magnetoreception in animals, one based on biogenic magnetite and another on radical-pair biochemical reactions, led to major efforts over recent decades to test predictions of the two models, as well as efforts to understand the ultrastructure and function of the possible magnetoreceptor cells. Unfortunately, progress in understanding the magnetic sense has been challenged by: (i) the availability of a relatively small number of techniques for analysing behavioural responses to magnetic fields by animals; (ii) difficulty in achieving reproducible results using the techniques; and (iii) difficulty in development and implementation of new techniques that might bring greater experimental power. As a consequence, laboratory and field techniques used to study the magnetic sense today remain substantially unchanged, despite the huge developments in technology and instrumentation since the techniques were developed in the 1950s. New methods developed for behavioural study of the magnetic sense over the last 30 years include the use of laboratory conditioning techniques and tracking devices based on transmission of radio signals to and from satellites. Here we consider methodological developments in the study of the magnetic sense and present suggestions for increasing the reproducibility and ease of interpretation of experimental studies. We recommend that future experiments invest more effort in automating control of experiments and data capture, control of stimulation and full blinding of experiments in the rare cases where automation is impossible. We also propose new experiments to confirm whether or not animals can detect magnetic fields using the radical-pair effect together with an alternate hypothesis that may explain the dependence on light of responses by animals to magnetic field stimuli.
BibTeX: @article{KirWinWal2010, author = {Kirschvink, Joseph L. and Winklhofer, Michael and Walker, Michael M.}, title = {Biophysics of magnetic orientation: strengthening the interface between theory and experimental design}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S179-S191}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S179.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0491.focus} }
Klotz2009592	Klotz, J. & Jander, R. Resh, V.H. & Cardé, R.T. (Hrsg.)	Magnetic Sense [BibTeX] [URL]	2009	Encyclopedia of Insects (Second Edition) , pp. 592 - 594	incollection	animal navigation
BibTeX: @incollection{Klotz2009592, author = {John Klotz and Rudolf Jander}, title = {Magnetic Sense}, booktitle = {Encyclopedia of Insects (Second Edition)}, publisher = {Academic Press}, year = {2009}, pages = {592 - 594}, edition = {Second Edition}, url = {http://www.sciencedirect.com/science/article/B8N7N-4XMDMBN-5X/2/f9048734bf3174134f06fb0a2698b60a}, doi = {DOI: 10.1016/B978-0-12-374144-8.00163-6} }
KumZylSriSheWeaJinMayHasRep1999	Kume, K.; Zylka, M.J.; Sriram, S.; Shearman, L.P.; Weaver, D.R.; Jin, X.; Maywood, E.S.; Hastings, M.H. & Reppert, S.M.	mCRY1 and mCRY2 Are Essential Components of the Negative Limb of the Circadian Clock Feedback Loop [Abstract] [BibTeX] [URL]	1999	Cell Vol. 98 (2) , pp. 193 - 205	article	animal navigation
Abstract: We determined that two mouse cryptochrome genes, mCry1 and mCry2, act in the negative limb of the clock feedback loop. In cell lines, mPER proteins (alone or in combination) have modest effects on their cellular location and ability to inhibit CLOCK:BMAL1-mediated transcription. This suggested cryptochrome involvement in the negative limb of the feedback loop. Indeed, mCry1 and mCry2 RNA levels are reduced in the central and peripheral clocks of Clock/Clock mutant mice. mCRY1 and mCRY2 are nuclear proteins that interact with each of the mPER proteins, translocate each mPER protein from cytoplasm to nucleus, and are rhythmically expressed in the suprachiasmatic circadian clock. Luciferase reporter gene assays show that mCRY1 or mCRY2 alone abrogates CLOCK:BMAL1-E box-mediated transcription. The mPER and mCRY proteins appear to inhibit the transcriptional complex differentially.
BibTeX: @article{KumZylSriSheWeaJinMayHasRep1999, author = {Kume, Kazuhiko and Zylka, Mark J and Sriram, Sathyanarayanan and Shearman, Lauren P and Weaver, David R and Jin, Xiaowei and Maywood , Elizabeth S and Hastings, Michael H and Reppert, Steven M}, title = {mCRY1 and mCRY2 Are Essential Components of the Negative Limb of the Circadian Clock Feedback Loop}, journal = {Cell}, year = {1999}, volume = {98}, number = {2}, pages = {193 - 205}, url = {http://www.sciencedirect.com/science/article/B6WSN-4194PJT-9/2/f36d26012695b5c4ebc574c5bd2971ad}, doi = {DOI: 10.1016/S0092-8674(00)81014-4} }
LauWagRodGreHor2010	Lau, J.C.S.; Wagner-Rundell, N.; Rodgers, C.T.; Green, N.J.B. & Hore, P.J.	Effects of disorder and motion in a radical pair magnetoreceptor [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S257-S264	article	animal navigation
Abstract: A critical requirement in the proposed chemical model of the avian magnetic compass is that the molecules that play host to the magnetically sensitive radical pair intermediates must be immobilized and rotationally ordered within receptor cells. Rotational disorder would cause the anisotropic responses of differently oriented radical pairs within the same cell to interfere destructively, while rapid molecular rotation would tend to average the crucial anisotropic magnetic interactions and induce electron spin relaxation, reducing the sensitivity to the direction of the geomagnetic field. So far, experimental studies have been able to shed little light on the required degree of ordering and immobilization. To address this question, computer simulations have been performed on a collection of radical pairs undergoing restricted rigid-body rotation, coherent anisotropic spin evolution, electron spin relaxation and spin-selective recombination reactions. It is shown that the ordering and motional constraints necessary for efficient magnetoreception can be simultaneously satisfied if the radical pairs are uniaxially ordered with a moderate order parameter and if their motional correlation time is longer than about a quarter of their lifetime.
BibTeX: @article{LauWagRodGreHor2010, author = {Lau, Jason C. S. and Wagner-Rundell, Nicola and Rodgers, Christopher T. and Green, Nicholas J. B. and Hore, P. J.}, title = {Effects of disorder and motion in a radical pair magnetoreceptor}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S257-S264}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S257.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0399.focus} }
LeeEtcCagLouRep2001	Lee, C.; Etchegaray, J.-P.; Cagampang, F.R.A.; Loudon, A.S.I. & Reppert, S.M.	Posttranslational Mechanisms Regulate the Mammalian Circadian Clock [Abstract] [BibTeX] [URL]	2001	Cell Vol. 107 (7) , pp. 855 - 867	article	animal navigation
Abstract: We have examined posttranslational regulation of clock proteins in mouse liver in vivo. The mouse PERIOD proteins (mPER1 and mPER2), CLOCK, and BMAL1 undergo robust circadian changes in phosphorylation. These proteins, the cryptochromes (mCRY1 and mCRY2), and casein kinase I epsilon (CKI[epsilon]) form multimeric complexes that are bound to DNA during negative transcriptional feedback. CLOCK:BMAL1 heterodimers remain bound to DNA over the circadian cycle. The temporal increase in mPER abundance controls the negative feedback interactions. Analysis of clock proteins in mCRY-deficient mice shows that the mCRYs are necessary for stabilizing phosphorylated mPER2 and for the nuclear accumulation of mPER1, mPER2, and CKI[epsilon]. We also provide in vivo evidence that casein kinase I delta is a second clock relevant kinase.
BibTeX: @article{LeeEtcCagLouRep2001, author = {Lee, Choogon and Etchegaray, Jean-Pierre and Cagampang, Felino R A and Loudon, Andrew S I and Reppert, Steven M}, title = {Posttranslational Mechanisms Regulate the Mammalian Circadian Clock}, journal = {Cell}, year = {2001}, volume = {107}, number = {7}, pages = {855 - 867}, url = {http://www.sciencedirect.com/science/article/B6WSN-44VDTRF-7/2/5525e6a459e3bf2badc0008ba9536742}, doi = {DOI: 10.1016/S0092-8674(01)00610-9} }
Levine1995535	Levine, R.L.; Dooley, J.K. & Bluni, T.D.	Magnetic field effects on spatial discrimination and melatonin levels in mice [Abstract] [BibTeX] [URL]	1995	Physiology & Behavior Vol. 58 (3) , pp. 535 - 537	article	animal navigation; magnetic resonance imaging; magnetic sense; spatial discrimination learning; melatonin
Abstract: Previous research has demonstrated a decrement in spatial discrimination learning following exposure to a .30 Tesla magnetic field. It has been suggested that those findings might be the result of an interaction between the magnetic field and physiological ferromagnetic material (magnetite). In the present study, mice were exposed for 100 min to a 2.0 Tesla field and both their left-right discrimination learning ability and serum melatonin levels were compared with a control group. Results indicated a significant interference with spatial discrimination learning following exposure, but no significant differences in serum melatonin levels. These findings appeared to rule out magnetically induced melatonin fatigue as an explanation of the decrement in spatial learning, as opposed to other possibilities such as magnetic effects on brain magnetite. However, additional controls are suggested for future research.
BibTeX: @article{Levine1995535, author = {Reed L. Levine and James K. Dooley and Thomas D. Bluni}, title = {Magnetic field effects on spatial discrimination and melatonin levels in mice}, journal = {Physiology & Behavior}, year = {1995}, volume = {58}, number = {3}, pages = {535 - 537}, url = {http://www.sciencedirect.com/science/article/B6T0P-3YYTMB4-4W/2/b5ac27b51ec30af7a99977b21b352c98}, doi = {DOI: 10.1016/0031-9384(95)00094-Y} }
LieMaeHenSchSimTimHorMou2007	Liedvogel, M.; Maeda, K.; Henbest, K.; Schleicher, E.; Simon, T.; Timmel, C.R.; Hore, P.J. & Mouritsen, H.	Chemical Magnetoreception: Bird Cryptochrome 1a Is Excited by Blue Light and Forms Long-Lived Radical-Pairs [Abstract] [BibTeX]	2007	PLoS ONE Vol. 2 (10) , pp. e1106	article	animal navigation
Abstract: Cryptochromes (Cry) have been suggested to form the basis of light-dependent magnetic compass orientation in birds. However, to function as magnetic compass sensors, the cryptochromes of migratory birds must possess a number of key biophysical characteristics. Most importantly, absorption of blue light must produce radical pairs with lifetimes longer than about a microsecond. Cryptochrome 1a (gwCry1a) and the photolyase-homology-region of Cry1 (gwCry1-PHR) from the migratory garden warbler were recombinantly expressed and purified from a baculovirus/Sf9 cell expression system. Transient absorption measurements show that these flavoproteins are indeed excited by light in the blue spectral range leading to the formation of radicals with millisecond lifetimes. These biophysical characteristics suggest that gwCry1a is ideally suited as a primary light-mediated, radical-pair-based magnetic compass receptor.
BibTeX: @article{LieMaeHenSchSimTimHorMou2007, author = {Liedvogel, Miriam and Maeda, Kiminori and Henbest, Kevin and Schleicher, Erik and Simon, Thomas and Timmel, Christiane R and Hore, P J and Mouritsen, Henrik}, title = {Chemical Magnetoreception: Bird Cryptochrome 1a Is Excited by Blue Light and Forms Long-Lived Radical-Pairs}, journal = {PLoS ONE}, year = {2007}, volume = {2}, number = {10}, pages = {e1106}, doi = {http://dx.doi.org/10.1371/journal.pone.0001106} }
LieMou2010	Liedvogel, M. & Mouritsen, H.	Cryptochromes - a potential magnetoreceptor: what do we know and what do we want to know? [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S147-S162	article	animal navigation
Abstract: Cryptochromes have been suggested to be the primary magnetoreceptor molecules underlying light-dependent magnetic compass detection in migratory birds. Here we review and evaluate (i) what is known about these candidate magnetoreceptor molecules, (ii) what characteristics cryptochrome molecules must fulfil to possibly underlie light-dependent, radical pair based magnetoreception, (iii) what evidence supports the involvement of cryptochromes in magnetoreception, and (iv) what needs to be addressed in future research. The review focuses primarily on our knowledge of cryptochromes in the context of magnetoreception.
BibTeX: @article{LieMou2010, author = {Liedvogel, Miriam and Mouritsen, Henrik}, title = {Cryptochromes -- a potential magnetoreceptor: what do we know and what do we want to know?}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S147-S162}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S147.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0411.focus} }
Lohmann2000S63	Lohmann, K.J. & Lohmann, C.M.	Orientation mechanisms of hatchling loggerhead sea turtles [BibTeX] [URL]	2000	Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 126 (Supplement 1) , pp. S63 - S63	article	animal navigation
BibTeX: @article{Lohmann2000S63, author = {Kenneth J Lohmann and Catherine M.F Lohmann}, title = {Orientation mechanisms of hatchling loggerhead sea turtles}, journal = {Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology}, year = {2000}, volume = {126}, number = {Supplement 1}, pages = {S63 - S63}, url = {http://www.sciencedirect.com/science/article/B6T2R-455P78J-4D/2/641083bb2d9415fb8760e962c972b80e}, doi = {DOI: 10.1016/S0305-0491(00)80124-8} }
Lohmann2007R102	Lohmann, K.J.	Sea Turtles: Navigating with Magnetism [Abstract] [BibTeX] [URL]	2007	Current Biology Vol. 17 (3) , pp. R102 - R104	article	animal navigation
Abstract: Young sea turtles use the Earth's magnetic field as a source of navigational information during their epic transoceanic migrations and while homing. A new study using satellite telemetry has now demonstrated for the first time that adult turtles also navigate using the Earth's magnetic field.
BibTeX: @article{Lohmann2007R102, author = {Kenneth J. Lohmann}, title = {Sea Turtles: Navigating with Magnetism}, journal = {Current Biology}, year = {2007}, volume = {17}, number = {3}, pages = {R102 - R104}, url = {http://www.sciencedirect.com/science/article/B6VRT-4N0932Y-K/2/41b04626e17bf3925cf54213af4320ce}, doi = {DOI: 10.1016/j.cub.2007.01.023} }
Lovetal2009	Lovett, J.E.; Hoffmann, M.; Cnossen, A.; Shutter, A.T.J.; Hogben, H.J.; , J.E.W.; , S.I.P.; Kay, C.W.M.; Timmel, C.R. & Anderson, H.L.	Probing Flexibility in Porphyrin-Based Molecular Wires Using Double Electron Electron Resonance [Abstract] [BibTeX] [URL] [NOTE]	2009	Journal of the American Chemical Society Vol. 131 (38) , pp. 13852-13859	article	darpa
Abstract: A series of butadiyne-linked zinc porphyrin oligomers, with one, two, three, and four porphyrin units and lengths of up to $75, have been spin-labeled at both ends with stable nitroxide TEMPO radicals. The pulsed EPR technique of double electron electron resonance (DEER) was used to probe the distribution of intramolecular end-to-end distances, under a range of conditions. DEER measurements were carried out at 50 K in two types of dilute solution glasses: deutero-toluene (with 10% deutero-pyridine) and deutero-o-terphenyl (with 5% 4-benzyl pyridine). The complexes of the porphyrin oligomers with monodentate ligands (pyridine or 4-benzyl pyridine) principally adopt linear conformations. Nonlinear conformations are less populated in the lower glass-transition temperature solvent. When the oligomers bind star-shaped multidentate ligands, they are forced to bend into nonlinear geometries, and the experimental end-to-end distances for these complexes match those from molecular mechanics calculations. Our results show that porphyrin-based molecular wires are shape-persistent, and yet that their shapes can deformed by binding to multivalent ligands. Self-assembled ladder-shaped 2:2 complexes were also investigated to illustrate the scope of DEER measurements for providing structural information on synthetic noncovalent nanostructures.
BibTeX: @article{Lovetal2009, author = {Lovett, Janet E. and Hoffmann, Markus and Cnossen, Arjen and Shutter, Alexander T. J. and Hogben, Hannah J. and , John E. Warren and , Sofia I. Pascu and Kay, Christopher W. M. and Timmel, Christiane R. and Anderson, Harry L.}, title = {Probing Flexibility in Porphyrin-Based Molecular Wires Using Double Electron Electron Resonance}, journal = {Journal of the American Chemical Society}, year = {2009}, volume = {131}, number = {38}, pages = {13852-13859}, note = {PMID: 19736940}, url = {http://pubs.acs.org/doi/abs/10.1021/ja905796z}, doi = {http://dx.doi.org/10.1021/ja905796z} }
MaeHenCinKupRodLidGusTimHor2008	Maeda, K.; Henbest, K.B.; Cintolesi, F.; Kuprov, I.; Rodgers, C.T.; Liddell, Paul A.and Gust, D.; Timmel, C.R. & Hore, P.J.	Chemical compass model of avian magnetoreception [BibTeX] [URL] [NOTE]	2008	Nature Vol. 453 (7193) , pp. 387-390	article	animal navigation
BibTeX: @article{MaeHenCinKupRodLidGusTimHor2008, author = {Maeda, Kiminori and Henbest, Kevin B. and Cintolesi, Filippo and Kuprov, Ilya and Rodgers, Christopher T. and Liddell, Paul A.and Gust, Devens and Timmel, Christiane R. and Hore, P. J.}, title = {Chemical compass model of avian magnetoreception}, journal = {Nature}, year = {2008}, volume = {453}, number = {7193}, pages = {387-390}, note = {It has long been known that animals of many kinds can orient themselves with respect to the Earth's magnetic field. The question is: how do they do it? There is evidence in some species that grains of magnetite are used as detectors. In others, though, the magnetic orientation seems to involve the eye, possibly via the magnetic modulation of a photochemical reaction. But it is not known whether such modulation is even possible, for any chemical system, given that the Earth's magnetic field is relatively weak. Now Maeda et al. present evidence that weak magnetic fields can modulate photochemical reactions in the expected manner. The model system is entirely artificial, and the temperature rather low — but the point has been made, and researchers can now seek with renewed confidence the mechanisms used in the real world for orientation and migration.}, url = {http://www.nature.com/nature/journal/v453/n7193/suppinfo/nature06834_S1.html}, doi = {http://dx.doi.org/10.1038/nature06834} }
Mar2010a	Martinez, T.J.	Physical chemistry: Seaming is believing [Abstract] [BibTeX] [URL] [NOTE]	2010	Nature Vol. 467 (7314) , pp. 412-413	article	animal navigation
Abstract: Do excited molecules relaxing to their ground state pass through a 'seam' connecting the potential energy profiles of the states? Experimental data suggest the answer to this long-standing question is 'yes'.
