Comparative transcriptomic analysis of ovary and testis reveals sex-related genes in roughskin sculpin Trachidermus fasciatus

The mechanisms underlying sex determination and differentiation have long intrigued researchers in the fields of development and evolutionary biology. The roughskin sculpin (Trachidermus fasciatus Heckel), displaying sexual dimorphism, provides an ideal model for studying the mechanisms. However, both genetic and genomic information concerning sex determination and differentiation, such as gonadal transcriptome data in roughskin sculpin, are lacking. Here, we present the first gonadal transcriptomes of roughskin sculpin and identify sex-related genes. We identified 8 531 differentially expressed genes (DEGs), among them 4 065 were upregulated in the ovary and 4 466 upregulated in the testis. Several sex-related gene ontology (GO) terms were enriched in ovary-biased genes, including "binding of sperm to zona pellucida", "egg coat formation", "positive regulation of acrosome reaction", "cell division", and "cell cycle", while the GO terms such as "spermatogenesis", "sperm axoneme assembly", "cilium assembly", "cilium movement", and "cilium movement involved in cell motility" were enriched in testis-biased genes. Moreover, six KEGG pathways were significantly enriched in the ovary, whereas only one was enriched in the testis. Of these DEGs, 40 sex-related genes were identified, which including 26 testis-biased genes (such as Dmrtb1, Gsdf, Sox9b, Wnt4b, Tcp11l2, and Efhb), and 14 ovary-biased genes (such as Cyp19a1a, Foxh1, Foxr1, Gdf3, Hsd17b12, and Igf2bp3). This gonadal transcript dataset would broaden our understanding of sex determination and differentiation mechanisms in roughskin sculpin, expand the genomic database, support future studies on sex-related gene functions, and facilitate molecular biology research into roughskin sculpin.