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Toxicogenomic responses of nanotoxicity in Daphnia magna exposed to silver nitrate and coated silver nanoparticles
Citation:
POYNTON, H., J. M. LAZORCHAK, CHRISTOPHER IMPELLITTERI, B. J. Blalock, K. R. ROGERS, H. J. ALLEN, A. Loguinov, J. L. Heckman, AND S. Govindasmawy. Toxicogenomic responses of nanotoxicity in Daphnia magna exposed to silver nitrate and coated silver nanoparticles. ENVIRONMENTAL SCIENCE & TECHNOLOGY. American Chemical Society, Washington, DC, 46(11):6288-6296, (2012).
Impact/Purpose:
The research described here is a complementary study aiming to identify specific biomarkers of exposure to AgNPs. We investigate the effects of two different coatings on the toxicity and gene expression profiles in D. magna providing new insight into the mechanism of toxicity of these particles to aquatic invertebrates. In addition, we identified nanoparticle specific biomarkers for the detection of AgNPs in the aquatic environment.
Description:
Applications for silver nanomaterials in consumer products are rapidly expanding, creating an urgent need for toxicological examination of the exposure potential and ecological effects of silver nanoparticles (AgNPs). The integration of genomic techniques into environmental toxicology has presented new avenues to develop exposure biomarkers and investigate the mode of toxicity of novel chemicals. In the present study we used a 15k oligonucleotide microarray for Daphnia magna, a freshwater crustacean and common indicator species for toxicity, to differentiate between particle specific and ionic silver toxicity and to develop exposure biomarkers for citrate-coated and PVP-coated AgNPs. Gene expression profiles revealed that AgNO3 and AgNPs have distinct expression profiles suggesting different modes of toxicity. However, the gene expression profiles of the different coated AgNPs were similar revealing similarities in the cellular effects of these two particles. Major biological processes disrupted by the AgNPs include protein metabolism and signal transduction. In contrast, AgNO3 caused a downregulation of developmental processes, particularly in sensory development. Metal responsive and DNA damage repair genes were induced by the PVP AgNPs, but not the other treatments. In addition, two specific biomarkers were developed for the environmental detection of PVP AgNPs; although further verification under different environmental conditions is needed.