Sex determination in the genus Salmo

Salmonids share a strictly genetic mechanism for sex determination with males being the heterogametic sex. FISH analysis using BACs containing sexlinked microsatellite markers in Atlantic salmon identified chromosome 2 as its sex chromosome. The same sized chromosome 2 pairs in both sexes suggesting that the sex chromosome in Atlantic salmon is not highly differentiated. Combining information from sex determination pathways in different phyla, I created a list of 14 candidate sex determining genes. Candidate gene mapping identified all gene locations. However, their positions rule them out as the master regulatory gene. Comparative genomic analysis shows that the closest related species brown trout sex linkage group (LG) is syntenic to Atlantic salmon autosomal LG 8. FISH analysis revealed the brown trout sex chromosomes as a pair of small submetacentric chromosomes. Although they are closely related, I predict that Atlantic salmon and brown trout are likely to have different sex determining genes.