title: Proteomic analyses of early response of unicellular eukaryotic microorganism Tetrahymena thermophila exposed to TiO₂ particles.
abstract: Key biological functions involved in cell survival have been studied to understand the difference between the impact of exposure to TiO2 nanoparticles (TiO2-NPs) and their bulk counterparts (bulk-TiO2). By selecting a unicellular eukaryotic model organism and applying proteomic analysis an overview of the possible impact of exposure could be obtained. In this study, we investigated the early response of unicellular eukaryotic protozoan Tetrahymena thermophila exposed to TiO2-NPs or bulk-TiO2 particles at subtoxic concentrations for this organism. The proteomic analysis based on 2DE + nLC-ESI-MS/MS revealed 930 distinct protein spots, among which 77 were differentially expressed and 18 were unambiguously identified. We identified alterations in metabolic pathways, including lipid and fatty acid metabolism, purine metabolism and energetic metabolism, as well as salt stress and protein degradation. This proteomic study is consistent with our previous findings, where the early response of T. thermophila to subtoxic concentrations of TiO2 particles included alterations in lipid and fatty acid metabolism and ion regulation. The response to the lowest TiO2-NPs concentration differed significantly from the response to higher TiO2-NPs concentration and both bulk-TiO2 concentrations. Alterations on the physiological landscape were significant after exposure to both nano- and bulk-TiO2; however, no toxic effects were evidenced even at very high exposure concentrations. This study confirms the relevance of the alteration of the lipid profile and lipid metabolism in understanding the early impact of TiO2-NPs in eukaryotic cells, for example, phagocytosing cells like macrophages and ciliated cells in the respiratory epithelium.
authors.affiliation: a Department of Animal Sciences .
authors.forename: K
authors.initials: K
authors.lastname: Rajapakse
authors.affiliation: b Department of Biology .
authors.forename: D
authors.initials: D
authors.lastname: Drobne
authors.affiliation: c Department of Agriculture , and.
authors.forename: D
authors.initials: D
authors.lastname: Kastelec
authors.affiliation: d Faculty of Chemistry and Chemical Technology , University of Ljubljana , Ljubljana , Slovenia .
authors.forename: K
authors.initials: K
authors.lastname: Kogej
authors.affiliation: e Jožef Stefan Institute , Ljubljana , Slovenia .
authors.forename: D
authors.initials: D
authors.lastname: Makovec
authors.affiliation: f Department of Clinical and Experimental Medicine , Cell Biology, Medical Faculty, Linköping University , Linköping , Sweden .
authors.forename: C
authors.initials: C
authors.lastname: Gallampois
authors.affiliation: g Department of Biochemistry and Biophysics , Stockholm University , Stockholm , Sweden .
authors.forename: H
authors.initials: H
authors.lastname: Amelina
authors.affiliation: g Department of Biochemistry and Biophysics , Stockholm University , Stockholm , Sweden .
authors.forename: G
authors.initials: G
authors.lastname: Danielsson
authors.affiliation: h Biotechnical Faculty, Department of Animal Science , University of Ljubjana , Slovenia , and.
authors.forename: L
authors.initials: L
authors.lastname: Fanedl
authors.affiliation: h Biotechnical Faculty, Department of Animal Science , University of Ljubjana , Slovenia , and.
authors.forename: R
authors.initials: R
authors.lastname: Marinsek-Logar
authors.affiliation: f Department of Clinical and Experimental Medicine , Cell Biology, Medical Faculty, Linköping University , Linköping , Sweden .|i Department of Physiology , Faculty of Medicine and Dentistry, IKERBASQUE, Basque Foundation for Science, University of the Basque Country , Leioa , Spain.
authors.forename: S
authors.initials: S
authors.lastname: Cristobal
mesh_terms: D004305:Dose-Response Relationship, Drug; D015227:Lipid Peroxidation / Q000187:drug effects; D053858:Metabolic Networks and Pathways / Q000187:drug effects; D053758:Nanoparticles / Q000737:chemistry / Q000633:toxicity*; D010316:Particle Size; D040901:Proteomics; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D053719:Tandem Mass Spectrometry; D016808:Tetrahymena thermophila / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D013997:Time Factors; D014025:Titanium / Q000737:chemistry / Q000633:toxicity*
chemical_list: D015800:Protozoan Proteins; C009495:titanium dioxide; D014025:Titanium
keywords: Nanotoxicology; particle toxicology; proteomics