Valdivia Karina, Jouanno Elodie, Volff Jean-Nicolas, Galiana-Arnoux Delphine, Guyomard René, Helary Louise, Mourot Brigitte, Fostier Alexis, Quillet Edwige, Guiguen Yann
INRA, UR1037 LPGP Fish Physiology and Genomics, F-35000, Rennes, France.
IGFL, UMR5242 CNRS/INRA/Université Claude Bernard Lyon I/ENS, Lyon, Cedex 07, France.
PLoS One. 2014 Dec 12;9(12):e113355. doi: 10.1371/journal.pone.0113355. eCollection 2014.
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.
鲑科鱼类通常被认为具有强大的遗传性别决定系统，具有简单的雄性异配型（XX/XY）。然而，在雌核发育的双倍体虹鳟鱼群体中发现了XX雌性的自发雄性化现象。对这种雄性化表型传递的分析支持了隐性突变（称为mal）参与其中的假设。由于在一些鲑科鱼类中已报道温度对性别分化有影响，在本研究中，我们详细调查了温度对这个携带mal的XX群体中雄性化的潜在影响。从携带mal的XX亲本产生的七个家系从孵化时起就暴露于不同的养殖水温（8、12和18°C），并通过对性腺的组织学分析确认了由此产生的性别比例。我们的结果表明，在最高温度处理（18°C）下，雄性化率大幅增加（高达近两倍）。有趣的是，我们还发现不同温度下左右性腺的雄性化存在明显差异，在较低温度（8和12°C）下，右侧性腺比左侧性腺更常发生雄性化。然而，雄性化率也强烈依赖于携带mal的XX家系的遗传背景。因此，携带mal的XX虹鳟鱼的雄性化可能是由温度处理与复杂的遗传背景之间的相互作用触发的，这种遗传背景可能涉及遗传性别分化调控级联的某些部分以及一些微小的性别影响位点。这些结果表明，尽管虹鳟鱼具有相当严格的遗传性别决定系统，但其性别分化仍可像许多其他鱼类一样受到温度的调节。
