Identification and Functional Analysis of Genes in Chinese Tongue Sole ().

The Chinese tongue sole () is a traditional, precious fish in China. Due to the large growth difference between males and females, the investigation of their sex determination and differentiation mechanisms receives a great deal of attention. Forkhead Box O () plays versatile roles in the regulation of sex differentiation and reproduction. Our recent transcriptomic analysis has shown that genes may participate in the male differentiation and spermatogenesis of Chinese tongue sole. In this study, six members (, , , , , and ) were identified. Phylogenetic analysis indicated that these six members were clustered into four groups corresponding to their denomination. The expression patterns of the gonads at different developmental stages were further analyzed. All members showed high levels of expression in the early stages (before 6 months post-hatching), and this expression was male-biased. In addition, promoter analysis found that the addition of C/EBPα and c-Jun transcription factors enhanced the transcriptional activities of , , , and The siRNA-mediated knockdown of the , , and genes in the testicular cell line of Chinese tongue sole affected the expression of genes related to sex differentiation and spermatogenesis. These results have broadened the understanding of 's function and provide valuable data for studying the male differentiation of tongue sole.