scholarly journals Consensus channelome of dinoflagellates revealed by transcriptomic analysis sheds light on their physiology

ALGAE ◽  
2021 ◽  
Vol 36 (4) ◽  
pp. 315-326
Author(s):  
Ilya Pozdnyakov ◽  
Olga Matantseva ◽  
Sergei Skarlato
Keyword(s):  
Ion Channels ◽  
Potassium Channels ◽  
Ion Channel ◽  
Chloride Channels ◽  
Cation Channels ◽  
Mechanosensitive Channels ◽  
Anion Channels ◽  
Voltage Gated ◽  
Calcium Activated Potassium Channels ◽  
Pore Domain

Ion channels are membrane protein complexes mediating passive ion flux across the cell membranes. Every organism has a certain set of ion channels that define its physiology. Dinoflagellates are ecologically important microorganisms characterized by effective physiological adaptability, which backs up their massive proliferations that often result in harmful blooms (red tides). In this study, we used a bioinformatics approach to identify homologs of known ion channels that belong to 36 ion channel families. We demonstrated that the versatility of the dinoflagellate physiology is underpinned by a high diversity of ion channels including homologs of animal and plant proteins, as well as channels unique to protists. The analysis of 27 transcriptomes allowed reconstructing a consensus ion channel repertoire (channelome) of dinoflagellates including the members of 31 ion channel families: inwardly-rectifying potassium channels, two-pore domain potassium channels, voltage-gated potassium channels (Kv), tandem Kv, cyclic nucleotide-binding domain-containing channels (CNBD), tandem CNBD, eukaryotic ionotropic glutamate receptors, large-conductance calcium-activated potassium channels, intermediate/small-conductance calcium-activated potassium channels, eukaryotic single-domain voltage-gated cation channels, transient receptor potential channels, two-pore domain calcium channels, four-domain voltage-gated cation channels, cation and anion Cys-loop receptors, small-conductivity mechanosensitive channels, large-conductivity mechanosensitive channels, voltage-gated proton channels, inositole-1,4,5- trisphosphate receptors, slow anion channels, aluminum-activated malate transporters and quick anion channels, mitochondrial calcium uniporters, voltage-dependent anion channels, vesicular chloride channels, ionotropic purinergic receptors, animal volage-insensitive cation channels, channelrhodopsins, bestrophins, voltage-gated chloride channels H+/Cl- exchangers, plant calcium-permeable mechanosensitive channels, and trimeric intracellular cation channels. Overall, dinoflagellates represent cells able to respond to physical and chemical stimuli utilizing a wide range of Gprotein coupled receptors- and Ca2+-dependent signaling pathways. The applied approach not only shed light on the ion channel set in dinoflagellates, but also provided the information on possible molecular mechanisms underlying vital cellular processes dependent on the ion transport.

scholarly journals Panama: A tool for ion channel biophysics simulation

2018 ◽  
Author(s):  
Anuj Guruacharya
Keyword(s):  
Ion Channels ◽  
Potassium Channels ◽  
Calcium Channels ◽  
Ion Channel ◽  
Chloride Channels ◽  
High Threshold ◽  
Spreadsheet Program ◽  
Online Tool ◽  
Voltage Gated ◽  
Web App

I have created an online tool and an R library that simulates biophysics of voltage-gated ion channels. It is made publicly available as an R library called Panama at github.com/anuj2054/panama and as a web app at neuronsimulator.com. A need for such a tool was observed after surveying available software packages. I found that the available packages are either not robust enough to simulate multiple ion channels, too complicated, usable only as desktop software, not optimized for mobile devices, not interactive, lacking intuitive graphical controls, or not appropriate for undergraduate education. My app simulates the physiology of 11 different channels - voltage-gated sodium, potassium, and chloride channels; channels causing A-current, M-current, and After-HyperPolarization (AHP) current; calcium-activated potassium channels; low threshold T type calcium channels and high threshold L type calcium channels; leak sodium and leak potassium channels. It can simulate these channels under both current clamp and voltage clamp conditions. As we change the input values on the app, the output can be instantaneously visualized on the web browser and downloaded as a data table to be further analyzed in a spreadsheet program. The app is a first of its kind, mobile-friendly and touch-screen-friendly online tool that can be used to teach undergraduate neuroscience classes. It can also be used by researchers on their local computers as part of an R library. It has intuitive touch-optimized controls, instantaneous graphical output, and yet is pedagogically robust for education and casual research purposes.Neuroscience education, ion channel biophysics, Hodgkin-Huxley simulation, web app for neuroscience

Uterine Excitability and Ion Channels and Their Changes with Gestation and Hormonal Environment

