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PM11 Wildlife Ecotoxicology
(PM203) Environmental contaminant-associated immunotoxicity in Pacific harbour seals: AhR expression and lymphocyte function.
Mos, L1, 2, Morsey, B3, Deguise, S3, Ross, PS2, 1 University of Victoria2 Institute of Ocean Sciences3 Universiy of Connecticut, Storrs, CT, USA
ABSTRACT- A number of virus-associated mass mortalities has taken place among marine mammal populations inhabiting industrial coastal areas. Environmental contamination with Persistent Organic Pollutants (POPs), such as polychlorinated biphenyls and -dioxins, may have played a role in the occurrence and severity of the events. Although no such mass mortality has been documented for marine mammals on the Pacific coast of North America, high levels of contamination in certain populations highlight their potential vulnerability. The presence of Morbillivirus (Canine Distemper Virus, Paramyxoviridae), implicated in previous marine mammal mortalities, in a British Columbia aquatic mammal, underlines the potential risk of a disease event in this area. To assess whether POP exposure of free-ranging harbour seals in British Columbia, Canada, and Washington State, USA leads to a disruption of immune function, we measured immune status using peripheral blood mononuclear cells (PBMC) of 4-6 week old pups. PBMCs were characterized for functionality, by mitogen-induced lymphocyte proliferation, and were quantified for aryl hydrocarbon receptor (AhR) expression, the primary mediator of dioxin-mediated immunotoxic effects. Significantly lower lymphocyte proliferation was observed in seals from the more contaminated, more urban, sites (n=43, p<0.05). While contamination may partly explain the difference, natural factors such as age, body weight and pathogen may have contributed. AhR expression was significantly induced in seal PBMC at all sites compared to a reference site (n=44, p<0.005). AhR expression did not correlate to the functionality of PBMCs. Our preliminary results suggests that AhR expression in PBMC may serve as a useful indicator of dioxin-like exposure in free-ranging marine mammals. In addition, harbour seals from more heavily contaminated sites on the Pacific coast may be more vulnerable to diseases.
Key words: immune function, harbour seal, aryl hydrocarbon receptor, AhR
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