Multifactorial regulation of reproduction in fish

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The long-term objective of my research is to understand the interactive mechanisms by which pituitary gonadotropins and locally derived hormones and protein growth factors regulate ovarian function in fish. The goal is to characterize ovarian signaling molecules and transduction pathways that mediate steroidogenesis, oocyte final maturation and ovulation and to integrate these responses at the whole animal level in terms of effects on spawning success. Specifically, we are studying the hormonal regulation of ovarian development in the preovulatory period through investigations of the interactive effects of gonadotropins, sex steroids, prostaglandins and insulin-like growth factors on the acquisition of follicle cell maturational competence, oocyte maturation, ovarian follicle hydration and ovulation. We are also studying the nature of the pheromonal signals from male zebrafish that contribute to endocrine changes and spawning success in the female. Our studies investigate the expression of ovarian hormones, their receptors and gene products through to reproductive success in terms of effects on spawning. This research involves both in vitro cultures of ovarian follicles and in vivo studies to characterize the hormonal regulation of the maturation and ovulation of ovarian follicles. We routinely use RIA and EIA methods to quantify ovarian steroid hormone and PG levels, RT-qPCR and in situ hybridization to characterize gene expression and immunohistochemical approaches to characterize ovarian protein hormone and receptor distribution. We will use pharmacological approaches and antisense morpholino oligonucleotides for loss of function studies to investigate the roles played by steroid hormones, PGs, peptide hormones and their receptors in relation to developmental competency and follicle survival. This knowledge is fundamental to understanding reproductive fitness and provides methods that enable examination of the mechanisms by which endocrine disrupting compounds and toxicants affect ovarian physiology in both wild and cultured fish.