For insects and other arthropods to grow they must molt. That is, they must shed their outer covering (exoskeleton) which restricts growth, while synthesizing a new and larger version. This ability to molt has allowed insects to survive and prosper for hundreds of millions of years. The actual molting process is elicited and controlled by a steroid hormone, 20-hydroxyecdysone (20E), which is synthesized by special glands. Mammals also use steroid hormones to control metabolic activities and secondary sexual characteristics. Although 20E was characterized chemically about 50 years ago, little was known about how it is synthesized until a few years ago when this laboratory used molecular genetic techniques to identify, clone and characterize genes encoding enzymes mediating the last four steps in the biosynthesis of 20E. However, there are several prior steps in this scheme for which no information exists, the so-called black box, and the goal of this proposal is to identify the genes controlling these steps. The experimental paradigms developed for this work involving the marriage of molecular genetics and biochemistry are novel and can be utilized for the study of steroid hormone biosynthesis in mammals including man. Further, unraveling the biosynthetic scheme for 20E may identify biochemical steps unique to the insect and could be probed with new inhibitors to control pests of biomedical and agricultural importance. This laboratory will continue to train undergraduates in the aforementioned technologies as it has in the past. Currently, two female students, one of minority heritage are slated to work on this project.
