Isolation and Characterization of Acidithiobacillus ferrooxidans Strain D3-2 Active in Copper Bioleaching from a Copper Mine in Chile

Acidithiobacillus ferrooxidans strain D3-2, which has a high copper bioleaching activity, was isolated from a low-grade sulfide ore dump in Chile. The amounts of Cu²⁺ solubilized from 1% chalcopyrite (CuFeS₂) concentrate medium (pH 2.5) by A. ferrooxidans strains D3-2, D3-6, and ATCC 23270 and 33020 were 1360, 1080, 650, and 600 mg·l ^?1·30 d^?1. The iron oxidase activities of D3-2, D3-6, and ATCC 23270 were 11.7, 13.2, and 27.9 μl O₂ uptake·mg protein^?1·min^?1. In contrast, the sulfite oxidase activities of strains D3-2, D3-6, and ATCC 23270 were 5.8, 2.9, and 1.0 μl O₂ uptake·mg protein^?1·min^?1. Both of cell growth and Cu-bioleaching activity of strains D3-6 and ATCC 23270, but not, of D3-2, in the chalcopyrite concentrate medium were completely inhibited in the presence of 5 mM sodium bisulfite. The sulfite oxidase of strain D3-2 was much more resistant to sulfite ion than that of strain ATCC 23270. Since sulfite ion is a highly toxic intermediate produced during sulfur oxidation that strongly inhibits iron oxidase activity, these results confirm that strain D3-2, with a unique sulfite resistant-sulfite oxidase, was able to solubilize more copper from chalcopyrite than strain ATCC 23270, with a sulfite-sensitive sulfite oxidase.     

Copper at the Fungal Pathogen-Host Axis

Fungal infections are responsible for millions of human deaths annually. Copper, an essential but toxic trace element, plays an important role at the host-pathogen axis during infection. In this review, we describe how the host uses either Cu compartmentalization within innate immune cells or Cu sequestration in other infected host niches such as in the brain to combat fungal infections. We explore Cu toxicity mechanisms and the Cu homeostasis machinery that fungal pathogens bring into play to succeed in establishing an infection. Finally, we address recent approaches that manipulate Cu-dependent processes at the host-pathogen axis for antifungal drug development.     

The Role of Copper and Zinc Toxicity in Innate Immune Defense against Bacterial Pathogens

Zinc (Zn) and copper (Cu) are essential for optimal innate immune function, and nutritional deficiency in either metal leads to increased susceptibility to bacterial infection. Recently, the decreased survival of bacterial pathogens with impaired Cu and/or Zn detoxification systems in phagocytes and animal models of infection has been reported. Consequently, a model has emerged in which the host utilizes Cu and/or Zn intoxication to reduce the intracellular survival of pathogens. This review describes and assesses the potential role for Cu and Zn intoxication in innate immune function and their direct bactericidal function.     

Structural Analysis of the Extracellular Polysaccharide Produced by Sphaerotilus natans

An extracellular polysaccharide (EPS) was recovered and purified from the culture fluid of a sheathed bacterium, Sphaerotilus natans. Glucose, rhamnose, and aldobiouronic acid were detected in the acid hydrolysate of EPS by thin-layer chromatography (TLC). The aldobiouronic acid was found to be composed of glucuronic acid and rhamnose by TLC and gas-liquid chromatography analyses of the corresponding neutral disaccharide. The structure of EPS was identified by methylation linkage analysis and nuclear magnetic resonance. Additionally, partial acid hydrolysates of EPS were prepared and put through fast atom bombardment-mass spectrometry to determine the sugar sequence of EPS. The resulting data showed that EPS produced by S. natans is a new gellan-like polysaccharide constructed from a tetrasaccharide repeating unit, as shown below.

→4)-α-D-Glcp-(1→2)-β-D-GlcAp-(1→2)-α-L-Rhap- (1→3)-β-L-Rhap-(1→     

Copper kinetics and hepatic metallothionein levels in the frog Rana ridibunda, after exposure to CuCl2

Adult female frogs Rana ridibunda were exposed to 50 and 100 ppm of Cu (as CuCl₂) dissolved in water for 5, 15 and 30 days. We measured the Cu content in the liver, kidneys, ventral skin, and large intestine. Hepatic metallothionein (MT) was also measured and we identified by elution the type of proteins bound to copper. Gross morphological characteristics of the frogs were not affected by Cu accumulation. Cu uptake took place first across the skin, then accumulated first in the large intestine, and then in the liver which was continuously accumulating Cu at all exposure concentrations and times. The highest concentration of the metal was recorded in the kidneys at 30 days and 100 ppm exposure. It appears that the kidneys act as the secondary route of Cu detoxification, probably after a Cu overload of liver. The concentration of hepatic MT increased with the increase of Cu concentration in liver at the 5^th and 15^th day of exposure but we observed a decrease by the end of the experiment. Cu was observed in the MT-fraction, and in the high-molecular weight protein fraction.     

