Transcriptional responses and mechanisms of copper nanoparticle toxicology on zebrafish embryos

Copper nanoparticles (CuNPs) are used widely due to their attractive antimicrobial properties. However, their biosafety and kinetics on vertebrate embryogenesis are still limited. In this study, CuNPs were revealed to induce eye hypoplasia and almost no digestive gut in zebrafish embryos in a dose-dependent manner. Then, transcriptional responses of zebrafish embryos to CuNPs were investigated, and it was revealed that the genes related to wound healing and stimulus responses were up-regulated, but the genes associated with phototransduction and metabolisms were down regulated. Differentially expressed genes (DEGs) in CuNPs-exposed and Cu2+-exposed embryos were compared further. Increased VEGF signaling and expression of flit were observed in CuNPs rather than Cu2+ treated embryos, but increased reactive oxygen species (ROS) and the resulting enhanced hemoglobin were observed in both CuNPs and Cu2+ treated embryos. This study for the first time revealed that CuNPs and Cu2+ both down-regulated the genes related to phototransduction and metabolisms, but up-regulated the genes associated with hemoglobin. Additionally, compared with Cu2+, CuNPs might be more effective in elevating blood vessels in embryos. Our results suggest that the biological effects of CuNPs are organogenesis-specific during fish embryogenesis, and both particles and ions might mediate their biological effects on embryogenesis. (C) 2017 Elsevier B.V. All rights reserved.