2020 ◽  
Vol 83 (1) ◽  
Author(s):  
Susan Wray ◽  
Sarah Arrowsmith
Keyword(s):  
Ion Channels ◽  
Inward Rectifier ◽  
Cation Channels ◽  
Annual Review ◽  
Publication Date ◽  
K Channels ◽  
Voltage Gated ◽  
New Findings ◽  
Voltage Dependent ◽  
Pore Domain

We address advances in the understanding of myometrial physiology, focusing on excitation and the effects of gestation on ion channels and their relevance to labor. This review moves through pioneering studies to exciting new findings. We begin with the myometrium and its myocytes and describe how excitation might initiate and spread in this myogenic smooth muscle. We then review each of the ion channels in the myometrium: L- and T-type Ca2+ channels, KATP (Kir6) channels, voltage-dependent K channels (Kv4, Kv7, and Kv11), twin-pore domain K channels (TASK, TREK), inward rectifier Kir7.1, Ca2+-activated K+ channels with large (KCNMA1, Slo1), small (KCNN1–3), and intermediate (KCNN4) conductance, Na-activated K channels (Slo2), voltage-gated (SCN) Na+ and Na+ leak channels, nonselective (NALCN) channels, the Na K-ATPase, and hyperpolarization-activated cation channels. We finish by assessing how three key hormones— oxytocin, estrogen, and progesterone—modulate and integrate excitability throughout gestation. Expected final online publication date for the Annual Review of Physiology, Volume 83 is February 10, 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

scholarly journals Inhibition of Potassium Channels Affects the Ability of Pig Spermatozoa to Elicit Capacitation and Trigger the Acrosome Exocytosis Induced by Progesterone

2021 ◽  
Vol 22 (4) ◽  
pp. 1992
Author(s):  
Federico Noto ◽  
Sandra Recuero ◽  
Julián Valencia ◽  
Beatrice Saporito ◽  
Domenico Robbe ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Potassium Channels ◽  
Intracellular Calcium ◽  
Sperm Motility ◽  
Specific Inhibitor ◽  
Sperm Capacitation ◽  
Membrane Hyperpolarization ◽  
Voltage Gated ◽  
Calcium Activated Potassium Channels ◽  
Pore Domain

During capacitation, sperm undergo a myriad of changes, including remodeling of plasma membrane, modification of sperm motility and kinematic parameters, membrane hyperpolarization, increase in intracellular calcium levels, and tyrosine phosphorylation of certain sperm proteins. While potassium channels have been reported to be crucial for capacitation of mouse and human sperm, their role in pigs has not been investigated. With this purpose, sperm samples from 15 boars were incubated in capacitation medium for 300 min with quinine, a general blocker of potassium channels (including voltage-gated potassium channels, calcium-activated potassium channels, and tandem pore domain potassium channels), and paxilline (PAX), a specific inhibitor of calcium-activated potassium channels. In all samples, acrosome exocytosis was induced after 240 min of incubation with progesterone. Plasma membrane and acrosome integrity, membrane lipid disorder, intracellular calcium levels, mitochondrial membrane potential, and total and progressive sperm motility were evaluated after 0, 120, and 240 min of incubation, and after 5, 30, and 60 min of progesterone addition. Although blocking potassium channels with quinine and PAX prevented sperm to elicit in vitro capacitation by impairing motility and mitochondrial function, as well as reducing intracellular calcium levels, the extent of that inhibition was larger with quinine than with PAX. Therefore, while our data support that calcium-activated potassium channels are essential for sperm capacitation in pigs, they also suggest that other potassium channels, such as the voltage-gated, tandem pore domain, and mitochondrial ATP-regulated ones, are involved in that process. Thus, further research is needed to elucidate the specific functions of these channels and the mechanisms underlying its regulation during sperm capacitation.

Channelopathies: Their Contribution to Our Knowledge About Voltage-Gated Ion Channels

Physiology ◽  
1997 ◽  
Vol 12 (3) ◽  
pp. 105-112
Author(s):  
F Lehmann-Horn ◽  
R Rudel
Keyword(s):  
Skeletal Muscle ◽  
Ion Channels ◽  
Ion Channel ◽  
Chloride Channels ◽  
Gene Products ◽  
Sodium Potassium ◽  
Voltage Gated ◽  
Voltage Dependent ◽  
Genes Encoding ◽  
Voltage Gated Ion Channels

Since 1990, many mutations in genes encoding voltage-dependent sodium, potassium, calcium, and chloride channels have been discovered to cause disorders of heart, skeletal muscle, brain, or kidney. Study of the defective gene products has furthered our knowledge not only of pathology but also of ion-channel function.

