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(062) Expression of genes specific for germ cell and gonadal development as a tool to study the effects of endocrine disrupters in fish. Scholz, Stefan1, Domaschke, Hagen1, Ostermann, Kai2, Rödel, Gerhard2, Gutzeit, Herwig1, 1 2 ABSTRACT- The effect of endocrine disrupters on sexual differentiation of fish are likely to be complex and could, for instance, result from hormone receptor-mediated gene expression or the interference with hormone metabolism or signal transduction pathways. We have begun to analyse three potentials target genes involved in germ cell and sexual differentiation of the model teleost medaka (Oryzias latipes): (1) gcl (germ cell less), the homologue of a gene involved in germ cell differentiation in Drosophila; (2) sox9, coding for a SRY-related transcription factor expressed sex-specifically during gonadal development; and (3) CYP19 aromatase, the gene product of which catalyses the synthesis of estrogens from androgen precursors in the follicular layer of the ovary. gcl and sox9 were identified and sequenced using degenerated primers. The sequences show a striking similarity to homologues of other vertebrates with the highest degree of identity to teleost species. In contrast to findings from other vertebrates gcl and sox9 were specifically expressed in the ovary and showed a low expression in the testis. Aromatase gene expression has been measured by RT-PCR in testis of juvenile fish exposed for 2 month to 17- Key words: Endocrine disrupters, Gene expression, Medaka, Sex differentiation |
-ethinylestradiol. The otherwise silent gene aromatase was induced in male testis possibly due to a regulation by a ERE-like sequence in its promoter region. Gene expression studies involving key genes in embryogenesis and sex differentiation are indispensable for the analysis of the molecular reactions of endocrine disrupters at this sensitive stage of development.