title: Differential gene expression in Daphnia magna suggests distinct modes of action and bioavailability for ZnO nanoparticles and Zn ions.
abstract: Zinc oxide nanoparticles (ZnO NPs) are being rapidly developed for use in consumer products, wastewater treatment, and chemotherapy providing several possible routes for ZnO NP exposure to humans and aquatic organisms. Recent studies have shown that ZnO NPs undergo rapid dissolution to Zn(2+), but the relative contribution of Zn(2+) to ZnO NP bioavailability and toxicity is not clear. We show that a fraction of the ZnO NPs in suspension dissolves, and this fraction cannot account for the toxicity of the ZnO NP suspensions to Daphnia magna. Gene expression profiling of D. magna exposed to ZnO NPs or ZnSO(4) at sublethal concentrations revealed distinct modes of toxicity. There was also little overlap in gene expression between ZnO NPs and SiO(x) NPs, suggesting specificity for the ZnO NP expression profile. ZnO NPs effected expression of genes involved in cytoskeletal transport, cellular respiration, and reproduction. A specific pattern of differential expression of three biomarker genes including a multicystatin, ferritin, and C1q containing gene were confirmed for ZnO NP exposure and provide a suite of biomarkers for identifying environmental exposure to ZnO NPs and differentiating between NP and ionic exposure.
authors.affiliation: National Exposure Research Laboratory, US Environmental Protection Agency, Cincinnati, Ohio, USA. helen.poynton@umb.edu
authors.forename: Helen C
authors.initials: HC
authors.lastname: Poynton
authors.forename: James M
authors.initials: JM
authors.lastname: Lazorchak
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Impellitteri
authors.forename: Mark E
authors.initials: ME
authors.lastname: Smith
authors.forename: Kim
authors.initials: K
authors.lastname: Rogers
authors.forename: Manomita
authors.initials: M
authors.lastname: Patra
authors.forename: Katherine A
authors.initials: KA
authors.lastname: Hammer
authors.forename: H Joel
authors.initials: HJ
authors.lastname: Allen
authors.forename: Chris D
authors.initials: CD
authors.lastname: Vulpe
mesh_terms: D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D002412:Cations / Q000378:metabolism / Q000633:toxicity; D019069:Cell Respiration / Q000187:drug effects; D003621:Daphnia / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression / Q000187:drug effects*; D020869:Gene Expression Profiling; D053768:Metal Nanoparticles / Q000633:toxicity*; D008969:Molecular Sequence Data; D018384:Oxidative Stress / Q000187:drug effects; D012098:Reproduction / Q000187:drug effects; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*; D015034:Zinc Oxide / Q000378:metabolism / Q000633:toxicity*
chemical_list: D015415:Biomarkers; D002412:Cations; D014874:Water Pollutants, Chemical; D015034:Zinc Oxide