title: High temperature increases the masculinization rate of the all-female (XX) rainbow trout "Mal" population.
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.
authors.affiliation: INRA, UR1037 LPGP Fish Physiology and Genomics, F-35000, Rennes, France.
authors.forename: Karina
authors.initials: K
authors.lastname: Valdivia
authors.affiliation: INRA, UR1037 LPGP Fish Physiology and Genomics, F-35000, Rennes, France.
authors.forename: Elodie
authors.initials: E
authors.lastname: Jouanno
authors.affiliation: IGFL, UMR5242 CNRS/INRA/Université Claude Bernard Lyon I/ENS, Lyon, Cedex 07, France.
authors.forename: Jean-Nicolas
authors.initials: JN
authors.lastname: Volff
authors.affiliation: IGFL, UMR5242 CNRS/INRA/Université Claude Bernard Lyon I/ENS, Lyon, Cedex 07, France.
authors.forename: Delphine
authors.initials: D
authors.lastname: Galiana-Arnoux
authors.affiliation: INRA, UMR1313 GABI Génétique Animale et Biologie Intégrative, Domaine de Vilvert, 78352, Jouy-en-Josas Cedex, France.
authors.forename: René
authors.initials: R
authors.lastname: Guyomard
authors.affiliation: INRA, UR1037 LPGP Fish Physiology and Genomics, F-35000, Rennes, France.
authors.forename: Louise
authors.initials: L
authors.lastname: Helary
authors.affiliation: INRA, UR1037 LPGP Fish Physiology and Genomics, F-35000, Rennes, France.
authors.forename: Brigitte
authors.initials: B
authors.lastname: Mourot
authors.affiliation: INRA, UR1037 LPGP Fish Physiology and Genomics, F-35000, Rennes, France.
authors.forename: Alexis
authors.initials: A
authors.lastname: Fostier
authors.affiliation: INRA, UMR1313 GABI Génétique Animale et Biologie Intégrative, Domaine de Vilvert, 78352, Jouy-en-Josas Cedex, France.
authors.forename: Edwige
authors.initials: E
authors.lastname: Quillet
authors.affiliation: INRA, UR1037 LPGP Fish Physiology and Genomics, F-35000, Rennes, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Guiguen
mesh_terms: D000818:Animals; D005260:Female; D006358:Hot Temperature; D008297:Male; D008957:Models, Genetic; D009154:Mutation; D017686:Oncorhynchus mykiss / Q000235:genetics* / Q000502:physiology; D010641:Phenotype; D019849:Sex Determination Processes; D012733:Sex Differentiation; D012744:Sex Ratio