Risk of human exposure to arsenic and other toxic elements from geophagy: trace element analysis of baked clay using inductively coupled plasma mass spectrometry.
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A novel approach for predicting the uptake and toxicity of metallic and metalloid ions.
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Electrostatic nature of plant plasma membrane (PM) plays significant roles in the ion uptake and toxicity. Electrical potential at the PM exterior surface (psi0o) influences ion distribution at the PM exterior surface, and the depolarization of psi0o negativity increases the electrical driving force for cation transport, but decreases the driving force for anion transport across the PMs. Assessing environmental risks of toxic ions has been a difficult task because the ion concentration (activity) in medium is not directly corrected to its potential effects. Medium characteristics like the content of major cations have important influences on the bioavailability and toxicity of ions in natural waters and soils. Models such as the Free Ion Activity Model (FIAM) and the Biotic Ligand Model (BLM), as usually employed, neglect the psi0o and hence often lead to false conclusions about interaction mechanisms between toxic ions and major cations for biology. The neglect of psi0o is not inconsistent with its importance, and possibly reflects the difficulty in the measurement of psi0o. Based on the dual effects of the psi0o, electrostatic models were developed to better predict the uptake and toxicity of metallic and metalloid ions. These results suggest that the electrostatic models provides a more robust mechanistic framework to assess metal(loid) ecotoxicity and predict critical metal(loid) concentrations linked to a biological effect, indicating its potential utility in risk assessment of metal(loid)s in water and terrestrial ecosystems. (+info)
Evaluation of trace metal levels in tissues of two commercial fish species in Kapar and Mersing coastal waters, Peninsular Malaysia.
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Characterization of stress responses of heavy metal and metalloid inducible promoters in synechocystis PCC6803.
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In several biotechnological applications of living bacterial cells with inducible gene expression systems, the extent of overexpression and the specificity to the inducer are key elements. In the present study, we established the concentration ranges of Zn(2+), Ni(2+), Co(2+), AsO(2)(-), and Cd(2+) ions that caused significant activation of the respective promoters of Synechocystis sp. without concomitant unspecific stress responses. The low expression levels can be increased up to 10-100-fold upon treatments with Cd(2+), AsO(2)(-), Zn(2+), and Co(2+) ions and up to 800-fold upon Ni(2+) treatment. These results facilitate the development of conditional gene expression systems in cyanobacteria. (+info)
Hygroscopic and chemical properties of aerosols collected near a copper smelter: implications for public and environmental health.
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