The aim of this work was to provide basic data on the antioxidant defences in the annelid Eisenia fetida andrei (E. f. a.). Methods for measurement of three antioxidant enzymes-catalase (CAT), glutathione peroxidase (GPX), and glutathione reductase (GR)-and of glutathione-S-transferase (GST) were optimized. GPX activity differed according to the substrate used: cumene hydroperoxide (CUOOH) or hydrogen peroxide (H2O2). The effects on the enzyme activities of storage up to 2 months at -80 degrees C, -20 degrees C, and +4 degrees C were evaluated. The subcellular distribution (in cytosol, mitochondrial, and microsomal fractions) was examined. The properties and subcellular distribution of the enzymes and glutathione were also characterized in dissected tissues and body fluids. The GR activity decreased at -80 degrees C and was the only one not stable at this temperature. The four enzymes were localized mainly in the cytosolic fraction. CAT distribution was unusual as it was not associated with peroxisomes, its properties being consistent with a catalase-peroxidase, rather than a true catalase. However, this result could also be an artifact linked to the use of an inappropriate method to obtain the fractions. Our observations indicate the presence of a distinct cytosolic selenium-dependent GPX (Se-GPX), and of a possible microsomal Se-GPX. A strong non-Se-GPX activity was measured in the CF and CL, which could be linked to the peroxidase activity of fetidins secreted by coelomocytes and with the ROS production of these cells. This study seems to indicate that E. f. a. is well equipped for the metabolism of electrophilic and pro-oxidants through glutathione.

No abstract

No abstract

No abstract

The garden snail (Helix aspersa) is currently used as bioindicator of metallic pollution. Our objective was to extend its use to organic chemicals by studying the effects and tissue concentrations of the organophosphorus pesticide dimethoate following dietary uptake. After exposure for four weeks to increasing doses of pesticide in the diet, the median lethal concentration (LC50) was determined to be 3,700 microg/g food. Clinical signs indicated a no-observed-effect concentration of 100 microg/g and a lowest-observed-effect concentration of 250 microg/g. The growth parameters were decreased with increasing exposure to the pesticide. The median effective concentration (EC50), which was evaluated based on both shell diameter and dry weight inhibitions, was 665 and 424 microg/g, respectively, and the EC10 was 180 and 145 microg/g, respectively. Accumulation in the viscera was related to the amount of dimethoate in the food. The bioconcentration factors were low (>6 x 10(-3)). Acetylcholinesterase (AChE) activity was strongly decreased (80% from 250 microg/g). In conclusion, we demonstrated that the species H. aspersa could be a useful sentinel organism for organophosphorus contamination surveys. Among the effects measured, the inhibition of AChE activities and clinical signs were the most sensitive, followed by the growth parameters. These results confirm the suitability of the garden snail for development of sublethal toxicity tests using primary consumers and aboveground organisms.