Researchers at the Forsyth Institute have discovered that the genes that influence the jaws of cichlid fish, tropical freshwater fish renowned for head shape diversity, offer insight into overall vertebrate diversity.
The scientific studies led by R. Craig Albertson, PhD., Staff Associate, show that the growth factor gene, bmp4, is both associated with and has the potential to alter jaw morphology in a way that approximates natural variation among fish species.
According to Dr. Albertson, "An understanding of the genetic factors that regulate bone shape is also vital to a better diagnostic comprehension of human craniofacial defects, and could lead to the development of biological therapies for facial traumas."
African cichlid fishes have evolved highly specialized modes of feeding through extensive adaptations of their jaws. This study, published in the current issue of Proceedings of the National Academy of the Sciences, (PNAS), explores the molecular basis of alternate jaw types in this species-rich group.
The opening and closing lever mechanisms of the lower jaw have traditionally been used to describe feeding techniques in bony fishes. Quantitative genetic analyses in cichlids demonstrate that opening and closing jaw mechanisms are regulated by distinct genetic factors, and are free to evolve independently. Allelic variations in bmp4 segregates with the mechanical advantage of closing. Further, species-specific differences in cichlid jaw shape are correlated with different patterns of bmp4 expression in the embryonic jaw. Finally, when bmp4 is over-expressed in a developmental model organism, the zebrafish, jaw shape changes in a way that parallels natural variation among cichlid species.