Oxidative stress and DNA damage in the earthworm Eisenia fetida induced by toluene, ethylbenzene and xylene

Abstract

Superoxide dismutase (SOD), guaiacol peroxidase (POD), catalase (CAT), and the comet assay (SCGE) were used as biomarkers to evaluate the oxidative stress and genotoxicity of toluene, ethylbenzene and xylene in earthworms (Eisenia fetida). The results indicated that the exposure of the three pollutants caused a stress response of the three enzymes, an approximate bell-shaped change (a tendency of inducement firstly and then inhibition with increasing concentrations of the pollutants) was mostly found. The three enzymes tested differed in their sensitivity to different pollutants. While the activity of POD was not significantly changed within the concentration range, the concentration thresholds for significant (P < 0.05) responses to toluene based on SOD and CAT were 5 mg kg(-1), respectively. Similarly, the concentration thresholds for significant (P < 0.05) responses to ethylbenzene based on CAT and POD were 10 and 5 mg kg(-1), respectively, while the activity of SOD was not significantly changed within the concentration range. Significant responses to xylene based on CAT and POD were 5 mg kg(-1), respectively, while the activity of SOD was significantly (P < 0.05) induced at 10 mg kg(-1). The SCGE assay results showed that these three pollutants could significantly (P < 0.01) induce DNA damage in earthworms and the clear dose-dependent relationships were displayed, indicating potential genotoxic effects of toluene, ethylbenzene, and xylene on E. fetida. The inducement of DNA damage may be attributed to the oxidative attack of toluene, ethylbenzene, and xylene. Toluene seemed to be more genotoxic as it could induce the higher extent of DNA damage than ethylbenzene and xylene. The results suggest that the SCGE assay of earthworms is simple and efficient for diagnosing the genotoxicity of pollutants in terrestrial environment.

Impact of Zn Nanoparticles on Growth, Survival and Activity of Antioxidant Enzymes in Eisenia Fetida

“…Eisenia fetida have CAT activity increased when reaching a concentration of nanoparticles in an artificial soil Zn 500 mg/kg and decreased at a dose of 1000 mg/kg. A similar effect of Zn NPs was registered by Liu et al (2010). This is possible due to the high activity of catalase in soil substrate and high turnover of metal between the substrate and the body of the worm (Chelikani et al, 2004).…”

Dysregulation of markers of oxidative stress and DNA damage among nail technicians despite low exposure to volatile organic compounds

“…While interpreting these outcomes, it seems reasonable to assume that increased activities of antioxidant enzymes might be indicative of increased oxidative stress, possibly caused by an occupational exposure of nail technicians. Indeed, exacerbation of oxidative stress has already been implicated in mechanisms underlying the effects exerted by the low-level exposure to VOC in both the animal models (22,45) and human subjects (10,11,46). Notwithstanding, the above-mentioned lack of any significant changes in levels of TBARS and DNA strand breaks between nail technicians and control subjects seems to contradict this thesis.…”

“…Even though these substances are considered to be neither carcinogenic nor genotoxic to humans (IARC class 3 carcinogens, ie, not classifiable as to their carcinogenicity to humans), there is a growing amount of evidence suggesting increased (i) levels of markers of oxidative stress (10)(11)(12), (ii) rate of chromosomal aberrations or sister chromatid exchange (12)(13)(14), and (iii) incidence of various cancers among workers occupationally exposed to toluene or xylene [even at occupational exposures far below the respective occupational limits (15)(16)(17)(18)(19)(20)(21)]. Although precise mechanisms underlying the effects of toluene and xylene remain unknown, the role of oxidative stress, oxidative DNA damage and dysregulated cellular antioxidant levels have been implicated (22)(23)(24). Methacrylates, another group of chemicals used in nail industry, are known sensitizers and were found to give positive results for in vitro genotoxicity, although in vivo outcomes are inconclusive (25,26).…”

Earthworm Biomarkers as Tools for Soil Pollution Assessment

“…The glutathione reductase enzyme also plays an important role in cellular protection by reducing glutathione in the oxidized form (GSSG) to GSH (reduced and active form). Several studies (Liu et al, 2010) indicate that exposure to either organic or inorganic pollutants are able to induce a stress response in the antioxidant enzymes, suggesting their potential application as general biomarkers for assessing effects of pollutants in terrestrial ecosystems at early stages and with low concentrations. However, the dose-dependent and time-dependent response of antioxidant enzymes to pollutant exposure is sometimes complex and a better understanding of their behaviour in stress condition is needed for their application in monitoring and assessment programmes.…”

“…However, the dose-dependent and time-dependent response of antioxidant enzymes to pollutant exposure is sometimes complex and a better understanding of their behaviour in stress condition is needed for their application in monitoring and assessment programmes. For example Liu et al (2010) demonstrated that exposure to toluene, ethylbenzene and xylene in earthworms (Eisenia fetida) induced a bellshaped change in superoxide dismutase and catalase activities with a tendency of inducement firstly and then inhibition with increasing concentrations of the pollutants. Moreover, Wu et al (2011) found superoxide dismutase to be induced during the early period of phenanthrene exposure while with longer exposure times its activity decreased.…”