Abstract

This study sought to determine the DNA damage, and the lipoperoxidative effect, as well as changes in the superoxide dismutase (SOD) and catalase (CAT) activities induced by CdSO₄ (Cd), and ZnSO₄ (Zn), in addition to two different mixtures of the metals. Planarian Dugesia dorotocephala collected in the Ignacio Ramirez reservoir, México, adapted to laboratory conditions, and exposed to the metals in a controlled system was used. Initially, LC₅₀ at 96 h of exposure was determined and the result obtained were 0.69 mg/L for Cd, 11.99 mg/L for Zn, 10.28 mg/L for mix 1, and 8.11 mg/L for mix 2. Then, the comet assay showed a DNA damage increase induced by Cd (0.13 and 0.2 mg/L) as high as 94% over the control level; the effect by Zn (from 0.2 to 2.7 mg/L) was clearly lower, although statistically significant with the high concentrations tested. As regards the two mixtures, we observed a concentration dependent increase. Similarly, in respect to lipoperoxidation, we found a strong effect by Cd, a slight effect by Zn, and a concentration dependent effect induced by the mixtures. Finally, the activity of the tested enzymes was modified by the metals in relation to the concentration applied.

Key words: Zinc, cadmium, planarian, DNA damage, oxidative stress.