The SoxE gene family in Siniperca scherzeri: Systematic characterization, spatiotemporal expression, and sexual dimorphism in early gonads.

This study systematically identified all six members of the soxE gene family (sox8a, sox8b, sox9a, sox9b, sox10a, sox10b) in Siniperca scherzeri for the first time. Their conserved HMG-box domains were confirmed through bioinformatics analysis. The expression patterns of these genes were analyzed across different tissues of adult fish and during various stages of gonad development. Additionally, the effects of 17α-methyltestosterone (MT) immersion treatment during the critical period of sex differentiation on soxE genes expression and gonad development were investigated. The results revealed that the expression levels of all soxE genes were significantly higher in male individuals, particularly in the testes, compared to females, indicating pronounced sexual dimorphism. Specifically, MT treatment significantly upregulated the expression of sox9a and sox9b, accompanied by an increase in the expression of the male-related gene dmrt1 and a decrease in the expression of the female-related gene cyp19a1a, thereby inducing sex reversal in genetic females. These findings suggest that the soxE gene family, particularly the two isoforms of sox9, may play crucial roles in male sex determination, gonad development, and the regulatory network of sex differentiation in Siniperca scherzeri, providing an important molecular foundation for understanding its sex determination mechanisms.