Meeting Abstract

9.6  Wednesday, Jan. 4  Immunotoxicity may be a more sensitive endpoint for sublethal polychlorinated biphenyl exposure in the northern leopard frog CARY, TL*; KARASOV, WH; University of Wisconsin, Madison, WI; University of Wisconsin, Madison, WI tcary@wisc.edu

Modulation of immune function due to contaminant exposure may be one way that amphibian populations are at increased risk to pathogens, as altered immune function may contribute to increased susceptibility. Additionally, at sublethal exposure levels, assessment of immune function may provide a more sensitive tool for determining toxicity. Polychlorinated biphenyls (PCBs) are a class of organochlorines that were used commercially in the mid-20th century as flame retardants, coolants and insulating fluids for transformers and capacitors. Due to the persistant nature of PCBs, they are still prevalent in the environment today and can be taken up by organisms and biomagnified through the food web. Beginning at the free-swimming stage, Lithobates (Rana) pipiens tadpoles were exposed to environmentally relevant dietary levels of PCB-126 (0, 0.37, 1.2, 5.0 ng PCB-126/g wet food) through metamorphic climax. Survivorship across all treatment levels ranged from 79.5 to 91.0%, with no significant treatment differences, supporting a sublethal exposure level. There were also no effects of dose level on growth and development of tadpoles, however, based on tissue residue levels and our earlier study of impacts of PCB-126 no major effects were expected for these endpoints. To assess how PCB-126 exposure affects the adaptive immune response, we used an enzyme-linked immunosorbent assay (ELISA) to measure specific-IgY production in post-metamorphic frogs following immunization with keyhole limpet hemacyanin (KLH). Results so far indicate that frogs exposed to PCB-126 at the highest dose had a lowered secondary antibody response compared to the controls, however, this result was not statistically significant. Supported by UW Sea Grant Institute (grant number NA16RG2257, project number R/EH-2).