DNA damage and ovarian ultrastructural lesions induced by nickel oxide nano-particles in Blaps polycresta (Coleoptera: Tenebrionidae).

Nickel oxide nanoparticles (NiO-NPs) have extensively used in industrial and consumer products. The present study conducted to gain more knowledge about the safe use of NiO-NPs and also to understand their impact on the environment and biological systems. Herein, we examined the genotoxic and ultra-structural effects of a sublethal dose of NiO-NPs (0.03 mg/g) on the ovarian tissues of the ground beetle, Blaps polycresta. The mean diameter of NiO-NPs was 24.49 ± 3.88 nm, as obtained through transmission electron microscopy (TEM). In terms of DNA damage levels, the frequency of micronucleus (MN) formation was highly significant in the NiO-NPs treated group versus the controls. Besides, NiO-NPs treatment resulted in a significant increase in the tail length of comets. Further, electron microscopy revealed a progressive increase in chromatin condensation of the ovarian nurse and follicular cells, in addition to the accumulation of lysosomes and endo-lysosomes in their cytoplasm. In conclusion, NiO-NPs are capable of gaining access to the ovary of B. polycresta and causing DNA damage and a high degree of cellular toxicity in the ovarian cells. The present study highlights, for the first time, the adverse effects of these NPs to female gonads of insects and raised the concern of its genotoxic potential. It would be of interest to investigate NiO-NPs mediated intracellular ROS generation in future studies.

Relative expression of microRNAs, apoptosis, and ultrastructure anomalies induced by gold nanoparticles in Trachyderma hispida (Coleoptera: Tenebrionidae).

The extensive use of nanomaterials generates toxic effects on non-target species and the ecosystem. Although gold nanoparticles (Au-NPs) are generally expected to be safe, the recent study contains conflicting data regarding their cytotoxicity in the darkling beetles Trachyderma hispida. The study postulated cellular perturbation in the ovarian tissue of the beetles induced by a sublethal dose of Au-NPs (0.01 mg/g). When compared with the controls, a significant inhibition in the activities of the antioxidant enzymes selenium-dependent (GPOX) and selenium-independent (GSTP) glutathione peroxidases (GPx) was observed in the treated beetles. The study proposed microRNAs (miRNA-282 and miRNA-989) as genotoxic markers for the first time, reporting a significant suppression in their transcriptional levels in the treated beetles. Furthermore, TUNEL (Terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling) and flow cytometry assays (annexin V-Fitc) indicated a significant increase in ovarian cell apoptosis in the treated beetles. Additionally, an ultrastructure examination revealed pathological changes in the ovarian cells of the treated beetles. The resulting anomalies in the present study may interrupt the fecundity of the beetles and lead to the future suppression of beetle populations.