Researchers reporting in the December issue of the Cell Press journal Developmental Cell provide new evidence that the development of hands and feet occurred through the gain of new DNA elements that activate particular genes.
"First, and foremost, this finding helps us to understand the power that the modification of gene expression has on shaping our bodies," says Dr. José Luis Gómez-Skarmeta of the CSIC-Universidad Pablo de Olavide-Junta de Andalucía, in Seville, Spain. "Second, many genetic diseases are associated with a 'misshaping' of our organs during development.
In the case of genes involved in limb formation, their abnormal functionis associated with diseases such as synpolydactyly and hand-foot-genital syndrome."
In order to understand how fins may have evolved into limbs, researchers led by Dr. Gómez-Skarmeta and his colleague Dr. Fernando Casares introduced an extra gene known to play a role in distinguishing body parts, at the tip of a zebrafish embryo's fin. Surprisingly, this led to the generation of new cartilage tissue and the reduction of fin tissue -- changes that strikingly recapitulate key aspects of land-animal limb development. This result indicates that molecular machinery capable of activating this control element was also present in the last common ancestor of finned and legged animals and is proven by its remnants in zebrafish," says Dr. Casares
StoryTeller : Dr. José Luis Gómez-Skarmeta, CSIC-Universidad Pablo de Olavide-Junta de Andalucía, Seville, Spain
Story Research: How Legs Evolved