Appearance Of Cl Research Articles

Negative Atmospheric Pressure Chemical Ionization of Chlorinated Hydrocarbons Studied by Ion Mobility Spectrometry (IMS) and IMS-MS Techniques

Negative polarity atmospheric pressure chemical ionization of selected chlorinated hydrocarbons (tetrachloromethane CCl4 and hexachloroethane C2Cl6, dichloromethane CH2Cl2, trichloromethane CHCl3, 1,1,1,2-tetrachloroethane 1,1,1,2-C2H2Cl4, 1,1,2,2-tetrachloroethane 1,1,2,2,-C2H2Cl4 1,1,2-trichloroethane 1,1,2-C2H3Cl3, and 1,1,2-trichloroethane 1,1,2-C2HCl3) was studied using ion mobility spectrometry (IMS) and IMS combined with time-of-flight mass spectrometer (IMS-TOF MS) techniques, in the dry air and at two different drift gas temperatures (323 and 373 K). The ionization was performed using the O2-CO2(H2O)0,1 reactant ions (RIs), and the dominant ionization reaction was the dissociative electron transfer. The ionization resulted in the appearance of Cl- ions for all substances and [O2H..Cl]- ions, which were absent in the case of perchlorinated substances. The quantum-chemical calculations at the density functional theory level of theory using the ωB97X-D/aug-cc-pVTZ method were performed to calculate the thermochemical data (heats of formations, electron affinities, reaction enthalpies) for RIs, neutral substances, neutral fragments, and the anionic fragments. The calculations supported the experimental observations regarding the endothermicity of the Cl- channel for all substances and the exothermicity of the [O2H..Cl]- channel for the tetrachloro- and trichloroethanes.

Expression profiling of candidate embryotrophic genes of buffalo oviduct during different stages of oestrous cycle

The aim of the present study was to identify the gene expression profile of three candidate genes namely heat shock protein 70, oviductal glycoprotein and osteopontin in buffalo oviduct during different stages of the oestrous cycle. Slaughter house derived buffalo oviducts were categorized as belonging to early, mid and late phase of the oestrous cycle based on the morphological appearance of CL and progesterone concentration. The relative abundance of each of the candidate gene transcript was quantified by real time RT-PCR. Transcripts of all the three candidate genes were found to be expressed in OEC throughout the oestrous cycle. The results of the present study demonstrate that gene expression in the buffalo oviduct is clearly regulated during the oestrous cycle, as these candidate genes play a crucial role in several reproductive processes. It was found that Hsp 70 gene was significantly upregulated in OEC belonging to the early and late phases when compared to mid phases of the cycle. The expression of OVGP mRNA was found to be maximum during the early phase and it remained low during the mid and late phases while expression of OPN mRNA was maximum during the early phase and declined sequentially during the mid and late phase of oestrus cycle.

Public Knowledge about and Detection of Canine Visceral Leishmaniasis in Urban Divinópolis, Brazil

Background. Leishmaniases are diseases with a wide spectrum of clinical manifestations including cutaneous (CL) and visceral (VL) forms. Many factors may affect their occurrence and expansion including environmental, geographic, and social conditions. In the past two decades, Divinópolis, Minas Gerais State, Brazil, has exhibited the potential for a disease outbreak, with the appearance of CL, and VL cases (human and canine). Hence, this study was initiated to monitor public knowledge of the disease. Questionnaires were administered in four neighborhoods (Jardim Belvedere, Esplanada, Danilo Passos I and II) where most of the human and canine cases have been reported. The analyses demonstrated that public knowledge of the disease is sparse and fragmented. A strong perception of the dog as the main reservoir was observed. Five veterinary clinics were evaluated for the presence of canine VL using serological (RIFI and ELISA) and molecular (PCR-RFLP) techniques. This is the first study demonstrating the occurrence of Leishmania infantum in Divinópolis, suggesting a possible urbanization of VL.

