Lysosomal characteristics and smooth endoplasmic reticulum (SER) associated NADPHfernhemoprotein (cytochrome P-450) reductase were measured cytochemically in the digestive cells of mussels A4ytilu.s edulis and periwinkles Littorina littorea exposed to environmental contaminants In Langesundfjord, Norway (PAHs, PCBs, metals) and to xenobiotics in an experimental facility (diesel oil and copper mixture). Lysosomal membrane stability was reduced in both mussels and periwinkles with increasing xenobiotic contamination In the field. Lysosomal and cytoplasmic unsaturated neutral lipid concentration was increased in contaminated mussels in the field, and lysosomal accumulation was associated with enlargement of secondary lysosomes; the latter was inversely correlated with lysosomal membrane stability. hpofuscin content and number of tertiary lysosomes increased in contaminated field mussels. These pathological changes are indicative of enhanced lysosomal autophagy and fatty degeneration. NADPH-ferrihemoprotein reductase activity was elevated in mussels from the 2 most heavily contaminated field sites. Activity of this enzyme was directly correlated with total PAHs. Lysosomal data from experimental exposures were less clear and difficult to interpret. Poor nutritional conditions possibly masked pollutant effects. However, mussels from the highest exposure concentration showed elevated lipofuscin. The observed sensitivity of the tests for lysosomal enlargement and lysosomal lipid, combined with their relative simplicity, indicate their potential for the detection of environmentally induced pathology, although better understanding of the mechanisms of toxicity would enhance theu utility.

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During the Bremerhaven Workshop, effects of contaminants along a well characterised North Sea contaminant gradient heading northwest of the port of Bremerhaven in the German Bight were determined in dab Limanda lirnanda using i n vitro techniques on isolated hepatocytes. Results demonstrated that lysosomal membrane integrity was impaired following contaminant exposure which resulted in an inability to retain the supravital dye neutral red and in reduced lysosomal uptake of the fluorescent probe acridine orange. There was an improvement in the condition of exposed hepatocytes in samples taken further offshore, and away from the source of the contaminant, however, this trend was reversed in samples taken from the furthermost station on the northeast tail of the Dogger Bank. These findings are related to the histopathological evidence of abnormal lysosomal enlargement and disturbance of liver cell structure.

INTRODUCTIONMarine bivalve molluscs have in recent years attracted considerable attention for a variety of reasons, not least of which is their importance as a source of food for man. Much of this research has concentrated on studies of reproduction; Mytilus viridis (India: Nagabhushanam & Mane, 1975), M. edulis aoteanus and Aulacomya maoriana (New Zealand: Kennedy, 1977);Choromytilus meridionalis and Aulacomya ater (South Africa: Berry, 1978); Mytilus (= Perna) perna (Brazil: Lunetta, 1969); M. edulis planulatus (Australia: Wilson & Hodgkin, 1967); Mytilus californianus and M. edulis (U.S.A.: Hines, 1979); Mytilus galloprovincialis (France: Lubet, 1959) and M. edulis (U.K.: Chipperfield, 1953; Seed, 1975; Bayne et al. 1978). A review of the literature revealed that in the majority of studies cytology was used as a descriptive tool for the ‘staging’ (Chipperfield, 1953; Lubet, 1957; Seed, 1975, 1976) of the developing gametes and certain anomalies were apparent with regard to the nomenclature of the connective tissue matrix of the mantle lobes.

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