Seminar: Dr. Nilli Zmora (Assistant Research Scientist, Department of Marine Biotechnology, UMBC)

Title: Challenging the paradigm of Gnrh control of reproduction: the case of Gnrh3 in zebrafish

Speaker: Dr. Nilli Zmora (Assistant Research Scientist, Department of Marine Biotechnology, UMBC)

Abstract: The recent developments in gene knockout (KO) technologies, especially in the intensively studied zebrafish (ZF) model, occasionally contradicted our knowledge and results from more traditional research methods. The hypophysiotropic gonadotropin-releasing hormone (Gnrh3) is one example of such a discrepancy. Inheritable gnrh3 gene KO has unexpectedly yielded fertile ZF, even though Gnrh3 neuronal ablation obstructs oogenesis. Moreover, the double Gnrh KO line (gnrh3-/-;gnrh2-/-) also displayed normal reproduction, thus another Gnrh isoform is not simply replacing Gnrh3. These findings have sparked a debate over the relevance of Gnrh3 in reproduction. Data will be presented on the efforts of proving that Gnrh3 is an essential reproductive player. Our studies on a possible compensation for the loss of Gnrh3 integrate multiple approaches, from transcriptome analyses of wild-type and gnrh3-/- adult brains and pituitaries to testing possible compensators. Overall, the brain and pituitary of the Gnrh3 KO fish display upregulation of genes involved in neurogenesis, axonogenesis and signal transduction, indicating for an increased signaling activity. In addition, some intriguing neuropeptides, who had no previously known reproductive relevance in fish, were implicated in the process. The results suggest that Gnrh3 is an important player in reproduction and that a multi-factorial compensatory mechanism is activated in its absence to guarantee proper reproduction."