Identification of TRPM5 Ion Channels in Type-II Taste Cells of Mice

TRPM5 are ion channels belonging to the TRP family, which demonstrate a nonselective permeability for monovalent cations and are activated by an increase in the intracellular calcium level. TRPM5 are present in taste receptor cells of type II responsible for reception of bitter, sweet, and umami taste sensations. Knockout of the trpm5 gene in mice results in a nearly complete loss of sensitivity to taste stimuli of the above-mentioned modalities (taste blindness). The physiological activity of TRPM5 in taste receptive cells has practically not been studied. Using a patch-clamp technique, we carried out a comparative analysis of the properties of recombinant TRPM5 and Ca2+-activated membrane channels in type-II taste cells in mice. Dialysis of the studied cells with a high-Ca2+ solution and application of a calcium ionophore, ionomycin, caused activation of outward-rectification ion channels permeable for Na+, Cs+, and K+ in CHO-strain cells with exogenous TRPM5. These channels were blocked by 100 μM triphenylphosphine oxide (TPPO). Calcium-activated channels in type-II taste cells also possessed analogous properties. Application of the calcium ionophore ionomycin or a stepwise increase in the intracellular Ca2+ level using photolysis (uncaging) caused activation of channels nonselective with respect to Na+ and Cs+ and impermeable for N-methyl-D-glucamine (NMDG+). These channels had the current–voltage characteristics of outward rectification and a high thermosensitivity (Q10 = 6.7 ± 0.5); they could be blocked by TPPO. It should be emphasized that TRPM5 were specific with respect to type-II cells. An increase in the intracellular calcium level induced the appearance of Cl– current in type-I cells and did not influence the basic current in type-III cells.

Evolution of host egg mimicry in a brood parasite, the great spotted cuckoo

Brood parasitism in birds is one of the best examples of coevolutionary interactions in vertebrates. Coevolution between hosts and parasites is assumed to occur because the parasite imposes strong selection pressures on its hosts, reducing their fitness and thereby favouring counter-adaptations (e.g. egg rejection) which, in turn, select for parasite resistance (e.g. egg mimicry). Great spotted cuckoos (Clamator glandarius) are usually considered a brood parasite with eggs almost perfectly mimicking those of their host, the magpie (Pica pica). However, Cl. glandarius also exploits South African hosts with very different eggs, both in colour and size, while the Cl. glandarius eggs are similar to those laid in nests of European hosts. Here, we used spectrophotometric techniques for the first time to quantify mimicry of parasitic eggs for eight different host species. We found: (1) non-significant differences in appearance of Cl. glandarius eggs laid in nests of different host species, although eggs laid in South Africa and Europe differed significantly; (2) contrary to the general assumption that Cl. glandarius eggs better mimic those of the main host in Europe (P. pica), Cl. glandarius eggs more closely resembled those of the azure-winged magpie (Cyanopica cyana), a potential host in which there is no evidence of recent parasitism; (3) the appearance of Cl. glandarius eggs was not significantly related to the appearance of host eggs. We discuss three possible reasons why Cl. glandarius eggs resemble eggs of some of their hosts. We suggest that colouration of Cl. glandarius eggs is an apomorphic trait, and that variation between eggs laid in South African and European host nests is due to genetic isolation among these populations and not due to variation in colouration of host eggs. © 2003 The Linnean Society of London, Biological Journal of the Linnean Society, 2003, 79, 551–563.

On low energy ion scattering spectroscopy and chlorine adsorption on silver

We present the results of a comparative study of Cl adsorption on Ag(111) by He + ISS and other methods, as well as a study of the He + neutralisation rate. Workfunction and time of flight spectroscopy show that Cl adsorption occurs rapidly in the 0–1.2 L range, and thereafter saturates. He + ISS illustrates the appearance of Cl at low exposures, but the signal remains very weak until about 1.5 L, when the Cl to Ag ISS peak ratio increases strongly. Measurements of He + neutralisation indicate an increase in neutralisation in the initial stages of adsorption, and then a decrease at exposures above 1.5 L, which we relate to AgCl island formation. The enhanced neutralisation in the submonolayer chemisorption range explains the low ISS signal corresponding to Cl. We associate the increase to a lower neutralisation on AgCl. The efficiency of Cl detection is thus environment dependent.

