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Channelrhodopsin

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https://www.readbyqxmd.com/read/29221794/glp-1-action-in-the-mouse-bed-nucleus-of-the-stria-terminalis
#1
Diana L Williams, Nicole A Lilly, Ian J Edwards, Pallas Yao, James E Richards, Stefan Trapp
Glucagon-like peptide-1 (GLP-1) injected into the brain reduces food intake. Similarly, activation of preproglucagon (PPG) cells in the hindbrain which synthesize GLP-1, reduces food intake. However, it is far from clear whether this happens because of satiety, nausea, reduced reward, or even stress. Here we explore the role of the bed nucleus of the stria terminalis (BNST), an area involved in feeding control as well as stress responses, in GLP-1 responses. Using cre-expressing mice we visualized projections of NTS PPG neurons and GLP-1R-expressing BNST cells with AAV-driven Channelrhodopsin-YFP expression...
December 5, 2017: Neuropharmacology
https://www.readbyqxmd.com/read/29211031/frequency-dependent-multi-well-cardiotoxicity-screening-enabled-by-optogenetic-stimulation
#2
Susanne Rehnelt, Daniela Malan, Krisztina Juhasz, Benjamin Wolters, Leo Doerr, Matthias Beckler, Ralf Kettenhofen, Heribert Bohlen, Tobias Bruegmann, Philipp Sasse
Side effects on cardiac ion channels causing lethal arrhythmias are one major reason for drug withdrawals from the market. Field potential (FP) recording from cardiomyocytes, is a well-suited tool to assess such cardiotoxic effects of drug candidates in preclinical drug development, but it is currently limited to the spontaneous beating of the cardiomyocytes and manual analysis. Herein, we present a novel optogenetic cardiotoxicity screening system suited for the parallel automated frequency-dependent analysis of drug effects on FP recorded from human-induced pluripotent stem cell-derived cardiomyocytes...
December 6, 2017: International Journal of Molecular Sciences
https://www.readbyqxmd.com/read/29201627/dual-color-emitting-carbon-nanodots-for-multicolor-bioimaging-and-optogenetic-control-of-ion-channels
#3
Hyemin Kim, Yoonsang Park, Songeun Beack, Seulgi Han, Dooyup Jung, Hyung Joon Cha, Woosung Kwon, Sei Kwang Hahn
The development of intrinsically multicolor-emitting carbon nanodots (CNDs) has been one of the great challenges for their various fields of applications. Here, the controlled electronic structure engineering of CNDs is performed to emit two distinct colors via the facile surface modification with 4-octyloxyaniline. The so-called dual-color-emitting CNDs (DC-CNDs) can be stably encapsulated within poly(styrene-co-maleic anhydride) (PSMA). The prepared water-soluble DC-CNDs@PSMA can be successfully applied to in vitro and in vivo dual-color bioimaging and optogenetics...
November 2017: Advanced Science (Weinheim, Baden-Wurttemberg, Germany)
https://www.readbyqxmd.com/read/29193078/termination-of-reentrant-atrial-tachycardia-via-optogenetic-stimulation-with-optimized-spatial-targeting-insights-from-computational-models
#4
Patrick M Boyle, Michael J Murphy, Thomas V Karathanos, Sohail Zahid, Robert C Blake, Natalia A Trayanova
Optogenetics has emerged as a potential alternative to electrotherapy for treating arrhythmia, but feasibility studies have been limited to ventricular defibrillation via epicardial light application. Here, we assess the efficacy of optogenetic atrial tachycardia (AT) termination in human hearts using a strategy that targets for illumination specific regions identified in an automated manner. In three patient-specific models reconstructed from late gadolinium-enhanced MRI scans, we simulated channelrhodopsin-2 (ChR2) expression via gene delivery...
November 28, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/29191773/expression-of-channelrhodopsin-2-localized-within-the-deep-ca1-hippocampal-sublayer-in-the-thy1-line-18-mouse
#5
Dorothy L Dobbins, David C Klorig, Thuy Smith, Dwayne W Godwin
Optogenetic proteins are powerful tools for advancing our understanding of neural circuitry. However, the precision of optogenetics is dependent in part on the extent to which expression is limited to cells of interest. The Thy1-ChR2 transgenic mouse is commonly used in optogenetic experiments. Although general expression patterns in these animals have been characterized, a detailed evaluation of cell-type specificity is lacking. This information is critical for interpretation of experimental results using these animals...
