Expression profile of doublesex/male abnormal‐3‐related transcription factor‐1 during gonadal sex change in the protogynous wrasse, Halichoeres trimaculatus

Sex change in fish involves a dramatic transformation of gonadal tissue and a switch in gametogenesis. Doublesex/male abnormal-3-related transcription factor-1 (DMRT1), encoded by the DMRT1 gene, is involved in testicular differentiation in a wide range of vertebrates as well as in sexual differentiation and gonadal sex change. In the present study, we investigated changes in the expression of dmrt1 during artificial gonadal sex change in the three-spot wrasse, Halichoeres trimaculatus, by real-time quantitative PCR and immunolocalization, using an anti-wrasse-Dmrt1 antibody that we prepared. We found that dmrt1 expression was predominantly observed in the testes, and that Dmrt1 was expressed in Sertoli cells of testes and a few granulosa cells surrounding vitellogenic oocytes of the ovary. Additionally, the upregulation of dmrt1 expression was consistent with an increase in spermatogenic cyst quantity rather than proliferation of presumptive spermatogonia, suggesting that dmrt1 is involved in the progression of spermatogenesis during sex change. Changes in the localization of Dmrt1 during gonadal sex change further implied that Sertoli cells originate from somatic cells adjacent to gonial germ cells during testicular formation in the three-spot wrasse.