The role of ion fluxes in Nod factor signalling in Medicago sativa

SummaryUsing ion‐selective microelectrodes, the basis of Nod factor‐induced changes in the plasma membrane potential was analysed by measuring the extracellular free concentrations of Ca2+, K+, H+ and Cl– in the root hair zone of alfalfa. After addition of the Rhizobium meliloti Nod factor NodRm‐IV(C16:2,S) at a concentration of 0.1 μM, a decrease in [Ca2+] was observed first, which was followed after a few seconds by an increase of [Cl–], by an alkalinization, and then by a delayed increase of [K+], all of which were transient changes. Simultaneously with the appearance of Cl– ions in the root hair zone, a decrease in cytosolic [Cl–] was measured. It was concluded that the depolarization was caused by temporary short‐circuiting of the proton pump through the rapid release of Cl– ions along their steep electrochemical gradient. Since under resting conditions the driving force for K+ ions was inwardly directed, their release was delayed until their driving force was inverted. This indicates that K+ serves as a charge balance that eventually stops depolarization and initiates repolarization. Since the decrease in [Ca2+] was observed seconds before the increase in [Cl–] and the depolarization, it is argued that Ca2+ entering into the cell does not cause the depolarization directly, but might initiate it by triggering the activation of an anion channel that then releases the chloride ions. The observations that the Ca2+ ionophore A23187 mimicks the Nod factor response, and that the Ca2+ channel antagonist nifedipine inhibits this response, support the idea that Ca2+ plays a primary role in the transduction of the Nod signal in alfalfa.

Generation of α-acetolactone and the acetoxyl diradical •CH 2COO • in the gas phase

The formation of neutral [C 2,H 2,O 2] has been investigated by tandem mass spectrometry in a sector instrument and by energy-resolved collision-induced dissociation in a flowing afterglow-triple quadrupole apparatus. The neutral species are generated by two different methods: (i) neutralization of the distonic anion radical •CH 2COO − by collisional electron detachment and (ii) collision-induced loss of halides X − concomitant with formation of [C 2,H 2,O 2] from α-haloacetate ions XCH 2COO −. The tandem mass spectrometry results suggest that neutralization of •CH 2COO − and high-energy collisional activation of α-haloacetate ions lead to a mixture of α-acetolactone, c-(CH 2C(O)O), and the acetoxyl diradical, •CH 2COO •. Low-energy collisions with α-chloroacetate ions in the triple quadrupole analyzer produce α-acetolactone exclusively at the dissociation threshold. From the dissociation threshold measured for the appearance of Cl − from ClCH 2COO − the heat of formation of acetolactone is determined to be ΔH f,298 = −47.3 ± 4.7 kcal/mol.

Elucidation of the degradation mechanism of 2-chloroethanol by hydrogen peroxide under ultraviolet irradiation

Oxidation of 2-chloroethanol by H 2O 2 under UV irradiation has been studied. Analysis of reactants and products was performed by gas and ion chromatography. In this study we have compared the disappearance of 2-chloroethanol with the contemporaneous appearance of Cl − ions and conductivity changes of the solution. It was found that the oxidation of 2-chloroethanol yields quantitative amounts of Cl − ions. Moreover, the rate of change of the solution conductivity is comparable with the rate of formation of Cl −. Acetic, glycolic and formic acids and acetaldehyde were formed in the reaction although at low concentrations.

Earthworm Macropores and Preferential Transport in a Long‐Term Manure Applied Typic Hapludalf

