Impairment of DNA in a Freshwater Gastropod (Lymnea luteola L.) after Exposure to Titanium Dioxide Nanoparticles

Abstract

The apoptotic and genotoxic potential of titanium dioxide nanoparticles (TiO 2 NPs) were evaluated in hemocyte cells of freshwater snail Lymnea luteola L. Before evaluation of the toxic potential, mean size of the TiO 2 NPs was determined using a transmission electron microscopy and dynamic light scattering. In this study, L. luteola were exposed to different concentrations of TiO 2 NPs (28, 56, and 84 μg/ml) over 96 h. Induction of oxidative stress in hemolymph was observed by a decrease in reduced glutathione and glutathione-S-transferase levels at different concentration of TiO 2 NPs and, in contrast, an increase in malondialdehyde and reactive oxygen species levels. Catalase activity was decreased at lower concentrations but increased at greater concentration of TiO 2 NPs. The extent of DNA fragmentation occurring in L. luteola due to ecotoxic impact TiO 2 NPs was further substantiated by alkaline single-cell gel electrophoresis assay and expressed in terms of % tail DNA and olive tail moment. The alkaline single-cell gel electrophoresis assay for L. luteola clearly shown relatively greater DNA damage at the highest concentration of TiO 2 NPs.The results indicate that the interaction of TiO 2 NPs with snail influences toxicity, which is mediated by oxidative stress according dose and in a time-dependent manner. The results of this study showed the importance of a multibiomarker approach for assessing the injurious effects of TiO 2 NPs to freshwater snail L. luteola, which may be vulnerable due to the continuous discharge of TiO 2 NPs into the aquatic ecosystems. The measurement of DNA integrity in L. luteola thus provides an early warning signal of contamination of the aquatic ecosystem by TiO 2 NPs.