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The present study was motivated by the paucity of reports on cellular internalization of ingested titanium dioxide (TiO2) nanoparticles (nano-TiO2). The model invertebrate ( Porcellio scaber, Isopoda, Crustacea) was exposed to food dosed with nano-TiO2 containing 100, 1,000, 3,000, or 5,000 µg nano-TiO2 per gram of food. After 14 d of exposure, the amount of Ti in the entire body was analyzed by inductively coupled plasma-mass spectrometry, and elemental analyses of tissue cross sections were performed by particle induced X-ray emission. In addition, a series of toxicological markers including feeding parameters, weight change, and survival, as well as cytotoxic effects such as digestive gland cell membrane stability, were monitored. Internalization of ingested nano-TiO2 by the isopod's digestive gland epithelial cells was shown to depend on cell membrane integrity. Cell membranes were found to be destabilized by TiO2 particles, and at higher extracellular concentrations of nano-TiO2, the nanoparticles were internalized. Environ. Toxicol. Chem. 2012; 31: 1083-1090. © 2012 SETAC [ABSTRACT FROM AUTHOR]

Abstract: A better understanding of the mechanisms that govern copper (Cu) uptake, distribution and tolerance in Brassica carinata plants in the presence of chelators is needed before significant progress in chelate-assisted Cu phytoextraction can be made. The aims of this study were therefore to characterise (S,S)-N,N′-ethylenediamine disuccinic acid (EDDS)-assisted Cu uptake, and to compare the spatial distribution patterns of Cu in the roots and leaves of B. carinata plants. The plants were treated with 30μM or 150μM CuSO4 or CuEDDS in hydroponic solution. Quantitative Cu distribution maps and concentration profiles across root and leaf cross-sections of the desorbed plants were obtained by micro-proton induced X-ray emission. In roots, the 30μM treatments with both CuSO4 and CuEDDS resulted in higher Cu concentrations in epidermal/cortical regions. At 150μM CuSO4, Cu was mainly accumulated in root vascular bundles, whereas with 150μM CuEDDS, Cu was detected in endodermis and the adjacent inner cortical cell layer. Under all treatments, except with a H+-ATP-ase inhibitor, the Cu in leaves was localised mainly in vascular tissues. The incubation of plants with 150μM CuEDDS enhanced metal translocation to shoots, in comparison to the corresponding CuSO4 treatment. Inhibition of H+-ATPase activity resulted in reduced Cu accumulation in 30μM CuEDDS-treated roots and 150μM CuEDDS-treated leaves, and induced changes in Cu distribution in the leaves. This indicates that active mechanisms are involved in retaining Cu in the leaf vascular tissues, which prevent its transport to photosynthetically active tissues. The physiological significance of EDDS-assisted Cu uptake is discussed. [Copyright &y& Elsevier]