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Gee Research Blog

Extinction and Species Declines:Defaunation in the Anthropocene

Mon, 18 Aug 2014 10:35:52 +0000

We are in the grips of a mass extinction. There have been mass extinctions throughout evolutionary history, what makes this one different is that we’re the ones causing it. A recent review paper from GEE’s Dr Ben Collen discusses the current loss of biodiversity and suggests that our main concerns are species and population declines, […]

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Defaunation in the Anthropocene
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Evolving Endemism in East Africa’s Sky Islands

Fri, 08 Aug 2014 14:16:32 +0000

The World’s biodiversity is not evenly distributed. Some regions are hot spots for species richness, and biologists have been trying better to understand why these regions are special and what drives evolution and diversification. A recent paper by GEE’s Dr Julia Day and recent PhD graduate Dr Siobhan Cox, investigated the diversification of White-Eye Birds […]

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Predicting Extinction Risk:The Importance of Life History and Demography

Mon, 28 Jul 2014 14:46:17 +0000

The changing climate is no longer simply a concern for the future, it is a reality. Understanding how the biodiversity that we share our planet with will respond to climate change is a key step in developing long-term strategies to conserve it. Recent research by UCL CBER’s Dr Richard Pearson identifies the key characteristics that […]

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The Importance of Life History and Demography
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It Pays to Be Different:Evolutionary Distinctiveness and Conservation Priorities

Tue, 15 Jul 2014 13:15:25 +0000

The world is currently experiencing an extinction crisis. A mass extinction on a scale not seen since the dinosaurs. While conservationists work tirelessly to try and protect the World’s biodiversity, it will not be possible to save everything, and it is important to focus conservation efforts intelligently. Evolutionary distinctiveness is a measure of how isolated […]

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Evolutionary Distinctiveness and Conservation Priorities
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Synthetic Biology and Conservation

Mon, 07 Jul 2014 16:20:18 +0000

Synthetic biology, a hybrid between Engineering and Biology, is an emerging field of research promising to change the way we think about manufacturing, medicine, food production, and even conservation and sustainability. A review paper released this month in Oryx, authored by Dr Kent Redford, Professor William Adams, Dr Rob Carlson, Bertina Ceccarelli and CBER’s Professor […]

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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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