In vivo evaluation of the toxic and genotoxic effects of exposure to cobalt nanoparticles in Drosophila melanogaster

Nanomaterials in general and cobalt nanoparticles (CoNPs) in particular, are of great interest not only because of their multiple applications and environmental impact, but also for their potential toxicity and safety issues. Since most of the mechanisms involved in the toxicity of CoNPs are not very well known, mainly in vivo, we used Drosophila melanogaster as a simple and reliable in vivo model, to investigate some toxicity-involved mechanisms. Thus, several toxicity-related approaches are used in this study including physicochemical characterization, viability, internalization, intracellular oxidative stress, and DNA damage (comet assay). In addition, changes in the expression of genes involved in general stress and antioxidant response, as well as in DNA repair response were evaluated. To better characterize the effects of CoNPs we have evaluated also the effects cobalt chloride (CoCl2) as a model of releasing ions agent. The obtained results indicated that ingested CoNPs could translocate through the intestinal barrier of Drosophila larvae affecting hemolymph cells. Hemocytes, as targeted cells, showed higher levels of intracellular reactive oxygen species (ROS) after CoCl2 exposure, but lower levels of DNA damage, in comparison with CoNPs. In addition, although general altered expression of different genes was observed, effects were different according if larvae were exposed to CoCl2 or CoNPs. Subsequently, the effects induced by CoNPS cannot be associated only to their chemical nature.