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Publications (5)15.19 Total impact


  • No preview · Article · Dec 1989 · Marine Environmental Research
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    ABSTRACT: Glutathione dependent enzymes have been implicated in the detoxification of organochlorine compounds by formation of GSH conjugates.1 The insecticide DDT is detoxified in resistant houseflies by a glutathione dependent enzyme which is probably a glutathione-S-transferase.2 Assays were carried out in accordance with the method of Habig et al.7 The assay is based on the conjugation of a substrate such as 1-chloro-2,4-dinitrobenzene with GSH to produce a thioether compound by nucleophilic attack. The assay employed is sufficiently sensitive to enable measurement of enzyme activity on milligram quantities of mussel tissue. Our studies show that there is up to a 1·7-fold increase in glutathione-S-transferase activity in mussels which have been exposed to dieldrin. This enzyme assay has the advantages of being rapid, simple and convenient, and as it is widely distributed in nature, could form the basis for the early detection of a stress response in organisms exposed to organochlorine compounds.
    No preview · Article · Dec 1988 · Marine Environmental Research
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    ABSTRACT: The aim of this investigation is to understand the factors influencing uptake of persistent organochlorine pesticides into a freshwater mussel (Sphaerium corneum). Previous work has shown that although a substantial proportion of dieldrin is bound to particulates in the river system, uptake is from the dieldrin in solution. This suggests partitioning of the hydrophobic xenobiotics into membranes as the major route of entry. Membrane composition was established using lipid fractionation into neutral lipids and phospholipids followed by derivatisation to fatty acid methyl esters and estimation using GC/FID. Membrane composition varied with acclimation temperature over the range 5–20°C. Dieldrin concentrations in the mussel at equilibrium with 2000 ng dieldrin/litre water burden were studied at one temperature under laboratory conditions using animals acclimated to different temperatures. Any differences may be explicable in terms of effects of membrane composition on partitioning or other physiological adaptations. To establish which of these factors is most significant a membrane fragment partition system has been analysed in vitro. Preliminary results indicate that although water/lipid partitioning may be important in entry (and exit) of non-polar xenobiotics, significant differences could not be found using current methods. The role of membrane composition and therefore temperature history of the organism may still be significant. The implications of this for attempted correlations between bioaccumulation factors and simple octanol/water partition coefficients are discussed.
    No preview · Article · Dec 1988 · Marine Environmental Research
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    ABSTRACT: The rate of dieldrin accumulation by Sphaerium corneum was determined in the field and under controlled conditions in the laboratory. The methods gave comparable results and it was established that Sphaerium attained an equilibrium concentration of dieldrin in its tissues in a short time period and exhibited a bioaccumulation factor of 1000. The rate of dieldrin accumulation by direct uptake from dieldrin in solution was compared to the rate obtained for indirect uptake from dieldrin adsorbed onto particulate material. The primary route of dieldrin uptake into Sphaerium was shown to be by direct partitioning of residues into lipoidal tissues from water. The effect of temperature on the rate of accumulation was also studied. The rate of accumulation increased with temperature in the range 5 degrees C to 20 degrees C. The frequency of gill cilia beat in relation to accumulation rate was studied in this temperature range and a correlation is shown.
    No preview · Article · Feb 1987 · Environmental Pollution

  • No preview · Article · Dec 1985 · Marine Environmental Research