A STUDY ON THE MECHANISM OF INTERCELLULAR ADHESION : Effects of Neuraminidase, Calcium, and Trypsin on the Aggregation of Suspended HeLa Cells

Aggregation of suspended HeLa cells is increased on removal of cell surface sialic acid. Calcium ions promote aggregation whereas magnesium ions have no effect. The calcium effect is abolished by previous treatment of the cells with neuraminidase. Trypsinization of the HeLa cells followed by thorough washing diminishes the rate of mutual cell aggregation. Subsequent incubation with neuraminidase restores the aggregation rate to the original value before trypsin treatment. Cells which had acquired a greater tendency for aggregation after removal of peripheral sialic acid lose this property when subsequently treated with trypsin. Calcium ions have no aggregative effect on trypsinized cells. In contrast to HeLa cells, aggregation of human erythrocytes was not increased after treatment with neuraminidase or on addition of calcium. The results with HeLa cells are interpreted as follows: (a) Trypsin-releasable material confers adhesiveness upon the cells. (b) The adhesive property of this material is counteracted by the presence of cell surface sialic acids. (c) Calcium ions exert their effect by attenuating the adverse effect of sialic acid.     

Selective Electrodiffusion of Zinc Ions in a Zrt-, Irt-like Protein,ZIPB

All living cells need zinc ions to support cell growth. Zrt-, Irt-like proteins (ZIPs) represent a major route for entry of zinc ions into cells, but how ZIPs promote zinc uptake has been unclear. Here we report the molecular characterization of ZIPB from Bordetella bronchiseptica, the first ZIP homolog to be purified and functionally reconstituted into proteoliposomes. Zinc flux through ZIPB was found to be nonsaturable and electrogenic, yielding membrane potentials as predicted by the Nernst equation. Conversely, membrane potentials drove zinc fluxes with a linear voltage-flux relationship. Direct measurements of metal uptake by inductively coupled plasma mass spectroscopy demonstrated that ZIPB is selective for two group 12 transition metal ions, Zn²⁺ and Cd²⁺, whereas rejecting transition metal ions in groups 7 through 11. Our results provide the molecular basis for cellular zinc acquisition by a zinc-selective channel that exploits in vivo zinc concentration gradients to move zinc ions into the cytoplasm.     

The Effects of Manganese (II) But Not Nickel (II) Ions on Enterococcus hirae Cell Growth, Redox Potential Decrease, and Proton-Coupled Membrane Transport

Enterococcus hirae grow well under anaerobic conditions by fermenting glucose, accompanied with the decrease of oxidation–reduction potential (E _h) from positive values to negative ones. It was shown that heavy metals—copper and iron ions—affect E. hirae growth and alter E _h and proton-potassium ions fluxes through the cell membrane. The aim of this study was to establish the effects of manganese (II) ions on bacterial growth within the concentration range of 0.01–1 mM and compare with nickel (II) ions’ effect. The presence of Mn²⁺ during E. hirae ATCC9790 growth had significant effects: The lag phase duration decreased while the specific growth rate was increased; decrease in E _h was shifted. In contrast, no visible changes in bacterial growth and E _h were observed in the case of Ni²⁺. The effects of these ions on proton-potassium ions fluxes through the cell membrane were estimated in the presence and absence of N,N′-dicyclohexylcarbodiimide (DCCD), inhibitor of the F_oF₁ ATPase. Stronger effect of Mn²⁺ on H⁺–K⁺ exchange was detected in the presence of DCCD that can be explained by a possible complex formation between these substances and its direct influence on membrane transport proteins.     

Characterization of O-trimethylsilyl derivatives of d-glucose,d-galactose,and d-mannose by gas-liquid chromatography-chemical-ionization mass spectrometry with ammonia as reagent gas

The per(trimethylsilyl) ethers of d-glucose, d-galactose, and d-mannose were analyzed by g.l.c.-c.i.m.s. with ammonia as the reagent gas. C.i.m.s. gave simple fragmentation and fragment ions of high intensity in the high-mass range where the QM⁺ ion is also detected. The β-d anomers gave ions at m/e 558 showing intensities 3–12 times those of the α-d anomers. The epimers could be distinguished by differences in the intensities of the ions and by the observation that d-glucose gave a base peak at m/e 198, d-galactose at m/e 468, and d-mannose at m/e 204. The pyranose and furanose structures could be distinguished by comparing the ion intensities at m/e 198, m/e 271, m/e 361, m/e 396, and m/e 451. A similar analysis was also performed with 2-methylpropane as the reagent gas.     

