Comparative effects of zinc oxide nanoparticles and dissolved zinc on zebrafish embryos and eleuthero-embryos: Importance of zinc ions

N.R. Brun, M. Lenz, B. Wehrli, K. Fent

Research output: Contribution to journalArticleAcademicpeer-review

84 Citations (Scopus)

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 5 mg/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 72 hours 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-1ß and TNFa. 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).
Original languageEnglish
Pages (from-to)657-666
JournalScience of the Total Environment
Volume476-477
DOIs
Publication statusPublished - 2014

Keywords

  • in-vitro evaluation
  • zno nanoparticles
  • oxidative stress
  • fresh-water
  • aggregation kinetics
  • silver nanoparticles
  • cell-line
  • bulk zno
  • toxicity
  • nanomaterials

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