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Ca2+ single

Tobias Eckrich, Kerstin Blum, Ivan Milenkovic, Jutta Engel
Before the onset of hearing, which occurs around postnatal day 12 (P12) in mice, inner hair cells (IHCs) of the immature cochlea generate sound-independent Ca2+ action potentials (APs), which stimulate the auditory pathway and guide maturation of neuronal circuits. During these early postnatal days, intercellular propagating Ca2+ waves elicited by ATP-induced ATP release are found in inner supporting cells (ISCs). It is debated whether IHCs are able to fire Ca2+ APs independently or require a trigger by an ISC Ca2+ wave...
2018: Frontiers in Molecular Neuroscience
Aravind S Kshatri, Alberto Gonzalez-Hernandez, Teresa Giraldez
Within the potassium ion channel family, calcium activated potassium (KCa ) channels are unique in their ability to couple intracellular Ca2+ signals to membrane potential variations. KCa channels are diversely distributed throughout the central nervous system and play fundamental roles ranging from regulating neuronal excitability to controlling neurotransmitter release. The physiological versatility of KCa channels is enhanced by alternative splicing and co-assembly with auxiliary subunits, leading to fundamental differences in distribution, subunit composition and pharmacological profiles...
2018: Frontiers in Molecular Neuroscience
Van Tran, Christian Stricker
Not only the amplitude but also the time course of a presynaptic Ca2+ transient determine multiple aspects of synaptic transmission. In small bouton-type synapses, the mechanisms underlying the Ca2+ decay kinetics have not been fully investigated. Here, factors that shape an action-potential-evoked Ca2+ transient were quantitatively studied in synaptic boutons of neocortical layer 5 pyramidal neurons. Ca2+ transients were measured with different concentrations of fluorescent Ca2+ indicators and analyzed based on a single-compartment model...
July 26, 2018: Biophysical Journal
Vera Flasbeck, Erika Atucha, Nozomu H Nakamura, Motoharu Yoshida, Magdalena M Sauvage
For the past decades, CA3 was considered as a single functional entity. However, strong differences between the proximal (close to the dentate gyrus) and the distal (close to CA2) parts of CA3 in terms of connectivity patterns, gene expression and electrophysiological properties suggest that it is not the case. We recently showed that proximal CA3 (together with distal CA1) preferentially deals with non-spatial information [1]. In contrast to proximal CA3, distal CA3 mainly receives and predominantly projects to spatially tuned areas...
August 8, 2018: Behavioural Brain Research
Stefania Mataragka, Colin W Taylor
All three subtypes of inositol 1,4,5-trisphosphate receptor (IP3 R) are intracellular Ca2+ channels that are co-regulated by IP3 and Ca2+ This allows IP3 Rs to evoke regenerative Ca2+ signals, the smallest of which are Ca2+ puffs that reflect the coordinated opening of a few clustered IP3 Rs. We use total internal reflection microscopy (TIRF) microscopy to record Ca2+ signals in HEK cells expressing all three IP3 R subtypes or a single native subtype. Ca2+ puffs are less frequent in cells expressing one IP3 R subtype, commensurate with them expressing fewer IP3 Rs than wild-type cells...
August 10, 2018: Journal of Cell Science
Mary S Kim, Alexander V Maltsev, Oliver Monfredi, Larissa A Maltseva, Ashley Wirth, Maria Cristina Florio, Kenta Tsutsui, Daniel R Riordon, Sean P Parsons, Syevda Tagirova, Bruce D Ziman, Michael D Stern, Edward G Lakatta, Victor A Maltsev
Current understanding of how cardiac pacemaker cells operate is based mainly on studies in isolated single sinoatrial node cells (SANC), specifically those that rhythmically fire action potentials similar to the in vivo behavior of the intact sinoatrial node. However, only a small fraction of SANC exhibit rhythmic firing after isolation. Other SANC behaviors have not been studied. Here, for the first time, we studied all single cells isolated from the sinoatrial node of the guinea pig, including traditionally studied rhythmically firing cells ('rhythmic SANC'), dysrhythmically firing cells ('dysrhythmic SANC') and cells without any apparent spontaneous firing activity ('dormant SANC')...
July 10, 2018: Cell Calcium
Laura Medlock, Lauren Shute, Mark Fry, Dominic Standage, Alastair V Ferguson
Subfornical organ (SFO) neurons exhibit heterogeneity in current expression and spiking behaviour, where the two major spiking phenotypes appear as tonic and burst firing. Insight into the mechanisms behind this heterogeneity is critical for understanding how the SFO, a sensory circumventricular organ, integrates and selectively influences physiological function. To integrate efficient methods for studying this heterogeneity, we built a single-compartment, Hodgkin-Huxley type model of an SFO neuron that is parameterized by SFO-specific in vitro patch clamp data...
