Influence of heavy metal ions on the electrophysical properties of Anacystis nidulans and Escherichia coli cells]

The influence of heavy metal ions (Ag+, Cu2+, Cd2+, Pb2+, Mn2+, Zn2+, Gd3+, 1 microM-1 mM) on Anacystis nidulans and Escherichia coli cells has been studied by means of electrophoresis and electro-orientation spectroscopy methods. It has been shown that changes of cell electrophoretic mobility (EM) and low-frequency (20 Hz) electro-orientation effect (EOE) observed with the increase of metal cation concentration characterize the adsorption of these ions on surface layers of cell envelopes. The degree and the character of these changes depend on cation valency and the initial value of cell EM. At the same time different changes of EM and EOE as a result of the multivalent cation adsorption allows to conclude that in that case the anisotropy of the cell surface increases. Cell damages were determined by changes in high-frequency EOE of cells which indicated the disturbance of barrier properties of their cytoplasmic membrane. Toxic effects of Ag+, Cu2+, Cd2+ ions on cells of both species and of Pb2+ on E.coli cells were observed. By toxic effects on the cytoplasmic membrane these ions could be placed in the order: for A.nidulans cells--Ag+ greater than Cu2+ greater than Cd2+; for E.coli cells Ag+ greater than Cu2+ greater than Cd2+ greater than Pb2+. Higher toxicity of heavy metals on E.coli cells seems to be connected with the more negative charge of deep layers of the cell surface.     

Optical fiber biosensor for the determination of low biochemical oxygen demand

An optical fiber biosensor was developed for the evaluation of low Biochemical Oxygen Demand (BOD) values in river waters. Artificial wastewater (AWW) solution was employed as standards for the calibration of the BOD sensor. The response time of the sensor was 15 min, and the optimal BOD response was observed at 30 degrees C, pH 7.0. A linear relationship was obtained between the output voltage and BOD5 values, and the range of determination was 1-10 mg l(-1) BOD. The sensor response was almost not influenced by chloride ion up to 1000 mg l(-1), and also not affected by heavy metal ions (Fe3+, Cu2+, Mn2+, Cr3+, Zn2+). The BOD of river waters was estimated by using the optical fiber biosensor, and good correlation between the sensor and BOD5 test was obtained (r2 = 0.971).     

Accumulation and removal of heavy metal ions by insolubilized-DNA and its interaction.

DNA was immobilized onto a porous glass bead by a treatment with UV irradiation. The immobilized DNA was insoluble in water and used for accumulation of heavy metal ion. When DNA-immobilized glass bead was added into aqueous solution containing heavy metal ions, such as Hg2+, Cd2+, Pb2+, Zn2+, Cu2+ and Fe3+, the concentration of these metal ions in the solution was decreased. However, the concentration of Mg2+ in the solution was not affected by the addition of the DNA-immobilized glass bead. These results suggested that UV-irradiated DNA selectively accumulated heavy metal ions.     

Petiolar felt-sheath of palm: a new biosorbent for the removal of heavy metals from contaminated water.

Biosorption of heavy metals such as Pb2+, Ni2+, Cd2+, Cu2+, Cr3+ and Zn2+ by petiolar felt-sheath of palm (PFP) from contaminated water was examined. PFP was found to efficiently remove all the toxic metal ions with selectivity order of Pb2+ > Cd2+ > Cu2+ > Zn2+ > Ni2+ > Cr3+. The uptake was rapid, with more than 70% completed within 15 min. The bound metal ions were successfully desorbed and the PFP fibrous-biomass remained effective after several adsorption-desorption cycles.     

汞、镉、铜污染对鱼草细胞膜系统的毒害作用

通过生理生化反应测定、激光共聚焦扫描显微镜及透射电镜观察等实验手段,研究了汞（Hg²⁺）、镉（Cd²⁺）、铜（Cu2⁺）对高等水生植物鱼草(Cabomba caroliniana A. Gray)细胞膜系统的毒害作用.结果表明：在3种重金属离子作用下,鱼草叶细胞活性氧（ROS）与丙二醛（MDA）含量上升,保护酶系统活性紊乱,膜脂过氧化程度加剧;质膜受损,膜透性增加,质壁分离;叶绿体膨胀至解体,类囊体膜上的光合色素光激发过程受阻,平均自发荧光强度降低;线粒体嵴突膨胀、减少,膜破损;核膜破裂.Hg²⁺、Cd²⁺、Cu²⁺对鱼草细胞膜系统的影响存在着一定的剂量效应关系.膜系统的稳定性在植物抗重金属胁迫的过程中起着关键性的作用.鱼草对Hg²⁺污染较为敏感,致死浓度为0.3～0.5 mg·L^-1,而对Cd²⁺、Cu²⁺具有较强的抗性,可用作生物防治中的抗性植物.     

