Steroid profile and ovarian gene expression in Genyatremus luteus (Teleostei, Perciformes: Haemulidae) during sexual maturation

The aim of the present study was to assess histological features, sex steroid profile, and ovarian gene expression throughout the ovarian maturation of Genyatremus luteus in Brazilian Coastal Equatorial Amazon. Specimens were categorized into different gonadal maturation stages–immature (n = 7), maturing (n = 7), mature (n = 7), and spawned (n = 7)–based on histological features of ovarian follicles and on oocyte development. Plasma E2, 11-KT and 17α-OHP levels were measured through enzyme-linked immunosorbent assays. The gene expression of estrogen (er) and LH (lhr) receptors in the ovary was analyzed through real-time polymerase chain reaction. The highest plasma E2 concentration was found in mature specimens (P< 0.05). Plasma 17α-OHP concentrations have significantly increased from the immature to the final maturation stage (P< 0.05). Maturational reproductive stage did not have any effect on plasma 11-KT concentrations. Er expression in ovaries has significantly increased throughout ovarian maturation (P < 0.05), and it remained high at mature and spawned stages. Lhr expression showed similar trend throughout the maturation process, although its peak was observed at spawned stage (P< 0.05). In conclusion, the gene expression profile of er and lhr and plasma E2 and 17α-OHP concentrations are proportional to oocyte development; they play important role in regulating ovarian development and ovulation in G. luteus.