Effects of Ammonium Ions, Oxygen, Carbon Monoxide, and Acetylene on Anaerobic and Aerobic Hydrogen Formation by Anabaena cylindrica B629

An investigation was made of various factors, both experimental and physiological, which influenced the formation of hydrogen gas by the heterocystous cyanobacterium Anabaena cylindrica B629 when incubated in both argon and air. A. cylindrica B629 produces hydrogen in air in the presence of carbon monoxide, acetylene, or both, with a short lag period. The rate of production in air at optimal concentrations of these compounds was found to be comparable with that in an argon atmosphere. Whereas under argon, ammonium ions (0.5 to 6 mM) were found to inhibit hydrogen formation in a manner which was dependent on light intensity and not relieved by oxygen (1 to 20% of gas phase), in air-carbon monoxide-acetylene, these ions (up to at least 0.5 mM) slightly stimulated hydrogen production for at least 24 h. Conclusions are drawn about short-term aerobic and anaerobic hydrogen formation by A. cylindrica B629 and the effects of ammonium ions, oxygen, carbon monoxide, and acetylene on these processes.     

Characterization of Lactobacillus brevis L62 strain, highly tolerant to copper ions

Lactic acid bacteria (LAB) as starter culture in food industry must be suitable for large-scale industrial production and possess the ability to survive in unfavorable processes and storage conditions. Approaches taken to address these problems include the selection of stress-resistant strains. In food industry, LAB are often exposed to metal ions induced stress. The interactions between LAB and metal ions are very poorly investigated. Because of that, the influence of non-toxic, toxic and antioxidant metal ions (Zn, Cu, and Mn) on growth, acid production, metal ions binding capacity of wild and adapted species of Leuconostoc mesenteroides L3, Lactobacillus brevis L62 and Lactobacillus plantarum L73 were investigated. The proteomic approach was applied to clarify how the LAB cells, especially the adapted ones, protect themselves and tolerate high concentrations of toxic metal ions. Results have shown that Zn and Mn addition into MRS medium in the investigated concentrations did not have effect on the bacterial growth and acid production, while copper ions were highly toxic, especially in static conditions. Leuc. mesenteroides L3 was the most efficient in Zn binding processes among the chosen LAB species, while L. plantarum L73 accumulated the highest concentration of Mn. L. brevis L62 was the most copper resistant species. Adaptation had a positive effect on growth and acid production of all species in the presence of copper. However, the adapted species incorporated less metal ions than the wild species. The exception was adapted L. brevis L62 that accumulated high concentration of copper ions in static conditions. The obtained results showed that L. brevis L62 is highly tolerant to copper ions, which allows its use as starter culture in fermentative processes in media with high concentration of copper ions.     

Application of Polypyrrole Multi-Walled Carbon Nanotube Composite Layer for Detection of Mercury,Lead and Iron Ions Using Surface Plasmon Resonance Technique

Polypyrrole multi-walled carbon nanotube composite layers were used to modify the gold layer to measure heavy metal ions using the surface plasmon resonance technique. The new sensor was fabricated to detect trace amounts of mercury (Hg), lead (Pb), and iron (Fe) ions. In the present research, the sensitivity of a polypyrrole multi-walled carbon nanotube composite layer and a polypyrrole layer were compared. The application of polypyrrole multi-walled carbon nanotubes enhanced the sensitivity and accuracy of the sensor for detecting ions in an aqueous solution due to the binding of mercury, lead, and iron ions to the sensing layer. The Hg ion bonded to the sensing layer more strongly than did the Pb and Fe ions. The limitation of the sensor was calculated to be about 0.1 ppm, which produced an angle shift in the region of 0.3° to 0.6°.     

The use of bis(mercaptoacetato-S,O)hydroxoiron(III) complex for the determination of hydroxamates

A rapid, indirect, spectrophometric procedure for the determination of hydroxamates, based on the competition for ferric ions of the bis(mercaptoacetato-S,O)hydroxoiron(III) complex, has been developed. The assay is remarkably free of interferences by common ions, thus rendering it useful in the quantitative determination of hydroxamates in culture fluids and crude preparations.     

