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The Journal of Neuroscience : the... Aug 2023Neurotransmission is shaped by extracellular pH. Alkalization enhances pH-sensitive transmitter release and receptor activation, whereas acidification inhibits these...
Neurotransmission is shaped by extracellular pH. Alkalization enhances pH-sensitive transmitter release and receptor activation, whereas acidification inhibits these processes and can activate acid-sensitive conductances in the synaptic cleft. Previous work has shown that the synaptic cleft can either acidify because of synaptic vesicular release and/or alkalize because of Ca extrusion by the plasma membrane ATPase (PMCA). The direction of change differs across synapse types. At the mammalian neuromuscular junction (NMJ), the direction and magnitude of pH transients in the synaptic cleft during transmission remain ambiguous. We set out to elucidate the extracellular pH transients that occur at this cholinergic synapse under near-physiological conditions and identify their sources. We monitored pH-dependent changes in the synaptic cleft of the mouse levator auris longus using viral expression of the pseudoratiometric probe pHusion-Ex in the muscle. Using mice from both sexes, a significant and prolonged alkalization occurred when stimulating the connected nerve for 5 s at 50 Hz, which was dependent on postsynaptic intracellular Ca release. Sustained stimulation for a longer duration (20 s at 50 Hz) caused additional prolonged net acidification at the cleft. To investigate the mechanism underlying cleft alkalization, we used muscle-expressed GCaMP3 to monitor the contribution of postsynaptic Ca Activity-induced liberation of intracellular Ca in muscle positively correlated with alkalization of the synaptic cleft, whereas inhibiting PMCA significantly decreased the extent of cleft alkalization. Thus, cholinergic synapses of the mouse NMJ typically alkalize because of cytosolic Ca liberated in muscle during activity, unless under highly strenuous conditions where acidification predominates. Changes in synaptic cleft pH alter neurotransmission, acting on receptors and channels on both sides of the synapse. Synaptic acidification has been associated with a myriad of diseases in the central and peripheral nervous system. Here, we report that in near-physiological recording conditions the cholinergic neuromuscular junction shows use-dependent bidirectional changes in synaptic cleft pH-immediate alkalinization and a long-lasting acidification under prolonged stimulation. These results provide further insight into physiologically relevant changes at cholinergic synapses that have not been defined previously. Understanding and identifying synaptic pH transients during and after neuronal activity provides insight into short-term synaptic plasticity synapses and may identify therapeutic targets for diseases.
Topics: Female; Male; Animals; Mice; Calcium; Synapses; Neuromuscular Junction; Synaptic Transmission; Cholinergic Agents; Mammals
PubMed: 37474311
DOI: 10.1523/JNEUROSCI.0815-23.2023 -
Environmental Pollution (Barking, Essex... Nov 2023The Xikuangshan (XKS) mine was selected for a comprehensive Sb-related hydrogeochemical study because of its significant Sb contamination in water systems. Hydrochemical...
Sources of antimony contamination and its migration into water systems of Xikuangshan, China: Evidence from hydrogeochemical and stable isotope (H, O, S, and Sr) signatures.
The Xikuangshan (XKS) mine was selected for a comprehensive Sb-related hydrogeochemical study because of its significant Sb contamination in water systems. Hydrochemical data, specifically multi-isotope (H, O, S, and Sr) data, were conducted to elucidate the primary sources and migration processes of Sb responsible for water system contamination. At the XKS Sb mine, water is near-neutral to alkaline and is characterized by high concentrations of SO and Sb. Sb occurs as Sb(OH) (the dominant species) in these oxidized waters. The hydrochemistry is mainly controlled by carbonate dissolution and silicate weathering. δH and δO values indicate that the infiltration recharge of mine water and mining activities regulate the migration of Sb in groundwater. δS and δO values indicate that dissolved SO and Sb primarily come from stibnite oxidation, bacterial SO reduction has either not occurred or is extremely weak, and the reductive dissolution of Fe (III) hydroxides does not significantly affect Sb migration in water. The Sr/Sr ratios further indicate that the discharge of solid mine wastes leaching and smelting water is a crucial source of Sb contamination in groundwater. In addition, the relationship between δS and δSr values suggests the complexity of the contamination source and migration of Sb in water. Finally, a robust conceptual hydrogeochemical model was developed using isotopic tools in combination with detailed hydrogeological and hydrochemistry characterization to describe the contamination source and migration of Sb in water systems at the XKS Sb mine.
