LAUSR

Sex regulation of bivalves is a complex process, and there has also been little research on their sex-determining genes. To better understand the sex determination/differentiation of bivalves, we analyzed the gonadal proteomics of Hyriopsis cumingii. We identified 673 peptides and 76 proteins. The 35 differentially expressed proteins identified included 19 upregulated and 16 downregulated proteins. FEM-1B protein associated with sex determination showed female-specific expression; the function of fem-1b gene was explored. The full-length cDNA of fem-1b cloned by RACE was 2105 bp. Quantitative PCR (qPCR) was performed on male and female tissues and early developmental stages; the results showed that fem-1b was expressed in both male and female tissues, and its expression level in gonads was significantly higher in females than in males (P < 0.01). In early embryonic development, the fem-1b mRNA expression increased significantly on the third day after fertilization (cleavage stage). Results of in situ hybridization showed a strong signal on oocyte membranes and no signal in male gonads. Our results indicate that fem-1b plays a certain role in sex determination and oocyte development of H. cumingii. This study provides valuable resources for understanding the mechanism and pathway of sex determination/differentiation of H. cumingii.