AbstractDeep burrowing earthworm species have been found to be present in soils with a history of manure application. This study was designed to quantify the effects of long‐term application of liquid dairy manure and inorganic fertilizer on the distribution of earthworm macropores and in turn on the preferential transport of water and tracer through a typical soil of the karst area of the upper mid‐western USA. Large (≈ 30 cm diam. by 90 cm long) undisturbed soil columns were taken from plots where liquid dairy manure or inorganic fertilizers had been applied continuously for 8 yr. The number and size distribution of macropores in soil columns were nearly the same for both inorganic and manure treatments, however, visible surface macropores were continuous to much deeper depth in soil columns taken from manure than from the inorganic fertilizer plot. Identification of the earthworms a year later showed the presence of Apporectodea tuberculata, A. trapezoides, and Lumbricus rubellus, subsurface burrowers, as well as, L. terristris, a deeper burrowing species in the manure applied plot. Apporectodea tuberculata was the only species present in the inorganic fertilizer plot. Number of macropores and macroporosity varied with soil depth. The maximum macroporosity was <2.5% and it occurred at 2‐cm depth. The predominant macropore sizes were between 1‐ and 2‐mm radii for both treatments. During breakthrough experiments, Cl− appeared earlier in soil columns taken from the manure plot thereby indicating a greater continuity of macropores in the manure compared with the inorganic fertilizer treatment. Thearly appearance of Cl− in the manure treatment, however, was much slower than one would expect based on the number of macropores and their continuity estimated from the serial sectioning. This suggests that intrusive serial sectioning and image analysis techniques probably overestimate the continuity of macropores possibly due to vacuuming of the earthworm casts and other debris that plugs the macropore channels. Based on macropore size distribution with depth and related breakthrough curves, it is likely that most existing models of water and contaminant transport that simulate macropore flow, will not accurately predict the transport of water and contaminant because of their assumption that surface visible macropores are continuous to deeper soil depths. Data from this study showed that macropore size distribution could be described by a normal or log‐normal distribution function. These functions in combination with information on continuity and tortuosity of macropores may be sufficient, when used in some current macropore models, to adequately describe the conducting efficiency of macropores in soils.

Expression of an abundant alternatively spliced form of the cystic fibrosis transmembrane conductance regulator (CFTR) gene is not associated with a cAMP-activated chloride conductance.

The cystic fibrosis transmembrane conductance regulator (CFTR) gene encodes a cAMP-activated chloride (Cl-) channel, and expression of the full length gene in vitro is sufficient to correct the Cl- conductance defect that is characteristic of cystic fibrosis (CF) epithelial cells. Alternatively spliced forms of CFTR mRNA have been identified in several tissues from normal individuals. One of the alternative transcripts, often present at high levels, results in the in-frame deletion of exon 9. Translation of this transcript would result in a CFTR protein missing the amino terminal portion of the first nucleotide binding fold (NBF). To evaluate the possible function of this form of CFTR, a cDNA representing this transcript (CFTR delta 9) was transduced into CFPAC cells, which are derived from a CF patient. CFTR delta 9 RNA was expressed in the transduced cell lines, but only immature, incompletely glycosylated protein was detectable by Western blot analysis. No increase in cAMP-activated anion permeability was detectable by 125I efflux assay or by means of the halide sensitive dye 6-methoxy-N-(3-sulfopropyl) quinolinium (SPQ). In a second assay system, in vitro synthesized mRNA representing CFTR delta D9 was injected into Xenopus oocytes, but expression of this alternatively spliced form of CFTR was not associated with the appearance of Cl- conductance. These results suggest that the protein produced by the CFTR delta 9 transcript is not properly processed and is not capable of generating Cl- conductance in response to cAMP. Whether this alternative transcript has some other function or represents 'noise' in the mRNA splicing mechanism remains unresolved.

Nystatin-induced liposome fusion. A versatile approach to ion channel reconstitution into planar bilayers

A simple method is described for promoting and detecting fusion of liposomes with planar bilayer membranes. Liposomes containing ergosterol are doped with the pore-forming antibiotic nystatin, and the planar bilayer is kept ergosterol-free. Under these conditions, when a transbilayer salt gradient is applied, liposomes added to the high-salt side of the bilayer elicit the appearance of abrupt conductance jumps of 5-300 pS. The increase in conductance is transient, decaying back to baseline on the order of 10 s. Each of these "spikes" represents the fusion of a single liposome with the bilayer, resulting in the simultaneous insertion of many nystatin channels. Relaxation of the conductance back to baseline occurs because ergosterol, required for the integrity of the nystatin pore, diffuses away into the sterol-free planar bilayer after liposome fusion. When Torpedo Cl- channels are reconstituted into liposomes containing ergosterol and nystatin, fusion spikes are observed simultaneously with the appearance of Cl- channels. This method allows the calculation of the density of functional ion channels in a preparation of proteoliposomes containing reconstituted channel protein.

Solubilization and reconstitution of a chloride transporter from tracheal apical membrane.