BibTeX: @article{Mar2010a, author = {Martinez, Todd J.}, title = {Physical chemistry: Seaming is believing}, journal = {Nature}, year = {2010}, volume = {467}, number = {7314}, pages = {412-413}, note = {News and Views on Polli, D. et al. Nature 467, 440–443 (2010).}, url = {http://dx.doi.org/10.1038/467412a} }
MartínezBanaclocha2010254	Banaclocha, M.A.M.; Bókkon, I. & Banaclocha, H.M.	Long-term memory in brain magnetite [Abstract] [BibTeX] [URL]	2010	Medical Hypotheses Vol. 74 (2) , pp. 254 - 257	article	animal navigation
Abstract: Summary Despite theoretical and experimental efforts to model neuronal networks, the origin of cerebral cognitive functions and memory formation are still unknown. Recently, we have proposed that in addition to chemical and electrical signals, the cellular components of the neocortex (especially neurons and astrocytes) may communicate with each other through magnetic signals generated by themselves. This magnetic communication would be the ground of short-term memory. In the present paper, we propose that brain magnetite may be a component of the mechanisms, conserved during evolution, to detect and transduce magnetic fields generated inside the cerebral neocortex. Specifically, we propose a possible role for magnetite nanoparticles, distributed through neuronal and astroglial membranes, in perception, transduction and storage of information that arrives to the neocortex.
BibTeX: @article{MartínezBanaclocha2010254, author = {Marcos Arturo Martínez Banaclocha and István Bókkon and Helios Martínez Banaclocha}, title = {Long-term memory in brain magnetite}, journal = {Medical Hypotheses}, year = {2010}, volume = {74}, number = {2}, pages = {254 - 257}, url = {http://www.sciencedirect.com/science/article/B6WN2-4XDFDRC-3/2/0a16745f27092548d61d1878cf01b54f}, doi = {DOI: 10.1016/j.mehy.2009.09.024} }
MerGegRep2009	Merlin, C.; Gegear, R.J. & Reppert, S.M.	Antennal Circadian Clocks Coordinate Sun Compass Orientation in Migratory Monarch Butterflies [Abstract] [BibTeX] [URL]	2009	Science Vol. 325 (5948) , pp. 1700-1704	article	animal navigation
Abstract: During their fall migration, Eastern North American monarch butterflies (Danaus plexippus) use a time-compensated Sun compass to aid navigation to their overwintering grounds in central Mexico. It has been assumed that the circadian clock that provides time compensation resides in the brain, although this assumption has never been examined directly. Here, we show that the antennae are necessary for proper time-compensated Sun compass orientation in migratory monarch butterflies, that antennal clocks exist in monarchs, and that they likely provide the primary timing mechanism for Sun compass orientation. These unexpected findings pose a novel function for the antennae and open a new line of investigation into clock-compass connections that may extend widely to other insects that use this orientation mechanism.
BibTeX: @article{MerGegRep2009, author = {Merlin, Christine and Gegear, Robert J. and Reppert, Steven M.}, title = {Antennal Circadian Clocks Coordinate Sun Compass Orientation in Migratory Monarch Butterflies}, journal = {Science}, year = {2009}, volume = {325}, number = {5948}, pages = {1700-1704}, url = {http://www.sciencemag.org/cgi/content/abstract/325/5948/1700}, doi = {http://dx.doi.org/10.1126/science.1176221} }
Moore1985657	Moore, F.R.	Integration of environmental stimuli in the migratory orientation of the savannah sparrow (Passerculus sandwichensis) [Abstract] [BibTeX] [URL]	1985	Animal Behaviour Vol. 33 (2) , pp. 657 - 663	article	animal navigation
Abstract: Two [`]cue-conflict' experiments were designed to evaluate the role of (1) solar cues at sunset and stars, and (2) solar cues at sunset and geomagnetic stimuli, in the migratory orientation of the savannah sparrow (Passerculus sandwichensis). A sunset and stars experiment exposed birds in the experimental group to a mirror-reflected sunset followed by an unmanipulated view of stars. Experimental birds shifted their migratory activity in accordance with the setting sun despite exposure to a normal night sky. The sunset and geomagnetism experiment exposed birds in the experimental group to a simultaneous shift in both the position of sunset and the earth's magnetic field. Again experimentals shifted their activity in accordance with the setting sun rather than the artificially shifted magnetic field. Savannah sparrows probaly use stars as celestial landmarks to maintain a preferred direction and do not reorient their activity when exposed to an alternative cue once a direction is established. Moreover, savannah sparrows with experience of migration do not require geomagnetic information in order to use the solar cues available at sunset to select a migratory direction.
BibTeX: @article{Moore1985657, author = {Frank R. Moore}, title = {Integration of environmental stimuli in the migratory orientation of the savannah sparrow (Passerculus sandwichensis)}, journal = {Animal Behaviour}, year = {1985}, volume = {33}, number = {2}, pages = {657 - 663}, url = {http://www.sciencedirect.com/science/article/B6W9W-4JR5H39-13/2/035236723cd0728adcd6652c3c21d87a}, doi = {DOI: 10.1016/S0003-3472(85)80089-0} }
Mouritsen2001713	Mouritsen, H.	Navigation in birds and other animals [Abstract] [BibTeX] [URL]	2001	Image and Vision Computing Vol. 19 (11) , pp. 713 - 731	article	animal navigation; orientation; bird migration; mobile robots
Abstract: This paper describes how different animals cope with the challenges of orienting in very diverse environments. First, a broad general overview is given. Then, as a case story, bird migration is treated in more detail. The aim of the paper is to encourage designers of mobile robots to consider the natural solutions already used by animals when developing navigation systems for their robots.
BibTeX: @article{Mouritsen2001713, author = {H. Mouritsen}, title = {Navigation in birds and other animals}, journal = {Image and Vision Computing}, year = {2001}, volume = {19}, number = {11}, pages = {713 - 731}, url = {http://www.sciencedirect.com/science/article/B6V09-43TG2YC-2/2/e517dbbeddf3dff82bdbeadda7cab02f}, doi = {DOI: 10.1016/S0262-8856(00)00110-4} }
Mouritsen20041946	Mouritsen, H.; Feenders, G.; Liedvogel, M. & Kropp, W.	Migratory Birds Use Head Scans to Detect the Direction of the Earth's Magnetic Field [Abstract] [BibTeX] [URL]	2004	Current Biology Vol. 14 (21) , pp. 1946 - 1949	article	animal navigation
Abstract: Night-migratory songbirds are known to use a magnetic compass [1], [2] and [3], but how do they detect the reference direction provided by the geomagnetic field, and where is the sensory organ located? The most prominent characteristic of geomagnetic sensory input, whether based on visual patterns [4], [5], [6] and [7] or magnetite-mediated forces [8] and [9], is the predicted symmetry around the north-south or east-west magnetic axis. Here, we show that caged migratory garden warblers perform head-scanning behavior well suited to detect this magnetic symmetry plane. In the natural geomagnetic field, birds move toward their migratory direction after head scanning. In a zero-magnetic field [10], where no symmetry plane exists, the birds almost triple their head-scanning frequency, and the movement direction after a head scan becomes random. Thus, the magnetic sensory organ is located in the bird's head, and head scans are used to locate the reference direction provided by the geomagnetic field.
BibTeX: @article{Mouritsen20041946, author = {Henrik Mouritsen and Gesa Feenders and Miriam Liedvogel and Wiebke Kropp}, title = {Migratory Birds Use Head Scans to Detect the Direction of the Earth's Magnetic Field}, journal = {Current Biology}, year = {2004}, volume = {14}, number = {21}, pages = {1946 - 1949}, url = {http://www.sciencedirect.com/science/article/B6VRT-4DRMNRG-W/2/74624ac2cdc226faa0ffeea8df7aec79}, doi = {DOI: 10.1016/j.cub.2004.10.025} }
Mouritsen2005406	Mouritsen, H. & Ritz, T.	Magnetoreception and its use in bird navigation [Abstract] [BibTeX] [URL] [NOTE]	2005	Current Opinion in Neurobiology Vol. 15 (4) , pp. 406 - 414	article	animal navigation
Abstract: Recent advances have brought new insight into the physiological mechanisms that enable birds and other animals to use magnetic fields for orientation. Many birds seem to have two magnetodetection senses, one based on magnetite near the beak and one based on light-dependent radical-pair processes in the bird's eye(s). Among the most exciting recent results are: first, behavioural responses of birds experiencing oscillating magnetic fields. Second, the occurrence of putative magnetosensory molecules, the cryptochromes, in the eyes of migratory birds. Third, detection of a brain area that integrates specialised visual input at night in night-migratory songbirds. Fourth, a putative magnetosensory cluster of magnetite in the upper beak. These and other recent findings have important implications for magnetoreception; however, many crucial open questions remain.
BibTeX: @article{Mouritsen2005406, author = {Henrik Mouritsen and Thorsten Ritz}, title = {Magnetoreception and its use in bird navigation}, journal = {Current Opinion in Neurobiology}, year = {2005}, volume = {15}, number = {4}, pages = {406 - 414}, note = {Sensory systems}, url = {http://www.sciencedirect.com/science/article/B6VS3-4GKW734-3/2/3374bc4a0473968588dd08fe9989b148}, doi = {DOI: 10.1016/j.conb.2005.06.003} }
MulAkePhi2008	Muheim, R.; Å S. & Phillips, J.B.	Response to R. Wiltschko et al. (J. Ornithol.): Contradictory results on the role of polarized light in compass calibration in migratory songbirds [BibTeX]	2008	J. Ornithol. Vol. 149 , pp. 659-662	article	animal navigation
BibTeX: @article{MulAkePhi2008, author = {Muheim, R and Å S and Phillips, J B}, title = {Response to R. Wiltschko et al. (J. Ornithol.): Contradictory results on the role of polarized light in compass calibration in migratory songbirds}, journal = {J. Ornithol.}, year = {2008}, volume = {149}, pages = {659-662}, doi = {http://dx.doi.org/10.1007/s10336-008-0337-3} }
MulPhiAke2006	Muheim, R.; Phillips, J.B. & Å S.	Polarized light cues underlie compass cue integration in migratory songbirds [BibTeX] [NOTE]	2006	Science Vol. 313 (5788) , pp. 837-839	article	animal navigation
BibTeX: @article{MulPhiAke2006, author = {Muheim, R and Phillips, J B and Å S}, title = {Polarized light cues underlie compass cue integration in migratory songbirds}, journal = {Science}, year = {2006}, volume = {313}, number = {5788}, pages = {837-839}, note = {For more papers see http://orn-lab.ekol.lu.se/~rachel/rachelpubl.php}, doi = {http://dx.doi.org/10.1126/science.1129709} }
Nesbit20091119	Nesbit, R.; Hill, J.; Woiwod, I.; Sivell, D.; Bensusan, K. & Chapman, J.	Seasonally adaptive migratory headings mediated by a sun compass in the painted lady butterfly, Vanessa cardui [Abstract] [BibTeX] [URL]	2009	Animal Behaviour Vol. 78 (5) , pp. 1119 - 1125	article	animal navigation; butterfly
Abstract: Many insects undertake long-distance migrations to exploit seasonally variable conditions at high latitudes, but the mechanisms used by migrants to select and maintain beneficial flight headings are poorly understood. Using computerized flight simulators, we performed controlled experiments to test the ability of an obligate migrant butterfly (Vanessa cardui) to orient in seasonally advantageous directions (i.e. northwards in spring and southwards in autumn). We also investigated the compass mechanism used to select and maintain these headings. Laboratory-reared autumn-generation butterflies flown in the U.K. displayed a highly significant mean orientation towards the south-southwest, consistent with return migration to winter breeding sites. However, seasonally adaptive flight headings were not observed in wild-caught adults flown at the same time. Spring-generation adults caught in Gibraltar (presumed to be migrating from winter breeding sites in North Africa into Europe) showed no evidence of northward flight headings, but produced a wide scatter of flight headings with a mean direction towards the west. Butterflies flown in the simulators when the sky was not visible produced a random scatter of flight headings and less-directed flight tracks, providing evidence that migrating V. cardui use a sun compass to select and maintain their flight headings. However, when butterflies were subjected to a 6 h clock shift, no change in orientation was observed relative to the control group. Field evidence for a return migration in autumn by V. cardui is surprisingly scarce in the literature, but we conclude that the species does attempt such southward movements and that individuals use a sun compass to select their migratory heading.
BibTeX: @article{Nesbit20091119, author = {R.L. Nesbit and J.K. Hill and I.P. Woiwod and D. Sivell and K.J. Bensusan and J.W. Chapman}, title = {Seasonally adaptive migratory headings mediated by a sun compass in the painted lady butterfly, Vanessa cardui}, journal = {Animal Behaviour}, year = {2009}, volume = {78}, number = {5}, pages = {1119 - 1125}, url = {http://www.sciencedirect.com/science/article/B6W9W-4X8HGS1-2/2/f2712bd74198097065c3ba55573fc5b4}, doi = {DOI: 10.1016/j.anbehav.2009.07.039} }
NewSci2008		Tropical ants use magnetic compass to find home [Abstract] [BibTeX] [URL] [NOTE]	2008	The New Scientist Vol. 197 (2647) , pp. 19 - 19	article	animal navigation
Abstract: Leafcutter ants use more than landmarks and celestial cues to navigate - reveals a study using an electromagnetic pulse to disrupt the insects' internal magnetic compasses
BibTeX: @article{NewSci2008,, title = {Tropical ants use magnetic compass to find home}, journal = {The New Scientist}, year = {2008}, volume = {197}, number = {2647}, pages = {19 - 19}, note = {Animal Navigation}, url = {http://www.sciencedirect.com/science/article/B83WY-4S2D17H-T/2/8e94d8346fa3d9e5a4c22ceb6e91c549}, doi = {DOI: 10.1016/S0262-4079(08)60648-X} }
Nishimura2009399	Nishimura, T. & Fukushima, M.	Why animals respond to the full moon: Magnetic hypothesis [Abstract] [BibTeX] [URL]	2009	Bioscience Hypotheses Vol. 2 (6) , pp. 399 - 401	article	animal navigation; full moon
Abstract: The geomagnetic field is typically about 50 [mu]T (range 20-90 [mu]T). Geomagnetic activity generally decreases by about 4% for the seven days leading up to a full moon, and increases by about 4% after the full moon, lasting for seven days. Animals can clearly detect the changes in magnetic field intensity that occur at full moon, as it has been shown that variations of just a few tens of nT are adequate to form a useful magnetic [`]map'. We think that moonlight increases the sensitivity of animals' magnetoreception because the radical pair model predicts that magnetoreception is light dependent. In fact, there have been some reports of changes in the sensitivity of magnetoreception with lunar phase. We propose a hypothesis that animals respond to the full moon because of changes in geomagnetic fields, and that the sensitivity of animals' magnetoreception increases at this time.
BibTeX: @article{Nishimura2009399, author = {Tsutomu Nishimura and Masanori Fukushima}, title = {Why animals respond to the full moon: Magnetic hypothesis}, journal = {Bioscience Hypotheses}, year = {2009}, volume = {2}, number = {6}, pages = {399 - 401}, url = {http://www.sciencedirect.com/science/article/B8JJ6-4WSG31S-2/2/3ab0644d3e04fdd00a8b99a7e3da9734}, doi = {DOI: 10.1016/j.bihy.2009.06.006} }
Olcese1988325	Olcese, J.; Reuss, S.; Stehle, J.; Steinlechner, S. & Vollrath, L.	Responses of the mammalian retina to experimental alteration of the ambient magnetic field [Abstract] [BibTeX] [URL]	1988	Brain Research Vol. 448 (2) , pp. 325 - 330	article	animal navigation; catecholamine
Abstract: The detection of earth strength magnetic fields by rodents has been demonstrated previously by numerous physiological and behavioral techniques. This phenomenon appears to require input from the eyes. In an effort to better understand this phenomenon retinal melatonin synthesis and catecholamine contents were assayed in rats exposed at night to an alteration of the ambient magnetic field. In normal animals both dopamine and norepinephrine levels in the retina were reduced by this stimulus, while retinal melatonin synthesis was unaffected. Animals that had lost their intact photoreceptors as a result of 8 weeks of previous constant light exposure did not show a catecholamine response to the magnetic stimulus. These results support the view that the mammalian retina participates in the relaying of magnetic information into the central nervous system.
BibTeX: @article{Olcese1988325, author = {J. Olcese and S. Reuss and J. Stehle and S. Steinlechner and L. Vollrath}, title = {Responses of the mammalian retina to experimental alteration of the ambient magnetic field}, journal = {Brain Research}, year = {1988}, volume = {448}, number = {2}, pages = {325 - 330}, url = {http://www.sciencedirect.com/science/article/B6SYR-485P8W1-MY/2/fe95ddf9e6676f81e9c7ea9a9b5a0022}, doi = {DOI: 10.1016/0006-8993(88)91271-1} }
Papi1983673	Papi, F.; Meschini, E. & Baldaccini, N.	Homing behaviour of pigeons released after having been placed in an alternating magnetic field [Abstract] [BibTeX] [URL]	1983	Comparative Biochemistry and Physiology Part A: Physiology Vol. 76 (4) , pp. 673 - 682	article	animal navigation
Abstract: 1. 1. Five series of test releases were performed by keeping homing pigeons in an alternating magnetic field for hr before release. 2. 2. In most cases initial orientation under sun was disturbed; two experiments showed that similar phenomena may occur under overcast skies too. 3. 3. The disturbance lagged behind treatment for some hours. 4. 4. The degree of disturbance was, to some extent, related to the length of treatment. 5. 5. Homing performances were never affected.