Topics: Antimony; Environmental Monitoring; Water; Water Pollutants, Chemical; Isotopes; Groundwater; China
PubMed: 37586690
DOI: 10.1016/j.envpol.2023.122381 -
Chemosphere Nov 2023The effects of different heavy metal pollution remediation methods on soil nutrient transformation and soil health remain unclear. In this study, the effects of...
The effects of different heavy metal pollution remediation methods on soil nutrient transformation and soil health remain unclear. In this study, the effects of phytoextraction (PE) and passivation remediation (PR) on Cd-polluted soil phosphorus transformation and availability were compared by pot experiment. The results showed that PE significantly reduced the concentrations of total and available Cd (both HO-Cd and DTPA-Cd) in soil, PR also decreased available Cd content but had no significant effect on total Cd content. PE slightly increased soil pH and NH-N content, while PR significantly increased soil pH, NO-N and AK content. PE promoted the conversion of stable P (including HCl-P and residual-P), and increased the content of labile P (including HO-P, NaHCO-P and NaHCO-P) and the proportion of moderately labile P (including NaOH-P and NaOH-P), while PR showed the opposite trend. PE showed a higher soil phoC gene abundance and acid phosphatase (ACP) activity, while PR showed a higher phoD gene copies and alkaline phosphatase (ALP) activity. Soil bacteria and phoD-harboring bacteria community was significantly affected by remediation methods and soil types. Compared with PR, PE reduced phoD-harboring bacterial diversity but significantly increased the abundance of genera associated with P dissolution (Streptomyces) and P conversion (Bradyrhizobium and Frankia), both of which were significantly positively correlated with labile P or moderately labile P. In general, compared with PR, PE can effectively remove soil Cd pollution, while maintaining a higher content of labile P and a higher proportion of moderately labile P, which can be considered as a green and sustainable remediation strategy conducive to soil quality.
Topics: Cadmium; Sodium Hydroxide; Bradyrhizobium; Phosphorus; Soil
PubMed: 37607600
DOI: 10.1016/j.chemosphere.2023.139902 -
Methods in Molecular Biology (Clifton,... 2024Ice-binding proteins (IBPs) are a diverse class of proteins that are essential for the survival of organisms in cold conditions. IBPs are diverse in their function and...
Ice-binding proteins (IBPs) are a diverse class of proteins that are essential for the survival of organisms in cold conditions. IBPs are diverse in their function and can prevent or promote ice growth and selectively bind to specific crystallographic planes of the growing ice lattice. Moreover, IBPs are widely utilized to modulate ice crystal growth and recrystallization in the food industry and as cryoprotectants to preserve biological matter. A key unresolved aspect of the mode of action is how the ice-binding sites of these proteins distinguish between ice and water and interact with multiple crystal facets of the ice. The use of molecular dynamics (MD) simulation allows us to thoroughly investigate the binding mechanism and energetics of ice-binding proteins, to complement and expand on the mechanistic understandings gained from experiments. In this chapter, we describe a series of molecular dynamics simulation methodologies to investigate the mechanism of action of ice-binding proteins. Specifically, we provide detailed instructions to set up MD simulations to study the binding and interaction of ice-binding proteins using atomistic and coarse-grained simulations.
Topics: Carrier Proteins; Ice; Molecular Dynamics Simulation; Caspase 1; Water
PubMed: 37943459
DOI: 10.1007/978-1-0716-3503-2_13 -
Environmental Research Sep 2023The production of reinforced composite materials can generally benefit greatly from the use of natural cellulosic woody fibers as good sustainable resources. Natural...
The production of reinforced composite materials can generally benefit greatly from the use of natural cellulosic woody fibers as good sustainable resources. Natural plants like hemp, cotton, and bamboo are great options for knitters and crocheters looking to make eco-friendly goods. The current study examines the properties of natural fiber obtained from the stem of the Acacia pennata (AP) plant, as well as its basic physico-chemical, structural, thermal, and mechanical characteristics. The key goal of this work was to investigate how alkali treatment affected the AP fibers' morphology, chemical composition, tensile capabilities, morphological changes, structural changes, and thermal degradation (APFs). The SEM image and pXRD analyses support the improved surface roughness of the fiber, and that was seen after the alkaline treatment. From XRD analysis, the fiber crystallinity index (54.65%) was improved and it was connected to their SEM pictograms in comparison to untreated APF. Alkali-treated AP fibers include a higher percentage of chemical components including cellulose (51.38%) and ash (5.13%). Alkali-treated AP fibers have a lower amount of hemi-cellulose (30.30%), lignin (20.96%), pectin (8.77%), wax (0.12%), and moisture (13.44%) than untreated APF. Their low density and high cellulosic content will improve their ability to fiber matrices. The thermal behavior of AP fiber at various temperatures was demonstrated by TG-DTA analysis, and tensile strength was also investigated.
