Gee Research Blog
Write About Research – A GEE Research Blog Competition
Tue, 03 Mar 2015 15:28:43 +0000
The GEE Research blog communicates UCL science with a wider, non-specialist audience, by providing short summaries of recent research in the department of UCL Genetics, Evolution and Environment. This provides an opportunity to engage with a broad audience, including other academics, students, members of the public, and even businesses and policy-makers. It is a great […]
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Was Fermentation Key to Yeast Diversification?
Tue, 17 Feb 2015 15:30:43 +0000
From bread to beer, yeast has shaped our diets and our recreation for centuries. Recent research in GEE shows how humans have shaped the evolution of this important microorganism. As well as revealing the evolutionary origins of modern fission yeast, the new study published in Nature Genetics this month shows how techniques developed for detecting […]Read more...
Planning for the Future – Resilience to Extreme Weather
Thu, 15 Jan 2015 15:13:14 +0000
As climate change progresses, extreme weather events are set to increase in frequency, costing billions and causing immeasurable harm to lives and livelihoods. GEE’s Professor Georgina Mace contributed to the recent Royal Society report on “Resilience to Extreme Weather”, which predicts the future impacts of increasing extreme weather events, and evaluates potential strategies for improving […]
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Mon, 05 Jan 2015 11:33:21 +0000
Classifying a species as either extinct or extant is important if we are to quantify and monitor current rates of biodiversity loss, but it is rare that a biologist is handy to actually observe an extinction event. Finding the last member of a species is difficult, if not impossible, so extinction classifications are usually estimates […]Read more...
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 […]Read more...
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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