November 27, 2017: Brain Research
https://www.readbyqxmd.com/read/29190499/crosstalk-between-developing-vasculature-and-optogenetically-engineered-skeletal-muscle-improves-muscle-contraction-and-angiogenesis
#6
Tatsuya Osaki, Vivek Sivathanu, Roger D Kamm
Capillary networks surrounding skeletal muscle play an important role in not only supplying oxygen and nutrients but also in regulating the myogenesis and repair of skeletal muscle tissues. Herein, we model the early stages of 3D vascularized muscle fiber formation in vitro using a sequential molding technique to investigate interactions between angiogenesis of endothelial cells and myogenesis of skeletal muscle cells. Channelrhodopsin-2 C2C12 muscle fiber bundles and 3D vascular structures (600 μm diameter) were formed at 500 μm intervals in a collagen gel...
November 25, 2017: Biomaterials
https://www.readbyqxmd.com/read/29184208/temporally-precise-single-cell-resolution-optogenetics
#7
Or A Shemesh, Dimitrii Tanese, Valeria Zampini, Changyang Linghu, Kiryl Piatkevich, Emiliano Ronzitti, Eirini Papagiakoumou, Edward S Boyden, Valentina Emiliani
Optogenetic control of individual neurons with high temporal precision within intact mammalian brain circuitry would enable powerful explorations of how neural circuits operate. Two-photon computer-generated holography enables precise sculpting of light and could in principle enable simultaneous illumination of many neurons in a network, with the requisite temporal precision to simulate accurate neural codes. We designed a high-efficacy soma-targeted opsin, finding that fusing the N-terminal 150 residues of kainate receptor subunit 2 (KA2) to the recently discovered high-photocurrent channelrhodopsin CoChR restricted expression of this opsin primarily to the cell body of mammalian cortical neurons...
December 2017: Nature Neuroscience
https://www.readbyqxmd.com/read/29173049/light-directed-migration-of-a-cluster-of-cells-in-the-centimeter-scale
#8
Abdullah Al Mosabbir, Kevin Truong
Protein-based systems for light directed migration of cells have been demonstrated up to distances of several hundred microns, but larger distances in the centimeter scale would allow new possible applications. Light activated migration in mammalian cells can be achieved by cells expressing channelrhodopsin-2 and an engineered Ca2+ sensitive Rac1 protein called RACer. In this study, light was used to induce wound healing, localize cells into a region of interest, and move cells over centimeter scale distances...
November 26, 2017: Small GTPases
https://www.readbyqxmd.com/read/29170223/channelrhodopsin-reveals-its-dark-secrets
#9
COMMENT
Klaus Gerwert
No abstract text is available yet for this article.
November 24, 2017: Science
https://www.readbyqxmd.com/read/29170206/structural-insights-into-ion-conduction-by-channelrhodopsin-2
#10
Oleksandr Volkov, Kirill Kovalev, Vitaly Polovinkin, Valentin Borshchevskiy, Christian Bamann, Roman Astashkin, Egor Marin, Alexander Popov, Taras Balandin, Dieter Willbold, Georg Büldt, Ernst Bamberg, Valentin Gordeliy
The light-gated ion channel channelrhodopsin 2 (ChR2) from Chlamydomonas reinhardtii is a major optogenetic tool. Photon absorption starts a well-characterized photocycle, but the structural basis for the regulation of channel opening remains unclear. We present high-resolution structures of ChR2 and the C128T mutant, which has a markedly increased open-state lifetime. The structure reveals two cavities on the intracellular side and two cavities on the extracellular side. They are connected by extended hydrogen-bonding networks involving water molecules and side-chain residues...
November 24, 2017: Science
https://www.readbyqxmd.com/read/29162453/combined-hypoxia-and-hypercapnia-but-not-hypoxia-alone-suppresses-neurotransmission-from-orexin-to-hypothalamic-paraventricular-spinally-projecting-neurons-in-weanling-rats
#11
Olga Dergacheva, David Mendelowitz
Both orexin neurons in the lateral hypothalamus and spinally-projecting pre-sympathetic neurons (PSNs) in the paraventricular nucleus of the hypothalamus (PVN) play an important role in the regulation of cardiovascular function under normal conditions and during cardiovascular challenges such as hypoxia and/or hypercapnia. We have previously established, using selective optogenetic excitation of orexin neurons and pathways, there is a heterogeneous neurotransmission from orexin neurons to PSNs in the PVN. This study was undertaken to test whether this pathway is altered by acute exposure to hypoxia alone and/or combined hypoxia and hypercapnia (H/H)...