Ion Channel Permeation and Selectivity

2019 ◽  
Author(s):  
Juan J. Nogueira ◽  
Ben Corry
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Ion Selectivity ◽  
Ionic Currents ◽  
Biological Processes ◽  
Ion Permeation ◽  
Voltage Gated ◽  
Physical Mechanisms ◽  
Theoretical Approaches ◽  
Mechanistic Insight

Many biological processes essential for life rely on the transport of specific ions at specific times across cell membranes. Such exquisite control of ionic currents, which is regulated by protein ion channels, is fundamental for the proper functioning of the cells. It is not surprising, therefore, that the mechanism of ion permeation and selectivity in ion channels has been extensively investigated by means of experimental and theoretical approaches. These studies have provided great mechanistic insight but have also raised new questions that are still unresolved. This chapter first summarizes the main techniques that have provided significant knowledge about ion permeation and selectivity. It then discusses the physical mechanisms leading to ion permeation and the explanations that have been proposed for ion selectivity in voltage-gated potassium, sodium, and calcium channels.

scholarly journals Cyclic Nucleotide-Gated Ion Channels

2002 ◽  
Vol 82 (3) ◽  
pp. 769-824 ◽  
Author(s):  
U. Benjamin Kaupp ◽  
Reinhard Seifert
Keyword(s):  
Ion Channels ◽  
Sensory Neurons ◽  
Cyclic Nucleotide ◽  
Cation Channels ◽  
Voltage Gated ◽  
Nonselective Cation Channels ◽  
Retinal Photoreceptors ◽  
Cng Channel ◽  
B Subunits ◽  
Gated Ion Channels

Cyclic nucleotide-gated (CNG) channels are nonselective cation channels first identified in retinal photoreceptors and olfactory sensory neurons (OSNs). They are opened by the direct binding of cyclic nucleotides, cAMP and cGMP. Although their activity shows very little voltage dependence, CNG channels belong to the superfamily of voltage-gated ion channels. Like their cousins the voltage-gated K+ channels, CNG channels form heterotetrameric complexes consisting of two or three different types of subunits. Six different genes encoding CNG channels, four A subunits (A1 to A4) and two B subunits (B1 and B3), give rise to three different channels in rod and cone photoreceptors and in OSNs. Important functional features of these channels, i.e., ligand sensitivity and selectivity, ion permeation, and gating, are determined by the subunit composition of the respective channel complex. The function of CNG channels has been firmly established in retinal photoreceptors and in OSNs. Studies on their presence in other sensory and nonsensory cells have produced mixed results, and their purported roles in neuronal pathfinding or synaptic plasticity are not as well understood as their role in sensory neurons. Similarly, the function of invertebrate homologs found in Caenorhabditis elegans, Drosophila,and Limulus is largely unknown, except for two subunits of C. elegans that play a role in chemosensation. CNG channels are nonselective cation channels that do not discriminate well between alkali ions and even pass divalent cations, in particular Ca2+. Ca2+ entry through CNG channels is important for both excitation and adaptation of sensory cells. CNG channel activity is modulated by Ca2+/calmodulin and by phosphorylation. Other factors may also be involved in channel regulation. Mutations in CNG channel genes give rise to retinal degeneration and color blindness. In particular, mutations in the A and B subunits of the CNG channel expressed in human cones cause various forms of complete and incomplete achromatopsia.

Voltage-Gated Ion Channels and Hereditary Disease

1999 ◽  
Vol 79 (4) ◽  
pp. 1317-1372 ◽  
Author(s):  
Frank Lehmann-Horn ◽  
Karin Jurkat-Rott
Keyword(s):  
Ion Channels ◽  
Ion Channel ◽  
Recombinant Dna ◽  
Hereditary Disease ◽  
Hereditary Diseases ◽  
Technological Advancement ◽  
Myotonia Congenita ◽  
Voltage Gated ◽  
Voltage Gated Ion Channels ◽  
Gated Ion Channels

By the introduction of technological advancement in methods of structural analysis, electronics, and recombinant DNA techniques, research in physiology has become molecular. Additionally, focus of interest has been moving away from classical physiology to become increasingly centered on mechanisms of disease. A wonderful example for this development, as evident by this review, is the field of ion channel research which would not be nearly as advanced had it not been for human diseases to clarify. It is for this reason that structure-function relationships and ion channel electrophysiology cannot be separated from the genetic and clinical description of ion channelopathies. Unique among reviews of this topic is that all known human hereditary diseases of voltage-gated ion channels are described covering various fields of medicine such as neurology (nocturnal frontal lobe epilepsy, benign neonatal convulsions, episodic ataxia, hemiplegic migraine, deafness, stationary night blindness), nephrology (X-linked recessive nephrolithiasis, Bartter), myology (hypokalemic and hyperkalemic periodic paralysis, myotonia congenita, paramyotonia, malignant hyperthermia), cardiology (LQT syndrome), and interesting parallels in mechanisms of disease emphasized. Likewise, all types of voltage-gated ion channels for cations (sodium, calcium, and potassium channels) and anions (chloride channels) are described together with all knowledge about pharmacology, structure, expression, isoforms, and encoding genes.

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