어류의 체내에서 성분화를 유도하는 물질이 성스테로이드호르몬(sex steroid hormone)이라는 사실이 잘 밝혀져 있으며, 성스테로이드 생합성 효소의 하나인 aromatase도 성분화에 직접적인 역할을 하는 것으로 알려져 있다. 본 연구에서는 유전적으로 암컷인 틸라피아 자어(larvae) 집단을 aromatase 저해제(aromatase inhibitor, AI)인 Fadrozole로 침지 처리하여 초기 발생단계 중 어느 시기에 aromatase가

Sex steroids are generally considered as natural sex inducers in fish, and aromatase (cytochrome P450 aromatase) that catalyzes androgens into estrogens in the steroidogenic pathway is also known to be involved in sex differentiation. The timing of aromatase action is, thus, of central importance in the study of fish sex differentiation. We treated sexually undifferentiated tilapia (Oreochromis niloticus) larvae with , a non-steroidal aromatase inhibitor (AI), by immersing the fish in a solution containing AI during the sex differentiation period to narrow down the critical period of aromatase action. Fish were treated once at 11 or 13 days post fertilization (dpf), or twice at 11 and 13 dpf. The concentrations of AI at each time of the treatment were 0 mg/L (control), 50 mg/L or 100 mg/L. Survival rate was not statistically associated with AI immersion treatment (p>0.25). However, sex ratio was significantly altered by the treatment, with higher concentration and double immersion being more effective in masculinizing genetic females (p<0.05). These results suggest that aromatase action for sex differentiation in this fish species would begin at least from 11 dpf which is much earlier than previously expected, and that only 3 hours of brief immersion in AI solution is powerful enough to alter genetically programed sex.

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