A temperature-induced sex reversal mechanism in ricefield eels

The ricefield eel (Monopterus albus), a protogynous hermaphrodite, is an important aquaculture freshwater fish in China. Intensive studies have focused on the sex reversal of this species, but the underlying mechanisms remain elusive. We performed comparative transcriptome analysis for gonadal tissues of female, intersex, and male ricefield eels. The results suggest that temperature may play a role in inducing the sex reversal. Moreover, an epithelial-mesenchymal transition (EMT) gene signature was found, suggesting an involvement of germinal epithelium in contributing to gonadal transformation. Our in vitro and in vivo experiments show that thermal cues are sensed by thermosensors such as Trpv4 in the gonadal cells of ricefield eels, which can be transduced to the sex determination cascades. The epithelial cells of germinal epithelium can become Sertoli cells via an EMT. Our study provides new insights into the molecular mechanisms underlying the sex reversal of ricefield eels.