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1.
The effects of fourteen metal ions (As3+, As5+, Cd2+, Co2+, Cr3+, Cr6+, Hg2+, Li+, Mg2+, Mn2+, Ni2+, Se4+, V5+, VO2+) on the proliferation and differentiation in mouse B16 melanoma cells cultivated in vitro were analyzed. Cell number assays, melanin, and protein measurements, a 3(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide reduction test (MTT survival test), and a clonal growth assay were performed. At 10−4 M, metal ions such as As3+, As5+, Cd2+, Cr6+, Se4+, V5+, VO2+, and, to a minor extent, Li+, Hg2+, and Co2+ significantly reduced the number of the B16 melanoma cells. For the same molar concentration, the order of the levels of cell toxicity of the metal compounds to B16 cells as measured by the MTT test was as follows: Hg2+>Cr6+=Cd2+>As3+, As5+>V5+, VO2+>Se4+=Ni2+=Co2+=Li+. An increased synthesis of melanin in B16 cells was noted after incubation with Co2+, Ni2+, Cd2+, and Li+, whereas Se4+ had, on the contrary, an inhibiting effect on melanogenesis.  相似文献   

2.

This paper reports the synthesis of azomethine-modified gold nanoparticles with azomethine (azomethine-AuNPs) in aqueous media, which were characterized by FT-IR spectroscopy, ultraviolet–visible spectroscopy (UV-Vis), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and transmission electron microscopy (TEM). The azomethine-AuNPs were employed as colorimetric for Cr3+ and Co2+ ions at pH 6.2–7.5 and 8.1–9.1, at room temperature in aqueous solution. In the presence of Cr3+ and Co2+, the azomethine-AuNPs induce aggregation of the nanoparticles. Upon aggregation, the surface plasmon absorption band red-shifts so that the nanoparticle solution appears a blue color. The sensitivity of azomethine-AuNPs towards other metal ions, Mg2+, Mn2+, Cr6+, Na+, Ni2+, Ag+, Al3+, Ca2+, Cd2+, Cu2+, Fe2+, Fe3+, Hg2+, Cd2+, K+, Co3+, Ni2+, Pb2+, and Zn2+ are negligible. This highly selective sensor allows a direct quantitative assay of Co2+ and Cr3+ with colorimetric detection limits of 83.22 and 108 nM, respectively.

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3.
The effect of heavy metal cations on the mitochondrial ornithine/citrulline transporter was tested in proteoliposomes reconstituted with the protein purified from rat liver. The transport activity was measured as [3H]ornithine uptake in proteoliposomes containing internal ornithine (ornithine/ornithine antiport mode) or as [3H]ornithine efflux in the absence of external substrate (ornithine/H+ transport mode). 0.1 mM Cu2+, Pb2+, Hg2+, Cd2+ and Zn2+ strongly inhibited (more than 85%) the antiport; whereas Mn2+, Co2+ and Ni2+ inhibited less efficiently (25, 47 and 69%, respectively). The IC50 values of the transporter for the different metal ions ranged from 0.71 to 350 μM. Co2+ and Ni2+ also inhibited the [3H]ornithine efflux whereas Cu2+, Pb2+, Hg2+, Cd2+ and Zn2+ stimulated the [3H]ornithine efflux. The stimulation of the [3H]ornithine efflux by Cu2+ and Cd2+ (as well as by Pb2+, Hg2+ and Zn2+) was not prevented by NEM and was reversed by DTE. These features indicated that the inhibition of the antiport was due to the interaction of the Cu2+, Pb2+, Hg2+, Cd2+ and Zn2+ with a population of SH groups, of the transporter, responsible for the inhibition of the physiological function; whereas the stimulation of [3H]ornithine efflux was due to the induction of a pore-like function of the transporter caused by interaction of cations with a different population of SH groups. Differently, the inhibition of the ornithine transporter by Ni2+, Co2+ or Mn2+ was caused by interaction with the substrate binding site, as indicated by the competitive or mixed inhibition.  相似文献   

