Scientists Discover Mechanism That Gives Shape to Life

First time accepted submitter mcswell writes "Daniël Noordermeer and Denis Duboule, two researchers at Ecole Polytechnique Fédérale de Lausanne and the University of Geneva claim to have discovered how vertebrae get built in sequence in embryos (and by extension, how ribs, arms and so forth wind up in the right place). The story is that the DNA strands contain a linear series of HOX genes, and that the strands slowly unwind over a period of two days, successively exposing each HOX gene, thereby allowing it to be transcribed to form the segments of the vertebra. Snakes, it seems, have a defect that causes the system not to shut down; eventually it 'runs out of steam.' The same process is said to apply in many invertebrates, including worms (presumably segmented worms) and insects."

For the non-molecular biologist among us

[GreatBunzinni]

What a Hox gene might be [wikipedia.org]

Re:It's in Science 'cuz now we can SEE it?

[Samantha Wright]

That may sound novel and exciting, but what you've described is how every transcription factor works. enderwig was making a point about the timing mechanism. If you leave a transcription-driven genetic circuit to keep its own clock without any assistance, it generally does a pretty bad job. There has to be something fairly elaborate guiding the chromatin unwinding.

Re:Snake?

[Samantha Wright]

It would either be short and fat, or dead because there wouldn't be enough room for its organs to grow. Either way, it wouldn't slither very well, and would be at something of a disadvantage.

The use of the word "defect," as you can probably already imagine, is a very biased way of looking at things and will probably do more harm than good. Although, of course, at the time the mutation first appeared, when snakes still had non-vestigial limbs, it probably was at least partially something of an inconvenience.