In recent decades it has become clear that animal development is remarkably parsimonious, with the same underlying regulators being used repeatedly to pattern different structures at different stages of the life cycle. In large part, this parsimony is achieved by changes over time in the responsiveness of target genes to these regulators. Such changes explain how the same regulator can activate or repress distinct sets of target genes at different stages of development. The goal of this research is to understand how target gene responsiveness is controlled during the life cycle. The focus of the work is insect metamorphosis, a process known to involve global shifts in such responsiveness. The work tests the hypothesis that pupa-specific target responsiveness in Drosophila is controlled by the E93 gene. E93 encodes a gene regulator that is expressed specifically at the pupal stage, and is required for most or all patterning processes that occur at this time. E93 is known to function during leg development to control the pupa-specific responsiveness of the Dll gene. This work tests whether other genes that change their responsiveness in the pupa are also regulated by E93, and determine the molecular mechanisms by which E93 acts. An understanding of how E93 controls target gene responsiveness will have broad significance, as similar mechanisms likely direct life cycle transitions in many other organisms, including ourselves. The work includes outreach activity at a local high school. In a project to characterize the evolution of E93, students will collect and classify local insects, purify their DNA, and conduct phylogenetic studies of the E93 gene. After a year of piloting, the project will be expanded to include selected schools within the city of St. Louis, engaging students who otherwise would have little or no exposure to research.
