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(272) Bivalve molluscs (Chamelea gallina) from Andalusian littoral areas exposed to metals and organic contaminants respond with increased antioxidant defenses. Rodriguez-Ortega, Manuel1, Funes, Victoria1, Alhama, Jose1, Gomez-Ariza, Jose2, Lopez-Barea, Juan1, Rodriguez-Ariza, Antonio1, 1 2 ABSTRACT- Several environmental contaminants, including metals, nitroaromatics, PCBs, quinones and PAHs, catalyse the generation of reactive oxygen species that induce antioxidant enzymes; in contrast, inhibition of such enzymes could lead to oxidant-mediated toxicity. Thus, these antioxidant defenses can be useful biochemical biomarkers showing exposure to such pollutants and their biological effects. The levels of several environmental contaminants and various molecular biomarkers were compared at different periods during 1999 in Chamaelea gallina (stripped venus) sampled at seven production sites of the Andalusian littoral in southern Spain to check possible correlations. Compared to Almeria animals (taken as reference), those sampled near Huelva Estuary, with increased contents of metals and organic contaminants, showed significantly higher contents of metallothionein and glutathione, and higher activities of ancillary antioxidative (glucose-6-P and isocitrate dehydrogenases, GSSG reductase) and glutathione-related enzymes (glyoxalases I and II, glutathione-S-transferase). In parallel, Huelva bivalves contained less peroxidised lipids, as shown by their lower malonaldehyde content, than Almeria animals. Seasonal biomarker changes showed also this inverse relationship: most antioxidative defenses were maximal in March and September, while malonaldehyde content reached maxima in June and December. Possible influence of reproductive cycle or pollutant inputs have been analysed. In conclusion, the defense against oxidative stress promoted in bivalves by metals and organic contaminants probably explains the increases of auxiliary antioxidative enzymes and of glutathione metabolism. Further research is needed to elucidate the significance of fundamental antioxidative processes, such as repair of oxidized biomolecules and maintenance of cellular redox status. (Grant 1FD1997-0610) Key words: bivalve molluscs, pollution biomarkers, oxidative stress, Chamelea gallina |
