Structural and functional insights of Wilson disease copper-transporting ATPase

Wilson disease is an autosomal recessive disorder of copper metabolism. The gene for this disorder has been cloned and identified to encode a copper-transporting ATPase (ATP7B), a member of a large family of cation transporters, the P-type ATPases. In addition to the core elements common to all P-type ATPases, the Wilson copper-transporting ATPase has a large cytoplasmic N-terminus comprised six heavy metal associated (HMA) domains, each of which contains the copper-binding sequence motif GMT/HCXXC. Extensive studies addressing the functional, regulatory, and structural aspects of heavy metal transport by heavy metal transporters in general, have offered great insights into copper transport by Wilson copper-transporting ATPase. The findings from these studies have been used together with homology modeling of the Wilson disease copper-transporting ATPases based on the X-ray structure of the sarcoplasmic reticulum (SR) calcium-ATPase, to present a hypothetical model of the mechanism of copper transport by copper-transporting ATPases.     

Heavy metals in the Rosetta estuary of the Nile and the adjoining Mediterranean waters: evidence of removal of dissolved heavy metals from waters as a result of possible binding to suspended matter

The Rosetta estuary was partially separated from the Rosetta branch of the Nile by Edfina Barrage, which controls the Nile discharge into the Mediterranean Sea. The study area covers the Rosetta estuary (lotic environment) and the adjoining seawaters (lentic environment) to investigate the local and seasonal distribution of dissolved and particulate copper and zinc, as well as dissolved cadmium in this estuary and to illustrate its influence on the distribution of these metal forms in the inshore seawaters. Besides, emphasis on the removal of dissolved heavy metals from waters by their adsorption onto suspended matter (SM) was also considered. Contrary to particulate copper (PCu), the vertical values of dissolved copper (DCu) decreased generally with depth. Planktonic scavenging and regeneration processes might determine the vertical profiles of the copper forms. The copper data suggest that the surface sources of DCu exceeded the bottom sources, contrary to the sources of PCu. The markedly high and maximum seasonal averages of DCu in the estuary and inshore seawater in July inspite of the high uptake in summer possibly reflect higher amounts of humic materials. The lowest seasonal average value of DCu in the inshore seawater in January suggests removal of copper in presence of maximum value of SM during highest discharge. The highest regional average of DCu at the estuarine mouth coincided with desorption process during mixing of the fresh and salt waters. The vertical values of dissolved zinc (DZn) and particulate zinc (PZn) showed irregular variations and their high concentrations in the surface of the estuarine and inshore seawater indicate possible land-based sources. The high bottom DZn values, however, resulted from its contribution from the interstitial water of the sediments. The data suggest that the surface sources of DZn exceeded the bottom sources and PZn showed the opposite trend in the open sea area. In the estuary, the maximum seasonal average value of DZn accompanied by the lowest seasonal average of PZn in April inspite of the high uptake in spring suggest that desorption was the dominant process. The minimum regional averages of both zinc forms at the estuarine opening and the highest average of PZn near Edfina Barage are correlated with the amounts of SM, which decreased toward the estuarine mouth. The vertical values of dissolved cadmium (DCd) were much lower in the estuary than the other metals. They showed in both environments irregular variations with depth. The bottom maximum value of DCd can be attributed mainly to contamination from the sediments. There was a distinct seasonal variation of DCd. The minimum seasonal average value of DCd in the estuary in April seems to be caused by its specific binding to living plankton found in abundance. The minimum regional average of DCd value was found at the estuarine mouth. The decrease in Cd concentration due to removal from dissolved state is most pronounced in the early stage of mixing. The correlation coefficients of DCd were positive with salinity and negative with SM, indicating that Cd increased seaward. Statistical correlation between Cd and Zn concludes that the factors affecting their distribution are generally the same.     

Assessment of Pollution-Induced Microbial Community Tolerance to Heavy Metals in Soil Using Ammonia-Oxidizing Bacteria and Biolog Assay

This study attempted to investigate if the tolerance of soil bacterial communities in general, and autotrophic ammonia-oxidizing bacteria (AOB) in particular, evolved as a result of prolonged exposure to metals, and could be used as an indigenous bioindicator for soil metal pollution. A soil contaminated with copper, chromium, and arsenic (CCA) was mixed with an uncontaminated garden soil (GS3) to make five test soils with different metal concentrations. A modified potential ammonium oxidation assay was used to determine the metal tolerance of the AOB community. Tolerance to Cr, Cu, and As was tested at the beginning and after up to 13 months of incubation. Compared with the reference GS3 soil, the five CCA soils showed significantly higher tolerance to Cr no matter which form of Cr (Cr³⁺, CrO₄ ^2?, or Cr₂O₇ ^2?) was tested, and the Cr tolerance correlated with the total soil Cr concentration. However, the tolerance to Cu²⁺, As³⁺, and As⁵⁺ did not differ significantly between the GS3 soil and the five CCA soils. Community level physiological profiles using Biolog microtiter plates were also used to examine the chromate tolerance of the bacterial communities extracted after six months of exposure. Our results showed that the bacterial community tolerance was altered and increased as the soil Cr concentration was increased, indicating that the culturable microbial community and the AOB community responded in a similar manner.     

