title: Fish exposure to nano-TiO2 under different experimental conditions: methodological aspects for nanoecotoxicology investigations.
abstract: The ecotoxicology of nano-TiO2 has been extensively studied in recent years; however, few toxicological investigations have considered the photocatalytic properties of the substance, which can increase its toxicity to aquatic biota. The aim of this work was to evaluate the effects on fish exposed to different nano-TiO2 concentrations and illumination conditions. The interaction of these variables was investigated by observing the survival of the organisms, together with biomarkers of biochemical and genetic alterations. Fish (Piaractus mesopotamicus) were exposed for 96 h to 0, 1, 10, and 100 mg/L of nano-TiO2, under visible light, and visible light with ultraviolet (UV) light (22.47 J/cm(2)/h). The following biomarkers of oxidative stress were monitored in the liver: concentrations of lipid hydroperoxide and carbonylated protein, and specific activities of superoxide dismutase, catalase, and glutathione S-transferase. Other biomarkers of physiological function were also studied: the specific activities of acid phosphatase and Na,K-ATPase were analyzed in the liver and brain, respectively, and the concentration of metallothionein was measured in the gills. In addition, micronucleus and comet assays were performed with blood as genotoxic biomarkers. Nano-TiO2 caused no mortality under any of the conditions tested, but induced sublethal effects that were influenced by illumination condition. Under both illumination conditions tested, exposure to 100 mg/L showed an inhibition of acid phosphatase activity. Under visible light, there was an increase in metallothionein level in fish exposed to 1 mg/L of nano-TiO2. Under UV light, protein carbonylation was reduced in groups exposed to 1 and 10 mg/L, while nucleus alterations in erythrocytes were higher in fish exposed to 10 mg/L. As well as improving the understanding of nano-TiO2 toxicity, the findings demonstrated the importance of considering the experimental conditions in nanoecotoxicological tests. This work provides information for the development of protocols to study substances whose toxicity is affected by illumination conditions.
authors.affiliation: Department of Biochemistry, Institute of Biology, State University of Campinas, Rua Monteiro Lobato 255, CEP 13083-862 Campinas, SP, Brazil; Laboratory of Ecotoxicology and Biosafety, Embrapa, Rodovia SP 340, Km 127.5, CP 69, CEP 13820-000, Jaguariúna, SP, Brazil. Electronic address: zairaclemente@hotmail.com.
authors.forename: Z
authors.initials: Z
authors.lastname: Clemente
authors.forename: V L
authors.initials: VL
authors.lastname: Castro
authors.forename: L O
authors.initials: LO
authors.lastname: Feitosa
authors.forename: R
authors.initials: R
authors.lastname: Lima
authors.forename: C M
authors.initials: CM
authors.lastname: Jonsson
authors.forename: A H N
authors.initials: AH
authors.lastname: Maia
authors.forename: L F
authors.initials: LF
authors.lastname: Fraceto
mesh_terms: D000135:Acid Phosphatase / Q000187:drug effects / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000201:enzymology; D060126:Characidae / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D054750:Ecotoxicology / Q000379:methods; D005880:Gills / Q000737:chemistry; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D053768:Metal Nanoparticles / Q000009:adverse effects* / Q000032:analysis; D008668:Metallothionein / Q000032:analysis; D018482:Muscle, Skeletal / Q000737:chemistry / Q000187:drug effects; D018384:Oxidative Stress / Q000187:drug effects; D000254:Sodium-Potassium-Exchanging ATPase / Q000187:drug effects / Q000378:metabolism; D014025:Titanium / Q000009:adverse effects* / Q000032:analysis; D014466:Ultraviolet Rays
chemical_list: C009495:titanium dioxide; D008668:Metallothionein; D014025:Titanium; D000135:Acid Phosphatase; D000254:Sodium-Potassium-Exchanging ATPase
keywords: Biomarkers; Ecotoxicology; Nanotoxicity; Oxidative stress; Titanium dioxide; Ultraviolet light