Seasonal reproduction in vertebrates is often characterized by specific increases in gonadal activity that is regulated by changes in steroid hormone production. These changes are often under control of the environment. However, the exact molecular mechanism that initiates the cascade of hormonal events set off by the changing environment is unknown. Steroidogenic Factor 1 (SF-1) is a protein that plays a vital role in inducing reproductively in appropriate hormone and receptor synthesis in several tissues. Dr. Propper and her associates propose that SF-1 may play a fundamental role in mediating environmentally regulated seasonal reproduction. In order to begin studies on the role of SF-1 in seasonal reproduction, she proposes to determine the amino acid sequence of SF-1 in an amphibian whose pattern of seasonal reproduction has been well-defined (American bullfrog, Rana catesbeiana). She will also determine the tissue and cell distribution of SF-1 in this species.