A flow cytometric comparison of DNA content and glutathione levels in hepatocytes of English sole (Parophyrs vetulus) from areas of differing water quality

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Abstract
English sole (Parophyrs vetulus) in Puget Sound, Washington, USA are at risk of hepatocarcinogenesis specifically in areas adjacent to polluting industrial effluents. A question concerning population and ecosystem survival is whether any of the effects of etiopathologic change are reversible. This has been approached by looking for evidence of tumor accelerating effects in an exposed population. Cellular parameters were determined by flow cytometry for hepatocytes of English sole. Cells containing hyperdiploid DNA not present in fish from reference waters, Port Madison, were found in all non-tumor-bearing and tumor bearing fish taken from a polluted site, Eagle Harbor, where incidence of hepatic neoplasia approaches 30%. Induction of altered DNA content in the exposed general hepatocyte population suggests environmental induction rather than an association with lesionsper se. In contrast, glutathione levels in hepatocytes (0.8–3.2 nmol/mg protein), were little influenced by the exposure site, consistent with the apparent lack of protection against chemically induced carcinogenesis in English sole. Association of altered DNA content with exposure site is significant for its potential contribution to biological acceleration and evidence of tumor promotion found at the tissue and organismic levels. The results support the notion that hepatocarcinogenesis in English sole in Eagle Harbor has a multi-year exposure etiology, in which potentially reversible accelerating influences have a role, and that glutathione conjugation is an inadequate mode of detoxification for these fish.