Summary: | Although male heterogamety controls Atlantic salmon sex, hormone treatment can induce sex reversal. In Australia where Atlantic salmon males are unmarketable, sex reversed females (neo-males) are crossed with females to produce all female stock. However, neo-males are indistinguishable from males making early male culling difficult. Therefore, a sex-specific genetic marker was needed to make this distinction. With no such marker available offspring sex was predicted via familial microsatellite analysis. Markers from Chromosome 2 (Ssa02), where the sex locus (SEX) previously mapped, predicted test family offspring sex inaccurately. A 64 SNP genome-wide scan suggested Chromosome 6 (Ssa06) housed SEX instead. Analysis of 38 male lineages revealed three sex loci on Ssa02, Ssa06 and Ssa03 with 34, 22 and 2 representative families respectively. An exon PCR test for the rainbow trout master sex-determining gene (sdY) was consistent with a single sex-determining gene that jumps around the genome in Atlantic salmon.
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