Expression of 20beta-hydroxysteroid dehydrogenase and P450 17alpha-hydroxylase/c17-20 lyase during hCG-induced in vitro oocyte maturation in snake head murrel Channa striatus.

Partial cDNAs encoding carbonyl reductase like 20beta-hydroxysteroid dehydrogenase (20beta-HSD) and P450 17alpha-hydroxylase/c17-20 lyase (CYP17) were isolated from the ovary of snake head murrel and they exhibited high sequence identity to the Nile tilapia and rainbow trout, respectively. A low transcript level of both 20beta-HSD and CYP17 were detected in pre-vitellogenic follicles, while the transcript level was high in full-grown immature follicles. In hCG-induced in vitro oocyte maturation, we found a significant increase in 20beta-HSD transcript level after 2 h. The CYP17 transcripts also showed a considerable increase following hCG-induction compared to saline-treated controls. On the other hand, Western blot analysis demonstrated no significant change in the CYP17 protein level during hCG-induced in vitro oocyte maturation. Taken together, we suggest that in addition to 20beta-HSD, the CYP17 might have a role in the shift in steroidogenesis during meiotic maturation of snake head murrel.