Abstract
Sex reversal induced by temperature change is a common feature in fish. Usually, the sex ratio shift occurs when temperature deviates too much from normal during embryogenesis or sex differentiation stages. Despite decades of work, the mechanism of how temperature functions during early development and sex reversal remains mysterious. In this study, we used Chinese tongue sole as a model to identify features from gonad transcriptomic and epigenetic mechanisms involved in temperature induced masculinization. Some of genetic females reversed to pseudomales after high temperature treatment which caused the sex ratio imbalance. RNA-seq data showed that the expression profiles of females and males were significantly different, and set of genes showed sexually dimorphic expression. The general transcriptomic feature of pesudomales was similar with males, but the genes involved in spermatogenesis and energy metabolism were differentially expressed. In gonads, the methylation level of cyp19a1a promoter was higher in females than in males and pseudomales. Furthermore, high-temperature treatment increased the cyp19a1a promoter methylation levels of females. We observed a significant negative correlation between methylation levels and expression of cyp19ala. In vitro study showed that CpG within the cAMP response element (CRE) of the cyp19a1a promoter was hypermethylated, and DNA methylation decreased the basal and forskolin-induced activities of cyp19a1a promoter. These results suggested that epigenetic change, i.e., DNA methylation, which regulate the expression of cyp19a1a might be the mechanism for the temperature induced masculinization in tongue sole. It may be a common mechanism in teleost that can be induced sex reversal by temperature.
Highlights
IntroductionThree main types of primary sex determination have been described in gonochoristic species: genotypic sex determination (GSD), temperature-dependent sex determination (TSD) and a combination of both (GSD ++ TSD) (Ospina-Álvarez and Piferrer, 2008; Yamamoto et al, 2014)
The types of sex determination are diversified in teleost
Since firstly described in Menidia menidia (Conover and Kynard, 1981), this phenomenon had been widely observed in fish, which showed that sex ratio would become unbalanced if the fish experienced high temperature during thermosensitive period (TSP)
Summary
Three main types of primary sex determination have been described in gonochoristic species: genotypic sex determination (GSD), temperature-dependent sex determination (TSD) and a combination of both (GSD ++ TSD) (Ospina-Álvarez and Piferrer, 2008; Yamamoto et al, 2014). High Temperature Induces Sex Reversal in the development process. Apart from fish, the temperature irreversibly determining gonadal sex has been well established in reptiles and amphibians (Sarre et al, 2011; Flament, 2016). The imbalance of sex ratio was caused by sex reversal. It can be divided into three types: (1) high temperature has positive correlation with the proportion of males. It can be divided into three types: (1) high temperature has positive correlation with the proportion of males. (2) High temperature induces females, and has a negative correlation with males. (3) Both low temperature and high temperature increase the proportion of males (Baroiller and D’Cotta, 2001; Devlin and Nagahama, 2002; Ospina-Álvarez and Piferrer, 2008)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