Picogram detection of metal ions by melanin-sensitized piezoelectric sensor

A heavy metal ion sensor was constructed by cross-linking melanin onto the gold electrode of quartz crystal microbalance (QCM). A mercury ion sensitivity of 518+/-37 Hz/ppm was observed, a substantial increase in sensitivity compared to previous reports of 10-50 Hz/ppm with the limit of detection at 5 ppb. Detection of other metal ions including Sn(2+), Ge(4+), Li(+), Zn(2+), Cu(2+), Bi(3+), Co(2+), Al(3+), Ni(2+), Ag(+), and Fe(3+) were also performed. Unexpectedly, binding of Mn(7+), Pb(2+), Cd(2+), and Cr(3+) increased resonant frequencies. The surface profile of melanin thin film upon binding to metal ions was investigated by atomic force microscopy (AFM). Structural change of melanin upon binding to metal ions was characterized by circular dichroism and by infrared spectroscopy. The current study provides the first example of melanin-coated piezoelectric sensor showing high sensitivity and selectivity to metal ions.     

重金属离子对凡纳滨对虾肝胰脏、鳃丝和血液SOD活力的影响

研究了3种重金属离子(Cu²⁺、Zn²⁺、Cd²⁺)在96 h内对凡纳滨对虾(Litopenaeus vannamei)对肝胰脏、鳃丝和血液超氧化物歧化酶(SOD)活力的影响.结果表明,凡纳滨对虾SOD活力在3种重金属离子作用下随取样时间变化显著(P＜0.0),Cu²⁺在实验浓度范围内(0.1～1 mg·L^-1),肝胰脏、鳃丝和血液的SOD活力随时间延长呈一峰值变化,Zn²⁺在10 mg·L^-1时对肝胰脏表现为显著抑制作用,Cd²⁺在0. mg·L^-1时对肝胰脏和鳃丝起显著抑制作用,0.2 mg·L^-1对鳃丝SOD活力无显著变化(P＞0.0),其他浓度Zn²⁺(＜10 mg·L^-1)、Cd²⁺(＜0.2 mg·L^-1)对各组织器官SOD活力的影响随时间延长均呈现先升高后下降的趋势.3种重金属离子对凡纳滨对虾肝胰脏、鳃丝、血液SOD活力的影响呈现明显的剂量-时间效应关系.其SOD活力大小顺序为肝胰脏＞鳃丝＞血液,3种重金属离子对凡纳滨对虾伤害大小顺序为Cd²⁺＞Cu²⁺＞Zn²⁺.     

A Cu(I)-sensing ArsR family metal sensor protein with a relaxed metal selectivity profile

ArsR (or ArsR/SmtB) family metalloregulatory homodimeric repressors collectively respond to a wide range of metal ion inducers in regulating homeostasis and resistance of essential and nonessential metal ions in bacteria. BxmR from the cyanobacterium Osciliatoria brevis is the first characterized ArsR protein that senses both Cu (I)/Ag (I) and divalent metals Zn (II)/Cd (II) in cells by regulating the expression of a P-type ATPase efflux pump (Bxa1) and an intracellular metallothionein (BmtA). We show here that both pairs of predicted alpha3N and alpha5 sites bind metal ions, but with distinct physicochemical and functional metal specificities. Inactivation of the thiophilic alpha3N site via mutation (C77S) abolishes regulation by both Cd (II) and Cu (I), while Zn (II) remains a potent allosteric negative effector of operator/promoter binding (Delta G c >or= +3.2 kcal mol (-1)). In contrast, alpha5 site mutant retains regulation by all four metal ions, albeit with a smaller coupling free energy (Delta G c approximately +1.7 (+/-0.1) kcal mol (-1)). Unlike the other metals ions, the BxmR dimer binds 4 mol equiv of Cu (I) to form an alpha3N binuclear Cu (I) 2S 4 cluster by X-ray absorption spectroscopy. BxmR is thus distinguishable from other closely related ArsR family sensors, in having evolved a metalloregulatory alpha3N site that can adopt an expanded range of coordination chemistries while maintaining redundancy in the response to Zn (II). The evolutionary implications of these findings for the ArsR metal sensor family are discussed.     

