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Gee Research Blog

Competitive Generosity Drives Charitable Donations

Fri, 17 Apr 2015 12:09:46 +0000

Unconditional generosity is a characteristic of humans on which we pride ourselves, and billions of dollars is donated to hundreds of thousands of charitable organisations every year. But look at it from an evolutionary perspective, and this trait seems difficult to explain. In some situations, giving may have evolved to advertise positive characteristics of the […]

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Annoucing the Winners of the Write About Research Competition

Fri, 10 Apr 2015 13:49:07 +0000

Thanks to everyone who entered our Write About Research competition. We received some great entries from GEE students and postdocs, covering a broad range of topics from conservation to genetics. The entries will be posted here over the coming months, so watch this space! The Winners are… Drum roll please … WINNER: David Curnick – […]

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Male Promiscuity Boosts Role of Chance in Sex Chromosome Evolution

Thu, 19 Mar 2015 15:02:31 +0000

Humans, like all mammals and birds, determine sex with chromosomes. Whether a fertilised egg develops into a male or female depends on what chromosomes it carries Scientists have long recognised that genes evolve a little differently on the sex chromosomes, and recent research in GEE suggests this may be due to differing patterns of inheritance […]

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Sloths Move Slow, Evolve Fast

Wed, 11 Mar 2015 18:20:41 +0000

Sloths might be notorious for their leisurely pace of life, but research published last year shows they are no slow coaches when it comes to evolution. Sloths, as we know and love them, are small, slow-moving creatures found in the trees of tropical rainforests. But modern sloths are pretty odd compared to their extinct relatives. […]

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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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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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