Mutation of medaka cyp27b1 promotes sex reversal of female to male

In previous study, we constructed a sex reversal medaka mutant and identified the different expression level of cyp27b1 gene compared with wild-type. However, whether cyp27b1 affects the sex determination and gonad differentiation has not been reported.

In this study, we constructed cyp27b1 heterozygote mutant by using CRISPR/Cas9 system in Japanese medaka. Phenotype analysis showed that sex reversal was occurred in the heterozygote mutant, in which the first and second sexual characteristics of male mutant (XX) was not significantly different from that of male wild-type (XY). In addition, knockout cyp27b1 gene leads to no effect on testis development. and the same phenotype was observed in the generation male mutants.