CLC proteins transport chloride (Cl
) ions across cellular membranes to regulate muscle excitability, electrolyte movement across epithelia, and acidification of intracellular organelles. Some CLC ...proteins are channels that conduct Cl
ions passively, whereas others are secondary active transporters that exchange two Cl
ions for one H
. The structural basis underlying these distinctive transport mechanisms is puzzling because CLC channels and transporters are expected to share the same architecture on the basis of sequence homology. Here we determined the structure of a bovine CLC channel (CLC-K) using cryo-electron microscopy. A conserved loop in the Cl
transport pathway shows a structure markedly different from that of CLC transporters. Consequently, the cytosolic constriction for Cl
passage is widened in CLC-K such that the kinetic barrier previously postulated for Cl
/H
transporter function would be reduced. Thus, reduction of a kinetic barrier in CLC channels enables fast flow of Cl
down its electrochemical gradient.
Intracellular Cl(-) concentrations (Cl(-)(i)) of sensory neurons regulate signal transmission and signal amplification. In dorsal root ganglion (DRG) and olfactory sensory neurons (OSNs), Cl(-) is ...accumulated by the Na(+)-K(+)-2Cl(-) cotransporter 1 (NKCC1), resulting in a Cl(-)(i) above electrochemical equilibrium and a depolarizing Cl(-) efflux upon Cl(-) channel opening. Here, we investigate the Cl(-)(i) and function of Cl(-) in primary sensory neurons of trigeminal ganglia (TG) of wild type (WT) and NKCC1(-/-) mice using pharmacological and imaging approaches, patch-clamping, as well as behavioral testing. The Cl(-)(i) of WT TG neurons indicated active NKCC1-dependent Cl(-) accumulation. Gamma-aminobutyric acid (GABA)(A) receptor activation induced a reduction of Cl(-)(i) as well as Ca(2+) transients in a corresponding fraction of TG neurons. Ca(2+) transients were sensitive to inhibition of NKCC1 and voltage-gated Ca(2+) channels (VGCCs). Ca(2+) responses induced by capsaicin, a prototypical stimulus of transient receptor potential vanilloid subfamily member-1 (TRPV1) were diminished in NKCC1(-/-) TG neurons, but elevated under conditions of a lowered Cl(-)(o) suggesting a Cl(-)-dependent amplification of capsaicin-induced responses. Using next generation sequencing (NGS), we found expression of different Ca(2+)-activated Cl(-) channels (CaCCs) in TGs of mice. Pharmacological inhibition of CaCCs reduced the amplitude of capsaicin-induced responses of TG neurons in Ca(2+) imaging and electrophysiological recordings. In a behavioral paradigm, NKCC1(-/-) mice showed less avoidance of the aversive stimulus capsaicin. In summary, our results strongly argue for a Ca(2+)-activated Cl(-)-dependent signal amplification mechanism in TG neurons that requires intracellular Cl(-) accumulation by NKCC1 and the activation of CaCCs.
Hydrothermal liquefaction(HTL) of empty fruit bunches(EFB) was performed with an autoclave reactor at various temperatures (240, 270, 300, and 330 °C) in the presence of transition metal ...chlorides(ZnCl2, CuCl2, and NiCl2) under high pressure(∼22 MPa) and N2 atmosphere. Main HTL products including hydrochar, gas, water-soluble fraction (WSF), and crude-like HTL oil were investigated. The yield of HTL oil gradually increased with increasing temperature, and the highest oil yield of 22.8 wt% was obtained at 300 °C. When transition metal chlorides (2.5–10.0% (w/w sample)) were added to the reaction, mass distributions of the four fractions were clearly modified based on the type of transition metal chloride as well as their concentration. In general, the yield of HTL oil decreased with an increase in transition metal concentration up to 10.0%, the water content increased and the chemical compounds decreased with an increase in the amount of metal. γ-Valerolactone (GVL) and levulinic acid (LA) were detected in the catalytic HTL oil, due to the presence of transition metal ion and high acidity. Unlike other metal chlorides, the presence of CuCl2 resulted in relatively low GVL and high LA concentration, which may inactivate the route from LA to GVL under acidic hydrothermal conditions.
•EFB was subjected to hydrothermal treatment in the presence of transition metals.•Distribution of degradation products was influenced by reaction temperature.•Transition metals affected the chemical composition of HTL oil.•Copper inactivates the hydrogenation of levulinic acid to γ-valerolactone.
We report, herein, a photoinduced iron-catalyzed direct chlorination of aromatic sulfonyl chloride at room temperature. In this protocol, FeCl
-catalyzed direct chlorination has been realized at room ...temperature under the irradiation of light (400-410 nm). During the process, many commercially or readily available substituted aromatic sulfonyl chlorides could produce the corresponding aromatic chlorides in moderate to good yields.
Invited for the cover of this issue is the group of Dillip Kumar Chand at the Indian Institute of Technology Madras. The image depicts the efficient chloride binding ability of a designer ...self-assembled coordination cage in water. The binding occurs selectively even in presence of models of biologically abundant anionic systems. Read the full text of the article at 10.1002/chem.202300891.
