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In an article published in Scientific Reports, the GenAqua team and its partners sought for the origin for these spontaneous masculinsations. To do this, the phenotypic sex of trout from a monosexed XX aquaculture population (Les Fils de Charles Murgat, Beaufort, France) were determined by gonad observation. Three categories were defined: female individuals (two ovaries), male individuals -two testicles) and intersexed individuals (simultaneous presence of ovarian and testicular tissues). By combining the average genotype density (30 000 SNP markers) from part of the individuals and complete genomic sequencing of their mothers, it was possible to identify a zone on chromosome 1, inependent of sdY, containing several punctual mutations present preferentially in male individuals (males and intersexed). In this region, three candidate genes potentially implicated in spontaneous masculinisation were identified: fgfa8, cyp17a1 along with an uncharacterized protein.

This study shows that spontaneous masculinization in female trout is in part controlled by genetic factors that coexist with a major determinant for sex. This is the first step towards an improved understanding of ther underlying mechanisms, leading to perspectives for the use of genetic markers to identify mutations favoring masculinisation.
 

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