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Channelrhodopsin

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https://www.readbyqxmd.com/read/28630812/molecular-properties-of-a-dtd-channelrhodopsin-from-guillardia-theta
#1
Yumeka Yamauchi, Masae Konno, Shota Ito, Satoshi P Tsunoda, Keiichi Inoue, Hideki Kandori
Microbial rhodopsins are membrane proteins found widely in archaea, eubacteria and eukaryotes (fungal and algal species). They have various functions, such as light-driven ion pumps, light-gated ion channels, light sensors and light-activated enzymes. A light-driven proton pump bacteriorhodopsin (BR) contains a DTD motif at positions 85, 89, and 96, which is unique to archaeal proton pumps. Recently, channelrhodopsins (ChRs) containing the DTD motif, whose sequential identity is ~20% similar to BR and to cation ChRs in Chlamydomonas reinhardtii (CrCCRs), were found...
2017: Biophysics and Physicobiology
https://www.readbyqxmd.com/read/28628197/vesicular-acetylcholine-transporter-vacht-overexpression-induces-major-modifications-of-striatal-cholinergic-interneuron-morphology-and-function
#2
Helena Janickova, Vania F Prado, Marco A M Prado, Salah El Mestikawy, Véronique Bernard
Striatal cholinergic interneurons (CIN) are pivotal for the regulation of the striatal network. Acetylcholine (ACh) released by CIN is centrally involved in reward behavior as well as locomotor or cognitive functions. Recently, BAC transgenic mice expressing channelrhodopsin-2 (ChR2) protein under the control of the choline acetyltransferase (ChAT) promoter (ChAT-ChR2) and displaying almost 50 extra copies of the VAChT gene were used to dissect cholinergic circuit connectivity and function using optogenetic approaches...
June 19, 2017: Journal of Neurochemistry
https://www.readbyqxmd.com/read/28611221/optogenetic-control-of-mitochondrial-metabolism-and-ca-2-signaling-by-mitochondria-targeted-opsins
#3
Tatiana Tkatch, Elisa Greotti, Gytis Baranauskas, Diana Pendin, Soumitra Roy, Luliaoana I Nita, Jennifer Wettmarshausen, Matthias Prigge, Ofer Yizhar, Orian S Shirihai, Daniel Fishman, Michal Hershfinkel, Ilya A Fleidervish, Fabiana Perocchi, Tullio Pozzan, Israel Sekler
Key mitochondrial functions such as ATP production, Ca(2+) uptake and release, and substrate accumulation depend on the proton electrochemical gradient (ΔμH(+)) across the inner membrane. Although several drugs can modulate ΔμH(+), their effects are hardly reversible, and lack cellular specificity and spatial resolution. Although channelrhodopsins are widely used to modulate the plasma membrane potential of excitable cells, mitochondria have thus far eluded optogenetic control. Here we describe a toolkit of optometabolic constructs based on selective targeting of channelrhodopsins with distinct functional properties to the inner mitochondrial membrane of intact cells...
June 13, 2017: Proceedings of the National Academy of Sciences of the United States of America
https://www.readbyqxmd.com/read/28592174/at-light-speed-advances-in-optogenetic-systems-for-regulating-cell-signaling-and-behavior
#4
Nicole A Repina, Alyssa Rosenbloom, Abhirup Mukherjee, David V Schaffer, Ravi S Kane
Cells are bombarded by extrinsic signals that dynamically change in time and space. Such dynamic variations can exert profound effects on behaviors, including cellular signaling, organismal development, stem cell differentiation, normal tissue function, and disease processes such as cancer. Although classical genetic tools are well suited to introduce binary perturbations, new approaches have been necessary to investigate how dynamic signal variation may regulate cell behavior. This fundamental question is increasingly being addressed with optogenetics, a field focused on engineering and harnessing light-sensitive proteins to interface with cellular signaling pathways...
June 7, 2017: Annual Review of Chemical and Biomolecular Engineering
https://www.readbyqxmd.com/read/28570519/whole-cell-patch-clamp-recordings-for-electrophysiological-determination-of-ion-selectivity-in-channelrhodopsins
#5
Christiane Grimm, Johannes Vierock, Peter Hegemann, Jonas Wietek
Over the past decade, channelrhodopsins became indispensable in neuroscientific research where they are used as tools to non-invasively manipulate electrical processes in target cells. In this context, ion selectivity of a channelrhodopsin is of particular importance. This article describes the investigation of chloride selectivity for a recently identified anion-conducting channelrhodopsin of Proteomonas sulcata via electrophysiological patch-clamp recordings on HEK293 cells. The experimental procedure for measuring light-gated photocurrents demands a fast switchable - ideally monochromatic - light source coupled into the microscope of an otherwise conventional patch-clamp setup...
May 22, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28562670/increased-threshold-of-short-latency-motor-evoked-potentials-in-transgenic-mice-expressing-channelrhodopsin-2
#6
Wei Wu, Wenhui Xiong, Ping Zhang, Lifang Chen, Jianqiao Fang, Christopher Shields, Xiao-Ming Xu, Xiaoming Jin
Transgenic mice that express channelrhodopsin-2 or its variants provide a powerful tool for optogenetic study of the nervous system. Previous studies have established that introducing such exogenous genes usually does not alter anatomical, electrophysiological, and behavioral properties of neurons in these mice. However, in a line of Thy1-ChR2-YFP transgenic mice (line 9, Jackson lab), we found that short-latency motor evoked potentials (MEPs) induced by transcranial magnetic stimulation had a longer latency and much lower amplitude than that of wild type mice...
