Y-chromosomal DNA markers for discrimination of chemical substance and effluent effects on sexual differentiation in salmon

Chinook salmon alevins were exposed during their labile period for sex differentiation to different concentrations of bleached kraft mill effluent (BKME), primary sewage effluent, secondary sewage effluent (SE), 17beta-estradiol, testosterone, and nonylphenol. After exposure for 29 days post hatching (DPH), fish were allowed to grow until 103 and 179 DPH, at which time their genetic sex was determined using Y-chromosomal DNA markers and their gonadal sex was determined by histology. Independent of treatment, all fish identified as genetic females (XX) in these experiments possessed normal female gonads. Only the highest dose of some treatments affected the development of gonads in genetic XY males. At 103 DPH, some genetic males treated with 1 mug estradiol/L, BKME 100% and SE 30% developed as physiological females, presenting ovaries identical to genetic females in the control group. The physiological female condition in XY fish was also observed in these treatments groups at 179 DPH, which suggests that the effect is permanent, whereas in other groups the effect changed between sampling periods. Identification of the genetic sex of individual animals using sex-linked DNA markers provides a useful tool for investigating environmental factors influencing sex determination and differentiation.