Molecular Mechanisms of Toxicity of Silver Nanoparticles in Zebrafish Embryos

Abstract

Silver nanoparticles cause toxicity in exposed organisms and are an environmental health concern. The mechanisms of silver nanoparticle toxicity, however, remain unclear. We examined the effects of exposure to silver in nano-, bulk-, and ionic forms on zebrafish embryos (Danio rerio) using a Next Generation Sequencing approach in an Illumina platform (High-Throughput SuperSAGE). Significant alterations in gene expression were found for all treatments and many of the gene pathways affected, most notably those associated with oxidative phosphorylation and protein synthesis, overlapped strongly between the three treatments indicating similar mechanisms of toxicity for the three forms of silver studied. Changes in oxidative phosphorylation indicated a down-regulation of this pathway at 24 h of exposure, but with a recovery at 48 h. This finding was consistent with a dose-dependent decrease in oxygen consumption at 24 h, but not at 48 h, following exposure to silver ions. Overall, our data provide support for the hypothesis that the toxicity caused by silver nanoparticles is principally associated with bioavailable silver ions in exposed zebrafish embryos. These findings are important in the evaluation of the risk that silver particles may pose to exposed vertebrate organisms.

Analytical approaches to support current understanding of exposure, uptake and distributions of engineered nanoparticles by aquatic and terrestrial organisms

“…For Analysis for understanding nanomaterial uptake by biological systems example, intact Ag ENPs were not found to traverse the chorionic membrane of exposed zebrafish embryos (Osborne et al 2013). This finding is not consistent with the results from other studies that have indicated that the embryo may be exposed to Ag ENPs via this route (Lee et al 2007;Nallathamby et al 2008;van Aerle et al 2013) suggesting that the potential for ENP transport into a biological system is governed by unique properties of the specific ENPs involved.…”

Silver and carbon nanoparticles toxicity in sea urchin Paracentrotus lividus embryos

“…In the same paper of Siller et al [15] the release of Ag + ions was so limited that the effects could not be ascribed to the ions. The effects of the bulk are negligible in relation to the effects exerted by the NPs and are measurable at longer time, much more long that the duration of our experiment (72 h) [27]. However, P. lividus embryos seemed to be much more resistant than oyster embryos, that underwent dramatic defects at low concentration of AgNPs [28].…”

Silver nanoparticles – a material of the future…?

“…However, it has been proved that silver nanoparticles are able to penetrate both types of cell wall and enter into the cell, resulting in the uncontrolled tyrosine phosphorylation. The phosphorylation process consists of binding of a phosphate residue to a nucleophilic atom (in this case the oxygen atom of the tyrosine -OH group) and consequently the bacterium is unable to survive [81,82] The presence of silver nanoparticles causes changes in regulation of expression of gens that encode proteins belonging to all complexes of phosphorylation pathway [83].…”