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Polychaetes, Eurythoe complanata, from the Gulf of Cariaco,Venezuela, were exposed to 0.3, 1.6, and 3.3% water-soluble fraction (WSF) of used crankcase oil during 15 and 21 days. The antioxidant enzymes glutathione peroxidase (GPX), glutathione reductase (GR), catalase (CAT), and glutathione-S-transferase (GST) were assayed in the body wall tissue. Furthermore, after chemical exposure, the polychaetes were cut into equal halves; then wound healing and the number of regenerated body segments were recorded periodically. GST activity was affected by all the experimental treatments, with activity increasing with WSF concentrations. GPx activity was altered for the contamination period. GR and CAT activities rose in response to increasing WSF concentrations, and were higher for long-term than for short-term exposures. The wound healing of the transected body regions was retarded by WSF exposure. WSF affected the tissue regeneration, which was almost abolished at 3.3% WSF. The exposure period did not affect the tissue-repairing responses. Alteration of GST in contaminated organisms suggested equivalent changes in detoxication of bioaccumulated organic contaminants. The variation of GR and CAT suggests induction of oxidative stress that could reduce the ability of WSF-exposed worms to repair damaged tissue.

With the aim of investigate the acute effects of two concentrations (25 and 100%) of N. 6 fuel oil-water-accommodated fraction (OWAF) on antioxidant enzyme activities and immunological responses, fishes Thalassophryne maculosa were sampled from the La Restiga Lagoon, Margarita island, in eastern Venezuela. The antioxidant enzymes, catalase (CAT), glutathione peroxidase (GPX), glutathione reductase (GR) and glutathione-S-transferase (GST) were measured in liver and gills. The macrophagic phagocytosis and antibacterial lysozyme activity of anterior kidney were the immune parameters examined. Increases in gill GST activity and hepatic GR activity were observed after the exposure to 25 and 100% OWAF, respectively. GPX, CAT and immune responses were not affected by the experimental treatments. Our results demonstrated that among the antioxidant enzymes tested, GR and GST activities were the most sensible to the acute treatment with fuel oil, indicating changes in the redox cellular state that may result in oxidative stress in T. maculosa.

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