Speciation of Campylobacter coli, C. jejuni, C. helveticus, C. lari, C. sputorum, and C. upsaliensis by Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry

Multiple strains of Campylobacter coli, C. jejuni, C. helveticus, C. lari, C. sputorum, and C. upsaliensis isolated from animal, clinical, or food samples have been analyzed by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS). Whole bacterial cells were harvested from colonies or confluent growth on agar and transferred directly into solvent and then to a spot of dried 3-methoxy-4-hydroxycinnamic acid (matrix). Multiple ions in the 5,000- to 15,000-Da mass range were evident in spectra for each strain; one or two ions in the 9,500- to 11,000-Da range were consistently high intensity. “Species-identifying” biomarker ions (SIBIs) were evident from analyses of multiple reference strains for each of the six species, including the genome strains C. jejuni NCTC 11168 and C. jejuni RM1221. Strains grown on nine different combinations of media and atmospheres yielded SIBI masses within ±5 Da with external instrument calibration. The highest-intensity C. jejuni SIBIs were cytosolic proteins, including GroES, HU/HCj, and RplL. Multiple intraspecies SIBIs, corresponding probably to nonsynonymous nucleotide polymorphisms, also provided some intraspecies strain differentiation. MALDI-TOF MS analysis of 75 additional Campylobacter strains isolated from humans, poultry, swine, dogs, and cats revealed (i) associations of SIBI type with source, (ii) strains previously speciated incorrectly, and (iii) “strains” composed of more than one species. MALDI-TOF MS provides an accurate, sensitive, and rapid method for identification of multiple Campylobacter species relevant to public health and food safety.     

A novel,stereospecific synthesis of β-D-glucopyranosyl phosphate

In alkaline solution, periodate ions form complexes with three consecutive hydroxyl groups in an axial-equatorial-axial arrangement but not with three syn-axial hydroxyl groups. Borate ions form complexes with three syn-axial hydroxyl groups but not with the axeqax sequence. Accordingly, cis-inositol gives a 1,2,3-periodate and a 1,3,5-borate complex. Cations form complexes with either type of conformation, but complex formation provides little energy towards achieving it by ring inversion. Lanthanide ions have been used to establish the sites of complex formation.     

Syntheses, structures and photophysical properties of a series of Zn-Ln coordination polymers (Ln = Nd, Pr, Sm, Eu, Tb, Dy)

Six novel heterometallic Zn-Ln coordination polymers {[ZnLnCl(pydc)₂(H₂O)₆]·3H₂O}_n (Ln = Nd 1, Pr 2, Sm 3, Eu 4, Tb 5, Dy 6; pydc = pyridine-2,5-dicarboxylate) were synthesized by the hydrothermal method, and their structures were measured by the single-crystal X-ray diffraction. The IR and UV-Vis-NIR absorption spectra, and the luminescence spectra in the visible and near-infrared (NIR) regions of the six complexes were determined at room temperature. They possess the same crystal structure, and the Zn(II) and Ln(III) ions in each complex are bridged into 1D infinite chain by pyridine-2,5-dicarboxylates. Meanwhile, there are numerous hydrogen bonds which result in the 3D hydrogen bonding network in the crystal. In the visible and NIR regions, the emission spectra of the complexes show the characteristic bands of the corresponding Ln(III) ions, which are mainly attributed to the sensitization from the d-L-moiety to f-L-moiety after forming the Zn-Ln complexes. In this paper, we first report the Zn-Sm complex which can exhibit the emission bands of Sm(III) in the NIR region, and discuss the sensitization from the d-L-moiety to f-L-moiety on the basis of the different characteristics of levels for different Ln(III) ions.     

Effect of nickel,copper, and zinc on emulsifier production and saturation of cellular fatty acids in the filamentous fungus Curvularia lunata

In the first step of this investigation the toxicity of Ni²⁺, Cu²⁺, and Zn²⁺ ions to the emulsifier producing strain of Curvularia lunata was assessed. Among all the heavy metals studied, Ni²⁺ ions were found to be the most toxic to C. lunata, whereas Zn²⁺ ions exhibited the lowest toxicity. Moreover, only Ni²⁺, when used at sublethal concentration (5 mM) caused lysis of some hyphal tip cells after a short-term exposure (5 h). In the next step, emulsifier production, accumulation of heavy metals by mycelia and emulsifier as well as saturation of cellular fatty acids were examined in 48-h-old cultures where fungal growth intensity was not inhibited by heavy metals (in the presence of Ni²⁺, Cu²⁺, and Zn²⁺ ions at the initial concentration of 1, 5, and 15 mM, respectively) and in cultures where approximately 50% biomass inhibition occurred (in the presence of Ni²⁺, Cu²⁺, and Zn²⁺ ions at the initial concentrations of 3, 10, and 17.5 mM, respectively). Among all the heavy metals studied only Ni²⁺ ions did not induce emulsifier production. As compared with the control, only biomass treated with Ni²⁺ ions displayed an increase in total lipid saturation. This effect resulted mainly from the decrease in linoleic acid (18:2) content correlated with the increase in the amount of stearic acid (18:0). The possible mechanisms by which Ni²⁺ ions could alter the fatty acid profile of C. lunata and the protective role of the emulsifier were also discussed.     