镉、铜和锌胁迫下黑藻活性氧的产生及抗氧化酶活性的变化研究

研究了不同Cd、Cu、Zn处理浓度对黑藻体内活性氧()产生及对抗氧化酶(SOD、POD、CAT)活性的分子毒理学效应以探讨高等水生植物抗氧化酶对重金属胁迫的反应。结果表明,三种重金属都不同程度地加快了产生速率;Cu使SOD、POD、CAT活性下降;Cd也都减弱了SOD和POD活性,而CAT活性在0.5—5mg/L处理浓度时增加;Zn对SOD活性也为抑制作用,当浓度为0.5—5mg/L时POD和CAT活性都上升。关联度分析发现Cd、Cu和Zn胁迫下黑藻起主要保护作用的分别为SOD、POD和CAT,而SOD最易受到影响。Cd、Cu处理下的叶绿素含量也都呈下降趋势,而0.5—5mg/L的Zn浓度刺激了叶绿素合成。所有Zn处理、0.5mg/L的Cu处理和0.5—1mg/L的Cd处理的叶绿素a/b值都大于对照值。除了Cu使可溶性蛋白含量减少外,0.5—5mg/L的Zn和0.5—1mg/L的Cd都使其含量增加。综合起来,Cu的毒性最强,其次为Cd,Zn最弱。致死阈浓度分别为:Cu:0.5—1mg/L;Cd:1—2mg/L;Zn:5—6mg/L。SOD是评价重金属对沉水植物毒性效应的灵敏指标。黑藻对水环境Cu污染反应敏感。       

Effect of metal ions on the aspartate transaminase (E.C.2.6.1.1.) activity in tobacco tissue culture

Aspartate transaminase enzyme was prepared from tobacco tissue cultures. Effect of 13 different metal ions on the enzyme activity was preliminarily studied. The enzyme activity was inhibited by five ions, namely Cd2+, Hg2+, Zn2+, Cu2+, and Ag+. None of the ions investigated enhanced the activity. Fe2+ caused an apparent activity increase in the reaction mixture. Pyridoxal-phosphate enhanced this effect of the Fe2+.     

Synthesis, spectroscopic, structural and complexation studies of a new tetra-naphthylmethylene pendant-armed macrocyclic ligand

A novel emissive tetra-naphthylmethylene pendant-armed macrocyclic ligand and a series of complexes with monovalent and divalent metal ions have been synthesized. Solid compounds have been isolated as mononuclear (Co(II), Cu(II) and Zn(II)) or dinuclear (Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Ag(I)), complexes, depending on the counterions used. The chemical and photophysical properties of the free ligand, the protonation behavior and its metal complexes have been investigated in solution. UV-Vis spectroscopy has revealed a 1:1 binding stoichiometry for Cu(II), Zn(II), Cd(II), Ni(II) and Co(II), and 2:1 molar ratio for Ag(I). In chloroform, the free ligand presents two emission bands related to the monomer naphthalene emission and a red-shifted band attibutable to an exciplex due to a charge transfer from the nitrogen lone electron pair to the excited chromophore. Upon protonation of the free amines or due to metal complexation, the exciplex band disappears. The crystal structure of [Ag₂L(NO₃)₂] is also reported. The structure reveals that both metal ions are into the macrocyclic cavity in a distorted square plane {AgN₃O} environment. Each Ag(I) atom interacts with two neighbouring amine nitrogen atoms, one pyridine nitrogen and one oxygen atom from a monodentate nitrate ion.     

匍茎翦股颖对Cu2+、Zn2+、Cd2+与Pb2+ 胁迫的生长响应与阈限浓度

采用砂培法,研究了匍茎翦股颖对Cu2+、Zn2+、Cd2+与Pb2+胁迫的生长响应及阈限浓度,结果表明:种子萌发率随着4种重金属浓度的增加而下降。对株高的影响是当重金属浓度小于100mg/L时会促进株高生长,高于100mg/L则产生抑制作用。Cu2+显著抑制根系生长,并随浓度的增加抑制效应愈加显著;在Cu2+浓度为600mg/L时匍茎翦股颖的根长比对照下降了93.75%。Cu2+、Zn2+、Pb2+浓度小于200mg/L时会促进地上生物量的增加,但高于200mg/L时,地上生物量会随着3种重金属的增加而减少。Cu2+、Zn2+浓度小于100mg/L或Cd2+、Pb2+浓度小于200mg/L会增加叶绿素的含量,高浓度会降低叶绿素的含量;Cd2+在浓度为600mg/L时显著降低叶绿素含量,与对照相比,下降了43.55%。匍茎翦股颖生长的综合效应分析表明,匍茎翦股颖对Cu2+胁迫最敏感,具有较低的阈限浓度,而Zn2+胁迫对匍茎翦股颖的生长影响最小,阈限浓度相对较高。     

Effect of different concentrations of heavy metal ions on the normal physical and chemical characteristics of the hemolymph of Palanorbarius purpura (Mollusca: Bulinidae) in the norm and during a trematode infection

Short-term simultaneous effect of high concentrations (LC25, LC50, LC75) of heavy metal ions. (Cu2+, Zn2+, Cd2+ and Pb2+) and infection with trematode partenites Echinoparyphium aconiatum onto haemolymph of mollusk has been investigated. It was noted that low doses of toxicant (2.5 and 10 maximum admitted concentrations) have variable effect. In infected molluscs the concentration of haemoglobin decreases, while in intact ones it increases. In relation to this index, it was found, that the ion Cu2+ is highly toxic, Zn2+ and Cd(2+)--toxic, Pb(2+)--moderately toxic.     

