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Comparative histopathological effects of metals on marine organisms
454
Abstracts
have demonstrated that copper treatment enhances the M D A content in mussel tissues. This stimulation of the lipid peroxidation process could result in a perturbation of the Ca homeostasis processes, leading to alterations of the cellular metabolism and of the cytoskeleton structures. Our data confirm that exposure of mussels for 1, 3 and 6 days to low Cu 2 + concentrations (20/~g/animal) results in a net metal accumulation associated with a progressive stimulation of lipid peroxidation, as judged by the increased tissue concentration of M D A in the gill cells of mussels.
Toxic, Carcinogenic and Hepatic Biochemical Effects of Ethylene Dibromide on the Japanese Medaka (Oryzias iatipes). W I L L I A M W. WALKER, W I L L I A M E. HAWKINS, C H E R I E S. H E A R D & ROBIN M. OVERSTREET. Gulf Research Laboratory, PO Box 7000, Ocean Springs, Mississippi 39564, USA. Ethylene dibromide (1,2-dibromoethane, EDB) has been used as an agricultural fumigant and an antiknock additive of gasoline. Although highly mutagenic, its carcinogenicity in rodent models is demonstrated only after high dose exposures and long latency periods or after application of complex initiation-promotion protocols. Because EDB is a groundwater contaminant, we tested the compound in chronic flow-through exposures to the Japanese medaka, Oryzias latipes. In a series of exposures incorporating EDB concentrations ranging from 0"1 to 26.0ppm and lasting up to 3 months, EDB reduced fecundity, percentage hatch, and survival of hatched fry and increased the frequency of abnormal embryos. Adult medaka concentrated EDB up to 16 times and passed the compound on to developing embryos. Exposure to 1.3 ppm EDB for 2 weeks caused hepatic glutathuone S-transferase (GST) activities to more than double. Gel electrophoresis of hepatic cytosolic fractions revealed a dark 26 kDa protein band that may well be a monomer of GST. Following 3-month exposures, EDB induced a wide range of hepatic and extrahepatic neoplastic lesions. These included, in decreasing order of incidence, hepatocellular, cholangiocellular and gall bladder neoplasms. All those lesions were dose-related whereas lymphosarcoma occurred sporadically. No neoplasms occurred in controls. These results demonstrated the utility of the medaka model in chronic flow-through exposures to examine the effects of volatile compounds occurring in water resources.
Comparative Histopathological Effects of Metals on Marine Organisms. PAUL P. YEVICH. US Environmental Protection Agency, Environmental Research Laboratory, South Ferry Road, Narragansett, Rhode Island 02882. USA.
Abstracts
455
During the past 23 years, numerous histopathologic studies were conducted at the US Environmental Protection Agency/ERL/N on marine organisms exposed to metals. In acute cadmium exposures, many species (i.e. Limulus polyphemus, Nassarius obsoletus, Crassostrea virginica and Fundulus heteroclitus) showed extensive necrosis of the epithelium of the gastrointestinal tract and of the excretory system. However, in chronic cadmium exposures, C. virginica, Spisula soludisima and Mercenaria mercenaria, showed necrosis of red gland, auricle wall and kidney epithelium first and then the epithelium of the gastrointestinal tract. The lesions were similar to those in humans exposed to cadmium. Animals exposed to silver (Crepidula jbrnicata, Mytilus edulis and Spisula soludisima) accumulated silver in the basement membrane and connective tissue as do humans suffering from silver poisoning (argyria). C. virginica exposed to arsenic (10--15 ppb for 20-24 weeks) showed stenosis and thromboangiitis obliterans of the blood vessels, a condition also observed in humans suffering from chronic arsenic poisoning. In chronic copper exposures, animals (Mytilus edulis, Ampelisca abdita, Argopecten irradiens and C. virginica) had lesions involving the digestive diverticula. C. virginica exposed to lead showed degeneration of the reproductive tract and digestive diverticula while A. abdita showed necrosis of the tips of the gill lamellae. No histopathologic changes were noted in animals exposed to chromium, nickel and zinc. These comparative studies showed that many species of marine invertebrates can serve as models for studying possible effects of metals on humans. Also of interest is the difference between acute and chronic responses. In acute studies (high concentrations, short-term exposures) there is extensive necrosis followed by death of the animal. However~ in chronic studies (low concentrations, long-term exposures) there is a much more subtle degenerative and necrotic effect on the tissues which may not lead to death but have a debilitating effect on the animal.