The Chemotactic Properties of Bradyrhizobium japonicum in the Presence of Natural Fine-Grained Minerals

The natural argillaceous minerals montmorillonite and palygorskite were found to enhance the motility of Bradyrhizobium japonicum cells and to slow down their chemotactic motion to glucose. The latter effect of the minerals is probably due to the adsorption of mineral particles on the cell surface and the blockade of the receptors that are responsible for the chemotactic behavior of the bacterium.     

Ascorbate Autoxidation in the Presence of Iron and Copper Chelates

Chelates can inhibit the iron- and copper-catalyzed autoxidation of ascorbate at pH 7.0. Diethylenetri-aminepentaacetic acid (DTPA or DETAPAC) and Desferal (deferoximane mesylate) slow the iron-catalyzed oxidation of ascorbate as effectively as reducing the trace levels of contaminating iron in buffers with Chelex resin. DETAPAC, EDTA and HEDTA (N-(2-hydroxyethyl)-ethylenediaminetriacetic acid) are effective at slowing the copper-catalyzed autoxidation of ascorbate while Desferal is ineffective. The ability to inhibit ascorbate autoxidation appears to parallel the rate of the reaction of superoxide with the iron chelate.     

Ascorbate Autoxidation in the Presence of Iron and Copper Chelates

Chelates can inhibit the iron- and copper-catalyzed autoxidation of ascorbate at pH 7.0. Diethylenetri-aminepentaacetic acid (DTPA or DETAPAC) and Desferal (deferoximane mesylate) slow the iron-catalyzed oxidation of ascorbate as effectively as reducing the trace levels of contaminating iron in buffers with Chelex resin. DETAPAC, EDTA and HEDTA (N-(2-hydroxyethyl)-ethylenediaminetriacetic acid) are effective at slowing the copper-catalyzed autoxidation of ascorbate while Desferal is ineffective. The ability to inhibit ascorbate autoxidation appears to parallel the rate of the reaction of superoxide with the iron chelate.     

Copper Ion Distribution in the surface waters of Lake George and Idd Amin

Copper ion distribution in the surface of Lakes George and Idd Amin (formerly L. Edward) has been determined using atomic absorption spectrophotometry and solution spectrophotometry. Some other chemolimnological paramerts (some of which affect copper ion distribution) have also been determined. The copper ion ranges from 0.07 to 0.13 ppm in L. George and from 0.00 to 0.02 ppm in L. Idd Amin.     

Characterization of the Large Picornaviral Polypeptides Produced in the Presence of Zinc Ion

Zinc ion inhibits the posttranslational cleavages of human rhinovirus-1A, encephalomyocarditis virus, and poliovirus polypeptides. Each virus displayed a different susceptibility to zinc. However, in each case the cleavages of the capsid precursor and the cleavages analogous to the C --> D --> E conversion in encephalomyocarditis virus were most sensitive to zinc. Higher concentrations of zinc resulted in the buildup of even larger precursor polypeptides of a size between 106,000 and 214,000 daltons. The sizes of these polypeptides and the relative position of their gene loci on the viral RNA were determined. These data were used to place these polypeptides in the over-all scheme of viral protein processing.     

Transformation of Copper Oxychloride Fungicide into Copper Oxalate by Tolerant Fungi and the Effect of Nitrogen Source on Tolerance

Aspergillus niger and Penicillium chrysogenum were able to grow on Czapek Dox medium amended with elevated concentrations [up to 500 ppm active ingredient (ai)] of the fungicide copper oxychloride. Solubilization of the fungicide in solid medium was evident by the appearance of a clear (halo) zone underneath and around the growing colonies. The halo formed with A. niger, grown on fungicide-containing nitrate nitrogen medium, was found subsequently to enclose concentric rings of newly crystalline precipitate. These crystals were extracted, examined by scanning electron microscopy and IR, and identified as copper oxalate. The supplemented nitrogen source to the medium greatly affected both fungicide solubilization and fungal tolerance. Ratios of fungicide solubilization rate (R(S)) in relation to the colony growth rate (R(G)) were significantly higher on ammonium than on nitrate nitrogen medium for both fungal strains. Growth ratios (the colony extension rate in the presence of a given concentration of the fungicide in relation to the control colony growth rate) of A. niger were markedly lower on ammonium than on nitrate nitrogen medium. The cellular copper contents, taken up from the fungicide, and the medium titratable acidity were higher in ammonium than in nitrate medium for both fungi. These results suggested fungal possession of variable tolerance mechanisms to this fungicide by complexation and/or precipitation of copper in the medium. Additionally, this work emphasizes the activity of fungi in transformation of insoluble inorganic metal-containing fungicides into insoluble organic metal compounds, which has a potentiality in metal cycling in biogeochemical and environmental context.     

