title: The role of selenium-dependent glutathione peroxidase (Se-GPx) against oxidative and genotoxic effects of mercury in haemocytes of mussel Mytilus galloprovincialis (Lmk.).
abstract: This study investigated whether mercury (Hg) oxidative and genotoxic effects are related with its ability to inhibit selenium-dependent glutathione peroxidase (Se-GPx) activity in haemocytes of mussel Mytilus galloprovincialis. Se-GPx activity was measured both in Se-free cells' cytosolic fraction and in Se-treated cells, pre-treated with 4 microg/l of Se (as sodium selenite), before the exposure to the metal. Hg at concentrations ranged within 10 or 20 microg/l, thus representing the onset of Hg toxic effects, showed to inhibit Se-GPx activity in Se-free cells, followed by increased levels of superoxide anions (()O(2)(-)) and nitric oxide (NO) generation, lipid peroxidation and DNA damage as well. On the other hand, increased enzymatic activity and a significant attenuation of Hg toxicity were measured in Se-treated cells exposed to Hg in all cases. The results of the present study showed that inhibition of Se-GPx activity by Hg could promote a shift in the balance between oxidants and antioxidants in favor of oxidants, resulted in the enhancement of Hg-induced oxidative and genotoxic effects. In addition, Se bioavailability within phagocytic cells, such as haemocytes, could regulate the antioxidant role of Se-GPx, thus reinforcing haemocytes' immune system against toxic effects induced by pro-oxidants, such as Hg.
authors.affiliation: Section of Animal Biology, Department of Biology, Faculty of Sciences, University of Patras, 26 500 Patras, Greece.
authors.forename: Victoria
authors.initials: V
authors.lastname: Chatziargyriou
authors.forename: Stefanos
authors.initials: S
authors.lastname: Dailianis
mesh_terms: D000818:Animals; D020552:Comet Assay; D004249:DNA Damage; D004305:Dose-Response Relationship, Drug; D005979:Glutathione Peroxidase / Q000378:metabolism*; D006434:Hemocytes / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D015227:Lipid Peroxidation / Q000187:drug effects; D008628:Mercury / Q000633:toxicity*; D049878:Mytilus / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects; D012643:Selenium / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D013481:Superoxides; D005979:Glutathione Peroxidase; D008628:Mercury; D012643:Selenium