Abstracts
have demonstrated that copper treatment enhances the M D A content in mussel tissues. This stimulation of the lipid peroxidation process could result in a perturbation of the Ca homeostasis processes, leading to alterations of the cellular metabolism and of the cytoskeleton structures. Our data confirm that exposure of mussels for 1, 3 and 6 days to low Cu 2 + concentrations (20/~g/animal) results in a net metal accumulation associated with a progressive stimulation of lipid peroxidation, as judged by the increased tissue concentration of M D A in the gill cells of mussels.
Toxic, Carcinogenic and Hepatic Biochemical Effects of Ethylene Dibromide on the Japanese Medaka (Oryzias iatipes). W I L L I A M W. WALKER, W I L L I A M E. HAWKINS, C H E R I E S. H E A R D & ROBIN M. OVERSTREET. Gulf Research Laboratory, PO Box 7000, Ocean Springs, Mississippi 39564, USA. Ethylene dibromide (1,2-dibromoethane, EDB) has been used as an agricultural fumigant and an antiknock additive of gasoline. Although highly mutagenic, its carcinogenicity in rodent models is demonstrated only after high dose exposures and long latency periods or after application of complex initiation-promotion protocols. Because EDB is a groundwater contaminant, we tested the compound in chronic flow-through exposures to the Japanese medaka, Oryzias latipes. In a series of exposures incorporating EDB concentrations ranging from 0"1 to 26.0ppm and lasting up to 3 months, EDB reduced fecundity, percentage hatch, and survival of hatched fry and increased the frequency of abnormal embryos. Adult medaka concentrated EDB up to 16 times and passed the compound on to developing embryos. Exposure to 1.3 ppm EDB for 2 weeks caused hepatic glutathuone S-transferase (GST) activities to more than double. Gel electrophoresis of hepatic cytosolic fractions revealed a dark 26 kDa protein band that may well be a monomer of GST. Following 3-month exposures, EDB induced a wide range of hepatic and extrahepatic neoplastic lesions. These included, in decreasing order of incidence, hepatocellular, cholangiocellular and gall bladder neoplasms. All those lesions were dose-related whereas lymphosarcoma occurred sporadically. No neoplasms occurred in controls. These results demonstrated the utility of the medaka model in chronic flow-through exposures to examine the effects of volatile compounds occurring in water resources.
Comparative Histopathological Effects of Metals on Marine Organisms. PAUL P. YEVICH. US Environmental Protection Agency, Environmental Research Laboratory, South Ferry Road, Narragansett, Rhode Island 02882. USA.
Abstracts
455
During the past 23 years, numerous histopathologic studies were conducted at the US Environmental Protection Agency/ERL/N on marine organisms exposed to metals. In acute cadmium exposures, many species (i.e. Limulus polyphemus, Nassarius obsoletus, Crassostrea virginica and Fundulus heteroclitus) showed extensive necrosis of the epithelium of the gastrointestinal tract and of the excretory system. However, in chronic cadmium exposures, C. virginica, Spisula soludisima and Mercenaria mercenaria, showed necrosis of red gland, auricle wall and kidney epithelium first and then the epithelium of the gastrointestinal tract. The lesions were similar to those in humans exposed to cadmium. Animals exposed to silver (Crepidula jbrnicata, Mytilus edulis and Spisula soludisima) accumulated silver in the basement membrane and connective tissue as do humans suffering from silver poisoning (argyria). C. virginica exposed to arsenic (10--15 ppb for 20-24 weeks) showed stenosis and thromboangiitis obliterans of the blood vessels, a condition also observed in humans suffering from chronic arsenic poisoning. In chronic copper exposures, animals (Mytilus edulis, Ampelisca abdita, Argopecten irradiens and C. virginica) had lesions involving the digestive diverticula. C. virginica exposed to lead showed degeneration of the reproductive tract and digestive diverticula while A. abdita showed necrosis of the tips of the gill lamellae. No histopathologic changes were noted in animals exposed to chromium, nickel and zinc. These comparative studies showed that many species of marine invertebrates can serve as models for studying possible effects of metals on humans. Also of interest is the difference between acute and chronic responses. In acute studies (high concentrations, short-term exposures) there is extensive necrosis followed by death of the animal. However~ in chronic studies (low concentrations, long-term exposures) there is a much more subtle degenerative and necrotic effect on the tissues which may not lead to death but have a debilitating effect on the animal.