Molecular cloning and expression analysis of estrogen receptor betas (ERβ1 and ERβ2) during gonad development in the Korean rockfish, Sebastes schlegeli.

Estrogen receptors (ER) play a crucial role in mediation of estrogen activities. Here we report the isolation and expression analysis of ERβ1 and ERβ2 from ovary Korean rockfish (Sebastes schlegeli). were isolated using reverse transcription-polymerase chain reaction (PCR) and rapid amplification of cDNA ends procedures. The cDNA of this study, ERβ1 (588 amino acids) and ERβ2 (659 amino acids) were identified using reverse-transcriptase PCR (RT-PCR) and rapid amplification of cDNA ends procedures. Structural analysis showed both ERβs contain six typical nuclear receptor-characteristic domains. Phylogenetic analysis indicated that Korean rockfish ERβs were highly conserved among teleost. RT-PCR confirmed that the ERβs were widely distributed in both gonads and extra gonadal tissues. Further, we analyzed the expression patterns of male and female S. schlegeli during the reproductive cycle using quantitative real-time PCR (qRT-PCR). The results showed that the highest expression levels were observed in testis at immature sperm stage for both of KrERβ1 and KrERβ2. For female, the expressions of KrERβ1 and KrERβ2 were significantly higher in the ovary at the early-oocyte stage. Cloning these two ERβ subtypes in the Korean rockfish, together with the information on expression levels in adult fish has given us the foundation to investigate their possible role in brain-pituitary-gonad neuroendocrine axis in future studies.