Effect of soil chloride level on cadmium concentration in sunflower kernels

Understanding soil factors related to cadmium (Cd) uptake and accumulation in plants is important for development of agronomic technologies, and breeding strategy to produce low Cd crops. The objective of the study was to examine the effect of soluble salts (chloride and sulfate) and other soil factors on the Cd concentration in sunflower (Helianthus annuus L.) kernels. Commercial nonoilseed hybrid kernels and soils were sampled from 22 farmer's production fields in North Dakota and Minnesota. The sites sampled included saline and nonsaline variants from 7 soil series. Soils were sampled at four depths. Relationships between kernel Cd level and soil physical and chemical characteristics were examined. The soil pH covered a narrow range (7.3–8.1) at these sampled sites. Regression analysis showed that there was no correlation between kernel Cd and soil pH at any depth. The kernel Cd level was highly correlated with DTPA-extractable Cd in all 4 depths, and with clay content in sub-soils. Soil chloride and sulfate concentrations varied among soil series and within soil series. The absence of a statistically significant effect of soil sulfate level on kernel Cd concentration, indicated that soil sulfate levels did not affect Cd uptake by sunflower plants. However, soil chloride levels in sub-soil were correlated with kernel Cd. The most important soil factor was DTPA-extractable Cd. When chloride was included in the multiple regression equations, R square (R²) values improved significantly. These results demonstrate that soil chloride concentration is another important factor related to Cd uptake in sunflower plants.     

The functional, oxygen-linked chloride binding sites of hemoglobin are contiguous within a channel in the central cavity

Chloride ion is a major allosteric regulator for many hemoglobins and particularly for bovine hemoglobin. A site-directed reagent for amino groups, methyl acetyl phosphate, when used forglobal rather thanselective modification of R (oxy) and T (deoxy) state bovine hemoglobin, can acetylate those functional amino groups involved in binding of chloride; the extensively acetylated hemoglobin tetramer retains nearly full cooperativity. The chloride-induced decrease in the oxygen affinity parallels the acetylation of bovine hemoglobin (i.e., their effects are mutually exclusive), suggesting that methyl acetyl phosphate is a good probe for the functional chloride binding sites in hemoglobins. Studies on theoverall alkaline Bohr effect indicates that the part of the contribution dependent on chloride and reduced by 60% after acetylation is due to amino groups, Val-1() and Lys-81(); the remaining 40% is contributed by the imidazole side chain of His-146(), which is not acetylated by methyl acetyl phosphate, and is not dependent on chloride. The five amino groups—Val-1(), Lys-99(), Met-1(), Lys-81(), and Lys-103()—of bovine hemoglobin that are acetylated in an oxygen-linked fashion are consideredfunctional chloride binding sites. Molecular modeling indicates that these functional chloride binding sites are contiguous from one end of the central cavity of hemoglobin to the other; some of them are aligned within a chloride channel connecting each end of the dyad axis. A generalization that can be made about hemoglobin function from these studies is that the blocking of positive charges within this channel either by binding of chloride or other anions, by covalent chemical modification such as acetylation, or by site-specific mutagenesis to create additional chloride binding sites each accomplish the same function of lowering the oxygen affinity of hemoglobin.     

Effects of azide on the S2 state EPR signals from Photosystem II

The anion azide, N₃ ^-, has been previously found to be an inhibitor of oxygen evolution by Photosystem II (PS II) of higher plants. With respect to chloride activation, azide acts primarily as a competitive inhibitor but uncompetitive inhibition also occurs [Haddy A, Hatchell JA, Kimel RA and Thomas R (1999) Biochemistry 38: 6104–6110]. In this study, the effects of azide on PS II-enriched thylakoid membranes were characterized by electron paramagnetic resonance (EPR) spectroscopy. Azide showed two distinguishable effects on the S₂ state EPR signals. In the presence of chloride, which prevented competitive binding, azide suppressed the formation of the multiline and g = 4.1 signals concurrently, indicating that the normal S₂ state was not reached. Signal suppression showed an azide concentration dependence that correlated with the fraction of PS II centers calculated to bind azide at the uncompetitive site, based on the previously determined inhibition constant. No evidence was found for an effect of azide on the Fe(II)Q_A ^- signals at the concentrations used. This result is consistent with placement of the uncompetitive site on the donor side of PS II as suggested in the previous study. In chloride-depleted PS II-enriched membranes azide and fluoride showed similar effects on the S₂ state EPR signals, including a notable increase and narrowing of the g = 4.1 signal. Comparable effects of other anions have been described previously and apparently take place through the chloride-competitive site. The two azide binding sites described here correlate with the results of other studies of Lewis base inhibitors.This revised version was published online in October 2005 with corrections to the Cover Date.     