Electrogenic Cl- transport in bovine tracheal membrane vesicles was studied by measuring the kinetics of Cl- efflux. Efflux from KCl-loaded vesicles was assayed as the appearance of Cl- in the medium using an anion-specific electrode. Maximal sensitivity was obtained by passage of the vesicles through a Sephadex column immediately before the assay to remove external Cl-. Two components of Cl- transport could be detected. Vesicles exhibited a characteristic spontaneous Cl- efflux that appears to be limited by the cation permeability of the membrane. Addition of the K+-conducting ionophore to increase selectively the permeability to K+ resulted in a stimulation of Cl- efflux. The electrically neutral ionophore nigericin caused only a slight transient increase in Cl- efflux. The valinomycin-dependent flux may be assumed to represent flux through a parallel conductive pathway. Valinomycin-dependent electrogenic Cl- flux was 240 +/- 36 nmol X mg protein-1 X min-1 (n = 4). Soluble extracts obtained with the nonionic detergent octyl glucoside were reconstituted by the freeze-thaw procedure. The reconstituted vesicles exhibited a number of similarities to the native vesicles. Efflux was maximally stimulated with the ionophore valinomycin in the presence of an outwardly directed K+ gradient. Nigericin had no effect on efflux, suggesting the reconstituted transporter is a conductive rather than exchange mechanism. The initial rate of the valinomycin-dependent component was 896 +/- 63 nmol X mg protein-1 X min-1 (n = 5), representing approximately a fourfold increase in specific activity compared with the native membrane vesicle.

Fertilization-induced ionic conductances in eggs of the frog, Rana pipiens.

Fertilization of the frog egg (Rana pipiens) elicits a positive-going shift in membrane potential (fertilization potential) that lasts 10-20 min and functions as a fast block to polyspermy. We examined the ion conductances underlying the fertilization potential, using the voltage-clamp technique. We measured the membrane capacitance during the fertilization potential by applying an alternating current. We also determined the intracellular K and Cl concentrations in the egg, using ion-selective micro-electrodes. The conductance is largest in the first 2 min after fertilization. Regardless of whether the stimulus is provided by one or by more than one sperm or by artificial activation, the size of the conductance increase is the same, reaching a maximum of about 40 microseconds. Two separate conductances are involved at fertilization: Cl and K. [K]i = 121 mM and [Cl]i = 44 mM. The natural external medium is pond water (approximated in our experiments by 10% Ringer solution); therefore, an increase in K and Cl conductances leads to an efflux of both ions. The equilibrium potential of the fertilization current is between the Cl and K equilibrium potentials (ECl and EK), closer to ECl. 10 mM-external tetraethylammonium (TEA) brings the equilibrium potential close to ECl and reduces the maximum conductance by about half. The Cl conductance is not blocked by 4-acetamido-4'-isothiocyanostilbene-2,2'-disulphonic acid (SITS). The time courses of the K and Cl conductances are similar. The TEA-resistant conductance (primarily Cl conductance) activated at fertilization increases as the membrane potential becomes more positive. A voltage-sensitive Na conductance present in the unfertilized egg disappears after fertilization. During fertilization this conductance is too small to contribute significantly to the fertilization potential. The membrane capacitance increases by an average of 1.9 times in the first 2 min following the rise of the fertilization potential, during the period of cortical vesicle exocytosis. Capacitance then gradually decreases; at 1 h after fertilization, capacitance is 82% of the value in the unfertilized egg. The conductance increase precedes the capacitance increase by several seconds. Therefore the initial appearance of Cl and K channels cannot be accounted for by addition of membrane by cortical vesicle exocytosis. The conductance subsequently decreases, suggesting that the disappearance of the Cl and K channels is not caused by membrane removal.

