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Nature Materials Sep 2022Solid-state ionic conduction is a key enabler of electrochemical energy storage and conversion. The mechanistic connections between material processing, defect...
Solid-state ionic conduction is a key enabler of electrochemical energy storage and conversion. The mechanistic connections between material processing, defect chemistry, transport dynamics and practical performance are of considerable importance but remain incomplete. Here, inspired by studies of fluids and biophysical systems, we re-examine anomalous diffusion in the iconic two-dimensional fast-ion conductors, the β- and β″-aluminas. Using large-scale simulations, we reproduce the frequency dependence of alternating-current ionic conductivity data. We show how the distribution of charge-compensating defects, modulated by processing, drives static and dynamic disorder and leads to persistent subdiffusive ion transport at macroscopic timescales. We deconvolute the effects of repulsions between mobile ions, the attraction between the mobile ions and charge-compensating defects, and geometric crowding on ionic conductivity. Finally, our characterization of memory effects in transport connects atomistic defect chemistry to macroscopic performance with minimal assumptions and enables mechanism-driven 'atoms-to-device' optimization of fast-ion conductors.
Topics: Diffusion; Electric Conductivity; Electrolytes; Ion Transport; Ions
PubMed: 35902748
DOI: 10.1038/s41563-022-01316-z -
Archives of Oral Biology Sep 2018Enamel is a highly calcified tissue. Its formation requires a progressive and dynamic system for the regulation of electrolyte concentration by enamel epithelia. A... (Review)
Review
Enamel is a highly calcified tissue. Its formation requires a progressive and dynamic system for the regulation of electrolyte concentration by enamel epithelia. A critical function of enamel epithelial cells, ameloblasts, is the secretion and movement of electrolytes via various channels and transporters to develop the enamel tissue. Enamel formation generates protons, which need to be neutralised. Thus, ameloblasts possess a buffering system to sustain mineral accretion. Normal tooth formation involves stage-dependent net fluctuations in pH during amelogenesis. To date, all of our information about ion transporters in dental enamel tissue is based solely on immunostaining-expression techniques. This review critically evaluates the current understanding and recent discoveries and physiological role of ion channels and transporters, Mg transporters, and Ca regulatory proteins during amelogenesis in enamel formation. The ways in which ameloblasts modulate ions are discussed in the context of current research for developing a novel morphologic-functional model of enamel maturation.
Topics: Ameloblasts; Amelogenesis; Animals; Calcium Signaling; Chloride-Bicarbonate Antiporters; Homeostasis; Humans; Hydrogen-Ion Concentration; Ion Transport; Phenotype; Water-Electrolyte Balance
PubMed: 29803993
DOI: 10.1016/j.archoralbio.2018.05.014 -
ELife Aug 2020In order to enter a cell, an ammonium ion must first dissociate to form an ammonia molecule and a hydrogen ion (a proton), which then pass through the cell membrane...
In order to enter a cell, an ammonium ion must first dissociate to form an ammonia molecule and a hydrogen ion (a proton), which then pass through the cell membrane separately and recombine inside.
Topics: Ammonia; Ammonium Compounds; Ion Transport; Nitrosomonas; Oxidation-Reduction
PubMed: 32840481
DOI: 10.7554/eLife.61148 -
The Journal of General Physiology Jul 2015The crystal structures of channels and transporters reveal the chemical nature of ion-binding sites and, thereby, constrain mechanistic models for their transport... (Review)
Review
The crystal structures of channels and transporters reveal the chemical nature of ion-binding sites and, thereby, constrain mechanistic models for their transport processes. However, these structures, in and of themselves, do not reveal equilibrium selectivity or transport preferences, which can be discerned only from various functional assays. In this Review, I explore the relationship between cation transport protein structures, equilibrium binding measurements, and ion transport selectivity. The primary focus is on K(+)-selective channels and nonselective cation channels because they have been extensively studied both functionally and structurally, but the principles discussed are relevant to other transport proteins and molecules.
