Meeting Abstract

P1.83  Monday, Jan. 4  Is SOX9 Expression Sexually Dimorphic in the Gonads of a Sex Changing Fish? SMITH, V.L.*; GROBER, M.S.; Georgia State University; Georgia State University vsmith8@student.gsu.edu

One approach to understanding the mechanisms that permit adult sex reversal is to determine the degree to which the highly conserved molecular cascades that generate gonadal tissues have come under the control of novel regulatory elements. One gene in particular, SRY-box 9 gene (SOX9), plays a key role in the male sexual differentiation cascade amongst all groups of extant vertebrates and throughout the animal kingdom. In most vertebrates, once sex has been determined, gonadal function is fixed for life. As a result, SOX9 is not expressed in the adult ovary, but is highly expressed in the adult testis. The bluebanded goby (Lythrypnus dalli) exhibits an alternative reproductive strategy called sequential hermaphroditism where fish respond to changes in social status by changing from male to female (protandry) or from female to male (protogyny) phenotype. We hypothesize that the highly conserved molecular cascades that produce vertebrate testes or ovaries have come under the control of social cues in L. dalli, allowing for gonadal sex change. This hypothesis assumes that sex-changing fishes utilize the conserved molecular cascades for the production of gonads. To examine this assumption, this experiment will measure SOX9 mRNA expression in the ovaries and testes of adult L. dalli. I have isolated and sequenced cDNA fragments of SOX9 using previously published primers for semi-quantitative PCR. Preliminary results (n=5) indicate that the gonads of adult L. dalli display the conserved sexual dimorphism in gonadal SOX9 expression. Confirmation of this conserved mechanism of differentiation is an initial step towards understanding the novel regulatory mechanisms that control adult sex reversal.