Identification and Expression Analysis of Dsx and Its Positive Transcriptional Regulation of IAG in Black Tiger Shrimp ( Penaeus monodon ).

() is a polymorphic transcription factor of the family, which is involved in male sex trait development and controls sexual dimorphism at different developmental stages in arthropods. However, the transcriptional regulation of the gene is largely unknown in decapods. In this study, we reported the cDNA sequence of in , which encodes a 257 amino acid polypeptide. It shared many similarities with Dsx homologs and has a close relationship in the phylogeny of different species. We demonstrated that the expression of the male sex differentiation gene was predominantly expressed in the testis, and that dsRNA injection significantly decreased the expression of the insulin-like androgenic gland hormone () and male sex-determining gene while increasing the expression of the female sex-determining gene. We also identified a 5'-flanking region of that had two potential cis-regulatory elements (CREs) for the transcription. Further, the dual-luciferase reporter analysis and truncated mutagenesis revealed that overexpression significantly promoted the transcriptional activity of the promoter via a specific CRE. These results suggest that is engaged in male reproductive development and positively regulates the transcription of the by specifically binding upstream of the promoter of the . It provides a theoretical basis for exploring the sexual regulation pathway and evolutionary dynamics of Dmrt family genes in .