Age-, gender-, and tissue-dependent transcriptional responses of cyp19a1 and vtg in Murray rainbow fish Melanotaenia fluviatilis exposed to17β-estradiol

Aromatase (Cyp19a1), a key steroidogenic enzyme, which plays a key role in sex determination and differentiation. Vitellogenin (Vtg), a female specific eggprotein. However, gene is also present in juveniles and males, but normally silent; when they are exposed to estrogenic chemicals <i>it</i> will be activated. Current study investigated the effect of exogenous 17β-estradiol on the mRNA expression of cyp19a1 and <i>vtg</i> in juveniles and adult rainbow fish with exposure to either 100 or 400 ng/L E2 for 14 days. The <i>cyp19a1</i> in the head and trunk region of juveniles, brain and gonads in both sexes of adult fish were studied using qPCR. <i>Cyp19a1b</i> was significantly elevated in the head and trunk region of juveniles at 400 ng/L E2 exposure but not at 100ng/L. <i>Vtg</i> showed concentration dependent increase in expression in the trunk regions of juveniles. In adults <i>cyp19a1b</i> significantly upregulated at 400 ng/L in brains of both sexes and in testes, but not in 100 ng/L E2. <i>Cyp19a1a</i> was not detected in tissues tested except for ovary and it decreased with increase in E2 concentration. In males, <i>vtg</i> was significantly upregulated in both concentrations of E2. Collectively, E2 at environmental concentrations can have a disruptive effect on the steroidogenic and reproductive pathways.