Comprehensive analysis of Sox genes in the Pacific oyster (Crassostrea gigas): Insights into expression and potential functions.

The Sox gene family characterized by the conserved HMG-box domain, plays crucial roles in various biological processes, including development and differentiation. In this study, we identified seven Sox genes in the genome of the Pacific oyster (Crassostrea gigas), and classified them into seven subgroups: SoxB1, SoxB2, SoxC, SoxD, SoxE, SoxF, and SoxH. All Sox proteins contained the conserved HMG domain, crucial for DNA binding and transcriptional regulation. Spatial expression analysis revealed tissue-specific expression patterns: CgSoxH was highly specific to gonads, CgSoxF to the digestive gland, and CgSoxB2 subgroup to the labial palps, indicating distinct biological roles. Developmental profiling showed CgSoxB1 and CgSoxC with maternal expression, while CgSoxD and CgSoxE were active from gastrulation onwards. In gonadal development, CgSoxB1 was prominent in female gonads, while CgSoxH was associated with male gonadal maturation, suggesting the potential roles in sex differentiation. These findings provide novel insights into the functional roles of Sox genes in the reproductive and developmental processes of C. gigas.