title: Distinct expression profiles of stress defense and DNA repair genes in Daphnia pulex exposed to cadmium, zinc, and quantum dots.
abstract: The ever-increasing production and use of nanocrystaline semiconductors (Quantum dots; QDs) will inevitably result in increased appearance of these nanomaterials in the aquatic environment. However, the behavior and potential toxicity of heavy metal constituted nanoparticulates in aquatic invertebrates is largely unknown, especially with regard to molecular responses. The freshwater crustacean Daphnia pulex is a well-suited toxicological and ecological model to study molecular responses to environmental stressors. In this study, D. pulex were exposed for 48 h to sublethal doses of QDs (25% and 50% of LC50) with differing spectral properties (CdTe and CdSe/ZnS QDs) and Cd and Zn salts. Our data suggest that acute exposure to both CdSO4 and Cd-based QDs leads to Cd uptake in vivo, which was biologically supported by the observation of increased expression of metallothionein (MT-1). Furthermore, Cd, Zn, and CdSe/ZnS QDs induced different patterns of gene expression regarding stress defense and DNA repair, which furthers our knowledge regarding which response pathways are affected by nanoparticulate forms of metals versus ionic forms in aquatic crustaceans.
authors.affiliation: The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416, USA; School of Environment and Sustainability, University of Saskatchewan, Saskatoon, SK S7N 5B3, Canada.
authors.forename: Song
authors.initials: S
authors.lastname: Tang
authors.affiliation: Department of Genetics, Stanford University, Stanford, CA 94305, USA.
authors.forename: Yonggan
authors.initials: Y
authors.lastname: Wu
authors.affiliation: The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416, USA.
authors.forename: Caitlin N
authors.initials: CN
authors.lastname: Ryan
authors.affiliation: The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416, USA.
authors.forename: Shuangying
authors.initials: S
authors.lastname: Yu
authors.affiliation: Institute of Toxicology, Guangxi Center for Disease Prevention and Control, Nanning, Guangxi 530028, China.
authors.forename: Guangqiu
authors.initials: G
authors.lastname: Qin
authors.affiliation: The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416, USA.
authors.forename: Donn S
authors.initials: DS
authors.lastname: Edwards
authors.affiliation: The Institute of Environmental and Human Health, Texas Tech University, Lubbock, TX 79416, USA; Mount Desert Island Biological Laboratory, Salisbury Cove, ME 04672, USA. Electronic address: greg.mayer@ttu.edu.
authors.forename: Gregory D
authors.initials: GD
authors.lastname: Mayer
mesh_terms: D000818:Animals; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D004260:DNA Repair / Q000235:genetics*; D003621:Daphnia / Q000187:drug effects* / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D004784:Environmental Monitoring; D005618:Fresh Water / Q000737:chemistry; D015870:Gene Expression / Q000187:drug effects; D053768:Metal Nanoparticles / Q000633:toxicity; D008668:Metallothionein / Q000378:metabolism; D018384:Oxidative Stress / Q000187:drug effects* / Q000235:genetics; D045663:Quantum Dots / Q000633:toxicity*; D023382:Toxicity Tests, Acute; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*; D015032:Zinc / Q000378:metabolism / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium; D008668:Metallothionein; D015032:Zinc
keywords: Crustacean; Heat shock proteins; Metallothionein; Nanoparticles; Reference genes; Superoxide dismutase