August 8, 2018: Journal of Neurophysiology
Petra Gawalek, Monika Stengl
For the hawkmoth Manduca sexta accumulating evidence suggests that pheromone transduction acts via a metabotropic signal transduction cascade, with G-protein-dependent phospholipase C (PLC) activations generating diacylglycerol (DAG) and inositol trisphosphate as the primary events in hawkmoth pheromone transduction. In contrast, ionotropic olfactory receptor (OR) coreceptor (Orco)-dependent mechanisms do not appear to be involved. In hawkmoths pheromones activated a specific sequence of PLC-dependent ion channels of unknown identity...
2018: Frontiers in Cellular Neuroscience
Dushyant Mishra, Natasha Thorne, Chika Miyamoto, Christopher Jagge, Hubert Amrein
Animals employ various types of taste receptors to identify and discriminate between different nutritious food chemicals. These macronutrients are thought to fall into 3 major groups: carbohydrates/sugars, proteins/amino acids, and fats. Here, we report that Drosophila larvae exhibit a novel appetitive feeding behavior towards ribose, ribonucleosides, and RNA. We identified members of the gustatory receptor (Gr) subfamily 28 (Gr28), expressed in both external and internal chemosensory neurons as molecular receptors necessary for cellular and appetitive behavioral responses to ribonucleosides and RNA...
August 2018: PLoS Biology
L C Morley, J Shi, H J Gaunt, A J Hyman, P J Webster, C Williams, K Forbes, J J Walker, N A B Simpson, D J Beech
STUDY QUESTION: Does the shear stress sensing ion channel subunit Piezo1 have an important mechanotransduction role in human fetoplacental endothelium? SUMMARY ANSWER: Piezo1 is present and functionally active in human fetoplacental endothelial cells, and disruption of Piezo1 prevents the normal response to shear stress. WHAT IS KNOWN ALREADY: Shear stress is an important stimulus for maturation and function of placental vasculature but the molecular mechanisms by which the force is detected and transduced are unclear...
August 2, 2018: Molecular Human Reproduction
Akiko Hida, Takahisa Tajima, Junichi Kato
The bacterial wilt pathogen Ralstonia pseudosolanacearum Ps29 exhibited chemotactic responses to citrate. This pathogen expresses 22 putative chemoreceptors. In screening a complete collection of mcp single-gene deletion mutants of Ps29, none showed a significant decrease in response to citrate compared with the wild-type strain. Analysis of a collection of stepwise- and multiple-deletion mutants of Ps29 revealed that the RS_RS07350 homolog (designated McpC) and McpP (chemoreceptor mediating both positive chemotaxis to phosphate and negative chemotaxis to maleate) are chemoreceptors for citrate...
August 3, 2018: Journal of Bioscience and Bioengineering
Douglas J Brusich, Ashlyn M Spring, Thomas D James, Catherine J Yeates, Timothy H Helms, C Andrew Frank
Gain-of-function mutations in the human CaV2.1 gene CACNA1A cause familial hemiplegic migraine type 1 (FHM1). To characterize cellular problems potentially triggered by CaV2.1 gains of function, we engineered mutations encoding FHM1 amino-acid substitutions S218L (SL) and R192Q (RQ) into transgenes of Drosophila melanogaster CaV2/cacophony. We expressed the transgenes pan-neuronally. Phenotypes were mild for RQ-expressing animals. By contrast, single mutant SL- and complex allele RQ,SL-expressing animals showed overt phenotypes, including sharply decreased viability...
August 6, 2018: PLoS Genetics
Rasmus Kordt Christensen, Rodolfo Delgado-Lezama, Raúl E Russo, Barbara Lykke Lind, Emanuel Loeza Alcocer, Martin Fredensborg Rath, Gabriela Fabbiani, Nicole Schmitt, Martin Lauritzen, Anders Victor Petersen, Eva Meier Carlsen, Jean-François Perrier
KEY POINTS SUMMARY: GABA is an essential molecule for sensory information processing. It is usually assumed to be released by neurons. Here we show that in the dorsal horn of the spinal cord, astrocytes respond to glutamate by releasing GABA. Our findings suggest a novel role for astrocytes in somatosensory information processing. ABSTRACT: Astrocytes participate in neuronal signalling by releasing gliotransmitters in response to neurotransmitters. We investigated if astrocytes from the dorsal horn of the spinal cord of adult red-eared turtles (Trachemys scripta elegans) release GABA in response to glutamatergic receptor activation...
August 5, 2018: Journal of Physiology
Brikha R Shrestha, Chester Chia, Lorna Wu, Sharon G Kujawa, M Charles Liberman, Lisa V Goodrich
In the auditory system, type I spiral ganglion neurons (SGNs) convey complex acoustic information from inner hair cells (IHCs) to the brainstem. Although SGNs exhibit variation in physiological and anatomical properties, it is unclear which features are endogenous and which reflect input from synaptic partners. Using single-cell RNA sequencing, we derived a molecular classification of mouse type I SGNs comprising three subtypes that express unique combinations of Ca2+ binding proteins, ion channel regulators, guidance molecules, and transcription factors...