November 18, 2017: Brain Research
https://www.readbyqxmd.com/read/29158498/activity-dependent-expression-of-channelrhodopsin-at-neuronal-synapses
#12
Francesco Gobbo, Laura Marchetti, Ajesh Jacob, Bruno Pinto, Noemi Binini, Federico Pecoraro Bisogni, Claudia Alia, Stefano Luin, Matteo Caleo, Tommaso Fellin, Laura Cancedda, Antonino Cattaneo
Increasing evidence points to the importance of dendritic spines in the formation and allocation of memories, and alterations of spine number and physiology are associated to memory and cognitive disorders. Modifications of the activity of subsets of synapses are believed to be crucial for memory establishment. However, the development of a method to directly test this hypothesis, by selectively controlling the activity of potentiated spines, is currently lagging. Here we introduce a hybrid RNA/protein approach to regulate the expression of a light-sensitive membrane channel at activated synapses, enabling selective tagging of potentiated spines following the encoding of a novel context in the hippocampus...
November 20, 2017: Nature Communications
https://www.readbyqxmd.com/read/29152380/wide-field-three-photon-excitation-in-biological-samples
#13
Christopher J Rowlands, Demian Park, Oliver T Bruns, Kiryl D Piatkevich, Dai Fukumura, Rakesh K Jain, Moungi G Bawendi, Edward S Boyden, Peter Tc So
Three-photon wide-field depth-resolved excitation is used to overcome some of the limitations in conventional point-scanning two- and three-photon microscopy. Excitation of chromophores as diverse as channelrhodopsins and quantum dots is shown, and a penetration depth of more than 700 μm into fixed scattering brain tissue is achieved, approximately twice as deep as that achieved using two-photon wide-field excitation. Compatibility with live animal experiments is confirmed by imaging the cerebral vasculature of an anesthetized mouse; a complete focal stack was obtained without any evidence of photodamage...
May 5, 2017: Light, Science & Applications
https://www.readbyqxmd.com/read/29125160/the-femtosecond-to-second-photochemistry-of-red-shifted-fast-closing-anion-channelrhodopsin-psacr1
#14
Yusaku Hontani, Matthias Broser, Arita Silapetere, Benjamin S Krause, Peter Hegemann, John T M Kennis
Anion channelrhodopsins (ACRs) are of great interest due to their ability to inhibit electrical signaling in optogenetic experiments. The photochemistry of ACRs is currently poorly understood and an improved understanding would be beneficial for rational design of ACRs with modified properties. Activation/deactivation of ACRs involves a series of photoreactions ranging from femtoseconds to seconds, thus real-time observation is essential to comprehend the full complexity of the photochemical processes. Here we investigate the photocycle of an ACR from Proteomonas sulcata (PsACR1), which is valuable for optogenetic applications due to the red-shifted absorption and action spectra compared to the prototype ACRs from Guillardia theta: GtACR1 and GtACR2, and the fast channel closing properties...
November 22, 2017: Physical Chemistry Chemical Physics: PCCP
https://www.readbyqxmd.com/read/29110301/studies-of-cortical-connectivity-using-optical-circuit-mapping-methods
#15
Paul G Anastasiades, Andre Marques-Smith, Simon J B Butt
An important consideration when probing the function of any neuron is to uncover the source of synaptic input onto the cell, its intrinsic physiology and efferent targets. Over the years, electrophysiological approaches have generated considerable insight into these properties in a variety of cortical neuronal subtypes and circuits. However, as researchers explore neuronal function in greater detail, they are increasingly turning to optical techniques to bridge the gap between local network interactions and behaviour...
