Characterization and application of a quantitative DNA marker that discriminates sex in chinook salmon (Oncorhynchus tshawytscha)

Abstract

A qualitative male-specific DNA marker (OT-24) was amplified by spPCR (single-primer polymerase chain reaction) from chinook salmon (Oncorhynchus tshawytscha ) DNA along with several non-sex-linked products. The termini of the male-specific product were sequenced, and a pair of PCR primers were constructed for marker-specific PCR amplification. Dual primer PCR (dpPCR), with the marker-specific primers, amplified a product from both males and females. The amount of dpPCR product amplified from males was at least 100-fold greater than that from females. The quantitative difference between males and females was consistent among geographically distinct populations from western U.S. rivers. In addition, DNA sequence analysis indicated that OT-24 was highly conserved among geographically distinct salmon populations. The qualitative spPCR product segregated through several genetic crosses indicating equal sex ratios among progeny. Identification of the male and female juveniles by dpPCR was consistent with the spPCR analysis. There was no tissue specificity observed by spPCR or dpPCR analysis of this marker. A rapid DNA extraction method and dpPCR analysis were used to nonlethally determine sex ratios in wild spring chinook salmon adults, withheld for genetic and behavioral studies, prior to their development of gross sexual differences in their external morphology. Resume : Nous avons amplifie un marqueur qualitatif de l'ADN specifique aux mâles (OT-24) par spPCR (reaction en chaine de la polymerase a amorce unique) a partir de l'ADN de saumon quinnat (Oncorhynchus tshawytscha ), ainsi que plusieurs produits non lies au sexe. Les extremites des produits specifiques aux mâles ont ete sequencees, et une paire d'amorces de la