Topics: Binding Sites; Cations; Crystallography, X-Ray; Ion Channel Gating; Ion Transport; Kinetics; Potassium Channels
PubMed: 26078056
DOI: 10.1085/jgp.201511371 -
Current Topics in Membranes 2019Myofibroblast differentiation is a critical process in the pathogenesis of tissue fibrosis. We focus our mini-review on recent data showing an implication of monovalent... (Review)
Review
Myofibroblast differentiation is a critical process in the pathogenesis of tissue fibrosis. We focus our mini-review on recent data showing an implication of monovalent ion transporters in fibroblast to myofibroblast transformation of human lung fibroblasts (HLF). In cultured HLF, cardiotonic steroids (CTS) known as potent inhibitors of Na,K-ATPase suppress myofibroblast differentiation in parallel with up- and down-regulated expression of cyclooxygenase-2 (COX-2) and TGF-β receptor subunit TGFBR2, respectively. K-free medium mimics antifibrotic action of CTS indicating a key role of elevated intracellular [Na]/[K] ratio. Augmented expression of COX-2 is abolished by inhibition of Na/Ca exchanger. Side-by-side with CTS acting via elevation of the [Na]/[K] ratio fibroblast to myofibroblast transformation is also suppressed by potent inhibitors of Ca-activated chloride channels tannic acid and K,Cl cotransporter DIOA. The relative impact of [Formula: see text] -mediated and -independent signaling triggered by elevated [Na]/[K] ratio and altered intracellular anion handling in transcriptomic changes involved in myofibroblast differentiation should be examined further.
Topics: Animals; Cell Differentiation; Humans; Ion Transport; Lung; Membrane Transport Proteins; Myofibroblasts; Signal Transduction
PubMed: 31196603
DOI: 10.1016/bs.ctm.2019.01.002 -
Advances in Experimental Medicine and... 2020Store-operated Ca entry (SOCE) is a ubiquitous mechanism for Ca influx in mammalian cells with important physiological implications. Since the discovery of SOCE more... (Review)
Review
Store-operated Ca entry (SOCE) is a ubiquitous mechanism for Ca influx in mammalian cells with important physiological implications. Since the discovery of SOCE more than three decades ago, the mechanism that communicates the information about the amount of Ca accumulated in the intracellular Ca stores to the plasma membrane channels and the nature of these channels have been matters of intense investigation and debate. The stromal interaction molecule-1 (STIM1) has been identified as the Ca sensor of the intracellular Ca compartments that activates the store-operated channels. STIM1 regulates two types of store-dependent channels: the Ca release-activated Ca (CRAC) channels, formed by Orai1 subunits, that conduct the highly Ca selective current I and the cation permeable store-operated Ca (SOC) channels, which consist of Orai1 and TRPC1 proteins and conduct the non-selective current I . While the crystal structure of Drosophila CRAC channel has already been solved, the architecture of the SOC channels still remains unclear. The dynamic interaction of STIM1 with the store-operated channels is modulated by a number of proteins that either support the formation of the functional STIM1-channel complex or protect the cell against Ca overload.
Topics: Animals; Calcium; Calcium Channels; Calcium Signaling; Ion Transport; Stromal Interaction Molecule 1
PubMed: 31646520
DOI: 10.1007/978-3-030-12457-1_17 -
Physiological Reviews Jan 2019The thick ascending limb plays a key role in maintaining water and electrolyte balance. The importance of this segment in regulating blood pressure is evidenced by the... (Review)
Review
The thick ascending limb plays a key role in maintaining water and electrolyte balance. The importance of this segment in regulating blood pressure is evidenced by the effect of loop diuretics or local genetic defects on this parameter. Hormones and factors produced by thick ascending limbs have both autocrine and paracrine effects, which can extend prohypertensive signaling to other structures of the nephron. In this review, we discuss the role of the thick ascending limb in the development of hypertension, not as a sole participant, but one that works within the rich biological context of the renal medulla. We first provide an overview of the basic physiology of the segment and the anatomical considerations necessary to understand its relationship with other renal structures. We explore the physiopathological changes in thick ascending limbs occurring in both genetic and induced animal models of hypertension. We then discuss the racial differences and genetic defects that affect blood pressure in humans through changes in thick ascending limb transport rates. Throughout the text, we scrutinize methodologies and discuss the limitations of research techniques that, when overlooked, can lead investigators to make erroneous conclusions. Thus, in addition to advancing an understanding of the basic mechanisms of physiology, the ultimate goal of this work is to understand our research tools, to make better use of them, and to contextualize research data. Future advances in renal hypertension research will require not only collection of new experimental data, but also integration of our current knowledge.