BibTeX: @article{Papi1983673, author = {F Papi and E Meschini and N.E Baldaccini}, title = {Homing behaviour of pigeons released after having been placed in an alternating magnetic field}, journal = {Comparative Biochemistry and Physiology Part A: Physiology}, year = {1983}, volume = {76}, number = {4}, pages = {673 - 682}, url = {http://www.sciencedirect.com/science/article/B6T2P-4867WV1-XX/2/6933e70f71dd56c996af8bf41e582458}, doi = {DOI: 10.1016/0300-9629(83)90128-7} }
Penninga1995279	Penninga, I.; de Waard, H.; Moskowitz, B.M.; Bazylinski, D.A. & Frankel, R.B.	Remanence measurements on individual magnetotactic bacteria using a pulsed magnetic field [Abstract] [BibTeX] [URL]	1995	Journal of Magnetism and Magnetic Materials Vol. 149 (3) , pp. 279 - 286	article	animal navigation
Abstract: We describe pulsed-magnetic-field remanence measurements of individual, killed, undisrupted cells of three different types of magnetotactic bacteria. The measurement technique involved the observation of aligned, individual magnetotactic bacteria with a light microscope as they were subjected to magnetic pulses of increasing amplitude. We show that for MM cells, the hysteresis loop is square, with the coercive field variable from cell to cell. This is consistent with just two magnetization states for the single chain of magnetite particles. For MR and MMP cells, the hysteresis loops are not square, indicating that there are several different magnetization states, and that individual cells can be demagnetized. The coercive fields in the MR and MMP cells are less variable than for the MM cells.
BibTeX: @article{Penninga1995279, author = {Ietje Penninga and Hendrik de Waard and Bruce M. Moskowitz and Dennis A. Bazylinski and Richard B. Frankel}, title = {Remanence measurements on individual magnetotactic bacteria using a pulsed magnetic field}, journal = {Journal of Magnetism and Magnetic Materials}, year = {1995}, volume = {149}, number = {3}, pages = {279 - 286}, url = {http://www.sciencedirect.com/science/article/B6TJJ-3Y5FMDD-21/2/f86b20555d7bf02c411ce04d15dfee2e}, doi = {DOI: 10.1016/0304-8853(95)00078-X} }
Perks201032	Perks, B.	Marathon migration: Insects with altitude [Abstract] [BibTeX] [URL]	2010	The New Scientist Vol. 206 (2763) , pp. 32 - 34	article	animal navigation
Abstract: Moths and butterflies can live for only weeks, so how do they complete their long migrations?
BibTeX: @article{Perks201032, author = {Bea Perks}, title = {Marathon migration: Insects with altitude}, journal = {The New Scientist}, year = {2010}, volume = {206}, number = {2763}, pages = {32 - 34}, url = {http://www.sciencedirect.com/science/article/B83WY-507D2W3-1R/2/57a37c1a68489460eab58b9419795456}, doi = {DOI: 10.1016/S0262-4079(10)61384-X} }
Pettersson1991533	Pettersson, J.; Sandberg, R. & Alerstam, T.	Orientation of robins, Erithacus rubecula, in a vertical magnetic field [BibTeX] [URL]	1991	Animal Behaviour Vol. 41 (3) , pp. 533 - 536	article	animal navigation
BibTeX: @article{Pettersson1991533, author = {Jan Pettersson and Roland Sandberg and Thomas Alerstam}, title = {Orientation of robins, Erithacus rubecula, in a vertical magnetic field}, journal = {Animal Behaviour}, year = {1991}, volume = {41}, number = {3}, pages = {533 - 536}, url = {http://www.sciencedirect.com/science/article/B6W9W-4JW7GFC-R/2/a4dd59fc81a4cab04b6143460d1142ed}, doi = {DOI: 10.1016/S0003-3472(05)80858-9} }
PhiBor1992	Phillips, J.B. & Borland, S.C.	Magnetic compass orientation is eliminated under near-infrared light in the eastern red-spotted newt Notophthalmus viridescens [BibTeX] [URL]	1992	Animal Behaviour Vol. 44 (4) , pp. 796 - 797	article	animal navigation
BibTeX: @article{PhiBor1992, author = {Phillips, John B and Borland, S Chris}, title = {Magnetic compass orientation is eliminated under near-infrared light in the eastern red-spotted newt Notophthalmus viridescens}, journal = {Animal Behaviour}, year = {1992}, volume = {44}, number = {4}, pages = {796 - 797}, url = {http://www.sciencedirect.com/science/article/B6W9W-4JS7Y6B-T/2/9a54fb1d318774899339402738b3bbc4}, doi = {DOI: 10.1016/S0003-3472(05)80311-2} }
PhiJorMuh2010	Phillips, J.B.; Jorge, P.E. & Muheim, R.	Light-dependent magnetic compass orientation in amphibians and insects: candidate receptors and candidate molecular mechanisms [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S241-S256	article	animal navigation
Abstract: Magnetic compass orientation by amphibians, and some insects, is mediated by a light-dependent magnetoreception mechanism. Cryptochrome photopigments, best known for their role in circadian rhythms, are proposed to mediate such responses. In this paper, we explore light-dependent properties of magnetic sensing at three levels: (i) behavioural (wavelength-dependent effects of light on magnetic compass orientation), (ii) physiological (photoreceptors/photopigment systems with properties suggesting a role in magnetoreception), and (iii) molecular (cryptochrome-based and non-cryptochrome-based signalling pathways that are compatible with behavioural responses). Our goal is to identify photoreceptors and signalling pathways that are likely to play a specialized role in magnetoreception in order to definitively answer the question of whether the effects of light on magnetic compass orientation are mediated by a light-dependent magnetoreception mechanism, or instead are due to input from a non-light-dependent (e.g. magnetite-based) magnetoreception mechanism that secondarily interacts with other light-dependent processes.
BibTeX: @article{PhiJorMuh2010, author = {Phillips, John B. and Jorge, Paulo E. and Muheim, Rachel}, title = {Light-dependent magnetic compass orientation in amphibians and insects: candidate receptors and candidate molecular mechanisms}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S241-S256}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S241.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0459.focus} }
Phillips198855	Phillips, J.B. & Waldvogel, J.A.	Celestial polarized light patterns as a calibration reference for sun compass of homing pigeons [Abstract] [BibTeX] [URL]	1988	Journal of Theoretical Biology Vol. 131 (1) , pp. 55 - 67	article	animal navigation
Abstract: Homing pigeons (Columba livia) housed as short-term residents in #deflector##lofts# which generate clockwise or counterclockwise rotations of both light cues and wind-borne odors exhibit a corresponding clockwise or counterclockwise bias in homeward orientation upon release from a distant site. Although the biased orientation of deflector loft birds has been cited as evidence that the deflector lofts are rotating an olfactory #map# derived from wind-borne odors, recent experiments using altered deflector panels have shown instead that light cues and not odors are responsible for the deflector loft effect. This paper examines the relationship between behavioral evidence obtained in deflector loft experiments and measurements of the effect that deflector panels have on the distribution of celestial polarization cues visible within these lofts. The measurements show that the deflector panels' influence on the distribution of near-u.v. polarized light patterns which are present at sunrise and sunset matches the orientation bias observed for short-term residents. Furthermore, seasonal changes in the deflector lofts' effect on these polarization patterns parallel seasonal changes in the orientation behavior of deflector loft birds. These results therefore provide support for a theoretical model in which the pigeon's sun compass is calibrated with respect to celestial polarization patterns, and furthermore implicate a near-u.v. sensitive visual receptor in the perception of polarized light by the homing pigeon. The hypothesized compass reference system derived from celestial polarization patterns is also discussed in the light of an alternative model for calibration of the avian sun compass using magnetic cues.
BibTeX: @article{Phillips198855, author = {John B. Phillips and Jerry A. Waldvogel}, title = {Celestial polarized light patterns as a calibration reference for sun compass of homing pigeons}, journal = {Journal of Theoretical Biology}, year = {1988}, volume = {131}, number = {1}, pages = {55 - 67}, url = {http://www.sciencedirect.com/science/article/B6WMD-4KD4YDR-6/2/cfeb79730594b99cd67854c9522aae1d}, doi = {DOI: 10.1016/S0022-5193(88)80120-6} }
Phillips1996309	Phillips, J.B.	Magnetic Navigation [Abstract] [BibTeX] [URL]	1996	Journal of Theoretical Biology Vol. 180 (4) , pp. 309 - 319	article	animal navigation
Abstract: Recent evidence suggests that some amphibians, reptiles and birds may be capable of homing using information about geographic position (#map# information) derived from subtle geographic gradients in the earth's magnetic field. The #magnetic##map# hypothesis faces numerous theoretical difficulties, however, due to the extremely high level of sensitivity that would be necessary to detect natural magnetic gradients, and to the presence of spatial irregularities and temporal variation in the geomagnetic field that might make map coordinates derived from magnetic gradients unreliable. To date, the majority of studies carried out to test the magnetic map hypothesis have involved field observations of the effects on homing orientation of naturally occurring spatial or temporal variation in the geomagnetic field. While providing an important first step, these studies are subject to the criticism that the observed changes in homing orientation could result from effects on a magnetic compass, or some other unidentified component of the navigational system, rather than from effects on a magnetic map. The recent development of experimental systems in which navigational ability can be studied under controlled or semi-controlled laboratory conditions has opened up the possibility of using new experimental approaches to more rigorously test the magnetic map hypothesis. After briefly reviewing the available evidence of the geomagnetic field's involvement in the map component of homing, a simple graphical model is presented which describes how the home direction derived from a bicoordinate map varies as a function of the value of one of the map coordinates when the value of the second map coordinate is held constant. In studies of homing orientation in which the value of a specific magnetic field parameter (e.g., total intensity, inclination, etc.) can be varied independently of other putative map parameters, the graphical model can be used to generate qualitative predictions about the changes in the direction of homing orientation that should be observed if the magnetic field parameter being manipulated serves as one coordinate of a bicoordinate map. The relationship between the direction of homing orientation and the value of a putative magnetic map parameter can also be used to generate quantitative predictions about characteristics of the local gradient of that magnetic field parameter in the vicinity of the home site (i.e., the alignment and #home##value# of the local gradient) which can then be compared with actual measured values. Together, the qualitative and quantitative predictions of the graphical model permit rigorous tests of whether one or both coordinates of a bicoordinate navigational map are derived from the geomagnetic field.
BibTeX: @article{Phillips1996309, author = {Phillips, John B}, title = {Magnetic Navigation}, journal = {Journal of Theoretical Biology}, year = {1996}, volume = {180}, number = {4}, pages = {309 - 319}, url = {http://www.sciencedirect.com/science/article/B6WMD-45MGSJK-3H/2/38f2660832c35d390314f23a2e60d4d5}, doi = {DOI: 10.1006/jtbi.1996.0105} }
Pol(etal)2010	Polli, D.; Altoe, P.; Weingart, O.; Spillane, K.M.; Manzoni, C.; Brida, D.; Tomasello, G.; Orlandi, G.; Kukura, P.; Mathies, R.A.; Garavelli, M. & Cerullo, G.	Conical intersection dynamics of the primary photoisomerization event in vision [BibTeX] [URL]	2010	Nature Vol. 467 (7314) , pp. 440-443	article	animal navigation
BibTeX: @article{Pol(etal)2010, author = {Polli, Dario and Altoe, Piero and Weingart, Oliver and Spillane, Katelyn M. and Manzoni, Cristian and Brida, Daniele and Tomasello, Gaia and Orlandi, Giorgio and Kukura, Philipp and Mathies, Richard A. and Garavelli, Marco and Cerullo, Giulio}, title = {Conical intersection dynamics of the primary photoisomerization event in vision}, journal = {Nature}, year = {2010}, volume = {467}, number = {7314}, pages = {440-443}, url = {http://dx.doi.org/10.1038/nature09346} }
Prinz1992539	Prinz, K. & Wiltschko, W.	Migratory orientation of pied flycatchers: interaction of stellar and magnetic information during ontogeny [Abstract] [BibTeX] [URL]	1992	Animal Behaviour Vol. 44 (Part 3) , pp. 539 - 545	article	animal navigation
Abstract: To study the interaction between magnetic compass and star compass during ontogeny, young pied flycatchers, Ficedula hypoleuca, were hand-reared, and after becoming self-sufficient were transferred into outdoor aviaries with full view of the sky. They were divided into three groups: controls experienced the sky while sitting in the local magnetic field; for group WSW, magnetic north was turned by 120 ° anticlockwise to geographical west-southwest; and for group ESE it was turned 120 ° clockwise to eastsoutheast. The birds remained in the aviary until the onset of the migratory season. They were then transferred indoors and tested in the local geomagnetic field without access to celestial cues. The controls showed a significant preference for the seasonally appropriate migratory direction. The group WSW was significantly oriented with a mean 119 ° clockwise from that of the controls. This is in agreement with the hypothesis that celestial cues during the pre-migratory period override any innate magnetic information and establish a new compass course with respect to the magnetic field. The orientation of the group ESE was significantly more scattered, and the mean does not fit the hypothesis mentioned above. Possible reasons for this difference in behaviour are discussed. If it reflects a true asymmetry of the orientation system, the sense of rotation of the sky, being an asymmetric factor, might be involved in the sense that a transfer of information from one system to the other might occur more easily in the direction of rotation than against it.
BibTeX: @article{Prinz1992539, author = {Kai Prinz and Wolfgang Wiltschko}, title = {Migratory orientation of pied flycatchers: interaction of stellar and magnetic information during ontogeny}, journal = {Animal Behaviour}, year = {1992}, volume = {44}, number = {Part 3}, pages = {539 - 545}, url = {http://www.sciencedirect.com/science/article/B6W9W-4F1HR46-49/2/a8c351c8a914148abdabbefdf9e20bc8}, doi = {DOI: 10.1016/0003-3472(92)90063-F} }
Rep2006	Reppert, S.M.	A Colorful Model of the Circadian Clock [Abstract] [BibTeX] [URL]	2006	Cell Vol. 124 (2) , pp. 233 - 236	article	animal navigation
Abstract: The migration of the colorful monarch butterfly provides biologists with a unique model system with which to study the cellular and molecular mechanisms underlying a sophisticated circadian clock. The monarch circadian clock is involved in the induction of the migratory state and navigation over long distances, using the sun as a compass.
BibTeX: @article{Rep2006, author = {Reppert, Steven M}, title = {A Colorful Model of the Circadian Clock}, journal = {Cell}, year = {2006}, volume = {124}, number = {2}, pages = {233 - 236}, url = {http://www.sciencedirect.com/science/article/B6WSN-4J4B00R-4/2/8fad83820234b54907a9019486a336b0}, doi = {DOI: 10.1016/j.cell.2006.01.009} }
Reppert2010	Reppert, S.M.; Gegear, R.J. & Merlin, C.	Navigational mechanisms of migrating monarch butterflies [Abstract] [BibTeX] [URL]	2010	Trends in Neurosciences Vol. In Press, Corrected Proof , pp. -	article	animal navigation
Abstract: Recent studies of the iconic fall migration of monarch butterflies have illuminated the mechanisms behind their southward navigation while using a time-compensated sun compass. Skylight cues, such as the sun itself and polarized light, are processed through both eyes and are probably integrated in the brain's central complex, the presumed site of the sun compass. Time compensation is provided by circadian clocks that have a distinctive molecular mechanism and that reside in the antennae. Monarchs might also use a magnetic compass because they possess two cryptochromes that have the molecular capability for light-dependent magnetoreception. Multiple genomic approaches are now being used with the aim of identifying navigation genes. Monarch butterflies are thus emerging as an excellent model organism in which to study the molecular and neural basis of long-distance migration.
BibTeX: @article{Reppert2010, author = {Steven M. Reppert and Robert J. Gegear and Christine Merlin}, title = {Navigational mechanisms of migrating monarch butterflies}, journal = {Trends in Neurosciences}, year = {2010}, volume = {In Press, Corrected Proof}, pages = { - }, url = {http://www.sciencedirect.com/science/article/B6T0V-506X5JC-1/2/1b493d4289ad858c1b65239ab77a8e33}, doi = {DOI: 10.1016/j.tins.2010.04.004} }
RepZhuWhi2004	Reppert, S.M.; Zhu, H. & White, R.H.	Polarized Light Helps Monarch Butterflies Navigate [Abstract] [BibTeX] [URL]	2004	Current Biology Vol. 14 (2) , pp. 155 - 158	article	animal navigation
Abstract: During their spectacular migratory journey in the fall, North American monarch butterflies (Danaus plexippus) use a time-compensated sun compass to help them navigate to their overwintering sites in central Mexico [1], [2] and [3]. One feature of the sun compass mechanism not fully explored in monarchs is the sunlight-dependent parameters used to navigate. We now provide data suggesting that the angle of polarized skylight (the e-vector) is a relevant orientation parameter. By placing butterflies in a flight simulator outdoors and using a linear polarizing filter, we show that manipulating the e-vector alters predictably the direction of oriented flight. Butterflies studied in either the morning or afternoon showed similar responses to filter rotation. Monarch butterflies possess the anatomical structure needed for polarized skylight detection, as rhabdoms in the dorsalmost row of photoreceptor cells in monarch eye show the organization characteristic of polarized-light receptors. The existence of polarized-light detection could allow migrants to accurately navigate under a variety of atmospheric conditions and reveals a critical input pathway into the sun compass mechanism.
BibTeX: @article{RepZhuWhi2004, author = {Reppert, Steven M and Zhu, Haisun and White, Richard H}, title = {Polarized Light Helps Monarch Butterflies Navigate}, journal = {Current Biology}, year = {2004}, volume = {14}, number = {2}, pages = {155 - 158}, url = {http://www.sciencedirect.com/science/article/B6VRT-4BHSRC4-10/2/209c974fe160bd1d20ae9b506060d697}, doi = {DOI: 10.1016/j.cub.2003.12.034} }
RitAdeSch2000	Ritz, T.; Adem, S. & Schulten, K.	A Model for Photoreceptor-Based Magnetoreception in Birds [Abstract] [BibTeX] [URL]	2000	Biophysical Journal Vol. 78 (2) , pp. 707 - 718	article	animal navigation
Abstract: A large variety of animals has the ability to sense the geomagnetic field and utilize it as a source of directional (compass) information. It is not known by which biophysical mechanism this magnetoreception is achieved. We investigate the possibility that magnetoreception involves radical-pair processes that are governed by anisotropic hyperfine coupling between (unpaired) electron and nuclear spins. We will show theoretically that fields of geomagnetic field strength and weaker can produce significantly different reaction yields for different alignments of the radical pairs with the magnetic field. As a model for a magnetic sensory organ we propose a system of radical pairs being 1) orientationally ordered in a molecular substrate and 2) exhibiting changes in the reaction yields that affect the visual transduction pathway. We evaluate three-dimensional visual modulation patterns that can arise from the influence of the geomagnetic field on radical-pair systems. The variations of these patterns with orientation and field strength can furnish the magnetic compass ability of birds with the same characteristics as observed in behavioral experiments. We propose that the recently discovered photoreceptor cryptochrome is part of the magnetoreception system and suggest further studies to prove or disprove this hypothesis.
