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Gee Research Blog

Changing Perspectives in Conservation

Thu, 18 Dec 2014 12:15:44 +0000

Our views of the importance of nature and our place within have changed dramatically over the the last century, and the prevailing paradigm has profound influences on conservation from the science that is conducted to the policies that are enacted. In a recent perspectives piece for Science, GEE’s Professor Georgina Mace considered the impacts that […]

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Function Over Form: Phenotypic Integration and the Evolution of the Mammalian Skull

Mon, 08 Dec 2014 14:05:52 +0000

Our bodies are more than just a collection of independent parts – they are complex, integrated systems that rely upon precise coordination in order to function properly. In order for a leg to function as a leg, the bones, muscles, ligaments, nerves and blood vessels must all work together as an integrated whole. This concept, […]

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Phenotypic Integration and the Evolution of the Mammalian Skull
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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
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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
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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?
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13 May 2013

"Why does selection care about codon usage (or what really determines ribosome velocity)"


Speaker:

Laurence Hurst
(Bath)
Date & Time:
Wednesday, 22 May at 5pm
Venue: Medical Sciences AV Hill Lecture Theatre (map)
Host: Jurg Bahler (51602)


Abstract
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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