Metal, mutagenicity, and biochemical studies on bivalve molluscs from Spanish coasts

Abstract

Three species of marine bivalve molluscs (Chamelea gallina, Ruditapes decussatus, and Crassostrea gigas) have been studied in order to evaluate the levels of pollution on the South Atlantic Spanish littoral. Several transition metals (Cu, As, Cd, Sn, Hg, Pb) were determined as a general index of total contamination. Animals from putative contaminated areas exhibited higher metal contents than those from cleaner waters. C. gigas showed 5-20-fold higher total metal content than the other two species. The mutagenicity of ethanolic extracts was assayed by using both the His reversion and the Ara forward mutation tests. Mollusc tissues from the three species did not contain genotoxins active on TA98 (frameshift mutations) or TA100 (mainly G:C base-pair substitutions), but did contain direct-acting genotoxins of a polar nature and oxidative type. This was based on the following observations: 1) mammalian metabolic activation was not required for mutagenicity, 2) mutagens were eluted with the polar fraction from XAD-2 columns, and 3) mutagenic responses were observed with Salmonella typhimurium TA102 (A:T base-pair substitutions; sensitive to oxidative damages) and Escherichia coli catalase-deficient (AraR forward mutations) strains. No relevant differences were found in the mutagenicity of mollusc extracts from areas with different pollution levels. Otherwise, our data suggest that, in general, animals living in contaminated environments had fewer genotoxins of oxidative type than those from less polluted areas. Such a result might be explained by the observation of increased levels of a number of detoxifying and antioxidant enzymes, such as glutathione-S-transferase, glutathione-peroxidase, catalase, and superoxide dismutase. Thus, contaminated animals seem to be better protected against the oxidative damages induced by metals, in agreement with their lower malondialdehyde levels. To what extent the responsible mutagenic compounds are of endogenous origins, or "Nature's pesticides" (the major toxic chemicals ingested by phytoplankton filter-feeders), and/or the result of human activities remains to be determined.

Biochemical and histological hepatic changes of Nile tilapia Oreochromis niloticus exposed to carbaryl

“…The GSH/GSSG ratio is a good indicator of oxidative stress. For example, the GSSG/GSH ratio in contaminated bivalve molluscs from Spanish coast under oxidative stress conditions showed a significant increase [48]. In our case, after 14 days of exposure the GSH/GSSG ratio was higher than the control group, whereas in the remaining periods it was alike the control.…”

Antioxidant and detoxifying enzymes in the liver and kidney of pheasants after intoxication by herbicides MCPA and ANITEN

“…Some studies have demonstrated that organochlorine pesticides and other organic compounds induce oxidative stress by enhancing ROS accumulation in tissues (39,40). Although it is known that oxidative stress induces or enhances the activities of antioxidant enzymes (18,38,41,42), numerous studies showed wide individual differences in response to various oxidative attacks (18,(43)(44)(45)(46).…”

Use of oxidative stress biomarkers in Carcinus maenas to assess littoral zone contamination in Tunisia

“…The cytosolic activities of primary and ancillary antioxidant enzymes, and phase II biotransforming enzymes were assayed (as published) as biomarkers (Rodríguez-Ariza et al 1992). CAT was measured at 240 nm with 20 mM H 2 O 2 .…”