title: Evaluation of the effect of silver nanoparticles and silver ions using stress responsive gene expression in Chironomus riparius.
abstract: Silver nanoparticles (AgNPs) are extensively used in many commercial products because of their antimicrobial properties and they are therefore released into the environment from various products. A number of genes, especially those representing antioxidant and detoxification pathways, have potential application for studying mechanism of action of environmental pollutants at molecular level. In the present study, the stress responsive transcription of antioxidant and detoxification genes in response to AgNPs and Ag(+) ions exposure is studied in the ecotoxicologically important model species Chironomus riparius. The selected genes were superoxide dismutases (CuZnSOD and MnSOD), catalase (CAT), phospholipid hydroperoxide glutathione peroxidase 1 (PHGPx1), thioredoxin reductase 1 (TrxR1), and delta-3, sigma-4 and epsilon-1 classes of glutathione S-transferases (GSTs). The mRNA expression levels of each gene were determined after exposure of animals for 24h to three different AgNP and Ag(+) ion concentrations using Real-Time PCR method. Significant up-regulation of CuZnSOD and MnSOD was found after exposure to Ag(+) ions and AgNPs, respectively. The transcript levels of CAT, PHGPx1 and TrxR1 were significantly up-regulated only after exposure to AgNPs and no significant change was observed after exposure to Ag(+) ions. The expression levels of all the GSTs were more pronounced after exposure to AgNPs as compared to Ag(+) ions. The overall results suggest that AgNPs led to pronounced induction of genes related to oxidative stress and detoxification than Ag(+) ions.
authors.affiliation: School of Environmental Engineering and Graduate School of Energy and Environmental System Engineering, University of Seoul, 90 Jeonnong-dong, Dongdaemun-gu, Seoul 130-743, Republic of Korea.
authors.forename: Prakash M Gopalakrishnan
authors.initials: PM
authors.lastname: Nair
authors.forename: Sun Young
authors.initials: SY
authors.lastname: Park
authors.forename: Jinhee
authors.initials: J
authors.lastname: Choi
mesh_terms: D000818:Animals; D002414:Cations, Monovalent / Q000633:toxicity; D002683:Chironomidae / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics*; D005786:Gene Expression Regulation / Q000187:drug effects; D019476:Insect Proteins / Q000235:genetics; D053768:Metal Nanoparticles / Q000633:toxicity*; D018384:Oxidative Stress / Q000187:drug effects; D012834:Silver / Q000633:toxicity*
chemical_list: D002414:Cations, Monovalent; D019476:Insect Proteins; D012834:Silver