Toxicogenomic responses of C. elegans to gold nanoparticles

We used Au nanoparticles (Au-NPs) as a model for studying particle specific effects of manufactured nanomaterials (MNMs) by examining the toxicogenomic responses in a model soil organism, free living nematode Caenorhabditis elegans. Global genome expression for nematodes exposed to 4-nm citrate-coated Au-NPs at the LC10 (5.9 mg L-1) revealed significant differential expression of 797 genes. The levels of expression for five genes (apl-1, dyn-1, act-5, abu-11, and hsp-4) were confirmed independently with qRT-PCR. Seven common biological pathways associated with 38 of these genes were identified. Activation of 26 pqn/abu genes from noncanonical Unfolded Protein Response (UPR) pathway and up-regulation of molecular chaperones (hsp-16.1, hsp-70, hsp-3 and hsp-4) were observed and are likely indicative of endoplasmic reticulum stress. Inhibition of abu-11 with RNAi showed increase in mortality in Au-NP exposed nematodes suggesting possible involvement of abu-11 (a gene associated with specific to C. elegans UPR) in a protective mechanism against Au-NPs. Exposure to Au-NPs also caused activation of genes involved in apoptosis and necrosis and resulted ultimately in 10% mortality. These results demonstrate that Au-NPs are bioavailable and cause adverse effects to a model ecoreceptor which activate both general and specific biological pathways.

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Tsyusko OV, Unrine JM, Spurgeon D, Blalock E, Starnes D, Tseng M, Joice G, Bertsch PM