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Evaluation of Copper Effect on Juveniles of the Green Mussel Perna viridis by DNA Concentration and a RNA/DNA Ratio of Abductor Muscle

Abstract:

In this study, juveniles individuals of the mussel Pema viridis were exposed to different concentrations of copper (0.00, 0.05, 0.10, 0.20, 0.80, 1.20 y 3.40 mgCu L-1), during a period of 96 h. The lethal effect was determined by measuring the survival rate and the sublethal effect by estimating the concentrations of DNA and RNA/DNA ratio. The 0.8, 1.2 y 3.4 mgCu L-1 concentrations caused mortality rates of 20, 80 y 100%, respectively. The DL50 was 0.61 mgCu L-1 the upper and lower limits of confidence at 95% were 0.39 and 0.91 mgCu L-1 respectively. At the beginning of the experiment, the DNA levels in adductor muscle, and after their exposition to the different copper concentrations, did not indicated a significant variation. At the end of the experiment, the RNA/DNA ratio increased in the juveniles exposed to a concentration of up to 0.1 mgCu L-1, probably as a metabolic response due to the exposition to copper which may have activated protein synthesis. In the mussels exposed to 0.20 mgCu L-1 and 0.80 mgCu L-1, the RNA/DNA ratio decreased significantly, possibly because these higher levels of copper concentration caused them an advanced state of stress. Results suggest that RNA/DNA ratios of muscle tissue showa behavior relative to antitoxic response.