Toxicity of nano-Zinc Oxide on Planarians (Dugesia japonica) with Neurobehavioral endpoints

Abstract

The research aims to study the effects of Zinc Oxide nanoparticles (ZnO NPs) on planarians by using locomotion behaviors as the endpoints. Sub-lethal doses of ZnO NPs of various concentration, i.e., 100, 300, 500, 1000, and 2000 ppm were applied to the experimental groups, while the control groups were in artificial pond water (APW). Ten planarians per replicates, and three replicates were conducted. Planarians were observed morphological alterations and locomotion activities under stereo-microscope. Locomotion velocity (LV) and cumulative locomotion (CLM) were quantified as the number of gridlines crossed or re-crossed by planarians per minute over a 30-minute observation period. Data were collected every minute. Four patterns of planarian morphology, i.e., irregular-shaped, screw-like, elongated, and bridge-like were found. However, irregular-shaped was found only in control group and planarians exposed to low concentration of ZnO NPs (100 ppm). In addition, bridge-like pattern had shorter latency time of response when ZnO NPs concentrations were increase. Compare to the control, the LV of the planarians exposed to ZnO NPs reduced significantly (p ?? 0.05) in every concentration leading to CLM in all groups of planarians exposed to ZnO NPs was also reduced significantly. Since morphological alterations are as the results of muscle contractions under the control of the nervous system, it is concluded that ZnO NPs toxic to planarians and had neurobehavioral effects.