Plant & Animal Genomes XI Conference Plant & Animal Genomes XI ConferenceJanuary 11-15, 2003
Town & Country Convention Center
San Diego, CA
Poster: Aquaculture
Pacific salmon possess an XY sex determination system where the two sex chromsomes are still largely homologous and heteromorphic structure in the vicinity of the sex-determination locus (the differential region) is difficult to identify cytogenetically. Two Y-chromosomal DNA markers (OtY1 and GH-Y) have been examined for their association with male development among natural populations of chinook, coho, chum and pink salmon. In family crosses, the markers were found by PCR analysis to be tightly linked to the sex-determination locus (SEX) on the Y chromosome. In individuals collected from the wild, overall, normal linkage (i.e. males possessing and females lacking the Y-markers) has been observed in 97.8% of 2476 individuals examined among 70 populations in the four species. Some rare exceptions were also identified, including weakly-amplifying alleles or null alleles for GH-Y, weak alleles for OtY1 in both males and females, and structural variants identified by Southern blot analysis. Despite their close linkage with SEX in the four species examined, neither of the two markers are sex-linked in sockeye salmon, rainbow trout or Atlantic salmon indicating that this linkage was established after the early radiation of the Pacific salmon. The relatively recent genome duplication in salmonids followed by differential loss of duplicate genes among the species make comparative mapping within this group particularly interesting. The variants observed for these markers among natural populations provide a glimpse of evolutionary processes affecting the structure of the Y chromosome in salmonids.