title: Toxicity of copper excess on the lichen Dermatocarpon luridum: antioxidant enzyme activities.
abstract: The aim of this study was to investigate the toxicity of copper on the aquatic lichen Dermatocarpon luridum focusing on the activities of some antioxidant enzymes. Investigations were conducted using increasing copper concentrations (0.00, 0.25, 0.50, 0.75 and 1.00 mM CuSO(4) x 5H(2)O) in synthetic freshwater that emulated the major ion compositions of its natural water biota; time course measurement was 0, 3, 6, 12, 24 and 48 h. The copper concentration in thalli increased with its increase in the medium and the duration of treatment. Copper induced lipid peroxidation, measured using the hydroperoxi-conjugated dienes (HPCD) concentration. The decrease in the protein concentrations was similar in thalli exposed to copper concentrations above 0.50 mM and the decrease was twice lower in thalli exposed to 0.25 mM copper. The activities of antioxidant enzymes measured were differently affected by copper excess. For 0.25 mM copper, the activities of SOD (superoxide dismutase) and APX (ascorbate peroxidase) were unchanged when compared with unstressed thalli whereas the CAT (catalase) activity increased and the GR (glutathione reductase) activity decreased. The activities of SOD and APX increased in thalli exposed to concentrations above 0.50mM copper. The CAT activity increased after the first 3h of experiments at these concentrations and then decreased with the duration of treatment at an activity lower than in the unstressed plant. Whereas the APX activity increased, the GR activity similarly decreased for the copper concentration tested whatever the duration of the experiment.
authors.affiliation: Laboratoire des sciences de l'eau et de l'environnement, Faculté des sciences, Université de Limoges, 123 Avenue Albert Thomas, 87000 Limoges, France. fabien.monnet@univ-avignon.fr
authors.forename: Fabien
authors.initials: F
authors.lastname: Monnet
authors.forename: François
authors.initials: F
authors.lastname: Bordas
authors.forename: Véronique
authors.initials: V
authors.lastname: Deluchat
authors.forename: Michel
authors.initials: M
authors.lastname: Baudu
mesh_terms: D000975:Antioxidants / Q000378:metabolism; D001203:Ascomycota / Q000187:drug effects* / Q000378:metabolism; D060387:Ascorbate Peroxidases; D002374:Catalase / Q000187:drug effects; D003300:Copper / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004784:Environmental Monitoring / Q000379:methods; D004798:Enzymes / Q000187:drug effects* / Q000378:metabolism; D005618:Fresh Water; D005980:Glutathione Reductase / Q000187:drug effects; D008011:Lichens / Q000187:drug effects* / Q000201:enzymology; D015227:Lipid Peroxidation / Q000187:drug effects; D010544:Peroxidases / Q000187:drug effects; D011506:Proteins / Q000187:drug effects / Q000378:metabolism; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D000975:Antioxidants; D004798:Enzymes; D011506:Proteins; D014874:Water Pollutants, Chemical; D003300:Copper; D010544:Peroxidases; D060387:Ascorbate Peroxidases; D002374:Catalase; D005980:Glutathione Reductase