Using the Comet Assay to Assess the Combined and Separate Genotoxic Effects of Cd and Zn in Eisenia andrei (Oligochaeta) at Different Temperatures
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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.
KeywordsTail DNA percentage DNA damage Earthworms Metals
This study was sponsored by a SETAC/Procter & Gamble fellowship awarded to P. Voua Otomo and performed in facilities financially supported by the National Research Foundation of South Africa and Bourses et Stages Gabon. Any opinions, findings and conclusions expressed in this material are those of the authors and therefore the sponsors do not accept any liability in regard thereto.
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