High-performance liquid chromatography determination of residue levels on chicken carcasses treated with cetylpyridinium chloride

Cetylpyridinium chloride (CPC) has been found to be effective in reducing contamination of chicken carcasses from a variety of microorganisms, including Escherichia coli O157:H7, Salmonella typhimurium, Campylobacter jejuni, Aeromonas hydrophila, Listeria monocytogenes, and Staphylococcus aureus. A procedure has been developed to determine residue levels on chicken carcasses after CPC treatment. For the analysis, chicken carcasses were extracted with 95% ethanol. The CPC concentration in the extract was measured by high-performance liquid chromatography (HPLC) with ultraviolet detection using dodecylpyridinium chloride (DPC) as an internal standard. The method was validated in the concentration range of 3–200 μg/ml CPC in ethanolic extract. This assay is rapid, precise, and accurate.     

Isopropanol and acetone induces vinyl chloride degradation in<Emphasis Type="Italic"> Rhodococcus rhodochrous</Emphasis>

In situ bioremediation of vinyl chloride (VC)-contaminated waste sites requires a microorganism capable of degrading VC. While propane will induce an oxygenase to accomplish this goal, its use as a primary substrate in bioremediation is complicated by its flammability and low water solubility. This study demonstrates that two degradation products of propane, isoproponal and acetone, can induce the enzymes in Rhodococcus rhodochrous that degrade VC. Additionally, a reasonable number of cells for bioremediation can be grown on conventional solid bacteriological media (nutrient agar, tryptic soy agar, plate count agar) in an average microbiological laboratory and then induced to produce the necessary enzymes by incubation of a resting cell suspension with isopropanol or acetone. Since acetone is more volatile than isopropanol and has other undesirable characteristics, isopropanol is the inducer of choice. It offers a non-toxic, water-soluble, relatively inexpensive alternative to propane for in situ bioremediation of waste sites contaminated with VC.     

Random chemical modification of the oxygen-linked chloride-binding sites of hemoglobin: Those in the central dyad axis may influence the transition between deoxy- and oxy-hemoglobin

The features of random chemical modification are defined with reference to acetylation of bovine hemoglobin, which has been performed in a random manner so that all of the amino groups that participate in functional chloride binding (i.e., those that are oxygen-linked) could be identified. Random chemical modification, which has objectives different from those of both specific (selective) and extensive chemical modification, has been achieved for bovine hemoglobin with the mild reagent,¹⁴C-methyl acetate phosphate; retention of function was demonstrated by a Hill coefficient ofn=2.2 for the modified hemoglobin. After removal of unmodified Hb chains, the mixture of randomly modified acetylated or chains was subjected to tandem treatment with trypsin and chymotrypsin. Peptides were purified by HPLC and identified by amino acid analysis. The amount of radioactivity in the acetylated amino group of a purified peptide was taken as an estimate of the degree of chloride binding. For bovine Hb, two amino groups of the -chain (Val-1 and Lys-99) and three amino groups of the -chain (Met-1, Lys-81, and Lys-103) were shown to be oxygen-linked (i.e., to have incorporated significantly more radioactivity in the deoxy conformation compared to the same site in the oxy conformation). Three of these sites were already known chloride-binding sites [i.e., Val-1(), the N-terminus of the -chain, and two sites between the 2 -chains of bovine hemoglobin, Met-1() and Lys-81(); these findings support the conclusions of the random modification approach. Two other chloride-binding sites, Lys-99() and Lys-103(), align the sides of the central dyad axis connecting the two well-known major chloride-binding sites of bovine Hb. The interrelationship of these five chloride-binding sites was assessed by improved molecular graphics. When viewed through the central dyad axis, the functional chloride-binding sites in the central cavity appear to be symmetrically related and to connect the two major chloride-binding sites. Modifiers or mutants that are directed at these regions in the central dyad axis may favor the deoxy conformation to provide a lower oxygen affinity by preventing the constriction of the central cavity that normally occurs upon oxygenation.     

