bicoid evolution



I’ve written about this fascinating Drosophila gene, bicoid, several times before. It’s a maternal effect gene, a gene that is produced by the mother and packaged into her eggs to drive important early events in development, in this case, establishing polarity, or which end of the egg is anterior (bicoid specifies which end of the egg will form the fly’s head). Bicoid is also a transcription factor, or gene that regulates the activity of other genes. We also see evidence that it is a relatively new gene, one that is taking over a morphogenetic function that may have been carried out by several other more primitive genes in the ancestral insect.

Continue reading “Bicoid evolution” (on Pharyngula)


PZ, I have been working on a paper on bicoid and ID, since Paul Nelson uses bicoid as an example of Biological Specification in his mere creation paper.

Check out the paper in BioEssays – you’ll find it very useful, then.

There’s a telling experiment that reveals how trivial the function of nanos is. We can make flies in the lab that lack maternal nanos. We can make flies that lack maternal hunchback. We can make flies that lack both maternal nanos and maternal hunchback, and here’s the kicker, these flies produce embryos that develop completely normally. Maternal hunchback RNA is a mistake, a sloppy bit of unnecessary secretion that does nothing for the embryo, and maternal nanos is an elaborate, Rube-Goldberg mechanism that has been patched in to correct the stupid mistake.

Now if I were an intelligent designer building a fly from scratch, and I saw this little design defect, the way I would correct it is the obvious one: I’d fix the fly ovaries so that they weren’t dribbling a completely useless protein into the egg. I wouldn’t assemble a complex of a half-dozen proteins that were integrated into the cytoskeleton and pump a hunchback-suppressor to the right place, with other proteins floating around to make sure my hunchback-suppressor didn’t do damage in the places where hunchback is supposed to be turned on.

Absolutly fascinating. So it appears that the designers are fallible and capable of making mistakes? Perhaps (they?) are a bit like Microsoft, quick get the product out and then issue patches for the mistakes.

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This page contains a single entry by PZ Myers published on August 25, 2005 12:21 PM.

Beyond the fish wars was the previous entry in this blog.

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