4.
Chloride salts of Li+, Na+, K+, Mg2+, Ca2+, Cr3+, Mn2+, Fe2+, and Fe3+ had no effect on [3H]diazepam binding. Chloride salts of Co2+, Ni2+, Cu2+, and Zn2+ increased [3H]diazepam binding by 34 to 68% in a concentration-dependent fashion. Since these divalent cations potentiated the GABA-enhanced [3H]diazepam binding and the effect of each divalent cation was nearly additive with GABA, these cations probably act at a site different from the GABA recognition site in the benzodiazepine-receptor complex. Scatchard plots of [3H]diazepam binding without an effective divalent cation showed a single class of binding, with a Kd value of 5.3 mM. In the presence of 1 mM Co2+, Ni2+, Cu2+, or Zn2+, two distinct binding sites were evident with apparent Kd values of 1.0 nM and 5.7 nM. The higher-affinity binding was not detected in the absence of an effective divalent cation and is probably a novel, super-high-affinity binding site.  相似文献   

5.
A water‐soluble, high‐output fluorescent sensor, based on a lumazine ligand with a thiophene substituent for Cd2+, Hg2+ and Ag+ metal ions, is reported. The sensor displays fluorescence enhancement upon Cd2+ binding (log  β = 2.79 ± 0.08) and fluorescence quenching by chelating with Ag+ and Hg2+ (log β = 4.31 ± 0.15 and 5.42 ± 0.1, respectively). The mechanism of quenching is static and occurs by formation of a ground‐state non‐fluorescent complex followed by rapid intersystem crossing. The value of the Stern–Volmer quenching rate constant (kq) by Ag+ ions is close to 6.71 × 1012 mol/L/s at 298 K. The thermodynamic parameters (ΔG, ΔH and ΔS) were also evaluated and indicated that the complexation process is spontaneous, exothermic and entropically favourable. The quantitative linear relationship between the softness values of Klopman (σK) or Ahrland (σA) and the experimental binding constants (β) being in the order of Hg2+ > Ag+ > Cd2+ suggests that soft–soft interactions are the key for the observed sensitivity and selectivity in the presence of other metal ions, such as: Pb2+, Ni2+, Mn2+, Cu2+, Co2+, Zn2+ and Mg2+ ions. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

6.
We prepared an aminothiourea‐derived Schiff base (DA) as a fluorescent chemosensor for Hg2+ ions. Addition of 1 equiv of Hg2+ ions to the aqueous solution of DA gave rise to an obvious fluorescence enhancement and the subsequent addition of more Hg2+ induced gradual fluorescence quenching. Other competing ions, including Pb2+, Cd2+, Cr3+, Zn2+, Fe2+, Co3+, Ni2+, Ca2+, Mg2+, K+ and Na+, did not induce any distinct fluorescence changes, indicating that DA can selectively detect Hg2+ ions in aqueous solution. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

7.
A new rhodamine–ethylenediamine–nitrothiourea conjugate (RT) was synthesized and its sensing property as a fluorescent chemodosimeter toward metal ions was explored in water media. Analytical results from absorption and fluorescence spectra revealed that the addition of Hg2+ ions to the aqueous solution of the chemodosimeter RT caused a distinct fluorescence OFF–ON response with a remarkable visual color change from colorless to pink; however, no clear spectral and color changes were observed from other metal ions including: Zn2+, Cu2+, Cd2+, Pb2+, Ag+, Fe2+, Cr3+, Co3+, Ni2+, Ca2+, Mg2+, K+ and Na+. The sensing results and the molecular structure suggested that a Hg2+‐induced a desulfurization reaction and cyclic guanylation of the thiourea moiety followed by ring‐opening of the rhodamine spirolactam in RT are responsible for a distinct fluorescence turn‐on signal, indicating that RT is a remarkably sensitive and selective chemodosimeter for Hg2+ ions in aqueous solution. Hg2+ within a concentration range from 0.1 to 25 μM can be determined using RT as a chemodosimeter and a detection limit of 0.04 μM is achieved. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

