T5 AM Terrestrial Ecotoxicology
Tuesday, 15 November 2005: 8:00 AM - 11:40 AM in 321-323

(WIR-1117-836899) An evaluation of two genetic indicators of PCBs exposure in ranched and natural populations of American mink.

Wirgin, I¹, Maceda, L¹, Mayack, D.², ¹ Department of Environmental Medicine, NYU School of Medicine, Tuxedo, NY, United States² New York State Department of Environmental Conservation, Gloversville, NY, United States

ABSTRACT- The effects of PCBs on the health of the Hudson River ecosystem is of concern. Because they are piscivorous, live in small reproductively isolated demes, and are sensitive to the reproductive and early life-stage toxic effects of PCBs, mink Mustela vison is an ideal model to evaluate the bioavailability and population effects of these contaminants. We hypothesized that levels of CYP1A expression and levels and patterns of genetic variation in natural populations of mink reflect their exposure histories to PCBs. We evaluated the inducibility of CYP1A mRNA in ranched mink that were fed a diet of PCB contaminated fish. We also characterized patterns of microsatellite DNA variation in environmentally exposed mink from PCB contaminated and cleaner natural populations in New York, Rhode Island, Maine, Nova Scotia, and Ontario. Using a PCR-based approach, a partial CYP1A sequence was obtained from mink cDNA and this was used to design an RT-PCR assay to quantify levels of CYP1A mRNA expression in mink. We found that hepatic CYP1A mRNA expression was inducible by environmentally relevant PCB exposures and that levels of gene expression generally corresponded to tissue burdens of PCBs. More than 750 mink specimens were collected from sites in the northeast including specimens highly contaminated with PCBs from the corridor immediately adjacent to the upper Hudson River PCBs hotspots. Twenty-four of 192 mink exceeded the benchmark toxicity threshold of 9 ug sum of Aroclors/g lipid; levels ranged to a maximum of 139 ug sum of Aroclors/g lipid. We quantified levels of microsatellite variation at nine previously isolated microsatellite loci among these 750 mink samples. Levels of allelic diversity were high at all loci. Levels of allelic diversity, heterozygosity, and allelic-genotype frequencies will be compared among mink from demes with varying tissue burdens of PCBs and from different ecozones within New York and elsewhere.

Key words: PCBs, CYP1A expression, microsatellite DNA variation, Hudson River