Distribution of chloride in tobacco laminae and midribs as influenced by the chloride content of the irrigation water

The high variability of the ratio of midrib to lamina chloride in tobacco leaves delivered to the curing plant prompted two experiments which aimed to identify some of the causes of such variability. In young tobacco plants chloride concentration was highest in the third or fourth leaf from the base of the plant, but in more mature plants (when the inflorescence began to appear) leaf chloride increased linearly from the apex to the base of the plant. The ratio of the concentration of midrib chloride to that of lamina chloride was always highest in the basal leaves, and decreased with increasing chloride concentration in the irrigation water,i.e. with increasing chloride supply more chloride went to the lamina than to the midrib per unit dry weight. This was verified with reported chloride contents for two irrigation experiments.     

Hormonal control of blood chloride in the marine pulmonate,onchidium verruculatum

A search for endocrinological factors inO. verruculatum revealed that three hours after right pleural ganglion extirpation blood chloride is significantly (P<0.01) sinked. Administration of right pleural ganglion homogenate (I gang/animal) into depleuralised snails significantly (P<0.001) enhances the blood chloride level after three hrs. Removal of the ganglia other than the right pleural provokes a significant (P<0.01) decline in blood chloride profile in these animals. However, replacement therapy either via homogenate injection or reimplantation of the particular ganglion into extrapleural ganglionectomised animals is ineffective in restoring the chloride levels. It is argued that only right pleural ganglia control blood chloride via vascular channels.     

Enhanced plant regeneration in pearl millet (Pennisetum americanum) by ethylene inhibitors and cefotaxime

Cefotaxime, a cephalosporin antibiotic, and different ethylene inhibitors, such as silver nitrate, cobalt chloride, nickel chloride and O-acetyl salicylic acid, significantly delayed the loss of regeneration potential in embryogenic cultures of Pennisetum americanum. In the presence of these chemicals, ethylene content in the atmosphere of the culture vessel was less than that of the control. Cefotaxime, silver nitrate and O-acetyl salicyclic acid did not have any effect on callus growth based on fresh weight, while growth based on dry weight was enhanced by O-acetyl salicyclic acid.Abbreviations ASA O-acetyl salicylic acid - BA benzyladenine - CW coconut water - 2,4-D 2,4-dichlorophenoxyacetic acid - IAA indole-3-acetic acid - NAA -naphthaleneacetic acid - MS Murashige and Skoog     

Effects of trace elements on the telomere lengths of hepatocytes L-02 and hepatoma cells SMMC-7721

The effects of selenium, zinc, iron, chromium, and lead on telomere lengths of human cells have not been investigated. This article adopted flow cytometry and fluorescence in situ hybridization to investigate the impact of different elements on cellular apoptosis and telomere lengths of human hepatocytes L-02 and hepatoma cells SMMC-7721. Results showed that these trace elements under the following dosages did not have remarkable effect on cellular apoptosis. However, sodium selenite at doses of 0.5 and 2.5 μmol/L significantly extended the telomere length of hepatocytes L-02; 0.5 μmol/L lead acetate remarkably shortened the telomere length of L-02 cells; 80 μmol/L zinc sulfate, 20 μmol/L ferric chloride, and 200 μmol/L chromic chloride only had slight impact on the telomere length, respectively. Regarding hepatoma cells SMMC-7721, sodium seleite at 0.5 and 2.5 μmol/L had little impact on the telomere length; 80 μmol/L zinc sulfate significantly accelerated the loss of telomere length, whereas 20 μmol/L ferric chloride, 200 μmol/L chromic chloride, and 0.5 μmol/L lead acetate remarkably extended the telomere lengths, respectively. The results revealed differential effects of each trace element on the life-span of human hepatocytes and hepatoma cell lines, which suggested further research on somatic hepatocytes and hepatoma in vivo.     

