title: Comparative effects of zinc oxide nanoparticles and dissolved zinc on zebrafish embryos and eleuthero-embryos: importance of zinc ions.
abstract: The increasing use of zinc oxide nanoparticles (nZnO) and their associated environmental occurrence make it necessary to assess their potential effects on aquatic organisms. Upon water contact, nZnO dissolve partially to zinc (Zn(II)). To date it is not yet completely understood, whether effects of nZnO are solely or partly due to dissolved Zn(II). Here we compare potential effects of 0.2, 1 and 5mg/L nZnO and corresponding concentrations of released Zn(II) by water soluble ZnCl2 to two development stages of zebrafish, embryos and eleuthero-embryos, by analysing expressional changes by RT-qPCR. Another objective was to assess uptake and tissue distribution of Zn(II). Laser ablation-ICP-MS analysis demonstrated that uptake and tissue distribution of Zn(II) were identical for nZnO and ZnCl2 in eleuthero-embryos. Zn(II) was found particularly in the retina/pigment layer of eyes and brain. Both nZnO and dissolved Zn(II) derived from ZnCl2 had similar inhibiting effects on hatching, and they induced similar expressional changes of target genes. At 72hours post fertilization (hpf), both nZnO and Zn(II) delayed hatching at all doses, and inhibited hatching at 1 and 5 mg/L at 96 hpf. Both nZnO and Zn(II) lead to induction of metallothionein (mt2) in both embryos and eleuthero-embryos at all concentrations. Transcripts of oxidative stress related genes cat and Cu/Zn sod were also altered. Moreover, we show for the first time that nZnO exposure results in transcriptional changes of pro-inflammatory cytokines IL-1β and TNFα. Overall, transcriptional alterations were higher in embryos than eleuthero-embryos. The similarities of the effects lead to the conclusion that effects of nZnO are mainly related to the release of Zn(II).
authors: University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Institute for Ecopreneurship, Gründenstrasse 40, CH-4132 Muttenz, Switzerland; ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Universitätsstrasse 16, CH-8092 Zürich, Switzerland.
authors: Nadja Rebecca
authors: NR
authors: Brun
authors: University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Institute for Ecopreneurship, Gründenstrasse 40, CH-4132 Muttenz, Switzerland; Wageningen University, Department of Environmental Technology, NL-6708 WG Wageningen, The Netherlands.
authors: Markus
authors: M
authors: Lenz
authors: ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Universitätsstrasse 16, CH-8092 Zürich, Switzerland.
authors: Bernhard
authors: B
authors: Wehrli
authors: University of Applied Sciences and Arts Northwestern Switzerland, School of Life Sciences, Institute for Ecopreneurship, Gründenstrasse 40, CH-4132 Muttenz, Switzerland; ETH Zurich, Institute of Biogeochemistry and Pollutant Dynamics, Universitätsstrasse 16, CH-8092 Zürich, Switzerland. Electronic address: karl.fent@fhnw.ch.
authors: Karl
authors: K
authors: Fent
mesh_terms: D000818:Animals; D004625:Embryo, Nonmammalian / Q000187:drug effects*; D007477:Ions; D008668:Metallothionein / Q000378:metabolism; D053758:Nanoparticles / Q000633:toxicity*; D018384:Oxidative Stress; D014874:Water Pollutants, Chemical / Q000633:toxicity*; D015027:Zebrafish / Q000196:embryology; D015032:Zinc / Q000633:toxicity*; D015034:Zinc Oxide / Q000633:toxicity*
chemical_list: D007477:Ions; D014874:Water Pollutants, Chemical; D008668:Metallothionein; D015032:Zinc; D015034:Zinc Oxide
keywords: Embryotoxicity; Gene expression; Laser ablation bioimaging; Pro-inflammatory response; Zinc oxide nanoparticle; Zinc uptake