8.
Heavy metal sequestration by a multimetal resistant Pseudomonas strain isolated from a uranium mine was characterized for its potential application in metal bioremediation. 16S rRNA gene analysis revealed phylogenetic relatedness of this isolate to Pseudomonas fluorescens. Metal uptake by this bacterium was monophasic, fast saturating, concentration and pH dependent with maximum loading of 1048 nmol Ni2+ followed by 845 nmol Co2+, 828 nmol Cu2+ and 700 nmol Cd2+ mg?1 dry wt. Preferential metal deposition in cell envelope was confirmed by TEM and cell fractionation. FTIR spectroscopy and EDX analysis revealed a major role of carboxyl and phosphoryl groups along with a possible ion exchange mechanism in cation binding. Binary system demonstrated selective metal binding affinity in the order of Cu2+ > Ni2+ > Co2+ > Cd2+. A comparison with similar metal uptake reports considering live bacteria strongly indicated the superiority of this strain in metal sequestration, which could be useful for developing efficient metal removal system.  相似文献   

9.

Essentially all bacteria have genes for toxic metal ion resistances and these include those for Ag+, AsO 2 , AsO 3−4 , Cd2+, Co2+, CrO 2−4 , Cu2+, Hg2+, Ni2+, Pb2+, TeO 2−3 , Tl+ and Zn2+. The largest group of resistance systems functions by energy-dependent efflux of toxic ions. Fewer involve enzymatic transformations (oxidation, reduction, methylation, and demethylation) or metal-binding proteins (for example, metallothionein SmtA, chaperone CopZ and periplasmic silver binding protein SilE). Some of the efflux resistance systems are ATPases and others are chemiosmotic ion/proton exchangers. For example, Cd2+-efflux pumps of bacteria are either inner membrane P-type ATPases or three polypeptide RND chemiosmotic complexes consisting of an inner membrane pump, a periplasmic-bridging protein and an outer membrane channel. In addition to the best studied three-polypeptide chemiosmotic system, Czc (Cd2+, Zn2+, and Co2), others are known that efflux Ag+, Cu+, Ni2+, and Zn2+. Resistance to inorganic mercury, Hg2+ (and to organomercurials, such as CH3Hg+ and phenylmercury) involve a series of metal-binding and membrane transport proteins as well as the enzymes mercuric reductase and organomercurial lyase, which overall convert more toxic to less toxic forms. Arsenic resistance and metabolizing systems occur in three patterns, the widely-found ars operon that is present in most bacterial genomes and many plasmids, the more recently recognized arr genes for the periplasmic arsenate reductase that functions in anaerobic respiration as a terminal electron acceptor, and the aso genes for the periplasmic arsenite oxidase that functions as an initial electron donor in aerobic resistance to arsenite.

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10.
The heavy metal resistant ciliate, Stylonychia mytilus, isolated from industrial wastewater has been shown to be potential bioremediator of contaminated wastewater. The ciliate showed tolerance against Zn2+ (30 μg/mL), Hg2+ (16 μg/mL) and Ni2+ (16 μg/mL). The metal ions slowed down the growth of the ciliate as compared with the culture grown without metal stress. The reduction in cell population was 46% for Cd2+, 38% for Hg2+, 23% for Zn2+, 39% for Cu2+ and 51% for Ni2+ after 8 days of metal stress. S. mytilus reduced 91% of Cd2+, 90% of Hg2+ and 98% of Zn2+ from the medium after 96 h of incubation in a culture medium containing 10 μg/mL of the respective metal ions. Besides this, the ciliate could also remove 88% of Cu2+ and 73% Ni2+ from the medium containing 5 μg/mL of each metal after 96 h. The ability of Stylonychia to take up variety of heavy metals from the medium could be exploited for metal detoxification and environmental clean-up operations.  相似文献   

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