BibTeX: @article{RitAdeSch2000, author = {Ritz, Thorsten and Adem, Salih and Schulten, Klaus}, title = {A Model for Photoreceptor-Based Magnetoreception in Birds}, journal = {Biophysical Journal}, year = {2000}, volume = {78}, number = {2}, pages = {707 - 718}, url = {http://www.sciencedirect.com/science/article/B94RW-4TYB50X-H/2/2b0b9d4ea7b18a45b85ab183bc6d9cf6}, doi = {DOI: 10.1016/S0006-3495(00)76629-X} }
RitAhmMouWilWil2010	Ritz, T.; Ahmad, M.; Mouritsen, H.; Wiltschko, R. & Wiltschko, W.	Photoreceptor-based magnetoreception: optimal design of receptor molecules, cells, and neuronal processing [Abstract] [BibTeX]	2010	J. R. Soc. Interface Vol. 7 (Supplement 2) , pp. S135-S146	article	animal navigation
Abstract: The sensory basis of magnetoreception in animals still remains a mystery. One hypothesis of magnetoreception is that photochemical radical pair reactions can transduce magnetic information in specialized photoreceptor cells, possibly involving the photoreceptor molecule cryptochrome. This hypothesis triggered a considerable amount of research in the past decade. Here, we present an updated picture of the radical-pair photoreceptor hypothesis. In our review, we will focus on insights that can assist biologists in their search for the elusive magnetoreceptors.
BibTeX: @article{RitAhmMouWilWil2010, author = {Ritz, Thorsten and Ahmad, Margaret and Mouritsen, Henrik and Wiltschko, Roswitha and Wiltschko, Wolfgang}, title = {Photoreceptor-based magnetoreception: optimal design of receptor molecules, cells, and neuronal processing}, journal = {J. R. Soc. Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S135-S146}, doi = {http://dx.doi.org/10.1098/rsif.2009.0456.focus} }
RitThoSch2000	Ritz, T.; Adem, S. & Schulten, K.	A model for photoreceptor-based magnetoreception in birds [Abstract] [BibTeX]	2000	Biophysical Journal Vol. 78 , pp. 707-718	article	animal navigation
Abstract: A large variety of animals has the ability to sense the geomagnetic field and utilize it as a source of directional (compass) information. It is not known by which biophysical mechanism this magnetoreception is achieved. We investigate the possibility that magnetoreception involves radical pair processes which are governed by anisotropic hyperfine coupling between (unpaired) electron and nuclear spins. We will show theoretically that fields of geomagnetic field strength and weaker can produce significantly different reaction yields for different alignments of the radical pairs with the magnetic field. As a model for a magnetic sensory organ we propose a system of radical pairs being (1) orientationally ordered in a molecular substrate and (2) exhibiting changes in the reaction yields that affect the visual transduction pathway. We evaluate three-dimensional visual modulation patterns that can arise from the influence of the geomagnetic field on radical pair systems. The variations of these patterns with orientation and field strength can furnish the magnetic compass ability of birds with the same characteristics as observed in behavioral experiments. We propose that the recently discovered photoreceptor cryptochrome is part of the magnetoreception system and suggest further studies to prove or disprove this hypothesis.
BibTeX: @article{RitThoSch2000, author = {Ritz, Thorsten and Adem, Salih and Schulten, Klaus}, title = {A model for photoreceptor-based magnetoreception in birds}, journal = {Biophysical Journal}, year = {2000}, volume = {78}, pages = {707-718} }
Ritz2000707	Ritz, T.; Adem, S. & Schulten, K.	A Model for Photoreceptor-Based Magnetoreception in Birds [Abstract] [BibTeX] [URL]	2000	Biophysical Journal Vol. 78 (2) , pp. 707 - 718	article	animal navigation
Abstract: A large variety of animals has the ability to sense the geomagnetic field and utilize it as a source of directional (compass) information. It is not known by which biophysical mechanism this magnetoreception is achieved. We investigate the possibility that magnetoreception involves radical-pair processes that are governed by anisotropic hyperfine coupling between (unpaired) electron and nuclear spins. We will show theoretically that fields of geomagnetic field strength and weaker can produce significantly different reaction yields for different alignments of the radical pairs with the magnetic field. As a model for a magnetic sensory organ we propose a system of radical pairs being 1) orientationally ordered in a molecular substrate and 2) exhibiting changes in the reaction yields that affect the visual transduction pathway. We evaluate three-dimensional visual modulation patterns that can arise from the influence of the geomagnetic field on radical-pair systems. The variations of these patterns with orientation and field strength can furnish the magnetic compass ability of birds with the same characteristics as observed in behavioral experiments. We propose that the recently discovered photoreceptor cryptochrome is part of the magnetoreception system and suggest further studies to prove or disprove this hypothesis.
BibTeX: @article{Ritz2000707, author = {Thorsten Ritz and Salih Adem and Klaus Schulten}, title = {A Model for Photoreceptor-Based Magnetoreception in Birds}, journal = {Biophysical Journal}, year = {2000}, volume = {78}, number = {2}, pages = {707 - 718}, url = {http://www.sciencedirect.com/science/article/B94RW-4TYB50X-H/2/2b0b9d4ea7b18a45b85ab183bc6d9cf6}, doi = {DOI: 10.1016/S0006-3495(00)76629-X} }
Ritz2002503	Ritz, T.; Dommer, D.H. & Phillips, J.B.	Shedding Light on Vertebrate Magnetoreception [Abstract] [BibTeX] [URL]	2002	Neuron Vol. 34 (4) , pp. 503 - 506	article	animal navigation
Abstract: We review the challenges and recent progress in elucidating the physiological basis of animal magnetoreception. Behavioral and theoretical studies suggest a link between photoreception and magnetoreception in some animals. Neurophysiological studies have the potential to prove this link and identify the location of and the mechanism underlying the magnetoreception system.
BibTeX: @article{Ritz2002503, author = {Thorsten Ritz and David H Dommer and John B Phillips}, title = {Shedding Light on Vertebrate Magnetoreception}, journal = {Neuron}, year = {2002}, volume = {34}, number = {4}, pages = {503 - 506}, url = {http://www.sciencedirect.com/science/article/B6WSS-4621C0F-5/2/c5d03acc7f91300bdf477bb7fd9d2fd0}, doi = {DOI: 10.1016/S0896-6273(02)00707-9} }
Ritz20093451	Ritz, T.; Wiltschko, R.; Hore, P.; Rodgers, C.T.; Stapput, K.; Thalau, P.; Timmel, C.R. & Wiltschko, W.	Magnetic Compass of Birds Is Based on a Molecule with Optimal Directional Sensitivity [Abstract] [BibTeX] [URL]	2009	Biophysical Journal Vol. 96 (8) , pp. 3451 - 3457	article	animal navigation
Abstract: The avian magnetic compass has been well characterized in behavioral tests: it is an #inclination##compass# based on the inclination of the field lines rather than on the polarity, and its operation requires short-wavelength light. The #radical##pair# model suggests that these properties reflect the use of specialized photopigments in the primary process of magnetoreception; it has recently been supported by experimental evidence indicating a role of magnetically sensitive radical-pair processes in the avian magnetic compass. In a multidisciplinary approach subjecting migratory birds to oscillating fields and using their orientation responses as a criterion for unhindered magnetoreception, we identify key features of the underlying receptor molecules. Our observation of resonance effects at specific frequencies, combined with new theoretical considerations and calculations, indicate that birds use a radical pair with special properties that is optimally designed as a receptor in a biological compass. This radical pair design might be realized by cryptochrome photoreceptors if paired with molecular oxygen as a reaction partner.
BibTeX: @article{Ritz20093451, author = {Thorsten Ritz and Roswitha Wiltschko and P.J. Hore and Christopher T. Rodgers and Katrin Stapput and Peter Thalau and Christiane R. Timmel and Wolfgang Wiltschko}, title = {Magnetic Compass of Birds Is Based on a Molecule with Optimal Directional Sensitivity}, journal = {Biophysical Journal}, year = {2009}, volume = {96}, number = {8}, pages = {3451 - 3457}, url = {http://www.sciencedirect.com/science/article/B94RW-4W351S1-1M/2/acc942aaf37ebe48e70e2e82872b67ad}, doi = {DOI: 10.1016/j.bpj.2008.11.072} }
Ritz2009609	Ritz, T. Squire, L.R. (Hrsg.)	Magnetic Sense in Animal Navigation [Abstract] [BibTeX] [URL]	2009	Encyclopedia of Neuroscience , pp. 609 - 614	incollection	animal navigation; cryptochrome
Abstract: Sensory perception of the geomagnetic field remains one of the most fascinating challenges of neurophysiology, and even basic questions still remain to be answered. We provide a brief overview of the best-established behavioral evidence for the use of magnetic senses. The two most likely sensory mechanisms - magnetic sensing based on magnetite or other magnetic iron oxides and sensing based on magnetically sensitive radical-pair reactions - are explained. Both mechanisms are discussed in the light of novel theoretical considerations, behavioral and neurophysiological approaches that have recently established a significant body of evidence supporting the existence of both sensory mechanisms.
BibTeX: @incollection{Ritz2009609, author = {T. Ritz}, title = {Magnetic Sense in Animal Navigation}, booktitle = {Encyclopedia of Neuroscience}, publisher = {Academic Press}, year = {2009}, pages = {609 - 614}, url = {http://www.sciencedirect.com/science/article/B98GH-4TVBCX5-1FX/2/ef9384931f83aa830a73b232d20295b5}, doi = {DOI: 10.1016/B978-008045046-9.01984-7} }
RivSry2008	Riveros, A.J. & Srygley, R.B.	Do leafcutter ants, Atta colombica, orient their path-integrated home vector with a magnetic compass? [Abstract] [BibTeX] [NOTE]	2008	Animal Behaviour Vol. 75 (4) , pp. 1273-1281	article	animal navigation
Abstract: Leafcutter ants, Atta colombica, forage over 250 m in structurally complex, Neotropical rainforests that occlude sun or polarized light cues. Night foraging makes the use of celestial cues and landmarks all the more difficult. We investigated the directional cues used by leafcutter ants to orient homeward by experimentally reversing the polarity of the local magnetic field and by experimentally subjecting the ants to a strong magnetic pulse to disrupt a magnetic compass. In both experiments, we transferred homewardbound ants from a foraging trail to a table in a chamber that occluded landmark and celestial cues. In both experiments, control ants showed path integration and walked directly towards the nest. In the reversed field, one-half of the experimental ants oriented according to the reversed field (geographically $180^rc$ opposite to the nest’s direction), indicating that they used a magnetic compass to update their positional reference derived from path integration. The other half walked towards the nest, suggesting that they may have used an egocentric reference to measure their rotation when displaced, although other explanations have not been entirely excluded. With application of a very brief, but strong, magnetic pulse, experimental ants oriented randomly.We conclude that the leafcutter ants use the earth’s magnetic field as a reference by which to orient when path-integrating towards home.
BibTeX: @article{RivSry2008, author = {Riveros, A J and Srygley, R B}, title = {Do leafcutter ants, Atta colombica, orient their path-integrated home vector with a magnetic compass?}, journal = {Animal Behaviour}, year = {2008}, volume = {75}, number = {4}, pages = {1273-1281}, note = {Animal Navigation}, doi = {http://dx.doi.org/10.1016/j.anbehav.2007.09.030} }
RobinBaker1982543	Baker, R.R. & Mather, J.G.	Magnetic compass sense in the large yellow underwing moth, Noctua pronuba L. [Abstract] [BibTeX] [URL]	1982	Animal Behaviour Vol. 30 (2) , pp. 543 - 548	article	animal navigation
Abstract: Many animals are now known to have a magnetic sense which they use when moving from one place to another. Among insects, this sense has only been studied in any detail in the honey bee. A role for a magnetic compass sense in cross-country migration has not so far been demonstrated for any insect. On clear nights the large yellow underwing moth, Noctua pronuba, has been shown to orientate by both the moon and the stars. However, radar studies have shown moths to be well-oriented on overcast nights as well as clear nights. We report here that when large yellow underwings are placed in an orientation cage on overcast nights and the Earth's normal magnetic field is reversed, there is a corresponding reversal in the orientation of the moth. We conclude that this species makes use of the Earth's magnetic field in maintaining compass orientation on overcast nights. We also show that the preferred compass orientation to the Earth's magnetic field is the same as the compass direction that results from orientation to the moon and stars.
BibTeX: @article{RobinBaker1982543, author = {R. Robin Baker and Janice G. Mather}, title = {Magnetic compass sense in the large yellow underwing moth, Noctua pronuba L.}, journal = {Animal Behaviour}, year = {1982}, volume = {30}, number = {2}, pages = {543 - 548}, url = {http://www.sciencedirect.com/science/article/B6W9W-4JTYB00-X/2/4d8faacb7828e451559cbaae68cfbee7}, doi = {DOI: 10.1016/S0003-3472(82)80067-5} }
RobinBaker198794	Baker, R.R.	Integrated use of moon and magnetic compasses by the heart-and-dart moth, Agrotis exclamationis [Abstract] [BibTeX] [URL]	1987	Animal Behaviour Vol. 35 (1) , pp. 94 - 101	article	animal navigation
Abstract: Use of the moon as a compass during migration appears difficult due to the complexity of the moon's change in azimuth during the lunar month. These apparent difficulties would be eased if the moon's position were calibrated at intervals against a constant reference source, such as the geomagnetic field. Yet, until now, no animal has been shown to integrate moon and magnetic compasses for orientation. In this study, light-traps were used on 15 nights during a lunar month to obtain samples of heart-and-dart moths, Agrotis exclamationis, characterized by a preference to fly [`]toward' (i.e.±90°) the moon's azimuth. The compass orientation of each sample was then tested in normal and reversed geomagnetic fields, out of sight of the moon. Compass orientation relative to the ambient magnetic field coincided with the compass bearing of the moon at the time of capture. Directional preference changed during the lunar month in a way that tracked the change in the moon's azimuth. It is concluded that moths use the geomagnetic field to calibrate a moon compass.
BibTeX: @article{RobinBaker198794, author = {R. Robin Baker}, title = {Integrated use of moon and magnetic compasses by the heart-and-dart moth, Agrotis exclamationis}, journal = {Animal Behaviour}, year = {1987}, volume = {35}, number = {1}, pages = {94 - 101}, url = {http://www.sciencedirect.com/science/article/B6W9W-4JT84SP-F/2/2b6d038182ccdf0ba7d5b90ee4203052}, doi = {DOI: 10.1016/S0003-3472(87)80214-2} }
RobTheWelDroPraTho2009	Robertson, J.A.; Théberge, J.; Weller, J.; Drost, D.J.; Prato, F.S. & Thomas, A.W.	Low-frequency pulsed electromagnetic field exposure can alter neuroprocessing in humans [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (44) , pp. 467-473	article	animal navigation, em health
Abstract: Extremely low-frequency magnetic fields (from DC to 300 Hz) have been shown to affect pain sensitivity in snails, rodents and humans. Here, a functional magnetic resonance imaging study demonstrates how the neuromodulation effect of these magnetic fields influences the processing of acute thermal pain in normal volunteers. Significant interactions were found between pre- and post-exposure activation between the sham and exposed groups for the ipsilateral (right) insula, anterior cingulate and bilateral hippocampus/caudate areas. These results show, for the first time, that the neuromodulation induced by exposure to low-intensity low-frequency magnetic fields can be observed in humans using functional brain imaging and that the detection mechanism for these effects may be different from those used by animals for orientation and navigation. Magnetoreception may be more common than presently thought.
BibTeX: @article{RobTheWelDroPraTho2009, author = {Robertson, John A. and Théberge, Jean and Weller, Julie and Drost, Dick J. and Prato, Frank S. and Thomas, Alex W.}, title = {Low-frequency pulsed electromagnetic field exposure can alter neuroprocessing in humans}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {44}, pages = {467-473}, url = {http://rsif.royalsocietypublishing.org/content/7/44/467.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0205} }
RodHor2009	Rodgers, C.T. & Hore, P.J.	Chemical magnetoreception in birds: The radical pair mechanism [Abstract] [BibTeX]	2009	PNAS Vol. 106 (2) , pp. 353-360	article	animal navigation
Abstract: Migratory birds travel vast distances each year, finding their way by various means, including a remarkable ability to perceive the Earth's magnetic field. Although it has been known for 40 years that birds possess a magnetic compass, avian magnetoreception is poorly understood at all levels from the primary biophysical detection events, signal transduction pathways and neurophysiology, to the processing of information in the brain. It has been proposed that the primary detector is a specialized ocular photoreceptor that plays host to magnetically sensitive photochemical reactions having radical pairs as fleeting intermediates. Here, we present a physical chemist's perspective on the "radical pair mechanism" of compass magnetoreception in birds. We outline the essential chemical requirements for detecting the direction of an Earth-strength $0 rmmu T$ magnetic field and comment on the likelihood that these might be satisfied in a biologically plausible receptor. Our survey concludes with a discussion of cryptochrome, the photoactive protein that has been put forward as the magnetoreceptor molecule.
