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 (TiO2NPs) were evaluated in hemocyte cells of freshwater snail Lymnea luteola L. Before evaluation of the toxic potential, mean size of the TiO2NPs was determined using a transmission electron microscopy and dynamic light scattering. In this study, L. luteola were exposed to different concentrations of TiO2NPs (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 TiO2NPs 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 TiO2NPs. The extent of DNA fragmentation occurring in L. luteola due to ecotoxic impact TiO2NPs 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 TiO2NPs.The results indicate that the interaction of TiO2NPs 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 TiO2NPs to freshwater snail L. luteola, which may be vulnerable due to the continuous discharge of TiO2NPs 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 TiO2NPs.