The chemical, methyl farnesoate (Mf), is a hormone that regulates reproduction, larval development, and sex determination in crustaceans and is structurally similar to juvenile hormone, which regulates a variety of physiological processes in insects. Despite their importance in arthropod physiology, the molecular mechanisms by which Mf or juvenile hormone act are poorly understood. This research will test the hypothesis that methyl farnesoate regulates gene expression in the crustacean, Daphnia magna, by interaction with a nuclear receptor protein of the NR2B subfamily. The hypothesis will be tested by definitively establishing the identity of the methyl farnesoate receptor (MfR) and evaluating the complimentary roles of methyl farnesoate and its receptor in regulating hemoglobin gene expression. Hemoglobin production is strongly regulated by methyl farnesoate and its induction will be measured using various biochemical and molecular techniques. The first objective of this study will be to identify MfR by sequencing the putative MfR isolated from D. magna and then determining whether this protein is biochemically related to other receptors of the NR2B subfamily. Next, MfR protein will be expressed using standard molecular approaches and used to characterize binding interactions between potential ligands and the receptor as well as the ability of the ligand/receptor complex to bind to responsive genes. Finally, the ability of the ligand/receptor complex to activate gene transcription will be evaluated. Identifying the receptor that mediates the action of one of the most influential hormones in crustaceans will be an important advance in the endocrinology of arthropods, the dominant animal group on the planet. In addition, findings from this research could be applied to crustacean aquaculture to increase productivity. This research project will also provide opportunities for training of students from communities that are underrepresented in graduate education and will provide a venue for high school students to interact with professional scientists.