Thiocyanate transport across fish intestine (Pleuronectes platessa)

Summary When bathed on both sides with identical chloride-containing salines thein vitro preparation of the plaice intestine maintains a negative (serosa to mucosa) short-circuit current of 107±11 A/cm², a transepithelial potential difference of 5.5±0.6 mV (serosa negative), and a mean mucosal membrane potential of –45.4±0.6 mV. Under these conditions the intracellular chloride activity is 32mm.If chloride in the bathing media is partially, or completely substituted by thiocyanate the measured electrical parameters do not change but transepithelial flux determinations show a reduction in chloride fluxes and the presence of a significant thiocyanate flux. The addition of piretanide (10^–4 m) reduced the short-circuit current and the mucosa-to-serosa fluxes of chloride and thiocyanate; this inhibition is similar to the effect of piretanide on chloride transport in this tissue.The results indicate that thiocyanate is transported in this tissue via the piretanide-sensitive chloride pathway and are compared with the effects of thiocyanate on other tissues reported in the literature.     

Ameliorative Effect of Chlormequat Chloride and IAA on Drought Stressed Plants of <Emphasis Type="Italic">Cymbopogon Martinii</Emphasis> and <Emphasis Type="Italic">C. winterianus</Emphasis>

Responses of Cymbopogon martinii and C. winterianus to drought stress and chlormequat chloride and IAA application are compared. These two species are important source of essential oil production in drought regions. For both species and their cultivars relative water content (RWC), herbage yield and oil amount decreased under drought, while oil biosynthesis increased. Oil concentration increased significantly under drought in C. winterianus while peroxidase activity increased in C. martinii. Amount of geraniol increased under drought stress in C. martinii while citronellal and geraniol accumulation decreased in C. winterianus. Ameliorative effects of chlormequat chloride and IAA were observed in drought stressed plants of both species. Herbage yield increased significantly in chlormequat chloride and IAA treated stressed plants of C. winterianus, while oil concentration increased in C. martinii. Ameliorative effect of IAA in increasing oil yield was significant in drought stressed plants of both the species. Changes in various morpho-physiological traits indicated that chlormequat chloride and IAA can partially alleviate the detrimental effect of drought in these aromatic grasses.     

Effect of chloride on ferrous iron oxidation by a Leptospirillum ferriphilum‐dominated chemostat culture

Biomining is the use of microorganisms to catalyze metal extraction from sulfide ores. However, the available water in some biomining environments has high chloride concentrations and therefore, chloride toxicity to ferrous oxidizing microorganisms has been investigated. Batch biooxidation of Fe²⁺ by a Leptospirillum ferriphilum‐dominated culture was completely inhibited by 12 g L^?1 chloride. In addition, the effects of chloride on oxidation kinetics in a Fe²⁺ limited chemostat were studied. Results from the chemostat modeling suggest that the chloride toxicity was attributed to affects on the Fe²⁺ oxidation system, pH homeostasis, and lowering of the proton motive force. Modeling showed a decrease in the maximum specific growth rate (µ_max) and an increase in the substrate constant (K_s) with increasing chloride concentrations, indicating an effect on the Fe²⁺ oxidation system. The model proposes a lowered maintenance activity when the media was fed with 2–3 g L^?1 chloride with a concomitant drastic decrease in the true yield (Y_true). This model helps to understand the influence of chloride on Fe²⁺ biooxidation kinetics. Biotechnol. Bioeng. 2010; 106: 422–431. © 2010 Wiley Periodicals, Inc.     