November 6, 2017: Journal of Physiology
https://www.readbyqxmd.com/read/29100543/characterization-of-a-thalamic-nucleus-mediating-habenula-responses-to-changes-in-ambient-illumination
#16
Ruey-Kuang Cheng, Seetha Krishnan, Qian Lin, Caroline Kibat, Suresh Jesuthasan
BACKGROUND: Neural activity in the vertebrate habenula is affected by ambient illumination. The nucleus that links photoreceptor activity with the habenula is not well characterized. Here, we describe the location, inputs and potential function of this nucleus in larval zebrafish. RESULTS: High-speed calcium imaging shows that light ON and OFF both evoke a rapid response in the dorsal left neuropil of the habenula, indicating preferential targeting of this neuropil by afferents conveying information about ambient illumination...
October 31, 2017: BMC Biology
https://www.readbyqxmd.com/read/29100505/optical-inhibition-of-larval-zebrafish-behaviour-with-anion-channelrhodopsins
#17
Gadisti Aisha Mohamed, Ruey-Kuang Cheng, Joses Ho, Seetha Krishnan, Farhan Mohammad, Adam Claridge-Chang, Suresh Jesuthasan
BACKGROUND: Optical silencing of activity provides a way to test the necessity of neurons in behaviour. Two light-gated anion channels, GtACR1 and GtACR2, have recently been shown to potently inhibit activity in cultured mammalian neurons and in Drosophila. Here, we test the usefulness of these channels in larval zebrafish, using spontaneous coiling behaviour as the assay. RESULTS: When the GtACRs were expressed in spinal neurons of embryonic zebrafish and actuated with blue or green light, spontaneous movement was inhibited...
November 3, 2017: BMC Biology
https://www.readbyqxmd.com/read/29097684/anion-conducting-channelrhodopsins-with-tuned-spectra-and-modified-kinetics-engineered-for-optogenetic-manipulation-of-behavior
#18
Jonas Wietek, Silvia Rodriguez-Rozada, Janine Tutas, Federico Tenedini, Christiane Grimm, Thomas G Oertner, Peter Soba, Peter Hegemann, J Simon Wiegert
Genetic engineering of natural light-gated ion channels has proven a powerful way to generate optogenetic tools for a wide variety of applications. In recent years, blue-light activated engineered anion-conducting channelrhodopsins (eACRs) have been developed, improved, and were successfully applied in vivo. We asked whether the approaches used to create eACRs can be transferred to other well-characterized cation-conducting channelrhodopsins (CCRs) to obtain eACRs with a broad spectrum of biophysical properties...
November 2, 2017: Scientific Reports
https://www.readbyqxmd.com/read/29097406/localized-optogenetic-targeting-of-rotors-in-atrial-cardiomyocyte-monolayers
#19
Iolanda Feola, Linda Volkers, Rupamanjari Majumder, Alexander Teplenin, Martin J Schalij, Alexander V Panfilov, Antoine A F de Vries, Daniël A Pijnappels
BACKGROUND: Recently, a new ablation strategy for atrial fibrillation has emerged, which involves the identification of rotors (ie, local drivers) followed by the localized targeting of their core region by ablation. However, this concept has been subject to debate because the mode of arrhythmia termination remains poorly understood, as dedicated models and research tools are lacking. We took a unique optogenetic approach to induce and locally target a rotor in atrial monolayers. METHODS AND RESULTS: Neonatal rat atrial cardiomyocyte monolayers expressing a depolarizing light-gated ion channel (Ca(2+)-translocating channelrhodopsin) were subjected to patterned illumination to induce single, stable, and centralized rotors by optical S1-S2 cross-field stimulation...
November 2017: Circulation. Arrhythmia and Electrophysiology
https://www.readbyqxmd.com/read/29093348/the-role-of-dopaminergic-signaling-in-the-medial-prefrontal-cortex-for-the-expression-of-cocaine-induced-conditioned-place-preference-in-rats
#20
Fumiya Shinohara, Hironori Kamii, Masabumi Minami, Katsuyuki Kaneda
The expression phase of cocaine-induced conditioned place preference (CPP) represents a cocaine-seeking behavior triggered by contextual cues associated with the rewarding effects of cocaine. However, the exact mechanisms underlying the cocaine CPP expression remain unclear. Here, we investigated the role of dopaminergic (DAergic) transmission in the medial prefrontal cortex (mPFC) for the expression of cocaine CPP. An intra-ventral tegmental area (VTA) injection of a cocktail of γ-aminobutyric acid (GABA)B and GABAA receptor agonists (baclofen and muscimol, respectively) immediately before the posttest inhibited the expression of cocaine CPP...
2017: Biological & Pharmaceutical Bulletin
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