Arsenic and cadmium resistance in environmental isolates of Yersinia enterocolitica and Yersinia intermedia

Environmental strains of Yersinia enterocolitica representing biotype 1A lack virulence plasmid (pYV) and are regarded as non-pathogenic. Though these occupy a diverse range of environmental niches, nothing is known about their resistance to heavy metals. The minimal inhibitory concentrations (MICs) of various metal ions, namely Ag+, Cu2+, Zn2+, Cd2+, As5+, and As3+, for strains of Yersinia enterocolitica (biotype 1A) and Yersinia intermedia (biotypes 1, 2, and 4), isolated from sewage effluents or pork, were determined. All isolates were resistant (MICs 2.5-5 mM) to Cd2+. The MICs of arsenic varied with bacterial strain and the chemical species of the arsenic used. For the majority of the strains, however, it was between 5-10 mM of Na2HAsO4.7H2O and NaAsO2, and 0.625-2.5 mM of As2O3. Except for one isolate, MICs of Ag+, Cu2+, and Zn2+ for these strains were in the range of 0.3-0.625 mM.     

Heavy metal cation-induced increase in the antimicrobial activity of gramicidin S. Increased sensitivity of metal-resistant mutants of Escherichia coli B to the antibiotic]

Gramicidin S response of metal resistant mutants of E. coli B and the effect of concentrations of Cu2+, Ag+, Co2+ and Cd2+ on the growth and sensitivity of E. coli B to cationic antibiotics, i.e. gramicidin S2+ and streptomycin2+, were studied. It was shown that the metal-cumulating mutants of E. coli B with two different mechanisms of cross resistance to Cu2+, Cd2+ and Ag+ had higher sensitivity to gramicidin S than the initial wild type strain of E. coli B. It was found that in the threshold or higher doses the salts of Cu, Ag, Co and Cd increased the gramicidin S antimicrobial action on actively metabolizing cells of E. coli B. Analysis of the experimental data as well as the literature ones suggested that the synergic action of gramicidin S and the heavy metals stemmed from an increase in the cationic conductivity of the cytoplasma membrane modified by the metals in the threshold doses which induced an increase in the transport and accumulation of the cations in the bacterial cells by the electric field gradient (with the negative sign inside). Withdrawal of Ca2+ and Mg2+ from the E. coli outer structures into the cytoplasm impaired the barrier properties of the outer membrane and promoted binding of the gramicidin S cations to the liberated anionic groups of the E. coli outer structures and potentiation of the gramicidin S antimicrobial activity as was shown in our experiments.     

Heavy metals in rat liver cadmium binding protein.

The simultaneous determination of heavy metals in microsamples of chromatographically isolated cadmium-binding protein (Cd-BP) from rat liver was performed by neutron activation analysis. The results suggested that metals other than those already reported (Cd, Zn, Cu, and Hg) can bind the protein. These observations were confirmed by in vivo radiotracer experiments by injecting i.p. 21 labelled metal ions in cadmium-treated rats. Of the metals tested, 109Cd, 65Zn, 64Cu, 203Hg, 106Ag and 113Sn were found incorporated in the Cd-BP. The incorporation of 35S-cysteine, used as an indicator of Cd-BP biosynthesis, was increased in rats exposed to cadmium as compared to untreated animals. In order to establish the influence of other metal ions on the biosynthesis of Cd-BP and the incorporation of cadmium in the protein, in vivo experiments were carried out by i.p. injection of 109Cd and 35S-cysteine. In the presence of 42 metal ions no influence was observed on the incorporation of the two radioisotopes in the Cd-BP. These observations tend to support the hypothesis that cadmium can act as a highly specific inducer of Cd-BP and that this protein might be involved in the metabolism of several heavy metals.     

Expression of human metallothionein III and its metalloabsorption capability in Escherichia coli

Human metallothionein III (MT III) gene was synthesized with Escherichia coli preference codon usage and expressed in E. coli in glutathione-S-transferase (GST) fusion form. The recombinant MT III was released by proteinase Factor Xa digestion and purified with the yield of 2 mg/L culture, and its specific Cd2+ binding capability was confirmed. E. coli strain BL21(DE3), expressing MT III, showed metal tolerance between 0.1 and 0.5 mM Cd2+ and bacterial growth was inhibited at 1 mM Cd2+. MT III expressing E. coli strain showed binding discrimination between different metal ions in combination use, with the preference order of Cd2+ > Cu2+ > Zn2+. It absorbed different metal ions with relatively constant ratio and showed a cumulative absorption capability for mixed heavy metals.