Microbial populations in acid mineral bioleaching systems of Tong Shankou Copper Mine, China

AIMS: To understand the composition and structure of microbial communities in different acid mineral bioleaching systems, and to present a more complete picture of microbially mediated acid mine drainage production. METHODS AND RESULTS: In Tong Shankou Copper Mine, China, two samples (named K1 and K2) from two different sites with bioleaching were studied. A bacterial 16S rDNA library and an archaeal 16S rDNA library of the sample from each site were constructed by 16S rDNA polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP) and sequencing. A total of 18 bacterial representative sequences and 12 archaeal representative sequences were obtained. Phylogenetic analysis indicated that 77.09% of the total bacterial clones were affiliated with Proteobacteria, and 21.22% of the total bacterial clones were closely related to Nitrospira. The rest of the bacterial clones were related to Firmicutes (1.68%). Sequences affiliated with the archaea of the Thermoplasma and Ferroplasma lineages were detected abundantly in the two samples. Unexpectedly, sequences affiliated with Sulfolobales and Methanothermus genera were also detected. CONCLUSIONS: The molecular studies appear to be consistent with the environmental conditions existing at the sites, which coincides with previous studies. High concentrations of some elements (such as copper, iron and sulfur) seemed to be the key factors resulting in the diverse distribution of typical iron-oxidizing bacteria such as Leptospirillum species and Acidithiobacillus ferrooxidans. SIGNIFICANCE AND IMPACT OF THE STUDY: Research on micro-organisms present in bioleaching systems especially archaea is not abundant. The acidophiles in the two bioleaching sites obtained from Tong Shankou Copper Mine, China, have not been reported until now. These results may expand our knowledge of the microbial diversity in the acid mineral bioleaching systems.     

FGFR3 Transmembrane Domain Interactions Persist in the Presence of Its Extracellular Domain

Isolated receptor tyrosine kinase transmembrane (TM) domains have been shown to form sequence-specific dimers in membranes. Yet, it is not clear whether studies of isolated TM domains yield knowledge that is relevant to full-length receptors or whether the large glycosylated extracellular domains alter the interactions between the TM helices. Here, we address this question by quantifying the effect of the pathogenic A391E TM domain mutation on the stability of the fibroblast growth factor receptor 3 dimer in the presence of the extracellular domain and comparing these results to the case of the isolated TM fibroblast growth factor receptor 3 domains. We perform the measurements in plasma membrane-derived vesicles using a Förster-resonance-energy-transfer-based method. The effect of the mutation on dimer stability in both cases is the same (∼−1.5 kcal/mol), suggesting that the interactions observed in simple TM-peptide model systems are relevant in a biological context.     

Extracellular Matrix in Platyhelminths,with Special Reference to the Presence of Fibronectin

The extracellular matrix (ECM) was studied in the turbellarians Polycelis nigra and Microstomum lineare, the cestode Diphyllobothrium dendriticum and the trematode Dicrocoelium dendriticum. Routine LM staining methods for connective tissue gave positive results only in P. nigra. Positive staining reactions were observed in the subepithelial basal lamina, around the pharynx and as strings in the tissues. Peroxidase-anti-peroxidase and immunofluorescence methods were used to identify fibronectin. Positive results were obtained in all species. Positive reactivity to anti-fibronectin was observed in the subepithelial basal lamina and as a thin network between the cells of the tissues. Some intracellular reactivity occurred, but the cell type was not identified. In M. lineare a strong positive reactivity was observed in the regenerating area.     

Influences of Electron Donor,Bicarbonate, and Sulfate on Bioreduction Processes and Manganese/Copper Redistributions among Minerals in a Water-Saturated Sediment

Bioreduction processes have profound influences on mobility and bioavailability of metals in soils and sediments. In this study, a series of microcosm studies were conducted to investigate bioreduction progresses (ferric iron and sulfate reduction) and their influences on manganese and copper element redistributions with the change of microbial community under various geochemical conditions. Results indicated that ethanol stimulated higher rates of bioreduction processes than acetate did. High-concentration bicarbonate and sulfate addition inhibited iron reduction but not sulfate reduction. Sequential extraction revealed that the exchangeable and carbonate bonding-iron were increased in ethanol amendment, whereas those of copper were decreased. The elevated bicarbonate concentration and sulfate addition both influenced the mobility and redistribution of metals. 16S rRNA analysis indicated that ethanol amendment stimulated the growths of microbial iron and sulfate reducer. A high concentration of bicarbonate suppressed the growth of iron reducer Geobacteraceae, but showed limited effect on sulfate reducers. This study concluded that geochemical conditions such as electron donor, bicarbonate and sulfate concentration influenced the microbial community and led to changes in bioreduction processes and metal distributions in the anerobic sediments.     

