A sex-specific transcription factor controls male identity in a simultaneous hermaphrodite

Abstract

Evolutionary transitions between hermaphroditic and dioecious reproductive states are found in many groups of animals. To understand such transitions, it is important to characterize diverse modes of sex determination utilized by metazoans. Currently, little is known about how simultaneous hermaphrodites specify and maintain male and female organs in a single individual. Here we show that a sex-specific gene, Smed-dmd-1 encoding a predicted doublesex/male-abnormal-3 (DM) domain transcription factor, is required for specification of male germ cells in a simultaneous hermaphrodite, the planarian Schmidtea mediterranea. dmd-1 has a male-specific role in the maintenance and regeneration of the testes and male accessory reproductive organs. In addition, a homologue of dmd-1 exhibits male-specific expression in Schistosoma mansoni, a derived, dioecious flatworm. These results demonstrate conservation of the role of DM domain genes in sexual development in lophotrochozoans and suggest one means by which modulation of sex-specific pathways can drive the transition from hermaphroditism to dioecy.

A premeiotic function for boule in the planarian Schmidtea mediterranea

“…As an additional control, we performed a parallel experiment with dmd1 (SI Appendix, Fig. S6A), a gene previously shown to be required for SSC respecification (29). We confirmed gene knockdowns at 14 d postamputation by quantitative real time-PCR (qRT-PCR) (SI Appendix, Fig.…”

“…In addition to their remarkable ability to regenerate all body parts and organ systems, planarians are capable of respecifying germ cells from amputated tissue fragments devoid of reproductive structures (24,25,29). Thus, like mammals, planarians can specify their germ line via inductive signals.…”

“…Is the premeiotic function of this protein family indeed derived, as currently hypothesized? We addressed these questions using the planarian Schmidtea mediterranea, a freshwater flatworm that has emerged as an important model for studying regeneration and germ cell biology (23)(24)(25)(26)(27)(28)(29).…”

“…4A). To determine the role of these genes in spermatogenesis, we performed RNAi during homeostasis (in sexually mature adults), during development (in hatchlings), as well as in sexually immature regenerates (animals fed dsRNA three times, amputated prepharyngeally to induce regression of testes (29), and refed dsRNA during regeneration). DAZAP1(RNAi) animals lacked elongated spermatids and mature sperm, whereas other male germ cells appeared intact in all three experimental conditions (n = 6/6 for all; Fig.…”

Expression characterization of testicular DMRT1 in both Sertoli cells and spermatogenic cells of polyploid gibel carp

“…Increasing evidences have indicated that most of the known sex determination genes discovered so far in vertebrates are derived from the duplicated homologs of Dmrt1 gene (Chong et al, 2013;Gamble and Zarkower, 2012;Gempe and Beye, 2011;Graves, 2013;Herpin and Schartl, 2011;Kikuchi and Hamaguchi, 2013;Matson and Zarkower, 2012;Siegal and Baker, 2005;Zhou and Gui, 2010). For gibel carp, as a unisexual lineage that is able to utilize gynogenesis as a unisexual reproduction mode, how male individuals arise and how male determination genes evolve will be the merit for further investigation.…”