Understanding evolution is critical to understanding basic biology and is equally important for applied aspects of science, including organismal interactions with the environment. This project probes evolutionary changes in regulatory genes, called Hox genes, and asks how they have impacted animal development. The Hox genes are patterning genes that encode transcription factors controlling embryonic development, which are remarkably conserved throughout the animal kingdom. This finding was initially surprising because Hox genes were first identified in fruit flies, where mutations result in bizarre phenotypes (called homeotic transformations) in which one body part is transformed to a different body part. However, cloning of these genes revealed that they are present in all animals, including humans. In addition, studies have shown that genes from mammals can substitute for those of the fly and recapitulate functions of the fly homologs when expressed in the fly, underscoring the high degree of relatedness of these genes and gene products among different organisms. How then does each animal achieve its own specific body form? This project addresses the question by tracking the evolutionary changes in one Hox gene, fushi tarazu (ftz). The roles of ftz in development have been shown to change during evolution due to changes in both its protein coding sequence and its expression pattern. Studies undertaken in this project will identify the points in evolutionary history at which these changes occurred and using living animals that represent different branches of an evolutionary tree, will determine how they impacted body patterning. In addition, this award will contribute to the training of three Ph.D. students and at least 3 undergraduate students.
