CoMPLEX news 2009




30 September 2009- CoMPLEX Fellowship Report: Samantha Lee

Samantha Lee, from UCL CoMPLEX has just returned from her visit to the Hughes lab at the Montana State University. Understanding when and how peptide hormones are secreted is of fundamental importance in understanding animal physiology. The aim of her project was to create a novel, FRET-based, peptide detection system to allow the following of peptide secretion in real time.To find out more about Samantha’s research and her exciting trip to the United States, head to the Case Studies Section of the CoMPLEX website.


9 September 2009-Quantifying the development of the peripheral naive CD4+ T-cell pool in humans

What are the rules that govern a naive T cell's prospects for survival or division after export from the thymus into the periphery? To help address these questions, Iren Bains (UCL CoMPLEX) combines data from existing studies with robust mathematical models to estimate the absolute contributions of thymopoiesis, peripheral division, and loss or differentiation to the human naive CD4+ T-cell pool between the ages of 0 and 20 years. Despite their decline in frequency in the blood, total body numbers of naive CD4+ T cells increase throughout childhood and early adulthood. Her analysis shows that postthymic proliferation contributes more than double the number of cells entering the pool each day from the thymus. This ratio is preserved with age; as the thymus involutes, the average time between naive T-cell divisions in the periphery lengthens. She also shows that the expected residence time of naive T cells increases with time. The naive CD4+ T-cell population thus becomes progressively less dynamic with age. Together with other studies, her results suggest a complex picture of naive T-cell homeostasis in which population size, time since export from the thymus, or time since the last division can influence a cell's prospects for survival or further divisions.

Read the full article on Blood Journal:http://bloodjournal.hematologylibrary.org/cgi/content/full/113/22/5480



9 September 2009-Combining Models of Naive T Cell Proliferation and TCR Excision Circle Dynamics Gives an Explicit Measure of Thymic Output

Understanding T cell homeostasis requires knowledge of the export rate of new T cells from the thymus, a rate that has been surprisingly difficult to estimate. TCR excision circle (TREC) content has been used as a proxy for thymic export, but this quantity is influenced by cell division and loss of naive T cells and is not a direct measure of thymic export. Iren Bains (UCL CoMPLEX) presents in this study a method for quantifying thymic export in humans by combining two simple mathematical models. One uses Ki67 data to calculate the rate of peripheral naive T cell production, whereas the other tracks the dynamics of TRECs. Combining these models allows the contributions of the thymus and cell division to the daily production rate of T cells to be disentangled. The method is illustrated with published data on Ki67 expression and TRECs within naive CD4+ T cells in healthy individuals. She was able to obtain a quantitative estimate for thymic export as a function of age from birth to 20 years. The export rate of T cells from the thymus follows three distinct phases, as follows: an increase from birth to a peak at 1 year, followed by rapid involution until ~8 years, and then a more gradual decline until 20 years. The rate of involution shown by her model is compatible with independent estimates of thymic function predicted by thymic epithelial space. Her method allows nonintrusive estimation of thymic output on an individual basis and may provide a means of assessing the role of the thymus in diseases such as HIV.

Read the full article on the Journal of Immunology:http://www.jimmunol.org/cgi/content/abstract/jimmunol.0900743v1



1 September 2009- The Origins of Lactase Persistence in Europe

On the latest PLoS publication, Yuval Itan (UCL CoMPLEX) sheds light on the origins of lactase persistence in Europe. Most adults worldwide do not produce the enzyme lactase and so are unable to digest the milk sugar lactose. However, most people in Europe and many from other populations continue to produce lactase throughout their life (lactase persistence).  Yuval theorized that, since adult consumption of fresh milk was only possible after the domestication of animals, it is likely that lactase persistence coevolved with the cultural practice of dairying, although it is not known when lactase persistence first arose in Europe or what factors drove its rapid spread. To address these questions, he developed a simulation model of the spread of lactase persistence, dairying, and farmers in Europe, and have integrated genetic and archaeological data using newly developed statistical approaches. His results illustrate the possibility of integrating genetic and archaeological data to address important questions on human evolution.


