Flies with inner ears?
Drosophila Hmx gene directs development of mouse inner ear, an organ flies
don't possess
By David Secko

In a study which suggests that genetic mutation was not necessarily the
primary evolutionary force producing morphological change in mammals,
researchers report in the September issue of Developmental Cell that the
Drosophila Hmx gene partially rescued the development of the mouse inner
ear, revealing that the gene could direct the development of an organ it
does not even possess.

When thinking of how new traits evolve, people have mainly focused upon
mutations in protein sequences said Thomas Lufkin, of the Genome Institute
of Singapore, and senior author of the Developmental Cell study. "But, an
equal possibility is that, instead of the gene sequence mutating, the same
gene can acquire new expression domains," Lufkin told The Scientist.

This possibility became apparent as Lufkin, lead author Weidong Wang, and
their colleagues began to study a family of homeobox genes termed Hmx.
Drosophila has a single Hmx gene, termed DHmx, whose expression pattern
suggests it is involved in the development of the Drosophila central nervous
system (CNS). Two mouse Hmx genes, Hmx2 and Hmx3, are also involved in CNS
development, but have additional roles in sensory organ development. Thus,
Lufkin and colleagues wondered what Hmx functions were conserved during
evolution.

The researchers began by analyzing the phenotypes of Hmx2-/-, Hmx3-/- and
Hmx2-/-/Hmx3-/- knockout mice, revealing Hmx2 and Hmx3 to have overlapping
and distinct functions during development of the mouse inner ear. They went
on to create a mouse line with the Drosophila DHmx gene replacing Hmx3 and
lacZ replacing Hmx2. As might be expected, DHmx rescued murine CNS
development, an Hmx function that is conserved in Drosophila-but it also had
effects on the development of the mouse inner ear.

Full Text at TheScientist
http://www.biomedcentral.com/news/20040913/04

Posted by
Robert Karl Stonjek
---
þ RIMEGate(tm)/RGXPost V1.14 at BBSWORLD * Info{at}bbsworld.com

---
 * RIMEGate(tm)V10.2áÿ* RelayNet(tm) NNTP Gateway * MoonDog BBS
 * RgateImp.MoonDog.BBS at 9/13/04 11:08:55 PM