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  • 1
    ISSN: 1573-5117
    Keywords: environnement ; bioindicateur ; lysosomes ; malate déshydrogénase ; pollution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Environmental stressors as well as the direct or combined effects of pollutants could be harmful to the populations living in a marine environment and the reproductive and nutritive processes could be impaired in a deteriorating environment. Sublethal effects of pollutants were studied in the blue mussel Mytilus edulis L., a good bioaccumulator of contaminants. Blue mussels of 3.5 cm were sampled on a rocky substrate at Pointe-Mitis (48° 40′N, 68° 02′W) along the coast of the St-Lawrence estuary. Mussels were placed in experimental tanks, fed, supplemented with mineral salts and continuous sea water flow and kept 72 h before the exposure to 0.01 µg l−1 and 0.3 µg l−1 methylmercury hydroxide in the presence or absence of selenium, at a concentration of 125 µg l−1, a possible antagonist of methylmercury. The contamination protocol was performed during 45 days and a 14 day period of recuperation was allowed. The stress caused by the transplantation of mussels in the laboratory tanks and/or by the presence of pollutants was evaluated by a general indicator of stress developed in our laboratory, the measure of the lysosomal membrane fragility (LMF) of the digestive gland, according to the method developed by Moore (1976). The effects of contamination on metabolism were measured by the study of the variations of the malate dehydrogenase activity (MDH), a key enzyme of the aerobic metabolism. The first days of the contamination period led to an increased metabolism in the mantle and to a detoxifying mechanism in the hepatopancreas. At days 22 and 29 of the experiment, the affinity of the MDH was greatly decreased with both concentrations of methylmercury and selenium, suggesting a competitive inhibition of the enzymatic activity by the pollutants. LMF increased as the mussels were kept longer in the tanks. Methylmercury increased the stress undergone by the mussels. LMF gives information about the degree of stress of the organism while the biochemical indicator informs about the metabolic effects of sublethal concentrations of pollutants.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Applied Organometallic Chemistry 9 (1995), S. 683-691 
    ISSN: 0268-2605
    Keywords: mercury ; methylmercury ; glutathione ; mercaptoethanol ; thiols ; EDTA ; complexation ; starfish ; translocation ; invertebrates ; Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Mature starfish Leptasterias polaris, collected in the St Lawrence Estuary (eastern Canada), were exposed to two mercury species (HgCI2 and CH3HgCI) via injections into the coelomic fluid. In vivo effects of some complexing agents (glutathione, mercaptoethanol and EDTA) on the distribution of 203Hg-labelled species in starfish organs and tissues and their possible role in mercury transport through membranes were studied over a 24 h period. The excretion of ammonia and mercury was also measured. When injected alone, inorganic mercury and methylmercury [CH3Hg(II)] were distributed in all organs, with a preferential adsorption in gonads, pyloric caeca and stomach. Mercury excretion was very low under all conditions studied. Mercaptoethanol, a small thiol ligand, was very efficient in reducing both mercury species in the coelomic fluid and seems to have promoted translocation towards most organs of the starfish. Its action is attributed to the formation of small and neutral complexes, HgL2 and CH3HgL, which can diffuse through membranes preserving their integrity. Glutathione increased the translocation of CH3Hg(II) towards surrounding organs, but had no apparent effect on inorganic mercury. EDTA promoted the transport of inorganic mercury only. These results highlight (1) the particular interest of starfish to workers studying in vivo chemical complexation of mercury species, and (2) the potential role of complexing molecules in the biotransport of mercury species through living membranes.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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