Topics: Animals; Blood Pressure; Extremities; Humans; Hypertension; Ion Transport; Sodium; Water-Electrolyte Balance
PubMed: 30354966
DOI: 10.1152/physrev.00055.2017 -
Cell Calcium Jul 2017Enamel is the most calcified tissue in vertebrates. It differs from bone in a number of characteristics including its origin from ectodermal epithelium, lack of... (Review)
Review
Enamel is the most calcified tissue in vertebrates. It differs from bone in a number of characteristics including its origin from ectodermal epithelium, lack of remodeling capacity by the enamel forming cells, and absence of collagen. The enamel-forming cells known as ameloblasts, choreograph first the synthesis of a unique protein-rich matrix, followed by the mineralization of this matrix into a tissue that is ∼95% mineral. To do this, ameloblasts arrange the coordinated movement of ions across a cell barrier while removing matrix proteins and monitoring extracellular pH using a variety of buffering systems to enable the growth of carbonated apatite crystals. Although our knowledge of these processes and the molecular identity of the proteins involved in transepithelial ion transport has increased in the last decade, it remains limited compared to other cells. Here we present an overview of the evolution and development of enamel, its differences with bone, and describe the ion transport systems associated with ameloblasts.
Topics: Ameloblasts; Animals; Dental Enamel; Humans; Ion Transport
PubMed: 28389033
DOI: 10.1016/j.ceca.2017.03.006 -
Biochimica Et Biophysica Acta.... Jan 2018Gap junction channels facilitate the intercellular exchange of ions and small molecules. While this process is critical to all multicellular organisms, the proteins that... (Review)
Review
Gap junction channels facilitate the intercellular exchange of ions and small molecules. While this process is critical to all multicellular organisms, the proteins that form gap junction channels are not conserved. Vertebrate gap junctions are formed by connexins, while invertebrate gap junctions are formed by innexins. Interestingly, vertebrates and lower chordates contain innexin homologs, the pannexins, which also form channels, but rarely (if ever) make intercellular channels. While the connexin and the innexin/pannexin polypeptides do not share significant sequence similarity, all three of these protein families share a similar membrane topology and some similarities in quaternary structure. This article is part of a Special Issue entitled: Gap Junction Proteins edited by Jean Claude Herve.
Topics: Animals; Connexins; Gap Junctions; Humans; Ion Transport
PubMed: 28559187
DOI: 10.1016/j.bbamem.2017.05.016 -
International Journal of Molecular... Jul 2021Plants, being sessile, face an array of biotic and abiotic stresses in their lifespan that endanger their survival. Hence, optimized uptake of mineral nutrients creates... (Review)
Review
Plants, being sessile, face an array of biotic and abiotic stresses in their lifespan that endanger their survival. Hence, optimized uptake of mineral nutrients creates potential new routes for enhancing plant health and stress resilience. Recently, minerals (both essential and non-essential) have been identified as key players in plant stress biology, owing to their multifaceted functions. However, a realistic understanding of the relationship between different ions and stresses is lacking. In this context, ionomics will provide new platforms for not only understanding the function of the plant ionome during stresses but also identifying the genes and regulatory pathways related to mineral accumulation, transportation, and involvement in different molecular mechanisms under normal or stress conditions. This article provides a general overview of ionomics and the integration of high-throughput ionomic approaches with other "omics" tools. Integrated omics analysis is highly suitable for identification of the genes for various traits that confer biotic and abiotic stress tolerance. Moreover, ionomics advances being used to identify loci using qualitative trait loci and genome-wide association analysis of element uptake and transport within plant tissues, as well as genetic variation within species, are discussed. Furthermore, recent developments in ionomics for the discovery of stress-tolerant genes in plants have also been addressed; these can be used to produce more robust crops with a high nutritional value for sustainable agriculture.
Topics: Adaptation, Biological; Crops, Agricultural; Ion Transport; Ions; Metabolomics; Plants, Genetically Modified; Quantitative Trait Loci; Spectrum Analysis; Stress, Physiological
PubMed: 34281232
DOI: 10.3390/ijms22137182