Topics: Acacia; Alkalies; Cellulose; Lignin; Tensile Strength
PubMed: 37343749
DOI: 10.1016/j.envres.2023.116415 -
Environmental Science & Technology Sep 2023Catalyst deactivation caused by alkali metal poisoning has long been a key bottleneck in the application of selective catalytic reduction of NO with NH (NH-SCR),...
Catalyst deactivation caused by alkali metal poisoning has long been a key bottleneck in the application of selective catalytic reduction of NO with NH (NH-SCR), limiting the service life of the catalyst and increasing the cost of environmental protection. Despite great efforts, continuous accumulation of alkali metal deposition makes the resistance capacity of 2 wt % KO difficult to enhance via merely loading acid sites on the surface, resulting in rapid deactivation and frequent replacement of the NH-SCR catalyst. To further improve the resistance of alkali metals, encapsulating alkali metals into the bulk phase could be a promising strategy. The bottleneck of 2 wt % KO tolerance has been solved by virtue of ultrahigh potassium storage capacity in the amorphous FePO bulk phase. Amorphous FePO as a support of the NH-SCR catalyst exhibited a self-adaptive alkali-tolerance mechanism, where potassium ions spontaneously migrated into the bulk phase of amorphous FePO and were anchored by PO with the generation of FeO at the NH-SCR reaction temperature. This ingenious potassium storage mechanism could boost the KO resistance capacity to 6 wt % while maintaining approximately 81% NO conversion. Besides, amorphous FePO also exhibited excellent resistance to individual and coexistence of alkali (KO and NaO), alkali earth (CaO), and heavy metals (PbO and CdO), providing long durability for CePO/FePO catalysts in flue gas with multipollutants. The cheap and accessible amorphous FePO paves the way for the development and implementation of poisoning-resistant NO abatement.
Topics: Potassium; Alkalies; Catalysis; Temperature
PubMed: 37695840
DOI: 10.1021/acs.est.3c05112 -
PeerJ 2023Alkaline lakes are a special aquatic ecosystem that act as important water and alkali resource in the arid-semiarid regions. The primary aim of the study is to explore...
Alkaline lakes are a special aquatic ecosystem that act as important water and alkali resource in the arid-semiarid regions. The primary aim of the study is to explore how environmental factors affect community diversity and structure, and to find whether there are key microbes that can indicate changes in environmental factors in alkaline lakes. Therefore, four sediment samples (S1, S2, S3, and S4) were collected from Hamatai Lake which is an important alkali resource in Ordos' desert plateau of Inner Mongolia. Samples were collected along the salinity and alkalinity gradients and bacterial community compositions were investigated by Illumina Miseq sequencing. The results revealed that the diversity and richness of bacterial community decreased with increasing alkalinity (pH) and salinity, and bacterial community structure was obviously different for the relatively light alkaline and hyposaline samples (LAHO; pH < 8.5; salinity < 20‰) and high alkaline and hypersaline samples (HAHR; pH > 8.5; salinity > 20‰). Firmicutes, Proteobacteria and Bacteriodetes were observed to be the dominant phyla. Furthermore, Acidobacteria, Actinobacteria, and low salt-tolerant alkaliphilic nitrifying taxa were mainly distributed in S1 with LAHO characteristic. Firmicutes, Clostridia, Gammaproteobacteria, salt-tolerant alkaliphilic denitrifying taxa, haloalkaliphilic sulfur cycling taxa were mainly distributed in S2, S3 and S4, and were well adapted to haloalkaline conditions. Correlation analysis revealed that the community diversity (operational taxonomic unit numbers and/or Shannon index) and richness (Chao1) were significantly positively correlated with ammonium nitrogen (r = 0.654, < 0.05; r = 0.680, < 0.05) and negatively correlated with pH (r = -0.924, < 0.01; r = -0.800, < 0.01; r = -0.933, < 0.01) and salinity (r = -0.615, < 0.05; r = -0.647, < 0.05). A redundancy analysis and variation partitioning analysis revealed that pH (explanation degrees of 53.5%, pseudo-F = 11.5, < 0.01), TOC/TN (24.8%, pseudo-F = 10.3, < 0.05) and salinity (9.2%, pseudo-F = 9.5, < 0.05) were the most significant factors that caused the variations in bacterial community structure. The results suggested that alkalinity, nutrient salt and salinity jointly affect bacterial diversity and community structure, in which one taxon (Acidobacteria), six taxa (Cyanobacteria, Nitrosomonadaceae, , , and ) and five taxa (, , , and ) are related to carbon, nitrogen and sulfur cycles, respectively. Classes Clostridia and Gammaproteobacteria might indicate changes of saline-alkali conditions in the sediments of alkaline lakes in desert plateau.