Gas chromatographic-mass spectrometric identification and quantitation of urinary phenols after derivatization with 4-carbethoxyhexafluorobutyryl chloride, a novel derivative

Urinary phenol is analyzed widely to determine benzene exposure in humans. Most methods utilize direct measurements of phenols after extraction from urine using gas chromatography or high-performance liquid chromatography. We describe a novel derivatization of urinary phenols using 4-carbethoxyhexafluorobutyryl chloride after extraction from urine and subsequent analysis by gas chromatography-mass spectrometry. The derivative elutes at significantly higher temperature than phenol and the method is free from interferences from more volatile components in urine. We also observed excellent chromatographic properties of these derivatives. In addition, we observed strong molecular ions for the 4-carbethoxyhexafluoro butyryl derivative of phenol (m/z 344), p-cresol (m/z 358) and the internal standard 3,4-dimethylphenol (m/z 372) and other characteristic ions in the electron ionization, thus aiding in unambiguous identification of these compounds. The protonated molecular ions (m/z 373 for derivatized phenol, m/z 359 for derivatized p-cresol and m/z 373 for the internal standard) were the base peaks (relative abundance 100%) in the chemical ionization, although other secondary peaks were less abundant. The assay is linear for phenol concentration of 1–100 mg/l. The within-run and between-run precisions were 4.8% ( ) and 8.1% ( ) respectively, and the detection limit was 0.5 mg/l.     

Purification and characterization of a chloride ion-dependent α-glucosidase from the midgut gland of Japanese scallop (Patinopecten yessoensis)

Marine glycoside hydrolases hold enormous potential due to their habitat-related characteristics such as salt tolerance, barophilicity, and cold tolerance. We purified an α-glucosidase (PYG) from the midgut gland of the Japanese scallop (Patinopecten yessoensis) and found that this enzyme has unique characteristics. The use of acarbose affinity chromatography during the purification was particularly effective, increasing the specific activity 570-fold. PYG is an interesting chloride ion-dependent enzyme. Chloride ion causes distinctive changes in its enzymatic properties, increasing its hydrolysis rate, changing the pH profile of its enzyme activity, shifting the range of its pH stability to the alkaline region, and raising its optimal temperature from 37 to 55 °C. Furthermore, chloride ion altered PYG’s substrate specificity. PYG exhibited the highest V_max/K_m value toward maltooctaose in the absence of chloride ion and toward maltotriose in the presence of chloride ion.     

Modulation of the redox state of the copper sites of human ceruloplasmin by chloride

Incubation of human ceruloplasmin with physiological concentrations of chloride at neutral pH invariably caused dramatic changes of both the spectroscopic and the functional properties of the protein. The optical intensity at 610 nm increased up to 60%, with a concomitant decrease at 330 nm and the appearance of new bands between 410 and 500 nm. Signals previously undetectable appeared in the EPR spectrum. On the basis of computer simulations, they were interpreted as stemming from an oxidized type 1 copper site and from a half-reduced type 3 copper pair. Removal of chloride completely restored the original optical and EPR lineshapes. Hydrogen peroxide, added to ceruloplasmin in the presence of chloride, was able to capture the electron of the half-reduced type 3 site and to yield a protein insensitive to subsequent removal and readdition of the anion. As a whole, the spectroscopic data indicate that a blue site is partially reduced in the resting protein and that, upon binding of chloride, human ceruloplasmin undergoes a structural change leading to displacement of an electron from the reduced type 1 site to the type 3 site pair. Chloride dramatically affected the catalytic efficiency of human ceruloplasmin. At neutral pH, the anion was an activator of the oxidase activity, being able to enhance up to tenfold the catalytic rate. AtpH < 6, in line with all previous reports, chloride strongly inhibited the activity. At intermediate pH values, i.e., around 6, the effect was composite, with an activating effect at low concentration and an inhibitory effect at higher concentration. Since chloride is present at very high concentrations in the plasma, these results suggest that human ceruloplasmin is, in the plasma, under control of this anion.     