植物修复──重金属污染土壤整治有效途径

系统论述了重金属污染土壤植物修复的概念、原理、方法与研究动态,列举了污染土壤植物修复的一些实例。探讨了土壤重金属超富集植物的类型、特点、应用潜力以及基因工程等现代生物技术的应用、效果与最新展望,为土壤污染的综合整治及生态修复提出了新的思路。     

Comparison of Extractants for Removing Heavy Metals from Contaminated Clayey Soils

This article describes the removal of heavy metals from contaminated clayey soils by soil washing using various extractants. Two clayey soils, kaolin, a low buffering soil with pH of 5, and glacial till, a high buffering soil with pH of 8, were used to represent various soil conditions. These soils were spiked with chromium (Cr), nickel (Ni), and cadmium (Cd) to simulate improper disposal of typical electroplating waste constituents. The following extracting solutions were investigated for the removal of heavy metals from the soils: deionized water, distilled water, and tap water; acetic acid and phosphoric acid; chelating agents ethylenediaminetetraacetic acid (EDTA) and citric acid; and the oxidizing agents potassium permanganate and hydrogen peroxide. The effect of extractant concentration on removal of heavy metals was also investigated. Complete removal of Cr was achieved using 0.1?M potassium permanganate for kaolin, while a maximum of 54% was removed from glacial till. A maximum Ni removal of 80% was achieved using tapwater for kaolin, while a maximum removal of 48 to 52% was achieved using either 1?M acetic acid or 0.1?M citric acid for glacial till. A maximum Cd removal of 50% was achieved using any of the extractants for kaolin, while a maximum removal of 45 to 48% was obtained using either acids or chelating agents for glacial till. Overall, this study showed that complete removal of Cr, Ni, and Cd from clayey soils is difficult to achieve using the soil-washing process, and also the use of one extractant may not be effective in removing all metals. A sequential extraction using different extractants may be needed for the removal of multiple metal contaminants from clayey soils.     

Multianalysis of trace elements in mosses with inductively coupled plasma-mass spectrometry

As a part of an air-pollution biomonitoring survey, a procedure using inductively coupled plasma-mass spectrometry (ICP-MS) and microwave digestion was developed to achieve a high sample throughput and guarantee the accuracy of the results. This article presents an analytical method to measure 22 trace elements. As, Ba, Cd, Ce, Co, Cr, Cs, Cu, Fe, Hg, La, Mo, Ni, Pb, Rb, Sb, Sr, Th, Tl, U, V, W were analyzed in 563 mosses collected in France. The digestion was performed in polytetrafluoroethylene (PTFE) vessel using the mixture HNO₃-H₂O₂-HF. The data were reprocessed taking into account the drift curve calculated for each element. The detection limits (DL) calculation was based on the standard deviations of the reagent blanks concentrations. The DL varied from one batch to another, because of the heterogeneity of the mosses’ elemental contents. The DL ranged between 0.001 μg/g (Cs, Tl) and 70 μg/g (Fe) and were mainly around 0.01 μg/g (As, Cd, Ce, Co, Hg, La, Mo, Sb, Sr, U, V, W). The detection limits obtained were in agreement with the concentrations observed in the samples, except for Hg and Ni. The reproducibility between duplicates and the analytical precision were near 10%. The procedure was tested with the mosses’ reference materials.     

Sister Chromatid Exchanges Induced by Heavy Metals in Vicia Faba

The induction of sister chromatid exchanges (SCE) by chloride and nitrate salts of nickel, cobalt, cadmium and zinc were studied in meristematic root cells of Vicia faba. Salts of nickel, cobalt and cadmium significantly increased the frequency of SCE, whereas chloride and nitrate salts of zinc did not increase the frequency of SCE significantly above the spontaneous level. The reported data demonstrate that the induction of SCE in Vicia faba may represent a valuable bioindicator for detecting the cytogenetic damage of heavy metals.     

铅锌尾矿上自然定居植物

在凡口1#铅锌尾矿库内共有10种植物自然定居,这些植物主要生长在尾矿库的边缘区域.植物在尾矿上的生长、分布明显受到表层尾矿某些物理性质如稳定状况、含水量等的影响,尾矿中的营养物质含量与植物的生长高度以及群落盖度有一定的关系.杜虹花(Callicarpa pedunculata)体内的Pb、Zn、Cu和Cd含量大小顺序为叶>根>茎,而盐肤木(Rhuschinensis)和美丽胡枝子(Lespedeza     

重金属镉（cd）对花生结瘤和生长发育的影响

试验结果表明：重金属镉对“天府９号”、‘鲁花９号”花生品种的结瘤和植株生长均有影响。镉浓度在１００ＰＰＭ下,花生植株根系发育受到抑制,快生型花生根瘤菌株８５—７虽能侵染,但结瘤数量显著减少。     

Rare earth complexation with 1,3,5-trideoxy-1,3,5-tris(2-hydroxybenzyl)amino-cis-inositol

The protonation constants of 1,3,5-trideoxy-1,3,5-tris(2-hydroxyl-benzyl)amino-cis-inositol (thci) in I = 1 M (NaClO₄) were determined to be: pK_a1 5.96 ± 0.03, pK_a2 7.21 ± 0.01, pK_a3 8.32 ± 0.07, pK_a4 8.95 ± 0.06. The solvent extraction studies were consistent with the formation of the Ln(thci)³⁺ and complexes. The log of the stability constants (log β₁ and log β₂) at 25 °C in 1 M (NaClO₄) at pH 4 for formation of these complexes are reported. Laser luminescence measurements of the ⁷F₀-⁵D₀ transition of Eu(III) complexed by thci indicated two species. The shifts in the peaks relative to that of Eu(aq)³⁺ were comparable to the values reported for other complexes of Eu(III) with organic ligands, but the intensities were greater. Luminescence lifetime measurements of the fluorescence spectra indicated that the complex has 5 inner sphere water molecules bound to the Eu(III) cation at pH 6.71-8.52. This was consistent with bidentate chelation of Eu(III) with each thci molecule. gaussian view energy calculations indicated bonding for M(III) to the amino and hydroxyl groups of the cyclohexanetriol and (2-hydroxybenzyl)amino moieties in the Ln(thci)³⁺ complex.