Liver cyp1A protein expression and pigmented macrophage aggregates as indicators of polychlorinated biphenyl exposure in carp Cyprinus carpio L. from the Kalamazoo River Superfund site, Michigan

Abstract

Cytochrome p450 1A (cyp1A), pigmented macrophage aggregate (PMA) variables and fish descriptive characteristics were measured in field‐caught adult carp Cyprinus carpio from two upstream reference sites and two downstream Superfund sites contaminated with polychlorinated biphenyls (PCBs) in the Kalamazoo River, MI, U.S.A. Liver PCB content in fish differed among sites, and immunocytochemical cyp1A protein expression was significantly elevated in fish liver at contaminated sites and with liver PCBs. PMA number (number per mm 2 ), mean size [mean size (area) per mm 2 ] and percentage area occupied (total area of PMAs per total field area evaluated) were significantly greater in fish livers from the contaminated sites. PMA number was significantly greater at one contaminated site, Lake Allegan, than at the Trowbridge Dam impoundment, the other contaminated site. The level of cyp1A protein was significantly correlated with PMA mean size and PMA per cent area but not with PMA number. These results suggest that carp are responding to PCB contamination and point to complex site dynamics related to fish condition in the Kalamazoo River.

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