Distinct transcriptomic responses of Caenorhabditis elegans to pristine and sulfidized silver nanoparticles

• Published in: Environmental pollution (1987) Vol. 213; pp. 314 - 321
• Main Authors: Starnes, Daniel L., Lichtenberg, Stuart S., Unrine, Jason M., Starnes, Catherine P., Oostveen, Emily K., Lowry, Gregory V., Bertsch, Paul M., Tsyusko, Olga V.
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.06.2016
• Subjects: Animals; Antimicrobial; Caenorhabditis elegans; Caenorhabditis elegans - drug effects; Caenorhabditis elegans - metabolism; Metal Nanoparticles - toxicity; Nanomaterial; Nematoda; Silver - toxicity; Silver Compounds - toxicity; Silver Nitrate - toxicity; Soil; Toxicogenomics; Transcriptome - drug effects; Waste Water; Wastewater; Antimicrobial; Soil; Wastewater; Nanomaterial; Toxicogenomics
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2016.01.020

Manufactured nanoparticles (MNP) rapidly undergo aging processes once released from products. Silver sulfide (Ag2S) is the major transformation product formed during the wastewater treatment process for Ag-MNP. We examined toxicogenomic responses of pristine Ag-MNP, sulfidized Ag-MNP (sAg-MNP), and AgNO3 to a model soil organism, Caenorhabditis elegans. Transcriptomic profiling of nematodes which were exposed at the EC30 for reproduction for AgNO3, Ag-MNP, and sAg-MNP resulted in 571 differentially expressed genes. We independently verified expression of 4 genes (numr-1, rol-8, col-158, and grl-20) using qRT-PCR. Only 11% of differentially expressed genes were common among the three treatments. Gene ontology enrichment analysis also revealed that Ag-MNP and sAg-MNP had distinct toxicity mechanisms and did not share any of the biological processes. The processes most affected by Ag-MNP relate to metabolism, while those processes most affected by sAg-MNP relate to molting and the cuticle, and the most impacted processes for AgNO3 exposed nematodes was stress related. Additionally, as observed from qRT-PCR and mutant experiments, the responses to sAg-MNP were distinct from AgNO3 while some of the effects of pristine MNP were similar to AgNO3, suggesting that effects from Ag-MNP is partially due to dissolved silver ions. [Display omitted] •Some effects of pristine silver nanoparticles can be linked to Ag+.•Sulfidized silver nanoparticles have effects independent of Ag+.•Sulfidized silver nanoparticle responses suggest cuticle damage.•Distinct toxicity pathways indicated for all three treatments. The toxicity of fully sulfidized Ag nanoparticles is not due to release of Ag ions.