Effects of exposure to soluble fraction of industrial solid waste on lipid peroxidation and DNA methylation in erythrocytes of Oreochromis niloticus, as assessed by quantification of MDA and m5dC rates

In this study, lipid peroxidation and DNA methylation were observed in erythrocytes of Oreochromis niloticus exposed to soluble fractions of textile, metal-mechanic and pulp and paper industrial waste, after a period of 48 h. Lipid peroxidation was quantified by the rate of malondialdehyde (MDA) and DNA methylation was quantified by the rate of 5-methyldeoxycytosine (m(5)dC). Soluble fractions of textile industrial waste caused metabolic changes for all studied samples. In organisms exposed to samples TX1 and TX2 (textile waste) MDA rates were 132.36 and 140.28 nM MDA/mg protein, respectively, while in control organism the MDA rates were 27.5 nM MDA/mg protein. All samples from soluble fractions of textile industrial waste induced increases in m(5)dC rates, increases varied between 300 percent and 700 percent when compared to the control organism. All the organisms exposed to soluble fractions of metal-mechanic industrial waste presented increases between 360 percent and 600 percent in the rates of MDA, and one of them (sample MM3) induced an increase of 180 percent in the rate of m(5)dC, when compared to control. Although a significant increase was not observed in the MDA rate of fish exposed to the soluble fractions of pulp and paper industrial waste, there was an increase of 460 percent in the rate of m(5)dC in one of the samples (sample PP2), when compared to control. The results showed that the soluble fractions of these industrial wastes are capable of inducing oxidative damage and altering the DNA methylation of O. niloticus. Thus, the MDA and m(5)dC rates demonstrated to be effective biomarkers of exposure, which could be used to evaluate the toxicity of soluble fractions of industrial solid waste. (C) 2011 Elsevier Inc. All rights reserved.