Localisation,par microsonde électronique,des ions K,Ca, Mg,et PO4 dans les ganglions nerveux des orthoptères

K, Ca, Mg, and PO₄ ions have been detected in the nervous ganglia of two species of Orthoptera. Potassium urates exist only in Locusta perineurium. In the two species, the diffusing potassium is exceptionally copious in acidic mucopolysaccharides (MPSA) in lacunae of the gial system; in this structure, the ionic amount increases when potassium is experimentally added to the haemolymph. PO₄, Ca, and Mg ions are concentrated in the perineurium and in the MPSA lacunae as diffusible ions and as phosphates. The latter may be associated with pigments in Locusta perineurium. At the larval-adult ecdysis, concretions appear in the lacunar system; they consist of Ca, Mg, and K phosphates in an organic matrix.The functional significance of the ganglionary structures is discussed.     

Equilibrium and kinetics of the dinuclear complex formation between N,N′-ethylenebis(salicylideneiminato)copper(II) and metal(II,I) ions in acetonitrile

The equilibrium constants and rate constants of the reactions between N,N′-ethylenebis(salicylideneiminato)copper(II) ([Cu(salen)]) and metal(II,I) ions in acetonitrile have been spectrophotometrically determined. [Cu(salen)] acts as a didentate ligand to form a dinuclear complex. The rate constants for the very labile Mn(II), Fe(II), and Zn(II) ions were directly evaluated using a variable flow-rate instrument that was newly constructed for this study. The rate constants of the dinuclear complex formation for a series of metal(II) ions vary in parallel with those of the acetonitrile solvent exchange on the corresponding metal(II) ions. This finding indicates that the dinuclear complex formation reaction of the metal(II) ions proceeds via almost the same reaction mechanism as for the acetonitrile solvent exchange reaction.     

Simultaneous measurement of aggregation, secretion, oxygen uptake, proton production, and intracellular metabolites in the same platelet suspension.

A cuvette is described for the simultaneous measurement of hydrogen ions, calcium ions, light transmission, and pO₂ in a single gel-filtered platelet suspension stirred at 37°C. A variable volume (2.5–10 ml) and special in- and outlets permit additions and sampling during incubation. Evidence is presented that changes in these parameters reflect lactate production in resting platelets (H⁺ measurement), secretion of dense granular content (Ca²⁺ measurement), shape change and aggregation (light transmission), and arachidonate oxidation and mitochondrial respiration (pO₂ measurement). The cuvette therefore enables direct correlation between function and energy metabolism in platelets.     

Calcium,magnesium and zinc ion coordination equilibria of vincristine

The zinc ion coordination of vincristine was studied by polarography; the analogous calcium ion coordination process was studied potentiometrically by a calcium ion selective electrode. In both cases, complexes of 1:1 composition were formed. The formation constant of the calcium complex was found to be 1g K = 3.27 ± 0.1. On the basis of the substitution of zinc in its vincristine complex by calcium and magnesium ions respectively, the ratio of the corresponding stability constants could be estimated as K_Zn:K_Ca (and K_Zn:K_Mg) ∼ 10⁵−3 × 10⁴. The complex formation processes proved to be pH-independent in the pH range 3.4–5.5, indicating that the metal ions are coordinated by the unprotonated oxygen donor atoms of vincristine.     

Biosorption of Nickel(II) from aqueous solution by the fungal mat of Trametes versicolor (rainbow) biomass: equilibrium, kinetics, and thermodynamic studies

