Developmental effects of zebrafish (Danio rerio) embryos after exposure to glyphosate and lead mixtures.

Natural aquatic environments have a heterogeneous composition; therefore, simultaneous exposure to multiple contaminants is relevant and more realistic when assessing exposure and toxicity. This study examines the combinatorial effects of two compounds found ubiquitously in drinking water across the United States: glyphosate and lead acetate. Zebrafish (Danio rerio) embryos were used as a model for investigating developmental delays following controlled exposures. Six different environmentally relevant exposure concentrations of glyphosate, ranging from 0.001 to 10 ppm, and lead acetate, ranging from 0.5 to 4 ppm, were applied first as single exposures and then as co-exposures. The sublethal endpoints of hatching and coagulation were quantified to determine potencies. Results indicate that higher concentrations of the individual chemicals correlate with later hatching with correlation coefficients of 0.71 and 0.40 for glyphosate and lead acetate respectively, while the co-exposure at lower concentrations induced earlier hatching with a correlation coefficient 0.74. In addition, increased levels of coagulation and glutathione reductase activity were observed following co-exposure, as compared to the individual exposures, suggesting potential toxicological interactions. These results support the need for further work assessing the combined potencies of aquatic contaminants rather than individual exposures.

Silver and Copper Nanoparticles Induce Oxidative Stress in Bacteria and Mammalian Cells.

Silver and copper nanoparticles (AgNPs and CuNPs) coated with stabilizing moieties induce oxidative stress in both bacteria and mammalian cells. Effective antibacterial agents that can overcome existing mechanisms of antibacterial resistance will greatly improve biomedical interventions. In this study, we analyzed the effect of nanoparticle-induced stress. Escherichia coli and normal human bronchial epithelial (BEAS-2B) cells were selected for this study. The nanoparticle constructs tested showed low toxicity to mammalian cells except for the polyvinylpyrrolidone-surface-stabilized copper nanoparticles. In fact, both types of copper nanoparticles used in this study induced higher levels of reactive oxygen species than the surface-stabilized silver nanoparticles. In contrast to mammalian cells, the surface-stabilized silver and copper nanoparticles showed varying levels of toxicity to bacteria cells. These data are expected to aid in bridging the knowledge gap in differential toxicities of silver and copper nanoparticles against bacteria and mammalian cells and will also improve infection interventions.