Molecular cloning and characterization of estrogen and androgen receptors in Mandarin fish, Siniperca chuatsi

Steroid hormones are essential for the normal reproductive activity in females and males, such as early sex differentiation, gonad development and sex reversal, which works by binding with the steroid receptors. In the present study, the full-length of estrogen receptors (ER alpha, ER beta 1 and ER beta 2) and androgen receptors (AR alpha and AR beta) cDNAs were isolated from the mandarin fish (Siniperca chuatsi). Real time quantitative PCR (RT-qPCR) revealed that ER alpha and ER beta 2 expressed mainly in the liver of females and males, and ER beta 1 mostly distributed in ovary and testis. Additionally, the high expressions of AR alpha and AR beta in both females and males were detected in gonads and livers respectively. During the early sex differentiation stage, the expressions of ERs and ARs in female were higher than in male during 5-30 day after hatching (dah), and reached the peak level at 30 dah. In males, the expressions of ER beta 1, ER beta 2, and AR beta increased largely during 30 dah to 60 dah, and revealed significantly higher levels than in females during 60-180 dah. In female, the expression of ER beta 2 in ovary increased sharply at 180 dah. Moreover, the result of gonadal histology revealed that the spermatocytes were observed at 45 dah and the spermatozoon could be found largely at 60 dah in males and oil droplets appeared for the first time in the oocytes at 180 dah. The expression levels of three ERs and AR beta were up-regulated and the AR alpha was down-regulated during female to male sex reversal induced by 17 alpha-methyltestosterone (MT). Furthermore, after MT treatment for 30 and 35 days, the expressions of ER beta 1, ER beta 2 and AR beta were significantly up-regulated. These results suggest that ER beta 1, ER beta 2 and AR beta may play critical roles in spermatogenesis and masculinization, while ER beta 2 and ER beta 1 may be essential for vitellogenesis and ovary development in female.

Automated summary

The study revealed that ER beta 1, ER beta 2, and AR beta play critical roles in spermatogenesis and masculinization, while ER beta 2 and ER beta 1 are essential for ovary development and vitellogenesis in females.