This study investigates the equilibrium, kinetics and thermodynamics of Nickel(II) biosorption from aqueous solution by the fungal mat of Trametes versicolor (rainbow) biomass. The optimum biosorption conditions like pH, contact time, biomass dosage, initial metal ion concentration and temperaturewere determined in the batch method. The biosorbent was characterized by FTIR, SEM and BET surface area analysis. The experimental data were analyzed in terms of pseudo-first-order, pseudo-secondorder and intraparticle diffusion kinetic models, further it was observed that the biosorption process of Ni(II) ions closely followed pseudo-second-order kinetics. The equilibrium data of Ni(II) ions at 303, 313, and 323 K were fitted to the Langmuir and Freundlich isotherm models. Langmuir isotherm provided a better fit to the equilibrium data andthe maximum monolayer biosorption capacity of the T. versicolor(rainbow) biomass for Ni(II) was 212.5 mg/g at pH 4.0. The calculated thermodynamic parameters, ΔG^○, ΔH^○, and ΔS^○, demonstrated that the biosorption of Ni(II) ions onto the T. versicolor (rainbow) biomass was feasible, spontaneous and endothermic at 303 ～ 323 K. The performance of the proposed fungal biosorbent was also compared with that of many other reported sorbents for Nickel(II) removal and it was observed that the proposed biosorbent is effective in terms of its high sorption capacity.     

Selectivity of Ni(II) and Zn(II) binding to Sporosarcina pasteurii UreE, a metallochaperone in the urease assembly: a calorimetric and crystallographic study

Urease is a nickel-dependent enzyme that plays a critical role in the biogeochemical nitrogen cycle by catalyzing the hydrolysis of urea to ammonia and carbamate. This enzyme, initially synthesized in the apo form, needs to be activated by incorporation of two nickel ions into the active site, a process driven by the dimeric metallochaperone UreE. Previous studies reported that this protein can bind different metal ions in vitro, beside the cognate Ni(II). This study explores the metal selectivity and affinity of UreE from Sporosarcina pasteurii (Sp, formerly known as Bacillus pasteurii) for cognate [Ni(II)] and noncognate [Zn(II)] metal ions. In particular, the thermodynamic parameters of SpUreE Ni(II) and Zn(II) binding have been determined using isothermal titration calorimetry. These experiments show that two Ni(II) ions bind to the protein dimer with positive cooperativity. The high-affinity site involves the conserved solvent-exposed His¹⁰⁰ and the C-terminal His¹⁴⁵, whereas the low-affinity site comprises also the C-terminal His¹⁴⁷. Zn(II) binding to the protein, occurring in the same protein regions and with similar affinity as compared to Ni(II), causes metal-driven dimerization of the protein dimer. The crystal structure of the protein obtained in the presence of equimolar amounts of both metal ions indicates that the high-affinity metal binding site binds Ni(II) preferentially over Zn(II). The ability of the protein to select Ni(II) over Zn(II) was confirmed by competition experiments in solution as well as by analysis of X-ray anomalous dispersion data. Overall, the thermodynamics and structural parameters that modulate the metal ion specificity of the different binding sites on the protein surface of SpUreE have been established.     

Zinc content, metal chelator inactivation and catalytic inhibition of D-lactate dehydrogenase from the barnacle, Balanus nubilus Darwin.

Purified NAD-linked d-lactate dehydrogenase from the depressor muscle of the giant barnacle, Balanus nubilus Darwin, is inactivated when incubated with the metal chelators o-phenanthroline and EDTA. M-Phenanthroline and p-phenanthroline, which lack metal chelating ability, are ineffective in inactivating the enzyme. Inactivated enzyme can be reactivated by the addition of zinc ions to the assay mixture. Atomic absorption spectrophotometric analysis of purified B. nubilusd-lactate dehydrogenase revealed that this enzyme contains stoichiometric amounts of zinc (2 g-atoms per mol of subunit), unlike other lactate dehydrogenases, which lack zinc. Zinc appears to be required for maximal catalytic activity. Aromatic, nitrogen-containing metal chelators and their nonchelating analogs are effective instantaneous inhibitors of B. nubilusd-lactate dehydrogenase. These compounds bind at the coenzyme binding site, as the mode of inhibition is distinctly competitive with respect to NADH. The different effects of metal chelators and their nonchelator analogs suggest that time-dependent inactivation (chelation of the enzyme zinc ions) and instantaneous inhibition (competition with NADH binding) have independent mechanisms.     

Induction by manganese, ethanol, phenobarbital, and herbicides of microsomal cytochrome P-450 in higher plant tissues

Cytochrome P-450 content and, to a lesser extent the activity of tr-cinnamic acid 4-hydroxylase, are induced in ageing Jerusalem artichoke (Helianthus tuberosus L.) tuber cells by manganese ions, ethanol, phenobarbital, and herbicides. Manganese, ethanol, and phenobarbital induced cytochrome P-450 and also modified the time-course of its appearance. In contrast the herbicides tested stimulated the cytochrome P-450 content without modifying its time-course. The extent of induction was enhanced when the aging medium was supplemented with iron.