Topics: Lakes; Ecosystem; Bacteria; Firmicutes; Acidobacteria; China; Alkalies; Ectothiorhodospiraceae
PubMed: 37637159
DOI: 10.7717/peerj.15909 -
Environmental Science & Technology Oct 2023The mineralization and bioavailability of phytic acid, the predominant organic phosphorus (OP) species in many soils, have generally been rendered limited due to its...
The mineralization and bioavailability of phytic acid, the predominant organic phosphorus (OP) species in many soils, have generally been rendered limited due to its interaction with soil minerals. In particularly calcareous and neutral to slightly alkaline soils, phytic acid is known to actively react with calcite, although how this interaction affects phytic acid mineralization is still unknown. This study, therefore, investigated the mechanisms regarding how the calcite-water interface influences phytic acid mineralization by phytase, at pHs 6 and 8 using in situ spectroscopic techniques including solution nuclear magnetic resonance and attenuated total reflection Fourier transform infrared spectroscopy. The findings indicated a pH-specific effect of the calcite-water interface. Inhibited phytase activity and thus impaired phytic acid mineralization were induced by calcite at pH 6, while the opposite effect was observed at pH 8. How the interaction between phytic acid and calcite and between phytase and calcite differed between the two pH values contributed to the pH-specific effect. The results demonstrate the importance of soil pH, enzyme-, and OP-clay mineral interactions in controlling the mineralization and transformation of OP and, consequently, the release of phosphate in soils. The findings can also provide implications for the management of calcite-rich and limed soils.
Topics: Phosphorus; Calcium Carbonate; Water; Phytic Acid; 6-Phytase; Minerals; Soil
PubMed: 37857378
DOI: 10.1021/acs.est.3c06364 -
Environmental Science and Pollution... Dec 2023Rapid degradation of quality and quantity of the available limited fresh water reserves has forced nations around the globe to search for alternate fresh water sources.... (Review)
Review
Rapid degradation of quality and quantity of the available limited fresh water reserves has forced nations around the globe to search for alternate fresh water sources. This has led to the development of various desalination technologies to generate potable water from abundantly available sea and brackish water. Desalination sector has undergone various upgradations to meet the rising fresh water demand in a sustainable way. One such upgradation is the utilization of solar energy as an energy source. High cost and associated environmental impacts with large-scale desalination systems have shifted the focus of researchers towards research and development of various small-scale efficient solar stills for cheap potable water production in rural, remote, arid, and coastal locations. In this review article, various configurations of a non-conventional solar still, namely inverted solar still, have been reviewed extensively by highlighting its classifications, design aspects, working principle, features, and economics. Moreover, the role of inverted solar still's evaporating and condensing surface characteristics and thermal properties on its distillate productivity has also been discussed. Inverted absorber multi-basin solar still and inverted multi-effect diffusion solar still configurations are highly productive. Economics of inverted solar still is better than other conventional solar still configurations and conventional reverse osmosis plant of few m/day capacity. This review article will facilitate researchers to select appropriate inverted solar still configuration for further performance improvement and commercialization. The scope for future research works on inverted solar still has also been listed.
Topics: Water; Drinking Water; Fresh Water; Solar Energy; Diffusion; Energy-Generating Resources; Water Purification
PubMed: 37964147
DOI: 10.1007/s11356-023-30760-w -
STAR Protocols Dec 2023Renewable energy-driven bipolar membrane water electrolyzers (BPMWEs) are a promising technology for sustainable production of hydrogen from seawater and other impure...
Renewable energy-driven bipolar membrane water electrolyzers (BPMWEs) are a promising technology for sustainable production of hydrogen from seawater and other impure water sources. Here, we present a protocol for assembling BPMWEs and operating them in a range of water feedstocks, including ultra-pure deionized water and seawater. We describe steps for membrane electrode assembly preparation, electrolyzer assembly, and electrochemical evaluation. For complete details on the use and execution of this protocol, please refer to Marin et al. (2023)..
Topics: Water; Membranes
PubMed: 37924520
DOI: 10.1016/j.xpro.2023.102606