An evolutionary & developmental biology lab

Month: February 2012

Fine structure of large-effect QTLs

Some of you remember the story of wing dimorphism in wasps from the talk that David Loehlin gave here a year ago.  Here it is finally published:

Evolution of Shape by Multiple Regulatory Changes to a Growth Gene

What I find most interesting about this story is that it adds to the still small collection of cases where a very large effect of a single gene on interspecific divergence is not due to any single large-effect mutation, but rather reflects a cumulative effect of many small(er) mutations accumulating at the same locus.  This is similar to what Ryan Bickel found in bab, and Alistair McGregor in svb.  I suspect the number of similar cases will keep growing.  Surely this is telling us something about the effect of pathway architecture on the course of evolution…

What a relief – conserved genes play some kind of role

I don’t think this will come as a surprise to anyone, but the experiment still had to be done.  It’s nice to know that genes conserved over millions of years are conserved because (gasp) losing them is bad for you.

Seriously though, this is a very nice paper.  As they say:

Almost all eukaryotic genes are conserved, suggesting that they have essential functions. However, only a minority of genes have detectable loss-of-function phenotypes in experimental assays, and multiple theories have been proposed to explain this discrepancy.

They show then that almost genes have significant effects on fitness if you just measure it properly.  Take a look:

The Majority of Animal Genes Are Required for Wild-Type Fitness

Very, very cool octopus paper: RNA Editing Underlies Temperature Adaptation

RNA Editing Underlies Temperature Adaptation in K+ Channels from Polar Octopuses

This is a fun story. I’ll just reproduce their whole abstract here:

To operate in the extreme cold, ion channels from psychrophiles must have evolved structural changes to compensate for their thermal environment. A reasonable assumption would be that the underlying adaptations lie within the encoding genes. Here, we show that delayed rectifier K+ channel genes from an Antarctic and a tropical octopus encode channels that differ at only four positions and display very similar behavior when expressed in Xenopus oocytes. However, the transcribed messenger RNAs are extensively edited, creating functional diversity. One editing site, which recodes an isoleucine to a valine in the channel’s pore, greatly accelerates gating kinetics by destabilizing the open state. This site is extensively edited in both Antarctic and Arctic species, but mostly unedited in tropical species. Thus adenosine-to-inosine RNA editing can respond to the physical environment.

Is this weird or what?

Properties of cis- and trans-regulatory mutations

Trisha Wittkopp’s lab has just published a very interesting paper where they look at the effects of cis– and trans-regulatory mutations in yeast.  This paper gives a nice picture of the properties of mutations that are potentially available for selection.  Definitely worth reading.

Contrasting Properties of Gene-Specific Regulatory, Coding, and Copy Number Mutations in Saccharomyces cerevisiae: Frequency, Effects, and Dominance

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