Morphological factors determining salt tolerance in citrus seedlings: the shoot to root ratio modulates passive root uptake of chloride ions and their accumulation in leaves

The results presented in this work were obtained with two citrus genotypes, the chloride-tolerant Cleopatra mandarin (Citrus reshni Hort. ex Tan.) and the chloride-sensitive Carrizo citrange [Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.]. The data show that chloride uptake under salinization is driven by passive forces. In both species, net rates of chloride root uptake increased linearly, without saturation, with the increase of external NaCl concentrations (30–240 mol m^–3). Uptake rates, on a μ g g root dry weight^–1 h^–1 basis, in Cleopatra and Carrizo decreased (from 38 to 21) and increased (from 21 to 35), respectively, with the increase (about three-fold) of the shoot to root ratio. With the appropriate shoot to root ratio in each genotype, it was demonstrated that at identical external doses of NaCl, Cl^– uptake rates and Cl^– xylem concentrations in the two species were very similar. Root pruning and defoliation showed that the amount of chloride taken by the plant was a function of the size of the root system, whereas leaf chloride concentration, the parameter responsible for salt damage, was dependent upon leaf biomass. Measurements of water transpiration suggested that chloride root uptake and leaf accumulation might be linked to water absorption and transpiration rates, respectively. The data indicate that plant morphology is a crucial factor determining salt-tolerance in citrus.     

Informational Content of Polytene Chromosome Bands and Puffs

Abstract

Three widely documented mechanisms of chloride transport across plasma membranes are anion-coupled antiport, sodium-coupled symport, and an electrochemical coupling process. No direct genetic evidence has yet been provided for primary active chloride transport despite numerous reports of cellular Cl-stimulated adenosine triphos-phate (ATP)ases coexisting in the same tissue with uphill chloride transport that could not be accounted for by the three common chloride transport processes. Ch-stimulated ATPases are a common property of practically all biological cells, with the major location being of mitochondrial origin. It also appears that plasma membranes are sites of Cl–stimulated ATPase activity. Recent studies of Cl'-stimulated ATPase activity and chloride transport in the same membrane system, including liposomes, suggest a mediation by the ATPase in net movement of chloride up its electrochemical gradient across plasma membranes. Further studies, especially from a molecular biological perspective, are required to confirm a direct transport role to plasma membrane-localized Ch-stimulated ATPases.     

Purifying Selection and Demographic Expansion Affect Sequence Diversity of the Ligand-Binding Domain of a Glutamate-Gated Chloride Channel Gene of Haemonchus placei

Ninety-five genomic sequences of the ligand-binding domain of glutamate-gated chloride channel genes of three populations of the parasitic nematode H. placei were evaluated for patterns of diversity, demography, and selection. These genes code for subunits of ion channels, which are involved in the mode of action of the most commonly used antiparasitic drugs, the macrocyclic lactones. An extremely high frequency of unique segregating sites in exons and introns was observed, with significantly negative neutrality tests in each population for noncoding, synonymous, and nonsynonymous sites. Several tests indicated that support for balancing selection, positive selection, and hitchhiking was lacking. McDonald–Kreitman tests using H. contortus or C. elegans as an outgroup revealed an extreme excess of replacement polymorphism, consistent with weak purifying selection. Although these tests agree that negative selection may explain the excess of replacement changes, an alternative interpretation is required for the significantly negative Fu and Lis D statistics based on silent and noncoding sites. These include homogeneous forces such as background selection and demographic expansion. The lack of population subdivision and the negative values of Tajimas D for this outbreeding parasitic nematode render background selection less likely than demographic expansion. Comparison of D statistics based on different site types using neutral coalescent simulations supported this interpretation. Although this statistic was more negative for nonsynonymous sites than for synonymous sites, most comparisons of the D statistic were not significantly different between mutation classes. A few significant site comparisons were also consistent with demographic expansion, because the observed test statistic (D_neutral – D_selected) were low relative to the neutral expectations. Finally, previous mitochondrial studies also identified a demographic expansion of this parasitic nematode species, which lends further support to a scenario involving both demographic and purifying forces in the ligand-binding domain of H. placei.