By outfitting mice with a chunk of DNA that directs wing development in bats, scientists have created rodents with abnormally long forelimbs, mimicking one of the steps in the evolution of the bat wing. Their work gives weight to the idea that variations in how genes are controlled, and not just mutations in the coding regions of genes, are a driving force in evolution.via Technology Review
The researchers focused on a gene, Prx1, that plays a part in the elongation of limb bones in mammals. The gene's expression is regulated by another sequence of DNA, called a Prx1 enhancer. To investigate how the enhancer shapes limb development, Richard Behringer, a professor of molecular genetics at the University of Texas MD Anderson Cancer Center, and his colleagues around the country put the bat version of the Prx1 enhancer into mice so that it controlled the mouse Prx1 gene. These transgenic animals developed forelimbs that were on average 6 percent longer than normal by the time they were born. It was a significant difference, although "the mice look like mice," Behringer says. "They're not going to fly out of the cage." The researchers report their work in the latest issue of Genes and Development.