9614940 Amemiya The Hox genes exist as highly conserved gene clusters within the chordates. The protochordate, Amphioxus, has a single gene cluster, while the mammals, birds, and fishes have four. The Hox genes play an important role in embryogenesis, specifying developmental identities along the anterior/posterior axis. Drs. Ruddle, Wagner, and Amemiya will determine by direct testing whether intermediate forms such as cyclostomes and elasmobranchs have intermediate cluster numbers and whether cluster duplication occurred once or several times independently during Chordate evolution. They will also determine whether different clades posses different Hox gene numbers, and if the loss or gain of genes has been the same or different. Differences and similarities in Hox gene composition will be correlated with the developmental status of the different species examined. They will study particular Hox orthologous genes in detail, especially examining similarities and differences in enhancer structure and function on a comparative basis. By these approaches, they hope to better understand the relationship between developmental regulation and evolutionary process.