Chloride intracellular channels (CLICs) are a unique family of evolutionarily conserved metamorphic proteins, switching between stable conformations based on redox conditions. CLICs have been ...implicated in a wide variety biological processes including ion channel activity, apoptosis, membrane trafficking, and enzymatic oxidoreductase activity. Understanding the molecular mechanisms by which CLICs engage in these activities is an area of active research. Here, the sole Drosophila melanogaster ortholog, Clic, was targeted for RNAi knockdown to identify genes and biological processes associated with Clic expression. Clic knockdown had a substantial impact on global transcription, altering expression of over 7% of transcribed Drosophila genes. Overrepresentation analysis of differentially expressed genes identified enrichment of Gene Ontology terms including Cytoplasmic Translation, Oxidation-Reduction Process, Heme Binding, Membrane, Cell Junction, and Nucleolus. The top term, Cytoplasmic Translation, was enriched almost exclusively with downregulated genes. Drosophila Clic and vertebrate ortholog Clic4 have previously been tied to ethanol sensitivity and ethanol-regulated expression. Clic knockdown-responsive genes from the present study were found to overlap significantly with gene sets from 4 independently published studies related to ethanol exposure and sensitivity in Drosophila. Bioinformatic analysis of genes shared between these studies revealed an enrichment of genes related to amino acid metabolism, protein processing, oxidation-reduction processes, and lipid particles among others. To determine whether the modulation of ethanol sensitivity by Clic may be related to co-regulated oxidation-reduction processes, we evaluated the effect of hyperoxia on ethanol sedation in Clic knockdown flies. Consistent with previous findings, Clic knockdown reduced acute ethanol sedation sensitivity in flies housed under normoxia. However, this effect was reversed by exposure to hyperoxia, suggesting a common set of molecular-genetic mechanism may modulate each of these processes. This study suggests that Drosophila Clic has a major influence on regulation of oxidative stress signaling and that this function overlaps with the molecular mechanisms of acute ethanol sensitivity in the fly.
Trypanocidal resistance is a major cause of treatment failure. This study evaluated the sensitivity of Trypanosoma evansi field isolates collected from Marsabit and Isiolo counties, Kenya. A total of ...2,750 camels were screened using parasitological tests for trypanosomes. Of the screened camels, 113 tested positive from which 40 T. evansi isolates were tested using the single dose mice sensitivity test. Five treatment groups each comprising of 6 mice were inoculated intraperitoneally with 1x105 trypanosomes of each isolate and treated 24 hours later with isometamidium chloride at 1 mg/kg, homidium chloride at 1mg/kg, diminazene aceturate at 20 mg/kg and quinapyramine sulphate & chloride at 1 mg/kg. The fifth group was left untreated (positive control). The mice were monitored daily for 60 days. A survey on camel owners' practices that influence development of resistance to trypanocidal drugs was then conducted. Results indicated presence of drug resistance in all the 7 study sites that had infected camels. Seven of the isolates tested were resistant to diminazene aceturate whereas, 28, 33 and 34 were resistant to isometamidium chloride, quinapyramine sulphate & chloride and homidium chloride, respectively. Seven (17.5%) isolates of the 40 tested were sensitive to all 4 drugs, whereas, 7.5%, 10%,55% and 10% were resistant to 1,2,3 and 4 drugs, respectively. The prevalence of multiple drug resistance was 75%. Survey data indicated that camel management practices influenced the prevalence and degree of drug resistance. In conclusion, the multiple drug resistance observed in the two counties may not be an indication of total trypanocidal drug failure. Judicious treatment of confirmed trypanosomiasis cases with correct dosage would still be effective in controlling the disease since the observed resistance was at the population and not clonal level. However, integrated control of the disease and the vectors using available alternative methods is recommended to reduce drug use.
The effect of magnesium and sulphate present in sea water on chloride binding in Portland cement paste was investigated. Ground well hydrated cement paste was exposed to MgCl2, NaCl, NaCl+MgCl2, ...MgSO4+MgCl2 and artificial sea water solutions with a range of concentrations at 20°C. Chloride binding isotherms are determined and pH of the solutions were measured. A selection of samples was examined by SEM-EDS to identify phase changes upon exposure. The experimental data were compared with calculations of a thermodynamic model. Chloride binding from sea water was similar to chloride binding for NaCl solutions. The magnesium content in the sea water lead to a slight decrease in pH, but this did not result in a notable increase in chloride binding. The sulphate present in sea water reduces both chloride binding in C–S–H and AFm phases, as the C–S–H incorporates more sulphates instead of chlorides, and part of the AFm phases converts to ettringite.
Recent studies suggest a role for T lymphocytes in hypertension. However, whether T cells contribute to renal sodium retention and salt-sensitive hypertension is unknown. Here we demonstrate that T ...cells infiltrate into the kidney of salt-sensitive hypertensive animals. In particular, CD8
T cells directly contact the distal convoluted tubule (DCT) in the kidneys of DOCA-salt mice and CD8
T cell-injected mice, leading to up-regulation of the Na-Cl co-transporter NCC, p-NCC and the development of salt-sensitive hypertension. Co-culture with CD8
T cells upregulates NCC in mouse DCT cells via ROS-induced activation of Src kinase, up-regulation of the K
channel Kir4.1, and stimulation of the Cl
channel ClC-K. The last event increases chloride efflux, leading to compensatory chloride influx via NCC activation at the cost of increasing sodium retention. Collectively, these findings provide a mechanism for adaptive immunity involvement in the kidney defect in sodium handling and the pathogenesis of salt-sensitive hypertension.
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Recently, we reported that silver(I) oxide mediated Koenigs-Knorr glycosylation reaction can be dramatically accelerated in the presence of catalytic acid additives. We have also ...investigated how well this reaction works in application to differentially protected galactosyl bromides. Reported herein is the stereoselective synthesis of α-galactosides with galactosyl chlorides as glycosyl donors. Chlorides are easily accessible, stable, and can be efficiently activated for glycosylation. In this application, the most favorable reactions conditions comprised cooperative Ag2SO4 and Bi(OTf)3 promoter system.
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