Studies on Phytoremediation of Copper Using Pteridium Aquilinum (Bracken Fern) In the Presence of Biostimulants and Bioassay Using Clarias Gariepinus Juveniles

A study was carried out to evaluate the uptake of copper from water containing 10 mg/L copper by Pteridium aquilinum (bracken fern) and Clarias gariepinus in the presence of five plant growth stimulants: Nitrogen: phosphorus: potassium (15-15-15: an inorganic fertilizer), pig, cattle, poultry, and a mixture of pig/cattle manures. A plant growth stimulant differentiated each treatment. A 96-hour bioassay using C. gariepinus was carried out at the end of the experiment to test the efficacy of the clean up by P. aquilinum. The control experiment contained no copper or plant growth stimulant. Fish survival, uptake of copper by P. aquilinum, C. gariepinus, concentration of copper in water, hematology and histopathology of the fish were assessed. Higher concentrations of copper were reported in P. aquilinum than in water or C. gariepinus. Low fish mortality was reported with the highest being 20% in the cattle manure–containing treatment.     

外源性铜对SD鼠脑内铜稳态与γ-氨基丁酸、谷氨酸含量影响的实验研究

目的：探讨脑内铜稳态与γ-氨基丁酸、谷氨酸含量之间的关联性,了解脑内铜代谢参与神经疾病的作用机制.方法：把实验动物分为8组：对照组,戊巴比妥组,腹腔注射CuCl2组（剂量分别为2 mg/kg、10 mg/kg、50 mg/kg）,CuCl2-戊巴比妥混合组（先腹腔注射CuCl2,再注射戊巴比妥）.检测SD鼠血清和海马内不同形态铜、γ-氨基丁酸和谷氨酸含量.结果：单一铜胁迫下发现随着外源铜升高血清和海马总铜及血清非蛋白结合铜和海马内谷氨酸含量显著升高,在50 mg/kg注射剂量下达到最高（P＜0.02）;海马非蛋白结合铜和神经递质γ-氨基丁酸含量在2 mg/kg注射剂量下达到最高（P＜0.02）,并随着外源铜浓度升高而降低.单一注射戊巴比妥后海马游离铜含量明显降低（P＜0.02）.铜胁迫1小时后注射1％戊巴比妥结果表明,戊巴比妥能明显降低铜胁迫下海马及血清总铜和游离铜含量（P＜0.05）.结论：外源铜能改变体内铜稳态;铜稳态失衡导致神经递质γ-氨基丁酸、谷氨酸含量变化,γ-氨基丁酸含量与非蛋白结合铜呈正相关.     

Copper exposure modifies the content and distribution of trace metals in mammalian cultured cells

With this work, we have determined the cellular content of Cu, Fe and Zn in different cell lines, by using total reflection X-ray fluorescence spectrometry (TXRF). In addition, we examined whether cellular exposure to 100 moles l^–1 of Cu-His modifies the intracellular content and distribution of these trace metals. Our results indicate that all the cell lines displayed the same pattern of relative intracellular abundance of trace metals (Cu相似文献   

DNA-Triggered Aggregation of Copper,Zinc Superoxide Dismutase in the Presence of Ascorbate

The oxidative damage hypothesis proposed for the function gain of copper, zinc superoxide dismutase (SOD1) maintains that both mutant and wild-type (WT) SOD1 catalyze reactions with abnormal substrates that damage cellular components critical for viability of the affected cells. However, whether the oxidative damage of SOD1 is involved in the formation of aggregates rich in SOD1 or not remains elusive. Here, we sought to explore the oxidative aggregation of WT SOD1 exposed to environments containing both ascorbate (Asc) and DNA under neutral conditions. The results showed that the WT SOD1 protein was oxidized in the presence of Asc. The oxidation results in the higher affinity of the modified protein for DNA than that of the unmodified protein. The oxidized SOD1 was observed to be more prone to aggregation than the WT SOD1, and the addition of DNA can significantly accelerate the oxidative aggregation. Moreover, a reasonable relationship can be found between the oxidation, increased hydrophobicity, and aggregation of SOD1 in the presence of DNA. The crucial step in aggregation is neutralization of the positive charges on some SOD1 surfaces by DNA binding. This study might be crucial for understanding molecular forces driving the protein aggregation.