Comparison of ZnO nanoparticles and ZnCl2 induced germ cell apoptosis in Caenorhabditis elegans

There is inadequate research data available on manufactured ZnO nanoparticles. Manufactured nanoparticles are widely used in various products and production of manufactured nanoparticles is becoming increasingly abundant. Humans are exposed to ZnO nanoparticles in products such as sunscreen, toothpaste, and cosmetic products. Due to the frequent human contact with nanoparticles, such as ZnO, research on the resulting biological effects is highly significant. In this study, we utilized the model organism Caenorhabditis elegans (C. elegans) to investigate the effects ZnO nanoparticle exposure can have on germ cell apoptosis and key genes involved in the apoptosis pathway. ZnCl2 (Zn²?) serves as a comparison of toxicity with ZnO nanoparticles in this study. It is known that ZnO nanoparticle exposure can have a severe effect on the reproduction process in C. elegans, however, it has yet to be tested whether or not ZnO nanoparticles affect germ cell apoptotic machinery as a possible mechanism of reproductive toxicity. Worms were exposed on an agar medium containing concentrations of ZnO nanoparticles and ZnCl2 (range, 6.14[times]10-1, 61.4, and 614 µM Zn). ZnO nanoparticles and ZnCl2 both significantly increased the number of apoptotic cells as compared to the control in the 61.4 and 614 µM treatment groups (p0.05). Therefore, the increased apoptosis resulting from ZnO nanoparticle exposure is likely CEP-1 dependent. Following exposure, possible ZnO nanoparticles were observed in vivo in the worms using transmission electron microscopy, suggesting that the worms can possibly absorb the nanoparticles via various routes