My research interests are the endocrine control of reproduction in fishes and other vertebrates and the effects of environmental factors such as hypoxia and pollutants on reproductive function. Research is conducted at the Marine Science Institute in Port Aransas and at field sites in the Gulf of Mexico region. A research emphasis is on the structure, functions and evolution of a new class of sex steroid receptors we recently discovered in fishes and subsequently have identified in other vertebrates. The novel receptors are structurally unrelated to nuclear steroid receptors and are located on the surface of cells where they elicit rapid biological responses to steroids by mechanisms not involving gene transcription. Recent studies in fish, amphibians, rodents and humans indicate these receptors mediate steroid regulation of meiosis in oocytes, sperm motility, gonadotropin-releasing hormone (GnRH) secretion and immune function, and are likely involved in the onset of labor in humans and in the progression of breast cancer.