Meeting Abstract

P2.47  Thursday, Jan. 5  Effects of Temperature on Gene Expression and Sex Determination during Embryogenesis in the Mangrove Rivulus, Kryptolebias mamoratus STRYKOWSKI, J.L.; ORLANDO, E.F.*; University of Maryland; University of Maryland eorlando@umd.edu

Rivulus is an androdioecious teleost fish, in which wild populations are comprised of mostly self-fertilizing hermaphrodites having a functional ovotestis and some males. Rivulus was the first fish found to have environmental sex determination, but no studies have investigated the effect of temperature on genes known to be part of the ovarian or testicular differentiation pathways. In the laboratory, embryonic incubation of rivulus at 25°C results in the development of the hermaphrodite phenotype containing ovarian and testicular tissue. 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 control (25°C), low (20°C), or high (31°C) temperatures during seven 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, quantitative PCR. The expression of cyp19a1a was downregulated at 20°C and the expression of ovarian-specific genes increased throughout embryogenesis. The downregulation of cyp19a1a, one of the aromatase genes, could cause a decrease in circulating estrogens, thus supporting testicular differentiation. These results provide the first data documenting how temperature affects the expression of genes relevant to sex determination during embryogenesis in rivulus.