Cortisol safeguards oogenesis by promoting follicular cell survival via Amh signaling

Oogenesis is mainly controlled by reproductive hormones. Even though the interference of stress hormones in fish oogenesis has been reported, it still needs to be elucidated by a genetic approach. cyp11c1, encoding 11hydroxylase, is the key gene involved in the synthesis of cortisol, the major glucocorticoid and in teleost. In the present study, a mutant line of cyp11c1 was established in tilapia by CRISPR/Cas9. cyp11c1+/- XX tilapia showed normal ovarian morphology but reduced egg quality as indicated by the lethality of embryos before 3 days post fertilization. This lethality could be partially rescued by the supplement of exogenous cortisol, instead of 11-ketotestosterone (11-KT, another product of 11hydroxylase) to the mother fish, rather than to the fertilized eggs. Transcriptome analyses revealed reduced expression of maternal genes in the eggs from the cyp11c1+/- XX fish.