Effects of Temperature on Gene Expression and Sex Determination in the Mangrove Rivulus, Kryptolebias Marmoratus

Title of Document: EFFECTS OF TEMPERATURE ON GENE EXPRESSION AND SEX DETERMINATION IN THE MANGROVE RIVULUS, KRYPTOLEBIAS MARMORATUS Jennifer Strykowski, Master of Science 2011 Directed by: Assistant Professor Dr. Edward F. Orlando, Department of Animal and Avian Sciences Rivulus is a hermaphroditic, self-fertilizing fish species that possesses an ovotestis and, in the wild, exist as androdioecious populations comprised of hermaphrodites and males. Following embryonic incubation at an ambient temperature of 25 °C, rivulus develop normally as hermaphrodites. Embryos exposed to a lower temperature of 20 °C during a critical phase of embryogenesis develop as males. In this study, rivulus embryos were maintained at ambient (25 °C), low (20 °C), or high (31 °C) temperatures during various stages of embryogenesis. The expression of seven evolutionary conserved genes with known relevance to gonadal differentiation including figα, foxl2, cyp19a1b, cyp19a1a, dmrt1, sox9a, and sox9b was measured using real-time PCR. The expression of cyp19a1a was downregulated at 20 °C and the expression of ovarian-specific genes increased throughout embryogenesis. These results provide the first data documenting how temperature affects the expression of genes relevant to sex determination during embryogenesis in rivulus. EFFECTS OF TEMPERATURE ON GENE EXPRESSION AND SEX DETERMINATION IN THE MANGROVE RIVULUS, KRYPTOLEBIAS MARMORATUS