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SALT LAKE CITY (AP) -- University of Utah researchers have identified genes involved in mammals' facial movements and expressions.
The genes ensure nerves develop in the correct part of the brain so mice can roll their eyeballs sideways, wiggle their whiskers, pull their ears back and blink their eyelids.
As the genes are common to all mammals, they likely help control human facial expressions such as smiles and frowns.
"In this study we looked at what nerves are made in a particular part of the brain, the hindbrain," said geneticist Mario Capecchi, professor and co-chairman of human genetics at the University of Utah School of Medicine and an investigator with the Howard Hughes Medical Institute.
"We see that in certain parts of the hindbrain, the embryo makes nerves that innervate (supply with nerves) the facial muscles, and in another part of the hindbrain, the embryo makes nerves that innervate eye movement," he said.
The findings will be published in the Nov. 1 issue of the journal Development.
The study used the gene-targeting method developed by Capecchi. It involves disabling genes in mice to see what goes wrong, thus learning what the genes normally do.
The researchers found that by crippling two genes, mice failed to develop nerves that normally connect to one of six sets of muscles controlling eyeball movements. Disabling other genes made mice develop an extra set of nerve fibers that control facial muscles.
The study involved homeobox or Hox genes, which orchestrate the actions of other genes to guide embryo development. The researchers looked specifically at how Hox genes direct development of rear part of the brain, so that nerve cells there extend cable-like fibers to control different parts of the body.
Capecchi has won numerous awards for his role in developing gene targeting, including the National Medal of Science and the Albert Lasker Award for Basic Medical Research in 2001 and the 2002-2003 Wolf Prize in Medicine.
(Copyright 2003 by The Associated Press. All Rights Reserved.)
