9306518 Petrino This research planning grant for women examines the periodic release of 17B-estradiol throughout the reproductive cycle of teleosts. It is crucial for oocyte growth (vitellogenesis) and appears to have a programming role in the regulation of spawning patterns. Therefore, it is of great interest to investigate the regulation of its periodic synthesis. The hormonal and molecular mechanisms of induction, maintenance or regulation of enzyme activity in the steroidogenic pathway during the cyclic spawning activity and follicle development in teleosts are not at all defined. This project focuses on ovarian aromatase, the enzyme required for the conversion of testosterone to estradiol that is located in the follicular (granolosa) cells surrounding the oocyte. The specific aims of this preliminary study are: 1) to construct a cDNA library, respresentative of ovarian mRNA from the cyclic spawner teleost Fundulus heteroclitus, and 2) to clone and sequence the cDNA for aromatase using specific probes. Segmants of the sequenced enzyme can then be used in future studies for generating radioactive probes necesaries to detect the levels of aromatase mRNA under gonadotropic stimulation and follicle development. Isolating F. heteroclitus aromatase cDNA will allow comparison amoung teleosts species that show a very differant pattern in spawning behavior, and thus it will contribute to a better understanding of the regulatory control mechanisms operating during cyclic reproduction in teleosts. This inforamtion will be helpful in an overall understanding of ovarian physiology and reproductive endocrinology in vertebrates. ***