July 28, 2018: Cell
Gloria J Partida, Anna Fasoli, Alex Fogli Iseppe, Genki Ogata, Jeffrey S Johnson, Vithya Thambiaiyah, Christopher L Passaglia, Andrew T Ishida
Repeated spike firing is useful both in transmitting information at synapses and in modulating spike timing, shape, and conduction velocity. These latter effects can result from voltage-induced changes in ion currents and may alter the signals carried by axons. Here, we test whether Ca2+ /calmodulin-dependent protein kinase II (CaMKII) regulates spike propagation in adult rat optic nerve. We find that small-, medium-, and large-diameter axons bind anti-Thr286-phosphorylated CaMKII (pT286) antibodies and that, in isolated optic nerves, electrical stimulation reduces pT286 levels; spike propagation is hastened by CaMKII autophosphorylation and slowed by CaMKII dephosphorylation; single and multiple spikes slow propagation of subsequently activated spikes; and more frequent stimulation produces greater slowing...
August 3, 2018: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Nidhi Sehgal, Saurabh Singh
The sporophytic system of self-incompatibility is a widespread genetic phenomenon in plant species, promoting out-breeding and maintaining genetic diversity. This phenomenon is of commercial importance in hybrid breeding of Brassicaceae crops and is controlled by single S locus with multiple S haplotypes. The molecular genetic studies of Brassica ' S ' locus has revealed the presence of three tightly linked loci viz. S-receptor kinase ( SRK ), S-locus cysteine-rich protein/S-locus protein 11 ( SCR / SP11 ), and S-locus glycoprotein ( SLG )...
August 2018: 3 Biotech
Ricardo Bezerra Costa, Patricia Targon Campana, Felipe Santiago Chambergo, Thiago Henrique Napoleão, Patrícia Maria Guedes Paiva, Hugo Juarez Vieira Pereira, Maria Luiza Vilela Oliva, Francis Soares Gomes
Genipa americana L., commonly known as genipap, is a plant with economical and medicinal importance, and a promising source of bioactive compounds. Lectins are carbohydrate-binding proteins with several biotechnological applications. This study reports the isolation and characterization of a G. americana bark lectin (GaBL). A single chromatographic procedure on Sephacryl S-100 resulted in isolation of GaBL, a protein with native molecular weight of over 200 kDa and pI 4.02, whose hemagglutinating activity was inhibited by lactose and fetuin, not affected by ions (Ca2+ and Mg2+ ), and stable upon heating (303-393 K) as well as over the pH range 5-10...
July 29, 2018: International Journal of Biological Macromolecules
Ke Zhou, Zhiping Xu
Recently experimental studies of selective ion transport across nanoporous membranes or through single nanochannels have unveiled interesting behaviors of dissolved ions under nanoconfinement. However, the exploration was limited by the resolution of experimental characterization. In this work, we present an atomistic simulation based study, showing how the nanoconfinement and surface functionalization of graphene and graphene oxide nanochannels renormalize the solvation of ions (Na+, K+, Mg2+, Ca2+, Cl-). We find that the spatial distribution of dissolved ions demonstrates a layered order in nanochannels...
July 30, 2018: ACS Applied Materials & Interfaces
Dae-Hyuk Kweon, Byoungjae Kong, Yeon-Kyun Shin
Neurons have the remarkable ability to release a batch of neurotransmitters into the synapse immediately after an action potential. This signature event is made possible by the simultaneous fusion of a number of synaptic vesicles to the plasma membrane upon Ca2+ entry into the active zone. The outcomes of both cellular and in vitro studies suggest that soluble N-ethylmaleimide-sensitive-factor attachment protein receptors (SNAREs) and synaptotagmin 1 (Syt1) constitute the minimal fast exocytosis machinery in the neuron...
July 26, 2018: Neuroscience
Arzu Şakul, Nuray Arı, Ruzenna Sotnikova, Gülgün Ozansoy, Çimen Karasu
We studied the effects of treatment with SMe1EC, a hexahydropyridoindole antioxidant, on vascular reactivity, endothelial function, and oxidonitrosative stress level of thoracic aorta in young and old rats with or without diabetes mellitus. The rats were grouped as young control (YC 3 months old), old control (OC 15 months old), young diabetic (YD), old diabetic (OD), young control treated (YCT), old control treated (OCT), young diabetic treated (YDT), and old diabetic treated (ODT). Diabetes was induced by streptozotocin injection and subsequently SMe1EC2 (10 mg/kg/day, p...
July 27, 2018: GeroScience
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