Chlorine nitrate photolysis by a new technique: very low pressure photolysis

Very low pressure photolysis (VLPØ) of chlorine nitrate was performed in a quartz Knudsen cell. The light source was a 2500 W high-pressure xenon lamp, and a modulated molecular-beam mass spectrometer was used to monitor the concentration of ClONO 2 and photolysis products. Because of the low pressures used (⩽ 10 −3 torr) and the short residence time in the cell (≈1 s), secondary reactions were unimportant and the primary products could be directly identified. The primary photolysis products (λ ≈ 2700 Å) are atomic chlorine and NO 3 free radical. Chlorine atoms were identified both by the appearance of Cl 2 (wall recombination product; the walls were not poisoned) and by HCl produced when C 2H 6 was added to the cell. Nitrate free radical was directly identified as a mass peak at m/e = 62, as well as by chemical titration with nitric oxide: NO 3 + NO → 2NO 2. It was verified by direct tests that the peak at m/e = 62 did not arise from possible HNO 3 contamination or from N 2O 5, a possible secondary product. This titration reaction was used to measure quantitatively a lower limit to the primary quantum yield, φ ⩾ 0.5 ± 0.3. This represents a lower limit because of the unknown extent of the secondary photolysis of NO 3 under our conditions. We believe this to be the first observation using mass spectrometry of the NO 3 free radical. The quantum yield for atomic chlorine is φ = 1.0 ± 0.2. N 2O was used to test for O( 1D) according to the reaction, O( 1D) + N 2O → products; none was observed. Triplet oxygen, O( 3P) was observed to the extent of ≈ 10% by the reaction O( 3P) + NO 2 → NO + O 2, but this yield can also be due to the photolysis of NO 3 free radical produced in the primary step. We conclude that the predominant reaction pathway is ▪.

Mass spectrometry of flames

A quadrupole mass spectrometric analyser for use in flame ionization is described, together with its application to the ions produced by traces of sodium, added as chloride, in premixed hydrogen-air flames. Negative ions (Cl¯ and OH¯) appear to be of subsidiary importance in the main ionization processes, which rather proceed through direct production of electrons. Nevertheless, it is established that the appearance of Cl¯ ions is consistent with dissociative attachment HCl+ e ¯ → Cl¯+H, rather than by three-body attachment Cl+ e ¯+ M → Cl¯+ M . Hydroxyl ions probably are formed in the same way. The ratios of the amounts of A + (alkali) and A + . H 2 O (alkali monohydrate) ions have been measured in the cases of lithium, sodium and potassium. Equilibrium constants for the reaction A + .H 2 O ⇌ A + + H 2 O are obtained and heats of monohydration of 44, 28 and 17 kcal/mole deduced respectively for A ≡ Li, Na, K. Small amounts of H 3 O + appear in the reaction zone because of traces of hydrocarbon impurities in the flame gas supplies. These are severely reduced by alkali addition, apparently by an exchange reaction A +H 3 O + → A + +H 2 O+H, with a rate constant of 1.1 x 10 -8 cm 3 /s at 2000 °K, rather than by recombination with electrons produced by direct ionization of alkali H 3 O + + e - → H 2 O+H. In contrast with the steady production of A + ions in the burnt gases by reactions of the type A + M → A + + e ¯+ M , there is an anomalously high rate of production in the reaction zone. This appears difficult to explain without introduction of processes involving ‘hot’ electrons.

Swarm Measurement of Cross Sections for Dissociative Electron Capture in Heavy Water, Chlorobenzene, and Bromobenzene

One established method for the measurement of the cross section for electron capture involves the introduction of small quantities of the gas under study (sample gas) into a carrier gas, which determines the distribution of electron energies for specified values of E/P. A summary of the available information on the distribution of electron energies in ethylene, nitrogen, and argon shows that for E/P values ranging from 0 to 2.0 V cm—1 Torr—1 the three carrier gases can be used to cover the important range of electron energies between thermal energy and 10 eV. This method has been used to study dissociative electron capture in D2O, C6H5Cl, and C6H5Br. Measurements show that the values for the energy integrated dissociative capture cross sections are approximately 4.6×10—18 cm2 eV for D2O, 1.4×10—17 cm2 eV for C6H5Cl, and 5.7×10—17 cm2 eV for C6H5Br occurring at electron energies near 6.5, 0.76, and 0.70 eV, respectively. That the low-energy processes in C6H5Cl and C6H5Br correspond to dissociative capture has been confirmed by the appearance of Cl— and Br— in a negative-ion time-of-flight mass spectrometer.