Functional Analysis Evolution History of Gonadal Soma-derived Factor (gsdf) in Black Rockfish, Sebastes schlegelii

As a teleost- and gonad-specific growth factor, gsdf has been indicated to play an important role in sex differentiation and determination. In this study, the complete open reading frame (ORF) of gsdf was isolated from black rockfish, Sebastes schlegelii. Bioinformatics analysis showed that there is a conserved transforming growth factor-β (TGF-β) domain located on the C-terminus of Gsdf. Multiple sequence alignments revealed that fish gsdf were highly conserved in TGF-β domain which suggested their functional conservatism. Synteny analysis provided evidence for the hypothesis that gsdf was originated from fish-specific genome duplication (FSGD). To further explore its function, the expression pattern was examined based on the RNA-seq data and the result showed that significantly sexually dimorphic expression existing between male and female individuals. These results suggested that gsdf might play an important role in maintenance of male characteristics in Sebastes schlegelii.