BibTeX: @article{RodHor2009, author = {Rodgers, Christopher T and Hore, P J}, title = {Chemical magnetoreception in birds: The radical pair mechanism}, journal = {PNAS}, year = {2009}, volume = {106}, number = {2}, pages = {353-360}, doi = {http://dx.doi.org/10.1073/pnas.0711968106} }
Rogers200866	Rogers, L.J.; Munro, U.; Freire, R.; Wiltschko, R. & Wiltschko, W.	Lateralized response of chicks to magnetic cues [Abstract] [BibTeX] [URL]	2008	Behavioural Brain Research Vol. 186 (1) , pp. 66 - 71	article	animal navigation; magnetic compass; chicks; lateralization; hemispheric specialization; monocular testing
Abstract: Previous research has shown that the ability to orient with the use of directional cues from the geomagnetic field is lateralized in three avian species: orientation is possible when the birds are restricted to use of their right eye, but not when they have to use their left eye. This has been interpreted as possible lateralization of the perception mechanisms for magnetic cues in favour of the right eye. Recent discovery of magnetic compass orientation in domestic chicks, a species in which lateralization has been well studied, has made available a model system in which to explore these lateralized processes more fully. Hence we tested chicks monocularly in the same test conditions as used previously to demonstrate the chick's use of a magnetic compass. In a magnetic field with North shifted by 90°, chicks using their right eye oriented according to magnetic cues, whereas chicks using the left eye did not, but continued to prefer the original direction. Analysis of the times taken to respond indicated longer latencies in the chicks using their left eye, suggesting a possible conflict between cues. The different behaviour of the chicks using their left eye might not be a matter of a right eye-left hemisphere specialization for detecting magnetic directions, but of hemispheric specialization for attending to specific types of cues.
BibTeX: @article{Rogers200866, author = {Lesley J. Rogers and Ursula Munro and Rafael Freire and Roswitha Wiltschko and Wolfgang Wiltschko}, title = {Lateralized response of chicks to magnetic cues}, journal = {Behavioural Brain Research}, year = {2008}, volume = {186}, number = {1}, pages = {66 - 71}, url = {http://www.sciencedirect.com/science/article/B6SYP-4P961WC-1/2/f48d783f288f8789a7724f214cf498ab}, doi = {DOI: 10.1016/j.bbr.2007.07.029} }
Rosenspire20053334	Rosenspire, A.J.; Kindzelskii, A.L.; Simon, B.J. & Petty, H.R.	Real-Time Control of Neutrophil Metabolism by Very Weak Ultra-Low Frequency Pulsed Magnetic Fields [Abstract] [BibTeX] [URL]	2005	Biophysical Journal Vol. 88 (5) , pp. 3334 - 3347	article	animal navigation
Abstract: In adherent and motile neutrophils NAD(P)H concentration, flavoprotein redox potential, and production of reactive oxygen species and nitric oxide, are all periodic and exhibit defined phase relationships to an underlying metabolic oscillation of ~20 s. Utilizing fluorescence microscopy, we have shown in real-time, on the single cell level, that the system is sensitive to externally applied periodically pulsed weak magnetic fields matched in frequency to the metabolic oscillation. Depending upon the phase relationship of the magnetic pulses to the metabolic oscillation, the magnetic pulses serve to either increase the amplitude of the NAD(P)H and flavoprotein oscillations, and the rate of production of reactive oxygen species and nitric oxide or, alternatively, collapse the metabolic oscillations and curtail production of reactive oxygen species and nitric oxide. Significantly, we demonstrate that the cells do not directly respond to the magnetic fields, but instead are sensitive to the electric fields which the pulsed magnetic fields induce. These weak electric fields likely tap into an endogenous signaling pathway involving calcium channels in the plasma membrane. We estimate that the threshold which induced electric fields must attain to influence cell metabolism is of the order of 10-4 V/m.
BibTeX: @article{Rosenspire20053334, author = {Allen J. Rosenspire and Andrei L. Kindzelskii and Bruce J. Simon and Howard R. Petty}, title = {Real-Time Control of Neutrophil Metabolism by Very Weak Ultra-Low Frequency Pulsed Magnetic Fields}, journal = {Biophysical Journal}, year = {2005}, volume = {88}, number = {5}, pages = {3334 - 3347}, url = {http://www.sciencedirect.com/science/article/B94RW-4V40XMK-10/2/745d85a7db9af3d0da671ef5c4298bfe}, doi = {DOI: 10.1529/biophysj.104.056663} }
Sandberg1988877	Sandberg, R.; Pettersson, J. & Alerstam, T.	Shifted magnetic fields lead to deflected and axial orientation of migrating robins, Erithacus rubecula, at sunset [Abstract] [BibTeX] [URL]	1988	Animal Behaviour Vol. 36 (3) , pp. 877 - 887	article	animal navigation
Abstract: The migratory orientation of the robin was tested in shifted magnetic fields during the twilight period after sunset, under clear skies and under simulated total overcast. The horizontal direction of the geomagnetic field was shifted 90° to the right or left in relation to the local magnetic field, without changing either the intensity of the field or its angle of inclination. Experiments were conducted during both spring and autumn, with robins captured as passage migrants at the Falsterbo and Ottenby bird observatories in southern Sweden as test subjects. Generally, the orientation of robins was affected by magnetic shifts compared to controls tested in the natural geomagnetic field. Autumn birds from the two capture sites differed in their responses, probably because of different migratory dispositions and body conditions. The robins most often changed their orientation to maintain their typical axis of migration relative to the shifted magnetic fields. However, preferred directions in relation to the shifted magnetic fields were frequently reverse from normal, or axial rather than unimodal. These results disagree with suggested mechanisms for orientation by visual sunset cues and with the proposed basis of magnetic orientation. They do, however, demonstrate that the geomagnetic field is involved in the sunset orientation of robins, probably in combination with additional visual or non-visual cues that contribute to establish magnetic polarity.
BibTeX: @article{Sandberg1988877, author = {R. Sandberg and J. Pettersson and T. Alerstam}, title = {Shifted magnetic fields lead to deflected and axial orientation of migrating robins, Erithacus rubecula, at sunset}, journal = {Animal Behaviour}, year = {1988}, volume = {36}, number = {3}, pages = {877 - 887}, url = {http://www.sciencedirect.com/science/article/B6W9W-4KRFX04-X/2/129c5496f5ab36003b46d9ae6e863662}, doi = {DOI: 10.1016/S0003-3472(88)80170-2} }
SauBriZhuShiFroStaYuaCasRep2005	Sauman, I.; Briscoe, A.D.; Zhu, H.; Shi, D.; Froy, O.; Stalleicken, J.; Yuan, Q.; Casselman, A. & Reppert, S.M.	Connecting the Navigational Clock to Sun Compass Input in Monarch Butterfly Brain [Abstract] [BibTeX] [URL]	2005	Neuron Vol. 46 (3) , pp. 457 - 467	article	animal navigation
Abstract: Summary Migratory monarch butterflies (Danaus plexippus) use a time-compensated sun compass to navigate to their overwintering grounds in Mexico. Although polarized light is one of the celestial cues used for orientation, the spectral content (color) of that light has not been fully explored. We cloned the cDNAs of three visual pigment-encoding opsins (ultraviolet [UV], blue, and long wavelength) and found that all three are expressed uniformly in main retina. The photoreceptors of the polarization-specialized dorsal rim area, on the other hand, are monochromatic for the UV opsin. Behavioral studies support the importance of polarized UV light for flight orientation. Next, we used clock protein expression patterns to identify the location of a circadian clock in the dorsolateral protocerebrum of butterfly brain. To provide a link between the clock and the sun compass, we identified a CRYPTOCHROME-staining neural pathway that likely connects the circadian clock to polarized light input entering brain.
BibTeX: @article{SauBriZhuShiFroStaYuaCasRep2005, author = {Sauman, Ivo and Briscoe, Adriana D and Zhu, Haisun and Shi, Dingding and Froy, Oren and Stalleicken, Julai and Yuan, Quan and Casselman, Amy and Reppert, Steven M}, title = {Connecting the Navigational Clock to Sun Compass Input in Monarch Butterfly Brain}, journal = {Neuron}, year = {2005}, volume = {46}, number = {3}, pages = {457 - 467}, url = {http://www.sciencedirect.com/science/article/B6WSS-4G3BYF8-K/2/ac7102bc58d21a31c33b59b7543a8b2f}, doi = {DOI: 10.1016/j.neuron.2005.03.014} }
Sch1982	Schulten, K. Treusch, J. (Hrsg.)	Magnetic field effects in chemistry and biology ( Festkörperprobleme ) [Abstract] [BibTeX]	1982	Festkörperprobleme Vol. 22 , pp. 61-83	inbook	animal navigation
Abstract: Chemical and biological photoprocesses which involve bimolecular reactions between non-zero spin intermediates, e.g. doublet molecules $^2A$ + $^2B$, often produce the intermediate molecular pair in a pure overall spin state, e.g. a singlet state $^1(^2A + ^2B)$, and select for the reaction channels again such spin states, e.g. a triplet state $^3(^2A +^2B)$. The necessary transition $^1(^2A + ^2B)$$$^3(^2A +^2B)$ is affected by magnetic interactions (hyperfine, Zeeman, zero field splitting) and can be influenced by magnetic fields. Examples are photoinduced electron transfer processes, e.g. the primary reaction of photosynthesis.
BibTeX: @inbook{Sch1982, author = {Schulten, Klaus}, title = {Festkörperprobleme}, publisher = {Vieweg}, year = {1982}, volume = {22}, pages = {61-83} }
Sch1986	Schulten, K. Bernhard, J.H. (Hrsg.)	Magnetic field effects on radical pair processes in chemistry and biology ( Biological Effects of Static and Extremely Low Frequency Magnetic Fields ) [Abstract] [BibTeX]	1986	Biological Effects of Static and Extremely Low Frequency Magnetic Fields , pp. 133-140	inbook	animal navigation
Abstract: Chemical and biological photoprocesses which involve reactions between paramagnetic molecules can be affected by magnetic interactions, in particular, by external magnetic fields. Examples discussed are photoinduced electron transfer reactions, the primary process in photosynthesis and other radical pair reactions. In this article we provide experimental evidence for magnetic field effects on well characterized molecular systems and explain the physical origin of these effects.
BibTeX: @inbook{Sch1986, author = {Schulten, Klaus}, title = {Biological Effects of Static and Extremely Low Frequency Magnetic Fields}, publisher = {MMV Medizin Verlag}, year = {1986}, pages = {133-140} }
SchFilKarGauBenAndArdBriMaeHenGiuMorLov2010	Schaffry, M.; Filidou, V.; Karlen, S.D.; Gauger, E.M.; Benjamin, S.C.; Anderson, H.L.; Ardavan, A.; Briggs, G.A.D.; Maeda, K.; Henbest, K.B.; Giustino, F.; Morton, J.J.L. & Lovett, B.W.	Entangling Remote Nuclear Spins Linked by a Chromophore [Abstract] [BibTeX]	2010	Phys. Rev. Lett. Vol. 104 (20) , pp. 200501	article	animal navigation
Abstract: Molecular nanostructures may constitute the fabric of future quantum technologies, if their degrees of freedom can be fully harnessed. Ideally one might use nuclear spins as low-decoherence qubits and optical excitations for fast controllable interactions. Here, we present a method for entangling two nuclear spins through their mutual coupling to a transient optically excited electron spin, and investigate its feasibility through density-functional theory and experiments on a test molecule. From our calculations we identify the specific molecular properties that permit high entangling power gates under simple optical and microwave pulses; synthesis of such molecules is possible with established techniques.
BibTeX: @article{SchFilKarGauBenAndArdBriMaeHenGiuMorLov2010, author = {Schaffry, M. and Filidou, V. and Karlen, S. D. and Gauger, E. M. and Benjamin, S. C. and Anderson, H. L. and Ardavan, A. and Briggs, G. A. D. and Maeda, K. and Henbest, K. B. and Giustino, F. and Morton, J. J. L. and Lovett, B. W.}, title = {Entangling Remote Nuclear Spins Linked by a Chromophore}, journal = {Phys. Rev. Lett.}, publisher = {American Physical Society}, year = {2010}, volume = {104}, number = {20}, pages = {200501}, doi = {http://dx.doi.org/10.1103/PhysRevLett.104.200501} }
SchmidtKoenig1980137	Schmidt-Koenig, K.	Bird orientation and navigation [Abstract] [BibTeX] [URL]	1980	Trends in Neurosciences Vol. 3 (6) , pp. 137 - 140	article	animal navigation
Abstract: Among the many animals that perform long distance migration, such as butterflies, fish, marine-turtles and marine mammals, birds represent the most impressive performers. They are also the best-studied group, with many more details known of their migratory accomplishments and the factors involved in their orientation, than in other groups. The main question of how birds actually do navigate, however, remains unanswered. In this article Professor Schmidt-Koenig reviews the available evidence and suggests that a multiplicity of cues and strategies may be involved.
BibTeX: @article{SchmidtKoenig1980137, author = {K. Schmidt-Koenig}, title = {Bird orientation and navigation}, journal = {Trends in Neurosciences}, year = {1980}, volume = {3}, number = {6}, pages = {137 - 140}, url = {http://www.sciencedirect.com/science/article/B6T0V-4D28340-1S/2/629d977e5524c11af6f30089503f4d11}, doi = {DOI: 10.1016/0166-2236(80)90051-X} }
SchSweWel1978	Schulten, K.; Swenberg, C.E. & Weller, A.	A biomagnetic sensory mechanism based on magnetic field modulated coherent electron spin motion [Abstract] [BibTeX]	1978	Zeitschrift für Physikalische Chemie Vol. NF111 , pp. 1-5	article	animal navigation
Abstract: Electron transfer processes which generate radical pairs in coherent electron spin states (singlet or triplet) are affected by weak magnetic fields [Schulten et al., Z physik. Chem. Neue Folge 101 (1976) 371]. Based on this finding we suggest a reaction mechanism for a chemical compass which exhibits a sensitivity on the orientation of the geomagnetic field originating from an anisotropy of the hyperfine interaction experienced by unpaired electron spins in a redox process. It is argued that such mechanism may explain the ability of many biological species to orient themselves in the geomagnetic field.
BibTeX: @article{SchSweWel1978, author = {Schulten, Klaus and Swenberg, Charles E. and Weller, Albert}, title = {A biomagnetic sensory mechanism based on magnetic field modulated coherent electron spin motion}, journal = {Zeitschrift für Physikalische Chemie}, year = {1978}, volume = {NF111}, pages = {1-5} }
SchWin1986	Schulten, K. & Windemuth, A. G. Maret, N.B. & Kiepenheuer, J. (Hrsg.)	Model for a physiological magnetic compass ( Biophysical Effects of Steady Magnetic Fields ) [BibTeX]	1986	Biophysical Effects of Steady Magnetic Fields Vol. 11 , pp. 99-106	inbook	animal navigation
BibTeX: @inbook{SchWin1986, author = {Schulten, Klaus and Windemuth, Andreas}, title = {Biophysical Effects of Steady Magnetic Fields}, publisher = {Springer}, year = {1986}, volume = {11}, pages = {99-106} }
SheSriWeaMayChaZheKumLeeHorHasRep2000	Shearman, L.P.; Sriram, S.; Weaver, D.R.; Maywood, E.S.; Chaves, I. e.; Zheng, B.; Kume, K.; Lee, C.C.; van der Horst, G.T.J.; Hastings, M.H. & Reppert, S.M.	Interacting Molecular Loops in the Mammalian Circadian Clock [Abstract] [BibTeX] [URL]	2000	Science Vol. 288 (5468) , pp. 1013-1019	article	animal navigation
Abstract: We show that, in the mouse, the core mechanism for the master circadian clock consists of interacting positive and negative transcription and translation feedback loops. Analysis of Clock/Clock mutant mice, homozygous Period2Brdm1 mutants, and Cryptochrome-deficient mice reveals substantially altered Bmal1 rhythms, consistent with a dominant role of PERIOD2 in the positive regulation of the Bmal1 loop. In vitro analysis of CRYPTOCHROME inhibition of CLOCK: BMAL1-mediated transcription shows that the inhibition is through direct protein:protein interactions, independent of the PERIOD and TIMELESS proteins. PERIOD2 is a positive regulator of the Bmal1 loop, and CRYPTOCHROMES are the negative regulators of the Period and Cryptochrome cycles.
BibTeX: @article{SheSriWeaMayChaZheKumLeeHorHasRep2000, author = {Shearman, Lauren P. and Sriram, Sathyanarayanan and Weaver, David R. and Maywood, Elizabeth S. and Chaves, Ins and Zheng, Binhai and Kume, Kazuhiko and Lee, Cheng Chi and van der Horst, Gijsbertus T J and Hastings, Michael H and Reppert, Steven M}, title = {Interacting Molecular Loops in the Mammalian Circadian Clock}, journal = {Science}, year = {2000}, volume = {288}, number = {5468}, pages = {1013-1019}, url = {http://www.sciencemag.org/cgi/content/abstract/288/5468/1013}, doi = {http://dx.doi.org/10.1126/science.288.5468.1013} }
SolChaSch2007	Solov'yov, I.A.; Chandler, D.E. & Schulten, K.	Magnetic field effects in Arabidopsis thaliana cryptochrome-1. [Abstract] [BibTeX]	2007	Biophysical Journal Vol. 92 , pp. 2711-2726	article	animal navigation
Abstract: The ability of some animals, most notably migratory birds, to sense magnetic fields is still poorly understood. It has been suggested that this "magnetic sense" may be mediated by the blue light receptor protein cryptochrome, which is known to be localized in the retinas of migratory birds. Cryptochromes are a class of photoreceptor signaling proteins found in a wide variety of organisms and which primarily perform regulatory functions, such as the entrainment of circadian rhythm in mammals and the inhibition of hypocotyl growth in plants. Recent experiments have shown that the activity of cryptochrome-1 in Arabidopsis thaliana is enhanced by the presence of a weak external magnetic field, confirming the ability of cryptochrome to mediate magnetic field responses. Cryptochrome's signaling is tied to the photoreduction of an internally bound chromophore, flavin adenine dinucleotide (FAD). The spin chemistry of this photoreduction process, which involves electron transfer from a chain of three tryptophans, is modulated by the presence of a magnetic field in an effect known as the radical pair mechanism. Here we present and analyze a model of the FAD-tryptophan chain system that incorporates realistic hyperfine coupling constants and reaction rate constants. Our calculations show that the radical pair mechanism in cryptochrome can produce an increase in the protein's signaling activity of approximately 10$ for magnetic fields on the order of five Gauss, which is consistent with experimental results. These calculations, combined with the high similarity between bird and plant cryptochromes, provide further support for a cryptochrome-based model of avian magnetoreception.
