His findings have led to new levels of understanding of evolutionary processes and shed light on human problems such as birth defects.
"I realized that if I wanted to understand how animal form changes during evolution, such as how the skeleton evolved or how snakes lost their legs, I had to understand development, because that's when the genetic blueprint for the body is being executed," Cohn said.
He began by studying chick embryos, a classic scientific model of limb development. At University College London, he discovered that the embryonic master switch for limb formation was a multifunctional protein called fibroblast growth factor. The finding, published in the journal Cell, was later proven true for other animals, including people.
After finding the trigger, Cohn set out to find what determines the precise positioning of limbs, such as hands on the ends of arms at the shoulders, and feet on the ends of legs protruding from the trunk.
His research led him to the Hox family of genes, which direct the formation of body structures in organisms ranging from worms to people. His work showing that Hox9 genes determine where limbs develop along the trunk was published in the journal Nature in 1997. He went on to discover the molecular basis for loss of limbs during snake evolution and the role of Hox genes in the origin of jaws findings that were published in Nature in 1999 and 2002.
Since arriving at UF in 2003, Cohn's group has discovered the evolutionary origin of the genetic program for fin development, shown how this program was modified to form fingers and toes
|Contact: John Pastor|
University of Florida