Identification and functional analysis of gene and the gene in the sexual development of sea cucumber, .

Members of the Doublesex and Mab-3-related transcription factor () gene family handle various vital functions in several biological processes, including sex determination/differentiation and gonad development. and ( in invertebrates) exhibit a very conserved interaction function during testis formation in vertebrates. However, the dynamic expression pattern and functional roles of the gene family and have not yet been identified in any echinoderm species. Herein, five members of the gene family (, , , and ) and the ancestor gene were identified from the genome of . Expression studies of family genes and in different tissues of adult males and females revealed different expression patterns of each gene. Transcription of , and was higher expressed in the tube feet and coelomocytes instead of in gonadal tissues. The expression of was found to be sustained throughout spermatogenesis. Knocking-down of by means of RNA interference (RNAi) led to the downregulation of and upregulation of the ovarian regulator in the testes. This indicates that may be a positive regulator of and may play a role in the development of the testes in the sea cucumber. The expression level of was higher in the ovaries than in the testes, and knocking down of by RNAi reduced and expression but conversely increased the expression of in the testes. In summary, this study indicates that and are indispensable for testicular differentiation, and might play a functional role during ovary differentiation in the sea cucumber.