Gee Research Blog
The Best of Both Worlds:Planning for Ecosystem Win-Wins
Sun, 16 Nov 2014 12:25:44 +0000
The normal and healthy function of ecosystems is not only of importance in conserving biodiversity, it is of utmost importance for human wellbeing as well. Ecosystems provide us with a wealth of valuable ecosystem services from food to clean water and fuel, without which our societies would crumble. However it is rare that only a […]
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Planning for Ecosystem Win-Wins appeared first on GEE Research.
Life Aquatic: Diversity and Endemism in Freshwater Ecosystems
Thu, 06 Nov 2014 11:22:07 +0000
Freshwater ecosystems are ecologically important, providing a home to hundreds of thousands of species and offering us vital ecosystem servies. However, many freshwater species are currently threatened by habitat loss, pollution, disease and invasive species. Recent research from GEE indicates that freshwater species are at greater risk of extinction than terrestrial species. Using data on […]
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Diversity and Endemism in Freshwater Ecosystems appeared first on GEE Research.
Handicaps, Honesty and VisibilityWhy Are Ornaments Always Exaggerated?
Thu, 23 Oct 2014 13:30:30 +0000
Sexual selection is a form of natural selection that favours traits that increase mating success, often at the expense of survival. It is responsible for a huge variety of characteristics and behaviours we observe in nature, and most conspicuously, sexual selection explains the elaborate ornaments such as the antlers of red deer and the tail […]
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Why Are Ornaments Always Exaggerated? appeared first on GEE Research.
PREDICTS Project: Land-Use Change Doesn’t Impact All Biodiversity Equally
Mon, 13 Oct 2014 09:17:53 +0000
Humans are destroying, degrading and depleting our tropical forests at an alarming rate. Every minute, an area of Amazonian rainforest equivalent to 50 football pitches is cleared of its trees, vegetation and wildlife. Across the globe, tropical and sub-tropical forests are being cut down to make way for expanding towns and cities, for agricultural land […]
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Calculated Risks: Foraging and Predator Avoidance in Rodents
Fri, 03 Oct 2014 10:07:08 +0000
Finding food is one of the most important tasks for any animal – most animal activity is focused on this job. But finding food usually involves some risks – leaving the safety of your burrow or nest to go out into a dangerous world full of predators, disease and natural hazards. Animals should therefore be […]
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Foraging and Predator Avoidance in Rodents appeared first on GEE Research.
13 May 2013
"Why does selection care about codon usage (or what really determines ribosome velocity)"
Date & Time:
||Wednesday, 22 May at 5pm|
|Venue:||Medical Sciences AV Hill Lecture Theatre (map)|
Jurg Bahler (51602)
Owing to the structure of the genetic code more than one codon can specify the same amino acid. At first sight natural selection should not care which of the multiple synonymous codons is employed as the translated protein will be the same regardless. That we see selection on codon usage is thus intruiging. Understanding why selection cares about codon usage is important for understanding how cells work and, in turn, for understanding how to intelligently engineer transgenes. I provide evidence that selection cares about codon usage because it minimizes errors: it ensures translation is accurate and, in mammals, it ensures splicing is accurate. It is also commonly assumed that, because common codons match common tRNAs, codon usage must affect ribosomal velocity. Using ribosome protection data I find no evidence that in normal conditions codon usage has any effect on ribosomal velocity. In retrospect this result makes sense as the original logic was flawed - it considered only tRNA supply, not codon driven tRNA demand. We expect evolution to drive towards supply:demand equilibrium at which point rare codons specified by rare tRNAs wait as long to be translated as common codons specified by common tRNAs. More generally, we see little or no evidence for RNA mediated effects on translational velocity (either codon usage or mRNA structure). This leaves the problem of what does actually determine ribosomal velocity. I show that positively charged amino acids entering into the negatively charged ribosome exit tunnel have a profound effect on ribosome velocity. This can explain the evolution of the polyA tail. Methods to improve transgenes are suggested by these results.
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