BibTeX: @article{SolChaSch2007, author = {Solov'yov, Ilia A. and Chandler, Danielle E. and Schulten, Klaus}, title = {Magnetic field effects in Arabidopsis thaliana cryptochrome-1.}, journal = {Biophysical Journal}, year = {2007}, volume = {92}, pages = {2711-2726} }
SolChaSch2008	Solov'yov, I.A.; Chandler, D.E. & Schulten, K.	Exploring the possibilities for radical pair effects in cryptochrome [Abstract] [BibTeX]	2008	Plant Signal Behav. Vol. 3 (9) , pp. 676-677	article	animal navigation
Abstract: The ability of some animals to sense magnetic fields has long captured the human imagination. In our recent paper, we explored how radical pair effects in the protein cryptochrome may underlie the magnetic orientation sense of migratory birds. Here we explain our model and discuss its relationship to experimental results on plant cryptochromes, as well as discuss the next steps in refining our model, and explore alternate but related possibilities for modeling and understanding cryptochrome as a magnetic sensor.
BibTeX: @article{SolChaSch2008, author = {Solov'yov, Ilia A and Chandler, Danielle E and Schulten, Klaus}, title = {Exploring the possibilities for radical pair effects in cryptochrome}, journal = {Plant Signal Behav.}, year = {2008}, volume = {3}, number = {9}, pages = {676-677} }
SolMouSch2010	Solov'yov, I.A.; Mouritsen, H. & Schulten, K.	Acuity of a cryptochrome and vision based magnetoreception system in birds [Abstract] [BibTeX]	2010	Biophysical Journal Vol. in press	article	animal navigation
Abstract: The magnetic compass of birds is embedded in the visual system and it has been hypothesized that the primary sensory mechanism is based on a radical pair reaction. Previous models of magnetoreception have assumed that the radical-pair forming molecules are rigidly fixed in space, and this assumption has been a major objection to the suggested hypothesis. In this paper, we investigate theoretically how much disorder is permitted for the radical-pair forming protein based magnetic compass in the eye to remain functional. Our study shows that only one rotational degree of freedom of the radical-pair forming protein needs to be partially constrained, while the other two rotational degrees of freedom do not impact the magnetoreceptive properties of the protein. The result implies that any membrane associated protein is sufficiently restricted in its motion to function as a radical-pair-based magnetoreceptor. We relate our theoretical findings to the cryptochromes, currently considered the likeliest candidate to furnish radical-pair based magnetoreception.
BibTeX: @article{SolMouSch2010, author = {Solov'yov, Ilia A. and Mouritsen, Henrik and Schulten, Klaus}, title = {Acuity of a cryptochrome and vision based magnetoreception system in birds}, journal = {Biophysical Journal}, year = {2010}, volume = {in press} }
SolSch2009	Solov'yov, I.A. & Schulten, K.	Magnetoreception through Cryptochrome May Involve Superoxide [Abstract] [BibTeX]	2009	Biophysical Journal Vol. 96 (12) , pp. 4804-4813	article	animal navigation
Abstract: In the last decades, it has been demonstrated that many animal species orient in the Earth magnetic field. One of the best-studied examples is the use of the geomagnetic field by migratory birds for orientation and navigation. However, the biophysical mechanism underlying animal magnetoreception is still not understood. One theory for magnetoreception in birds invokes the so-called radical-pair model. This mechanism involves a pair of reactive radicals, whose chemical fate can be influenced by the orientation with respect to the magnetic field of the Earth through Zeeman and hyperfine interactions. The fact that the geomagnetic field is weak, i.e., $asymp 0.5rm G$, puts a severe constraint on the radical pair that can establish the magnetic compass sense. For a noticeable change of the reaction yield in a redirected geomagnetic field, the hyperfine interaction has to be as weak as the Earth field Zeeman interaction, i.e., unusually weak for an organic compound. Such weak hyperfine interaction can be achieved if one of the radicals is completely devoid of this interaction as realized in a radical pair containing an oxygen molecule as one of the radicals. Accordingly, we investigate here a possible radical pair-based reaction in the photoreceptor cryptochrome that reduces the protein's flavin group from its signaling state $rm FADH^.$ to the inactive state $rm FADH^–$ (which reacts to the likewise inactive FAD) by means of the superoxide radical, $rm O_2^.–$. We argue that the spin dynamics in the suggested reaction can act as a geomagnetic compass and that the very low physiological concentration ($rm nM-mu M$) of otherwise toxic $rm O_2^.–$ is sufficient, even favorable, for the biological function.
BibTeX: @article{SolSch2009, author = {Solov'yov, Ilia A and Schulten, Klaus}, title = {Magnetoreception through Cryptochrome May Involve Superoxide}, journal = {Biophysical Journal}, year = {2009}, volume = {96}, number = {12}, pages = {4804-4813}, doi = {http://dx.doi.org/10.1016/j.bpj.2009.03.048} }
SolSchGre2010	Solov'yov, I.A.; Schulten, K. & Greiner, W.	How birds and other animals orient in the Earth magnetic field [Abstract] [BibTeX]	2010	Physik Journal Vol. 9 , pp. 23-28	article	animal navigation
Abstract: Many animals are able to sense the earth's magnetic field and use it for their orientation. Starting in the 1960s this magnetic sense was first described for higher organisms and later also experimentally shown for bacteria. The best investigated magnetic sense today is the compass of migrating birds. But even there, many details still elude the investigation.
BibTeX: @article{SolSchGre2010, author = {Solov'yov, Ilia A. and Schulten, Klaus and Greiner, Walter}, title = {How birds and other animals orient in the Earth magnetic field}, journal = {Physik Journal}, year = {2010}, volume = {9}, pages = {23-28} }
SonOztDenAraKaoZhuZhoRepSan2007	Song, S.-H.; Öztürk, N.; Denaro, T.R.; Arat, N. Kao, Y.-T.; Zhu, H.; Zhong, D.; Reppert, S.M. & Sancar, A.	Formation and Function of Flavin Anion Radical in Cryptochrome 1 Blue-Light Photoreceptor of Monarch Butterfly [Abstract] [BibTeX]	2007	Journal of Biological Chemistry Vol. 282 , pp. 17608-17612	article	animal navigation
Abstract: The monarch butterfly (Danaus plexippus) cryptochrome 1 (DpCry1) belongs in the class of photosensitive insect cryptochromes. Here we purified DpCry1 expressed in a bacterial host and obtained the protein with a stoichiometric amount of the flavin cofactor in the two-electron oxidized, $rm FAD_ox$, form. Exposure of the purified protein to light converts the $rm FAD_ox$ to the Formula flavin anion radical by intraprotein electron transfer from a Trp residue in the apoenzyme. To test whether this novel photoreduction reaction is part of the DpCry1 physiological photocycle, we mutated the Trp residue that acts as the ultimate electron donor in flavin photoreduction. The mutation, W328F, blocked the photoreduction entirely but had no measurable effect on the light-induced degradation of DpCry1 in vivo. In light of this finding and the recently published action spectrum of this class of Crys, we conclude that DpCry1 and similar insect cryptochromes do not contain flavin in the $rm FAD_ox$ form in vivo and that, most likely, the $rm FAD_oxhnuoverlongrightarrow FAD^buildrel - over .$ photoreduction reaction is not part of the insect cryptochrome photoreaction that results in proteolytic degradation of the photopigment.
BibTeX: @article{SonOztDenAraKaoZhuZhoRepSan2007, author = {Song, Sang-Hun and Öztürk, Nuri and Denaro, Tracy R and Arat, N Özlem and Kao, Ya-Ting and Zhu, Haisun and Zhong, Dongping and Reppert, Steven M and Sancar, Aziz}, title = {Formation and Function of Flavin Anion Radical in Cryptochrome 1 Blue-Light Photoreceptor of Monarch Butterfly}, journal = {Journal of Biological Chemistry}, year = {2007}, volume = {282}, pages = {17608-17612}, doi = {http://dx.doi.org/10.1074/jbc.M702874200} }
Srygley2006183	Srygley, R.B.; Dudley, R.; Oliveira, E.G. & Riveros, A.J.	Experimental evidence for a magnetic sense in Neotropical migrating butterflies (Lepidoptera: Pieridae) [Abstract] [BibTeX] [URL]	2006	Animal Behaviour Vol. 71 (1) , pp. 183 - 191	article	animal navigation
Abstract: We tested whether migrating Aphrissa statira butterflies orient with a magnetic compass. We captured migrants flying over Lake Gatún, Panama, and exposed experimental butterflies to a strong magnetic field. These and unmanipulated control butterflies were released back over the lake. Experimental butterflies had a more dispersed pattern of orientation than control butterflies. The average direction adopted was northeast, 160° anticlockwise to the natural migratory direction. Unmanipulated control butterflies adopted two diametrically opposed orientations: one shifted 33° clockwise, and another 147° anticlockwise, to the migratory direction. Control and experimental butterflies differed in that some controls oriented towards the migratory direction. These differences in orientation support the hypothesis of a sense for magnetic orientation cues. Unmanipulated butterflies released over the lake when the sky was completely overcast were significantly oriented towards their direction before capture (187° and 203°, respectively), further supporting the magnetic compass hypothesis. In a third experiment, we obstructed sun compass cues and reversed the horizontal component of the local geomagnetic field to position magnetic north towards the geographical south pole within a flight arena into which we released individual butterflies. Experimental butterflies experiencing the reversed magnetic field oriented on average 180° opposite to their natural migratory direction. Control butterflies, for which the position of magnetic north was unaltered, were oriented both towards and 180° opposite to the natural migratory direction. This difference between orientations of control and experimental butterflies also supports the hypothesis of a sense for magnetic orientation cues.
BibTeX: @article{Srygley2006183, author = {Robert B. Srygley and Robert Dudley and Evandro G. Oliveira and Andre J. Riveros}, title = {Experimental evidence for a magnetic sense in Neotropical migrating butterflies (Lepidoptera: Pieridae)}, journal = {Animal Behaviour}, year = {2006}, volume = {71}, number = {1}, pages = {183 - 191}, url = {http://www.sciencedirect.com/science/article/B6W9W-4HS3BYD-4/2/1ed5dd1b2f35c36faa7ce9edea79fd67}, doi = {DOI: 10.1016/j.anbehav.2005.04.013} }
StaNaq1977	Staerk, H. & Naqvi, K.R.	Magnetic field effects on spin-rephasing in a photochemically produced radical pair investigated by a double-pulse technique using a nitrogen laser [Abstract] [BibTeX] [URL]	1977	Chemical Physics Letters Vol. 50 (3) , pp. 386 - 388	article	animal navigation
Abstract: The effect of an external magnetic field on the yield of the benzophenone ketyl radical has been investigated by a new, double-pulse technique. The technique and its variants can be used not only for studying geminate recombination of photochemically produced radical pairs but also for continuous photoelectric recording of fluorescence spectra of the free radicals which can be generated by nitrogen laser irradiation.
BibTeX: @article{StaNaq1977, author = {Staerk, Hubert and Naqvi, K. Razi}, title = {Magnetic field effects on spin-rephasing in a photochemically produced radical pair investigated by a double-pulse technique using a nitrogen laser}, journal = {Chemical Physics Letters}, year = {1977}, volume = {50}, number = {3}, pages = {386 - 388}, url = {http://www.sciencedirect.com/science/article/B6TFN-44XDJ5Y-B2/2/421d8d683fd7a77d4076246d1b3d2a11}, doi = {DOI: 10.1016/0009-2614(77)80349-7} }
Stapput2008602	Stapput, K.; Thalau, P.; Wiltschko, R. & Wiltschko, W.	Orientation of Birds in Total Darkness [Abstract] [BibTeX] [URL]	2008	Current Biology Vol. 18 (8) , pp. 602 - 606	article	animal navigation
Abstract: Summary Magnetic compass orientation of migratory birds is known to be light dependent [1], [2], [3] and [4], and radical-pair processes have been identified as the underlying mechanism [5] and [6]. Here we report for the first time results of tests with European robins, Erithacus rubecula, in total darkness and, as a control, under 565 nm green light. Under green light, the robins oriented in their normal migratory direction, with southerly headings in autumn and northerly headings in spring. By contrast, in darkness they significantly preferred westerly directions in spring as well as autumn. This failure to show the normal seasonal change characterizes the orientation in total darkness as a #fixed##direction# response. Tests in magnetic fields with the vertical or the horizontal component inverted showed that the preferred direction depended on the magnetic field but did not involve the avian inclination compass. A high-frequency field of 1.315 MHz did not affect the behavior, whereas local anesthesia of the upper beak resulted in disorientation. The behavior in darkness is thus fundamentally different from normal compass orientation and relies on another source of magnetic information: It does not involve the radical-pair mechanism but rather originates in the iron-containing receptors in the upper beak.
BibTeX: @article{Stapput2008602, author = {Katrin Stapput and Peter Thalau and Roswitha Wiltschko and Wolfgang Wiltschko}, title = {Orientation of Birds in Total Darkness}, journal = {Current Biology}, year = {2008}, volume = {18}, number = {8}, pages = {602 - 606}, url = {http://www.sciencedirect.com/science/article/B6VRT-4S9G217-3/2/7f59b163a3e2fc2a5eb113c2654e6757}, doi = {DOI: 10.1016/j.cub.2008.03.046} }
tagkey200621		Bats have magnetic super-sense [BibTeX] [URL]	2006	The New Scientist Vol. 192 (2581) , pp. 21 - 21	article	animal navigation
BibTeX: @article{tagkey200621,, title = {Bats have magnetic super-sense}, journal = {The New Scientist}, year = {2006}, volume = {192}, number = {2581}, pages = {21 - 21}, url = {http://www.sciencedirect.com/science/article/B83WY-4MHPVJP-10/2/4c0932ffbe53441798f0ae5f7ef7992a}, doi = {DOI: 10.1016/S0262-4079(06)61315-8} }
tagkey200918		Birds seem to [`]see' magnetic fields while navigating [Abstract] [BibTeX] [URL]	2009	The New Scientist Vol. 204 (2732) , pp. 18 - 18	article	animal navigation
Abstract: An experiment with European robins suggests that birds that navigate using the Earth's magnetic field rely more on their eyes than on magnetic particles in their noses
BibTeX: @article{tagkey200918,, title = {Birds seem to [`]see' magnetic fields while navigating}, journal = {The New Scientist}, year = {2009}, volume = {204}, number = {2732}, pages = {18 - 18}, url = {http://www.sciencedirect.com/science/article/B83WY-4XK47BN-P/2/2f8de13e6ec4fac65ebdeb9b88ff46e5}, doi = {DOI: 10.1016/S0262-4079(09)62854-2} }
TimCinBroHor2001	Timmel, C.; Cintolesi, F.; Brocklehurst, B. & Hore, P.	Model calculations of magnetic field effects on the recombination reactions of radicals with anisotropic hyperfine interactions [Abstract] [BibTeX] [URL]	2001	Chemical Physics Letters Vol. 334 (4-6) , pp. 387 - 395	article	animal navigation
Abstract: The effects of anisotropic hyperfine interactions on the recombination reactions of spin correlated radical pairs in a weak applied magnetic field are discussed in the context of the radical pair mechanism (RPM). Model calculations are presented for radical pairs containing a single spin-1/2 nucleus with an axial or rhombic coupling to one of the unpaired electrons. The so-called low field effect (LFE) and various resonances in the magnetic field effect (MFE) are calculated. Approximate analytical expressions are given for the field positions of the resonances which are shown to arise from energy level crossings.
BibTeX: @article{TimCinBroHor2001, author = {C.R. Timmel and F. Cintolesi and B. Brocklehurst and P.J. Hore}, title = {Model calculations of magnetic field effects on the recombination reactions of radicals with anisotropic hyperfine interactions}, journal = {Chemical Physics Letters}, year = {2001}, volume = {334}, number = {4-6}, pages = {387 - 395}, url = {http://www.sciencedirect.com/science/article/B6TFN-429XS6T-X/2/4624d4b1a273ca349477e9ba8709e052}, doi = {DOI: 10.1016/S0009-2614(00)01436-6} }
UgoPez1995	Ugolini, A. & Pezzani, A.	Magnetic compass and learning of the Y axis (sea-land) direction in the marine isopodIdotea baltica basteri [Abstract] [BibTeX] [URL]	1995	Animal Behaviour Vol. 50 (2) , pp. 295 - 300	article	animal navigation
Abstract: Dark room trials on adult marine isopods,Idotea baltica basteri, under the natural magnetic field, with an artificial magnetic field deviated to the west, and with the horizontal component zeroed, showed that this species possesses a magnetic compass. Experiments revealed thatI. balticacan change its magnetic compass set point using information supplied by local orienting cues.
BibTeX: @article{UgoPez1995, author = {Ugolini, Alberto and Pezzani, Angela}, title = {Magnetic compass and learning of the Y axis (sea-land) direction in the marine isopodIdotea baltica basteri}, journal = {Animal Behaviour}, year = {1995}, volume = {50}, number = {2}, pages = {295 - 300}, url = {http://www.sciencedirect.com/science/article/B6W9W-45NHYBS-2/2/df4099632f55ffcaaea565a3d496e629}, doi = {DOI: 10.1006/anbe.1995.0245} }
Vargas2006158	Vargas, J.P.; Siegel, J.J. & Bingman, V.P.	The effects of a changing ambient magnetic field on single-unit activity in the homing pigeon hippocampus [Abstract] [BibTeX] [URL]	2006	Brain Research Bulletin Vol. 70 (2) , pp. 158 - 164	article	animal navigation; birds; columba livia; geomagnetic field; spatial orientation; magnetoreception
Abstract: The central representation of geomagnetic information in the avian brain continues to challenge researchers. Although the homing pigeon hippocampal formation primarily participates in the map-like representation of landmarks, some suggestive data indicate that it may also participate in spatial behavior guided by geomagnetic information. Forty-four isolated neurons were recorded from the hippocampal formation of homing pigeons trained to shuttle between two goal locations under changing (direction and intensity, and direction only) magnetic field conditions. Of the 37 slow-firing cells sampled (<14 spikes/s), none displayed a change in firing rate at the time of magnetic field transitions or during different ambient magnetic field conditions. By contrast, three of seven fast firing cells (>17 spikes/s) clearly displayed a phasic increase in firing during at least one of the magnetic field transitions used. The results are consistent with the hypothesis that a subset of hippocampal formation neurons receives information regarding changes in the earth's magnetic field that may be used to guide behavior.
