Increased cytotoxic and genotoxic tolerance of Eisenia fetida (Oligochaeta) to cadmium after long-term exposure.
ABSTRACT Since life-cycle studies showed that the earthworm species Eisenia fetida can develop increased tolerance after long-term exposure to a sub-lethal concentration of Cd in the laboratory, we assessed both the cytotoxicity and genotoxicity of Cd in a long-term Cd-exposed population. We exposed E. fetida specimens from this population, from a laboratory control population and from a field population to various concentrations of CdSO(4) in artificial soil water. Toxic effects were measured using the MTT test and the comet assay. The group that had been exposed to Cd for more than a decade was found to be more tolerant to the deleterious effects of Cd at both cellular and molecular levels than the laboratory control population. The field population, which came from a severely metal polluted environment, displayed high tolerance at molecular level as well. The results provide novel biomarker evidence of increased Cd tolerance in E. fetida, but the mechanisms supporting the apparent tolerance, still need to be clarified.
- SourceAvailable from: Marcelo Antonio Amaro Pinheiro[Show abstract] [Hide abstract]
ABSTRACT: In Brazil, the state of São Paulo contains both preserved areas (Juréia-Itatins Ecological Station) and extremely impacted ones (Cubatão Municipality). This study evaluated the concentrations of five metals (Cu, Cd, Cr, Pb, and Hg) in two mangroves with different levels of anthropogenic impact and the apparent genotoxicity to Ucides cordatus. Water and sediment samples were obtained, and metal concentrations were determined with an atomic absorption spectrophotometer. The genotoxic impact was quantified based on the number of micronucleated cells per 1,000 analyzed (MN‰), using hemolymph slides stained with Giemsa. Metal concentrations in water were below the detection limit, except for lead, although no significant difference was observed between the areas (P > 0.05). Sediment from Cubatão had higher concentrations of Cd, Pb, Cr, and Cu than sediment from Juréia-Itatins (P < 0.05), but no significant differences in metal concentrations were detected among depth strata of the sediment (P > 0.05). Crabs from Cubatão had a 2.6 times higher mean frequency of micronucleated cells (5.2 ± 1.8 MN‰) than those from Juréia-Itatins (2.0 ± 1.0 MN‰; P < 0.0001). The more-polluted conditions found in the mangrove sediments of Cubatão were reflected in the micronucleus assay, demonstrating their genotoxic effect; however, genetic damage should be attributed to a synergistic effect with other kinds of pollutants previously recorded in different environments of Cubatão. U. cordatus proved to be an excellent bioindicator of mangrove pollution. This study established, for the first time, the normal frequency of MN‰ in a population of this species within an ecological station.Environmental Monitoring and Assessment 04/2013; · 1.59 Impact Factor
Dataset: Klobucar et al 2011
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ABSTRACT: Using the comet assay, the genotoxicity of Cd, Zn and Cd/Zn mixtures in Eisenia andrei was assessed after 4 weeks of exposure at 15, 20 and 25°C. Relative to the controls, significant increases in TDNA% were observed in exposures to Cd alone at 500 and 1,000 mg/kg soil at both 20 and 25°C, while a general decrease occurred at 15°C. For Zn alone, a decreasing trend in TDNA% occurred at all three temperatures with increasing Zn concentration. For the Cd/Zn mixtures at 15°C, genotoxicity was reduced at all mixture concentrations relative to the control. At 20°C, the genotoxic response was similar to the control at all exposures. At 25°C, the response was elevated at the 50 + 50 and 250 + 250 mg/kg mixture concentrations. In the remaining treatments at 25°C, TDNA% was similar to the values in the respective control. The lack of consistently significant mixture genotoxicity may indicate antagonistic interactions between Cd and Zn in the mixtures. However, this was not conclusively determined because temperature alone had an inconsistent effect upon TDNA% readings in the control exposures.Bulletin of Environmental Contamination and Toxicology 11/2013; · 1.11 Impact Factor