Read the full article at PLoS : The Origins of Lactase Persistence in Europe


26 August 2009- A Flexible Simulator of Biological Sequence Evolution

On a new publication, William Fletcher and Ziheng Yang (from UCL CoMPLEX) have implemented a portable and flexible application, named INDELible, for generating nucleotide, amino acid and codon sequence data by simulating insertions and deletions (indels) as well as substitutions. Many methods exist for reconstructing phylogenies from molecular sequence data, but few phylogenies are known and can be used to check their efficacy. Simulation remains the most important approach to testing the accuracy and robustness of phylogenetic inference methods. However, current simulation programs are limited, especially concerning realistic models for simulating insertions and deletions. With its many unique features, INDELible should be useful for evaluating the performance of many inference methods, including those for multiple sequence alignment, phylogenetic tree inference, and ancestral sequence, or genome reconstruction. 

Read the full article at Oxford Journals: A Flexible Simulator of Biological Sequence Evolution


20 August 2009- Lewis Dartnell at Your Universe Event

UCL is celebrating the International Year of Astronomy 2009.  In a fascinating series of events held at UCL, young scientists explain how and why they are contributing to the advancement of our knowledge of the Universe. From extra-solar planets to the mystery behind dark energy; holding rocks older than the our own planet to playing God by building the Universe from the big bang to our days are some of the many events along a 14 metre time line. Lewis Dartnell, from UCL CoMPLEX, discussed Astrobiology and the quest for extraterrestrial life on a recent interview by the Guardian. He will give a public lecture on the topic of astrobiology on Sunday at 5pm as part of the Your Universe event. All events are free of charge and on a first come first served basis. More…


9 July 2009: Spread your sperm the smart way

Attractive males release fewer sperm per mating to maximise their chances of producing offspring across a range of females, according to a new paper on the evolution of ejaculation strategies. The findings by researchers at UCL (University College London) and the University of Oxford suggest that, paradoxically, matings with attractive males may be less fertile than those with unattractive ones.  More...



22 June 2009: UCL’s ‘Sophia’ magazine publishes third issue

We are pleased to announce the publication of Issue 3 of Sophia – UCL's magazine for academic journalism – featuring a diverse range of articles from the impact of tsunamis and why did altruism evolve to tales from the folk bible and dreams in the cinema. Edited by Ed Long (UCL CoMPLEX), the magazine is readily available for download at www.sophiamagazine.co.uk, and print copies are available in common rooms in various locations around UCL.


11 May 2009: CoMPLEX Official opening - Thursday 11 June - 3:30 pm

The official opening of the new CoMPLEX office suite was cancelled in February due to adverse weather conditions which brought most of London to a halt!

The new date was set for Thursday 11 June. The official opening went ahead despite the tube strike. Professor David Price, Vice Provost (Research) officially opened the new CoMPLEX offices, welcoming both staff and students.


5 March 2009: UCL's 'Sophia' Magazine publishes second issue

Currently edited by Ed Long (UCL, CoMPLEX), ‘Sophia’ is a UCL magazine of academic journalism established in 2008, whose mission is to showcase talent in research, writing and art from current staff and graduate students. The magazine can be accessed at www.sophiamagazine.co.uk, and print copies are available in common rooms in various locations around UCL. more...


28 January 2009: The Search for Life Beyond Earth

UCL astrobiology researcher Dr Lewis Dartnell will be grappling with these and other questions in his Royal Institution lecture on 24 February. Dr Dartnell takes his audience on a tour of the solar system and beyond to the newly discovered worlds that orbit distant stars, to consider which of these alien planets is the most Earth-like. more...


16 January 2009: Why you can’t hurry love

Scientists have developed a mathematical model of the mating game to help explain why courtship is often protracted. The study, by Rob Seymour at CoMPLEX, UCL (University College London) and Peter Sozou of the University of Warwick, LSE (London School of Economics and Political Science) and a CoMPLEX affiliate, shows that extended courtship enables a male to signal his suitability to a female and enables the female to screen out the male if he is unsuitable as a mate. more...



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