BibTeX: @article{Vargas2006158, author = {Juan Pedro Vargas and Jennifer J. Siegel and Verner P. Bingman}, title = {The effects of a changing ambient magnetic field on single-unit activity in the homing pigeon hippocampus}, journal = {Brain Research Bulletin}, year = {2006}, volume = {70}, number = {2}, pages = {158 - 164}, url = {http://www.sciencedirect.com/science/article/B6SYT-4JS1XP6-1/2/bf43edc9fe75eb9ef395d1f57b1f8977}, doi = {DOI: 10.1016/j.brainresbull.2006.03.018} }
Voustianiouk20001934	Voustianiouk, A. & Kaufmann, H.	Magnetic fields and the central nervous system [BibTeX] [URL]	2000	Clinical Neurophysiology Vol. 111 (11) , pp. 1934 - 1935	article	animal navigation
BibTeX: @article{Voustianiouk20001934, author = {Andrei Voustianiouk and Horacio Kaufmann}, title = {Magnetic fields and the central nervous system}, journal = {Clinical Neurophysiology}, year = {2000}, volume = {111}, number = {11}, pages = {1934 - 1935}, url = {http://www.sciencedirect.com/science/article/B6VNP-41JTNGT-5/2/9da171572836b386abcfee3af239547f}, doi = {DOI: 10.1016/S1388-2457(00)00487-9} }
WajAcoAlvOliFerSryEsq2010	Wajnberg, E.; Acosta-Avalos, D.; Alves, O.C.; de Oliveira, J.F.; Srygley, R.B. & Esquivel, D.M.S.	Magnetoreception in eusocial insects: an update [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S207-S225	article	animal navigation
Abstract: Behavioural experiments for magnetoreception in eusocial insects in the last decade are reviewed. Ants and bees use the geomagnetic field to orient and navigate in areas around their nests and along migratory paths. Bees show sensitivity to small changes in magnetic fields in conditioning experiments and when exiting the hive. For the first time, the magnetic properties of the nanoparticles found in eusocial insects, obtained by magnetic techniques and electron microscopy, are reviewed. Different magnetic oxide nanoparticles, ranging from superparamagnetic to multi-domain particles, were observed in all body parts, but greater relative concentrations in the abdomens and antennae of honeybees and ants have focused attention on these segments. Theoretical models for how these specific magnetosensory apparatuses function have been proposed. Neuron-rich ant antennae may be the most amenable to discovering a magnetosensor that will greatly assist research into higher order processing of magnetic information. The ferromagnetic hypothesis is believed to apply to eusocial insects, but interest in a light-sensitive mechanism is growing. The diversity of compass mechanisms in animals suggests that multiple compasses may function in insect orientation and navigation. The search for magnetic compasses will continue even after a magnetosensor is discovered in eusocial insects.
BibTeX: @article{WajAcoAlvOliFerSryEsq2010, author = {Wajnberg, Eliane and Acosta-Avalos, Daniel and Alves, Odivaldo Cambraia and de Oliveira, Jandira Ferreira and Srygley, Robert B. and Esquivel, Darci M. S.}, title = {Magnetoreception in eusocial insects: an update}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S207-S225}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S207.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0526.focus} }
WakHay1994	Wakasa, M. & Hayashi, H.	Magnetic field effect on the dynamic behavior of a radical pair involving an Sn-centered radical [Abstract] [BibTeX] [URL]	1994	Chemical Physics Letters Vol. 229 (1-2) , pp. 122 - 126	article	animal navigation
Abstract: The photoreduction of xanthone with triethyltinhydride in a sodium dodecylsulfate solution was investigated with the aid of a time-resolved ESR and a nanosecond laser flash photolysis. Upon irradiation of xanthone with triethyltinhydride, the hydrogen abstraction occurred and the ketyl-type and cyclohexadienyl-type radicals were observed by CIDEP spectra. The escaped xanthone ketyl radical increased with increasing magnetic field strength up to 1.29 T. The observed magnetic filed effects can be interpreted by a combination of the hyperfine coupling and the relaxation mechanisms in the case of a triplet radical pair.
BibTeX: @article{WakHay1994, author = {Wakasa, Masanobu and Hayashi, Hisaharu}, title = {Magnetic field effect on the dynamic behavior of a radical pair involving an Sn-centered radical}, journal = {Chemical Physics Letters}, year = {1994}, volume = {229}, number = {1-2}, pages = {122 - 126}, url = {http://www.sciencedirect.com/science/article/B6TFN-45DHM54-R/2/24d1ac31a927fd6aa1cec73cc8fdfdc1}, doi = {DOI: 10.1016/0009-2614(94)01014-5} }
WalDieHauPanMonGre1997	Walker, M.M.; Diebel, C.E.; Haugh, C.V.; Pankhurst, P.M.; Montgomery, J.C. & Green, C.R.	Structure and function of the vertebrate magnetic sense [Abstract] [BibTeX] [URL]	1997	Nature Vol. 390 (6658) , pp. 371-376	article	animal navigation
Abstract: Some vertebrates can navigate over long distances using the Earth's magnetic field, but the sensory system that they use to do so has remained a mystery. Here we describe the key components of a magnetic sense underpinning this navigational ability in a single species, the rainbow trout ( Oncorhynchus mykiss). We report behavioural and electrophysiological responses to magnetic fields and identify an area in the nose of the trout where candidate magnetoreceptor cells are located. We have tracked the sensory pathway from these newly identified candidate magnetoreceptor cells to the brain and associated the system with a learned response to magnetic fields.
BibTeX: @article{WalDieHauPanMonGre1997, author = {Walker, Michael M. and Diebel, Carol E. and Haugh, Cordula V. and Pankhurst, Patricia M. and Montgomery, John C. and Green, Colin R.}, title = {Structure and function of the vertebrate magnetic sense}, journal = {Nature}, year = {1997}, volume = {390}, number = {6658}, pages = {371-376}, url = {http://dx.doi.org/10.1038/37057} }
Wallraff1983643	Wallraff, H.G.	Relevance of atmospheric odours and geomagnetic field to pigeon navigation: What is the #map# basis? [Abstract] [BibTeX] [URL]	1983	Comparative Biochemistry and Physiology Part A: Physiology Vol. 76 (4) , pp. 643 - 663	article	animal navigation
Abstract: 1. 1. Pigeon homing is highly affected by olfactory deprivation, as can be seen from an almost complete lack of homeward orientation of initial bearings, from widely dispersed recovery sites, and from a strong reduction of homing success which achieves, in inexperienced pigeons displaced over longer distances, a level of zero. 2. 2. Orientational deficits can be produced not only by various methods to eliminate the sense of smell, but also by elimination of odorous substances from the ambient air. 3. 3. It is concluded that the observed deficits result from an interruption of an information flow necessary for navigation, and are not due to some general, nonspecific distraction or reduced motivation to home. 4. 4. The range of olfactory navigation is large (radius up to 500 km and more), but not unlimited. Within this range, the pigeons do not depend on olfactory stimuli perceived during displacement to the release site. 5. 5. Despite some controversial discussions of the matter, no experimental findings have been published contradicting the above statements and conclusions. 6. 6. Experimental interference with perception of the geomagnetic field resulted, under sun (and thus with the sun compass capable to operate), in increased scatter of initial bearings, sometimes in slightly reduced homing speeds, but not in disoriented or poorly oriented recovery bearings and not in reduced homing success. 7. 7. Correlations between initial orientation and spatial as well as temporal variations of the geomagnetic field, as reported by several authors, are unsuited to prove involvement of geomagnetism in the process of site localization. 8. 8. It is concluded that atmospheric odours are a necessary component of the pigeons' navigational #map# system, whereas the geomagnetic field is not. It seems unlikely that the latter is involved in this system at all, and if it is, its role is expected to be quite subordinate and redundant at best.
BibTeX: @article{Wallraff1983643, author = {Hans G Wallraff}, title = {Relevance of atmospheric odours and geomagnetic field to pigeon navigation: What is the #map# basis?}, journal = {Comparative Biochemistry and Physiology Part A: Physiology}, year = {1983}, volume = {76}, number = {4}, pages = {643 - 663}, url = {http://www.sciencedirect.com/science/article/B6T2P-4867WV1-XV/2/8ddf67596456a4c6b25b18d3ce6f4392}, doi = {DOI: 10.1016/0300-9629(83)90126-3} }
Weindler1995227	Weindler, P.; Beck, W.; Liepa, V. & Wiltschko, W.	Development of migratory orientation in pied flycatchers in different magnetic inclinations [Abstract] [BibTeX] [URL]	1995	Animal Behaviour Vol. 49 (1) , pp. 227 - 234	article	animal navigation
Abstract: To examine whether magnetic orientation in young birds was affected by magnetic conditions in the region where they grew up, the orientation behaviour of pied flycatchers, Ficedula hypoleuca (Muscicapidae), hand-raised in Riga, Latvia (50 000 nT, 73° inclination), was compared with that of conspecifics hand-raised in Frankfurt a.M., Germany (46 000 nT, 66° inclination). Orientation was recorded during autumn migration in funnel cages in the local geomagnetic field under non-visual conditions. Birds that had been hand-raised in Germany without a view of the sky showed a unimodal tendency in their migratory direction, whereas in Latvia, the behaviour of birds raised under similar conditions was bimodal along the migratory axis. A second group of Latvian birds that had been exposed to a rotating planetarium sky prior to the tests also showed a unimodal preference. This suggests that celestial rotation observed during the pre-migratory period may play an important role in helping birds to decide which end of the magnetic axis points towards the wintering area.
BibTeX: @article{Weindler1995227, author = {Peter Weindler and Willy Beck and Varis Liepa and Wolfgang Wiltschko}, title = {Development of migratory orientation in pied flycatchers in different magnetic inclinations}, journal = {Animal Behaviour}, year = {1995}, volume = {49}, number = {1}, pages = {227 - 234}, url = {http://www.sciencedirect.com/science/article/B6W9W-4B7PWGF-V/2/b26e6b7533ee71521ea7695bc42c682b}, doi = {DOI: 10.1016/0003-3472(95)80171-5} }
WilMunForWil2008	Wiltschko, R.; Munro, U.; Ford, H. & Wiltschko, W.	Response to the comments by R. Muheim, S. Åkesson, and J.B. Phillips to our paper “Contradictory results on the role of polarized light in compass calibration in migratory songbirds” [BibTeX] [URL] [NOTE]	2008	Journal of Ornithology Vol. 149 , pp. 663-664	article	animal navigation
BibTeX: @article{WilMunForWil2008, author = {Wiltschko, Roswitha and Munro, Ursula and Ford, Hugh and Wiltschko, Wolfgang}, title = {Response to the comments by R. Muheim, S. Åkesson, and J.B. Phillips to our paper “Contradictory results on the role of polarized light in compass calibration in migratory songbirds”}, journal = {Journal of Ornithology}, publisher = {Springer Berlin / Heidelberg}, year = {2008}, volume = {149}, pages = {663-664}, note = {10.1007/s10336-008-0336-4}, url = {http://dx.doi.org/10.1007/s10336-008-0336-4} }
WilStaThaWil2010	Wiltschko, R.; Stapput, K.; Thalau, P. & Wiltschko, W.	Directional orientation of birds by the magnetic field under different light conditions [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S163-S177	article	animal navigation
Abstract: This paper reviews the directional orientation of birds with the help of the geomagnetic field under various light conditions. Two fundamentally different types of response can be distinguished. (i) Compass orientation controlled by the inclination compass that allows birds to locate courses of different origin. This is restricted to a narrow functional window around the total intensity of the local geomagnetic field and requires light from the short-wavelength part of the spectrum. The compass is based on radical-pair processes in the right eye; magnetite-based receptors in the beak are not involved. Compass orientation is observed under "white" and low-level monochromatic light from ultraviolet (UV) to about 565 nm green light. (ii) "Fixed direction" responses occur under artificial light conditions such as more intense monochromatic light, when 590 nm yellow light is added to short-wavelength light, and in total darkness. The manifestation of these responses depends on the ambient light regime and is "fixed" in the sense of not showing the normal change between spring and autumn; their biological significance is unclear. In contrast to compass orientation, fixed-direction responses are polar magnetic responses and occur within a wide range of magnetic intensities. They are disrupted by local anaesthesia of the upper beak, which indicates that the respective magnetic information is mediated by iron-based receptors located there. The influence of light conditions on the two types of response suggests complex interactions between magnetoreceptors in the right eye, those in the upper beak and the visual system.
BibTeX: @article{WilStaThaWil2010, author = {Wiltschko, Roswitha and Stapput, Katrin and Thalau, Peter and Wiltschko, Wolfgang}, title = {Directional orientation of birds by the magnetic field under different light conditions}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S163-S177}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S163.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0367.focus} }
Wiltschko1980140	Wiltschko, W.	The earth's magnetic field and bird orientation [Abstract] [BibTeX] [URL]	1980	Trends in Neurosciences Vol. 3 (6) , pp. 140 - 144	article	animal navigation
Abstract: Although once a suggestion regarded with derision, the influence natural magnetic fields have on behaviour is now an established fact. The ability to detect the direction of ambient magnetic fields provides an important directional cue for birds and may underlie the navigational abilities of many different species, as Wolfgang Wiltschko describes in this review.
BibTeX: @article{Wiltschko1980140, author = {Wolfgang Wiltschko}, title = {The earth's magnetic field and bird orientation}, journal = {Trends in Neurosciences}, year = {1980}, volume = {3}, number = {6}, pages = {140 - 144}, url = {http://www.sciencedirect.com/science/article/B6T0V-4D28340-1T/2/7d3e05247f94b3611e656fda5561f9f1}, doi = {DOI: 10.1016/0166-2236(80)90052-1} }
Wiltschko1983701	Wiltschko, R.	The ontogeny of orientation in young pigeons [Abstract] [BibTeX] [URL]	1983	Comparative Biochemistry and Physiology Part A: Physiology Vol. 76 (4) , pp. 701 - 708	article	animal navigation
Abstract: When young pigeons begin to fly, their only means of orientation appears to be a magnetic compass provided by their innate ability to perceive the geomagnetic field. This magnetic compass enables the birds to calibrate other potential orientation stimuli found in their environment thus establishing complex learned mechanisms of orientation preferentially used by experienced birds, like the sun compass and the navigational #map#. The learning processes are described and discussed.
BibTeX: @article{Wiltschko1983701, author = {Roswitha Wiltschko}, title = {The ontogeny of orientation in young pigeons}, journal = {Comparative Biochemistry and Physiology Part A: Physiology}, year = {1983}, volume = {76}, number = {4}, pages = {701 - 708}, url = {http://www.sciencedirect.com/science/article/B6T2P-4867WV1-Y1/2/847827ec58c4ef2523ec339cf4aaad13}, doi = {DOI: 10.1016/0300-9629(83)90131-7} }
Wiltschko1983709	Wiltschko, W.	Compasses used by birds [Abstract] [BibTeX] [URL]	1983	Comparative Biochemistry and Physiology Part A: Physiology Vol. 76 (4) , pp. 709 - 717	article	animal navigation
Abstract: Birds can make use of the geomagnetic field, of the sun and the stars to find geographic directions. The magnetic compass represents an innate mechanism based on the birds' ability to perceive the earth's magnetic field while the sun compass and the star compass are learned. In the establishment of the latter, celestial rotation as well as the magnetic field have been shown to be involved. The operation modes of these compass systems and also the role of other factors known to affect birds' directional selections (e.g. sunset point, landmarks, wind etc.) are described and discussed.
BibTeX: @article{Wiltschko1983709, author = {Wolfgang Wiltschko}, title = {Compasses used by birds}, journal = {Comparative Biochemistry and Physiology Part A: Physiology}, year = {1983}, volume = {76}, number = {4}, pages = {709 - 717}, url = {http://www.sciencedirect.com/science/article/B6T2P-4867WV1-Y2/2/b2519f09627e8be2a9cf3d1c24569484}, doi = {DOI: 10.1016/0300-9629(83)90132-9} }
Wiltschko198813	Wiltschko, W. & Wiltschko, R.	Magnetic versus celestial orientation in migrating birds [Abstract] [BibTeX] [URL]	1988	Trends in Ecology & Evolution Vol. 3 (1) , pp. 13 - 15	article	animal navigation
Abstract: When experimental orientation research began more than 35 years ago, the sun, the stars and later the magnetic field were shown to be involved in the orientation of migrating birds, together with wind, weather and certain landscape features. The interaction of these cues, however, was little understood and became a subject of intensive research. Just recently we have begun to understand how these different mechanisms might work together to enable birds to cope with the navigational tasks of migration over distances of up to 5000 km and more.
