Role of NR5A2 in regulating sex differentiation, steroidogenesis, and gonadal development in Chlamys farreri.

Chlamys farreri is a commercially important bivalve species in global aquaculture. However, research on the mechanisms regulating its sex differentiation and reproduction remains relatively sparse. In this study, the role of nuclear receptor subfamily 5 group A member 2 (NR5A2) in sex differentiation, steroidogenesis, and gonadal development in C. farreri was investigated using a 28-day RNA interference experiment. RNA-seq data analysis revealed differentially expressed genes between males and females following NR5A2 knockdown. Weighted gene co-expression network analysis (WGCNA) further identified gene modules closely associated with reproductive development, with the yellow module demonstrating a significant correlation with the sex phenotype. Gene set enrichment analysis (GSEA) identified several signaling pathways related to reproduction that were suppressed, including ovarian follicle development, cholesterol metabolism, and ovarian steroidogenesis. Based on the above analysis, we identified 25 differentially expressed genes linked to these processes. Histological observations revealed that NR5A2 knockdown significantly delayed gonadal development in both sexes of scallops, as indicated by a notable decrease in follicular cell number and size. Taken together, NR5A2 knockdown significantly affected signaling pathways related to cholesterol metabolism, ovarian steroidogenesis, sex differentiation and gonadal development, providing a novel theoretical basis for understanding sex differentiation and reproductive development in invertebrates.