Female-biased expression and potential regulatory roles of lsm14bl during ovarian development and sex differentiation in Cynoglossus semilaevis

The lsm14b (protein_LSM14_homolog_B), an important member of the LSM14 protein family, plays a key role in oocyte development and maturation. However, the role of lsm14b in sex differentiation in fish remains poorly understood. This study aimed to investigate the expression patterns, cellular localization, and potential regulatory roles of lsm14b subfamily ( Cs_lsm14b and Cs_lsm14bl ) during ovarian development and sex differentiation in Cynoglossus semilaevis . The results showed that Cs_lsm14b and Cs_lsm14bl both contain the conserved LSM14 and FDF domains, which show a high homology to fish and mammalian LSM14B in the phylogenetic analysis. Besides, Spatiotemporal expression profiling and in situ hybridization revealed that Cs_lsm14b genes were predominantly localized to oocytes across multiple developmental stages and displayed a distinct female-biased expression pattern. In addition, Cs_lsm14bl overexpression in testicular cells significantly affected pathways related to DNA replication, cell cycle, homologous recombination, p53 signaling, oocyte meiosis, and progesterone-mediated oocyte maturation. Meanwhile, the significantly differential expression of several sex differentiation-related genes ( adcy1l , adcy3l , wnt7b , rspo2 ) participating in Wnt and GnRH signaling pathways, may suggest the potential regulatory functions of Cs_lsm14bl in gonadal development. Overall, the findings of this study may suggest that Cs_lsm14b subfamily involvement in ovarian development and oocyte maturation in C. semilaevis , providing a molecular basis for understanding the evolution and function of the LSM14 family and the mechanisms of sex differentiation and oocyte development in fish.