Abstract
Salmonids are generally considered to have a robust genetic sex determination system with a simple male heterogamety (XX/XY). However, spontaneous masculinization of XX females has been found in a rainbow trout population of gynogenetic doubled haploid individuals. The analysis of this masculinization phenotype transmission supported the hypothesis of the involvement of a recessive mutation (termed mal). As temperature effect on sex differentiation has been reported in some salmonid species, in this study we investigated in detail the potential implication of temperature on masculinization in this XX mal-carrying population. Seven families issued from XX mal-carrying parents were exposed from the time of hatching to different rearing water temperatures ((8, 12 and 18°C), and the resulting sex-ratios were confirmed by histological analysis of both gonads. Our results demonstrate that masculinization rates are strongly increased (up to nearly two fold) at the highest temperature treatment (18°C). Interestingly, we also found clear differences between temperatures on the masculinization of the left versus the right gonads with the right gonad consistently more often masculinized than the left one at lower temperatures (8 and 12°C). However, the masculinization rate is also strongly dependent on the genetic background of the XX mal-carrying families. Thus, masculinization in XX mal-carrying rainbow trout is potentially triggered by an interaction between the temperature treatment and a complex genetic background potentially involving some part of the genetic sex differentiation regulatory cascade along with some minor sex-influencing loci. These results indicate that despite its rather strict genetic sex determinism system, rainbow trout sex differentiation can be modulated by temperature, as described in many other fish species.
Highlights
The primary causal signal responsible for sex determination in vertebrates is variable [1]
Two main types of primary sex determination have been described in gonochoristic species: genotypic sex determination (GSD) and environmental sex determination (ESD)
These results suggest that despite its rather strict GSD system, thermal effects in combination with special genetic backgrounds can influence rainbow trout sex differentiation, a developmental trait described in many other fish species
Summary
The primary causal signal responsible for sex determination in vertebrates is variable [1]. A large range of sexuality types has been described, from hermaphroditism to gonochorism [8] This variability is due to the high diversity of sex determination systems [9] that include several stages between full GSD and full ESD [10, 11]. A detailed review on the influence of temperature [7] on sex differentiation in teleosts distinguished a full and physiological TSD system from the thermal effects on GSD In both cases, high temperatures consistently induced male-biased sex ratios [7]; with only a few notable exceptions, including the sockeye salmon, Oncorhynchus nerka, in which a female-biased sex ratio was observed at high temperatures [12]. A more recent and thorough study on rainbow trout demonstrated that high temperatures (18 ̊C)
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 callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