BibTeX: @article{Wiltschko198813, author = {Wolfgang Wiltschko and Roswitha Wiltschko}, title = {Magnetic versus celestial orientation in migrating birds}, journal = {Trends in Ecology & Evolution}, year = {1988}, volume = {3}, number = {1}, pages = {13 - 15}, url = {http://www.sciencedirect.com/science/article/B6VJ1-49YDDX7-27/2/4c3ea7c169ae0320832c0207b774ce2f}, doi = {DOI: 10.1016/0169-5347(88)90076-6} }
Wiltschko1998155	Wiltschko, W. & Wiltschko, R. Balda, R.P.; Pepperberg, I.M. & Kamil, A.C. (Hrsg.)	The Navigation System of Birds and Its Development [BibTeX] [URL]	1998	Animal Cognition in Nature , pp. 155 - 199	incollection	animal navigation
BibTeX: @incollection{Wiltschko1998155, author = {Wolfgang Wiltschko and Roswitha Wiltschko}, title = {The Navigation System of Birds and Its Development}, booktitle = {Animal Cognition in Nature}, publisher = {Academic Press}, year = {1998}, pages = {155 - 199}, url = {http://www.sciencedirect.com/science/article/B83XW-4MT66YV-5/2/ef37a6156e17ef5c74a268c7320289c0}, doi = {DOI: 10.1016/B978-012077030-4/50058-1} }
Wiltschko2000S107	Wiltschko, W. & Wiltschko, R.	Interaction of magnetic and celestial cues in migratory oriention [BibTeX] [URL]	2000	Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology Vol. 126 (Supplement 1) , pp. S107 - S107	article	animal navigation
BibTeX: @article{Wiltschko2000S107, author = {Wolfgang Wiltschko and Roswitha Wiltschko}, title = {Interaction of magnetic and celestial cues in migratory oriention}, journal = {Comparative Biochemistry and Physiology Part B: Biochemistry and Molecular Biology}, year = {2000}, volume = {126}, number = {Supplement 1}, pages = {S107 - S107}, url = {http://www.sciencedirect.com/science/article/B6T2R-455P78J-7H/2/3028e21edf71cd3b66c527a3fc87b39f}, doi = {DOI: 10.1016/S0305-0491(00)80211-4} }
Wiltschko20051518	Wiltschko, R.; Ritz, T.; Stapput, K.; Thalau, P. & Wiltschko, W.	Two Different Types of Light-Dependent Responses to Magnetic Fields in Birds [Abstract] [BibTeX] [URL]	2005	Current Biology Vol. 15 (16) , pp. 1518 - 1523	article	animal navigation
Abstract: Summary A model of magnetoreception [1] proposes that the avian magnetic compass is based on a radical pair mechanism, with photon absorption leading to the formation of radical pairs. Analyzing the predicted light dependency by testing migratory birds under monochromatic lights, we found that the responses of birds change with increasing intensity [2]. The analysis of the orientation of European robins under 502 nm turquoise light revealed two types of responses depending on light intensity: under a quantal flux of 8·1015 quanta m-2 s-1, the birds showed normal migratory orientation in spring as well as in autumn, relying on their inclination compass [3]. Under brighter light of 54·1015 quanta m-2 s-1, however, they showed a #fixed# tendency toward north that did not undergo the seasonal change and proved to be based on magnetic polarity, not involving the inclination compass. When birds were exposed to a weak oscillating field, which specifically interferes with radical pair processes [4], the inclination compass response was disrupted, whereas the response to magnetic polarity remained unaffected. These findings indicate that the normal inclination compass used for migratory orientation is based on a radical-pair mechanism, whereas the fixed direction represents a novel type of light-dependent orientation based on a mechanism of a different nature.
BibTeX: @article{Wiltschko20051518, author = {Roswitha Wiltschko and Thorsten Ritz and Katrin Stapput and Peter Thalau and Wolfgang Wiltschko}, title = {Two Different Types of Light-Dependent Responses to Magnetic Fields in Birds}, journal = {Current Biology}, year = {2005}, volume = {15}, number = {16}, pages = {1518 - 1523}, url = {http://www.sciencedirect.com/science/article/B6VRT-4GXV66S-T/2/715cb7a0c2d0f003024a721ec5992e8c}, doi = {DOI: 10.1016/j.cub.2005.07.037} }
WilWilGunWilPri2010	Wilzeck, C.; Wiltschko, W.; Gütürkün, O.; Wiltschko, R. & Prior, H.	Lateralization of magnetic compass orientation in pigeons [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S235-S240	article	animal navigation
Abstract: The aim of our study was to test for lateralization of magnetic compass orientation in pigeons. Having shown that pigeons are capable of learning magnetic compass directions in an operant task, we wanted to know whether the brain hemispheres contribute differently and how the lateralization pattern relates to findings in other avian species. Birds that had learnt to locate food in an operant chamber by means of magnetic directions were tested for lateralization of magnetic compass orientation by temporarily covering one eye. Successful orientation occurred under all conditions of viewing. Thus, pigeons can perceive and process magnetic compass directions with the right eye and left brain hemisphere as well as the left eye and right brain hemisphere. However, while the right brain hemisphere tended to confuse the learned direction with its opposite (axial response), the left brain hemisphere specifically preferred the correct direction. Our findings demonstrate bilateral processing of magnetic information, but also suggest qualitative differences in how the left and the right brain deal with magnetic cues.
BibTeX: @article{WilWilGunWilPri2010, author = {Wilzeck, Christiane and Wiltschko, Wolfgang and Gütürkün, Onur and Wiltschko, Roswitha and Prior, Helmut}, title = {Lateralization of magnetic compass orientation in pigeons}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S235-S240}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S235.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0436.focus} }
Win2010	Winklhofer, M.	Magnetoreception [BibTeX]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S131-S134	article	animal navigation
BibTeX: @article{Win2010, author = {Winklhofer, Michael}, title = {Magnetoreception}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S131-S134}, doi = {http://dx.doi.org/10.1098/rsif.2010.0010.focus} }
WinKir2010	Winklhofer, M. & Kirschvink, J.L.	A quantitative assessment of torque-transducer models for magnetoreception [Abstract] [BibTeX] [URL]	2010	Journal of The Royal Society Interface Vol. 7 (Supplement 2) , pp. S273-S289	article	animal navigation
Abstract: Although ferrimagnetic material appears suitable as a basis of magnetic field perception in animals, it is not known by which mechanism magnetic particles may transduce the magnetic field into a nerve signal. Provided that magnetic particles have remanence or anisotropic magnetic susceptibility, an external magnetic field will exert a torque and may physically twist them. Several models of such biological magnetic-torque transducers on the basis of magnetite have been proposed in the literature. We analyse from first principles the conditions under which they are viable. Models based on biogenic single-domain magnetite prove both effective and efficient, irrespective of whether the magnetic structure is coupled to mechanosensitive ion channels or to an indirect transduction pathway that exploits the strayfield produced by the magnetic structure at different field orientations. On the other hand, torque-detector models that are based on magnetic multi-domain particles in the vestibular organs turn out to be ineffective. Also, we provide a generic classification scheme of torque transducers in terms of axial or polar output, within which we discuss the results from behavioural experiments conducted under altered field conditions or with pulsed fields. We find that the common assertion that a magnetoreceptor based on single-domain magnetite could not form the basis for an inclination compass does not always hold.
BibTeX: @article{WinKir2010, author = {Winklhofer, Michael and Kirschvink, Joseph L.}, title = {A quantitative assessment of torque-transducer models for magnetoreception}, journal = {Journal of The Royal Society Interface}, year = {2010}, volume = {7}, number = {Supplement 2}, pages = {S273-S289}, url = {http://rsif.royalsocietypublishing.org/content/7/Suppl_2/S273.abstract}, doi = {http://dx.doi.org/10.1098/rsif.2009.0435.focus} }
ZhuCasRep2008	Zhu, H.; Casselman, A. & Reppert, S.M.	Chasing Migration Genes: A Brain Expressed Sequence Tag Resource for Summer and Migratory Monarch Butterflies (Danaus plexippus) [Abstract] [BibTeX]	2008	PLoS ONE Vol. 3 (1) , pp. e1345	article	animal navigation
Abstract: North American monarch butterflies (Danaus plexippus) undergo a spectacular fall migration. In contrast to summer butterflies, migrants are juvenile hormone (JH) deficient, which leads to reproductive diapause and increased longevity. Migrants also utilize time-compensated sun compass orientation to help them navigate to their overwintering grounds. Here, we describe a brain expressed sequence tag (EST) resource to identify genes involved in migratory behaviors. A brain EST library was constructed from summer and migrating butterflies. Of 9,484 unique sequences, 6068 had positive hits with the non-redundant protein database; the EST database likely represents $asymp 52 of the gene-encoding potential of the monarch genome. The brain transcriptome was cataloged using Gene Ontology and compared to Drosophila. Monarch genes were well represented, including those implicated in behavior. Three genes involved in increased JH activity (allatotropin, juvenile hormone acid methyltransfersase, and takeout) were upregulated in summer butterflies, compared to migrants. The locomotion-relevant turtle gene was marginally upregulated in migrants, while the foraging and single-minded genes were not differentially regulated. Many of the genes important for the monarch circadian clock mechanism (involved in sun compass orientation) were in the EST resource, including the newly identified cryptochrome 2. The EST database also revealed a novel $rm Na^+/K^+$ ATPase allele predicted to be more resistant to the toxic effects of milkweed than that reported previously. Potential genetic markers were identified from 3,486 EST contigs and included 1599 double-hit single nucleotide polymorphisms (SNPs) and 98 microsatellite polymorphisms. These data provide a template of the brain transcriptome for the monarch butterfly. Our "snap-shot" analysis of the differential regulation of candidate genes between summer and migratory butterflies suggests that unbiased, comprehensive transcriptional profiling will inform the molecular basis of migration. The identified SNPs and microsatellite polymorphisms can be used as genetic markers to address questions of population and subspecies structure.
BibTeX: @article{ZhuCasRep2008, author = {Zhu, Haisun and Casselman, Amy and Reppert, Steven M}, title = {Chasing Migration Genes: A Brain Expressed Sequence Tag Resource for Summer and Migratory Monarch Butterflies (Danaus plexippus)}, journal = {PLoS ONE}, year = {2008}, volume = {3}, number = {1}, pages = {e1345}, doi = {http://dx.doi.org/10.1371/journal.pone.0001345} }
ZhuGegCasKanRep2009	Zhu, H.; Gegear, R.J.; Casselman, A.; Kanginakudru, S. & Reppert, S.M.	Defining behavioral and molecular differences between summer and migratory monarch butterflies [Abstract] [BibTeX]	2009	BMC Biology Vol. 7 (14)	article	animal navigation
Abstract: .BACKGROUND: In the fall, Eastern North American monarch butterflies (Danaus plexippus) undergo a magnificent long-range migration. In contrast to spring and summer butterflies, fall migrants are juvenile hormone deficient, which leads to reproductive arrest and increased longevity. Migrants also use a time-compensated sun compass to help them navigate in the south/southwesterly direction en route for Mexico. Central issues in this area are defining the relationship between juvenile hormone status and oriented flight, critical features that differentiate summer monarchs from fall migrants, and identifying molecular correlates of behavioral state. RESULTS: Here we show that increasing juvenile hormone activity to induce summer-like reproductive development in fall migrants does not alter directional flight behavior or its time-compensated orientation, as monitored in a flight simulator. Reproductive summer butterflies, in contrast, uniformly fail to exhibit directional, oriented flight. To define molecular correlates of behavioral state, we used microarray analysis of 9417 unique cDNA sequences. Gene expression profiles reveal a suite of 40 genes whose differential expression in brain correlates with oriented flight behavior in individual migrants, independent of juvenile hormone activity, thereby molecularly separating fall migrants from summer butterflies. Intriguing genes that are differentially regulated include the clock gene vrille and the locomotion-relevant tyramine beta hydroxylase gene. In addition, several differentially regulated genes (37.5% of total) are not annotated. We also identified 23 juvenile hormone-dependent genes in brain, which separate reproductive from non-reproductive monarchs; genes involved in longevity, fatty acid metabolism, and innate immunity are upregulated in non-reproductive (juvenile-hormone deficient) migrants. CONCLUSION: The results link key behavioral traits with gene expression profiles in brain that differentiate migratory from summer butterflies and thus show that seasonal changes in genomic function help define the migratory state.
BibTeX: @article{ZhuGegCasKanRep2009, author = {Zhu, H and Gegear, R J and Casselman, A and Kanginakudru, S and Reppert, S M}, title = {Defining behavioral and molecular differences between summer and migratory monarch butterflies}, journal = {BMC Biology}, year = {2009}, volume = {7}, number = {14} }
ZhuSauYuaCasEmeEmeRep2008	Zhu, H.; Sauman, I.; Yuan, Q.; Casselman, A.; Emery-Le, M.; Emery, P. & Reppert, S.M.	Cryptochromes Define a Novel Circadian Clock Mechanism in Monarch Butterflies That May Underlie Sun Compass Navigation [Abstract] [BibTeX]	2008	PLoS Biology Vol. 6 (1) , pp. e4	article	animal navigation
Abstract: The circadian clock plays a vital role in monarch butterfly (Danaus plexippus) migration by providing the timing component of time-compensated sun compass orientation, a process that is important for successful navigation. We therefore evaluated the monarch clockwork by focusing on the functions of a Drosophila-like cryptochrome (cry), designated cry1, and a vertebrate-like cry, designated cry2, that are both expressed in the butterfly and by placing these genes in the context of other relevant clock genes in vivo. We found that similar temporal patterns of clock gene expression and protein levels occur in the heads, as occur in DpN1 cells, of a monarch cell line that contains a light-driven clock. CRY1 mediates TIMELESS degradation by light in DpN1 cells, and a light-induced TIMELESS decrease occurs in putative clock cells in the pars lateralis (PL) in the brain. Moreover, monarch cry1 transgenes partially rescue both biochemical and behavioral light-input defects in cryb mutant Drosophila. CRY2 is the major transcriptional repressor of CLOCK:CYCLE-mediated transcription in DpN1 cells, and endogenous CRY2 potently inhibits transcription without involvement of PERIOD. CRY2 is co-localized with clock proteins in the PL, and there it translocates to the nucleus at the appropriate time for transcriptional repression. We also discovered CRY2-positive neural projections that oscillate in the central complex. The results define a novel, CRY-centric clock mechanism in the monarch in which CRY1 likely functions as a blue-light photoreceptor for entrainment, whereas CRY2 functions within the clockwork as the transcriptional repressor of a negative transcriptional feedback loop. Our data further suggest that CRY2 may have a dual role in the monarch butterfly's brain—as a core clock element and as an output that regulates circadian activity in the central complex, the likely site of the sun compass.
BibTeX: @article{ZhuSauYuaCasEmeEmeRep2008, author = {Zhu, Haisun and Sauman, Ivo and Yuan, Quan and Casselman, Amy and Emery-Le, Myai and Emery, Patrick and Reppert, Steven M}, title = {Cryptochromes Define a Novel Circadian Clock Mechanism in Monarch Butterflies That May Underlie Sun Compass Navigation}, journal = {PLoS Biology}, year = {2008}, volume = {6}, number = {1}, pages = {e4}, doi = {http://dx.doi.org/10.1371/journal.pbio.0060004} }
ZhuYuaFroCasRep2005	Zhu, H.; Yuan, Q.; Froy, O.; Casselman, A. & Reppert, S.M.	The two CRYs of the butterfly [BibTeX]	2005	Current Biology Vol. 15 (23) , pp. R953-R954	article	animal navigation
BibTeX: @article{ZhuYuaFroCasRep2005, author = {Zhu, Haisun and Yuan, Quan and Froy, Oren and Casselman, Amy and Reppert, Steven M.}, title = {The two CRYs of the butterfly}, journal = {Current Biology}, year = {2005}, volume = {15}, number = {23}, pages = {R953-R954}, doi = {http://dx.doi.org/10.1016/j.cub.2005.11.030} }
Zimmerman2009204	Zimmerman, P.H.; Pope, S.J.; Guilford, T. & Nicol, C.J.	Involvement of the sun and the magnetic compass of domestic fowl in its spatial orientation [Abstract] [BibTeX] [URL]	2009	Applied Animal Behaviour Science Vol. 116 (2-4) , pp. 204 - 210	article	animal navigation
Abstract: Domestic chicks are able to find a food goal at different times of day, with the sun as the only consistent visual cue. This suggests that domestic chickens may use the sun as a time-compensated compass, rather than as a beacon. An alternative explanation is that the birds might use the earth's magnetic field. In this study, we investigated the role of the sun compass in a spatial orientation task using a clock-shift procedure. Furthermore, we investigated whether domestic chickens use magnetic compass information when tested under sunny conditions. Ten ISA Brown chicks were housed in outdoor pens. A separate test arena comprised an open-topped, opaque-sided, wooden octagonal maze. Eight goal boxes with food pots were attached one to each of the arena sides. A barrier inside each goal box prevented the birds from seeing the food pot before entering. After habituation, we tested in five daily 5-min trials whether chicks were able to find food in an systematically allocated goal direction. We controlled for the use of olfactory cues and intra-maze cues. No external landmarks were visible. All tests were done under sunny conditions. Circular statistics showed that nine chicks significantly oriented goalwards using the sun as the only consistent visual cue during directional testing. Next, these nine chicks were subjected to a clock-shift procedure to test for the role of sun-compass information. The chicks were housed indoors for 6 days on a light-schedule that was 6 h ahead of the natural light-dark schedule. After clock-shifting, the birds were tested again and all birds except one were disrupted in their goalward orientation. For the second experiment, six birds were re-trained and fitted with a tiny, powerful magnet on the head to disrupt their magnetic sense. The magnets did not affect the chicks' goalward orientation. In conclusion, although the strongest prediction of the sun-compass hypothesis (significant re-orientation after clock-shifting) was neither confirmed nor refuted, our results suggest that domestic chicks use the sun as a compass rather than as a beacon. These findings suggest that hens housed indoors in large non-cage systems may experience difficulties in orientation if adequate alternative cues are unavailable. Further research should elucidate how hens kept in non-cage systems orient in space in relation to available resources.
BibTeX: @article{Zimmerman2009204, author = {Patrick H. Zimmerman and Stuart J. Pope and Tim Guilford and Christine J. Nicol}, title = {Involvement of the sun and the magnetic compass of domestic fowl in its spatial orientation}, journal = {Applied Animal Behaviour Science}, year = {2009}, volume = {116}, number = {2-4}, pages = {204 - 210}, url = {http://www.sciencedirect.com/science/article/B6T48-4TW535G-1/2/10de771dd251cd3096d720746b18b0c0}, doi = {DOI: 10.1016/j.applanim.2008.09.006} }

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