Allelic diversification gave rise to the sablefish (A. fimbria) gsdfX and gsdfY genes with sexually dimorphic expression. (A) Maps of the full-length sablefish gsdfX and gsdfY mRNAs, including polymorphisms and alternative poly-adenylation sites. (CDS) Coding sequence, (UTR) untranslated region, (SNP) single nucleotide polymorphism. (B) PCR amplification of gsdfX and gsdfY on X and Y Chromosomes, respectively, based on specific inserts upstream of the coding sequences. Amplification of an upstream sequence common to the two gsdf paralogs was used as a control. Bands represent amplification from 10 genotypic males (XY) and 10 genotypic females (XX). The depiction shows the general gene structure and placement of assay primers.