2017: PloS One
https://www.readbyqxmd.com/read/28526883/openspritzer-an-open-hardware-pressure-ejection-system-for-reliably-delivering-picolitre-volumes
#7
C J Forman, H Tomes, B Mbobo, R J Burman, M Jacobs, T Baden, J V Raimondo
The ability to reliably and precisely deliver picolitre volumes is an important component of biological research. Here we describe a high-performance, low-cost, open hardware pressure ejection system (Openspritzer), which can be constructed from off the shelf components. The device is capable of delivering minute doses of reagents to a wide range of biological and chemical systems. In this work, we characterise the performance of the device and compare it to a popular commercial system using two-photon fluorescence microscopy...
May 19, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28521132/linking-neurons-to-network-function-and-behavior-by-two-photon-holographic-optogenetics-and-volumetric-imaging
#8
Marco Dal Maschio, Joseph C Donovan, Thomas O Helmbrecht, Herwig Baier
We introduce a flexible method for high-resolution interrogation of circuit function, which combines simultaneous 3D two-photon stimulation of multiple targeted neurons, volumetric functional imaging, and quantitative behavioral tracking. This integrated approach was applied to dissect how an ensemble of premotor neurons in the larval zebrafish brain drives a basic motor program, the bending of the tail. We developed an iterative photostimulation strategy to identify minimal subsets of channelrhodopsin (ChR2)-expressing neurons that are sufficient to initiate tail movements...
May 17, 2017: Neuron
https://www.readbyqxmd.com/read/28518090/flash-and-freeze-a-novel-technique-to-capture-membrane-dynamics-with-electron-microscopy
#9
Shuo Li, Sumana Raychaudhuri, Shigeki Watanabe
Cells constantly change their membrane architecture and protein distribution, but it is extremely difficult to visualize these events at a temporal and spatial resolution on the order of ms and nm, respectively. We have developed a time-resolved electron microscopy technique, "flash-and-freeze," that induces cellular events with optogenetics and visualizes the resulting membrane dynamics by freezing cells at defined time points after stimulation. To demonstrate this technique, we expressed channelrhodopsin, a light-sensitive cation channel, in mouse hippocampal neurons...
May 1, 2017: Journal of Visualized Experiments: JoVE
https://www.readbyqxmd.com/read/28514446/identification-of-preoptic-sleep-neurons-using-retrograde-labelling-and-gene-profiling
#10
Shinjae Chung, Franz Weber, Peng Zhong, Chan Lek Tan, Thuc Nghi Nguyen, Kevin T Beier, Nikolai Hörmann, Wei-Cheng Chang, Zhe Zhang, Johnny Phong Do, Shenqin Yao, Michael J Krashes, Bosiljka Tasic, Ali Cetin, Hongkui Zeng, Zachary A Knight, Liqun Luo, Yang Dan
In humans and other mammalian species, lesions in the preoptic area of the hypothalamus cause profound sleep impairment, indicating a crucial role of the preoptic area in sleep generation. However, the underlying circuit mechanism remains poorly understood. Electrophysiological recordings and c-Fos immunohistochemistry have shown the existence of sleep-active neurons in the preoptic area, especially in the ventrolateral preoptic area and median preoptic nucleus. Pharmacogenetic activation of c-Fos-labelled sleep-active neurons has been shown to induce sleep...
May 25, 2017: Nature
https://www.readbyqxmd.com/read/28506879/a-new-platform-for-long-term-tracking-and-recording-of-neural-activity-and-simultaneous-optogenetic-control-in-freely-behaving-caenorhabditis-elegans
#11
Keiko Gengyo-Ando, Yuko Kagawa-Nagamura, Masamichi Ohkura, Xianfeng Fei, Min Chen, Koichi Hashimoto, Junichi Nakai
BACKGROUND: Real-time recording and manipulation of neural activity in freely behaving animals can greatly advance our understanding of how neural circuits regulate behavior. Ca(2+) imaging and optogenetic manipulation with optical probes are key technologies for this purpose. However, integrating the two optical approaches with behavioral analysis has been technically challenging. NEW METHOD: Here, we developed a new imaging system, ICaST (Integrated platform for Ca(2+) imaging, Stimulation, and Tracking), which combines an automatic worm tracking system and a fast-scanning laser confocal microscope, to image neurons of interest in freely behaving C...
May 12, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28500713/photochemical-properties-of-the-red-shifted-channelrhodopsin-chrimson
#12
David Urmann, Charlotte Lorenz, Stephanie M Linker, Markus Braun, Josef Wachtveitl, Christian Bamann
Color-tuned variants of channelrhodopsins allow for selective optogenetic manipulation of different host cell populations. Chrimson is the channelrhodopsin with the longest wavelength absorbance maximum. We characterize its photochemical properties at different pH values corresponding to two protonation states of the counterion for the protonated Schiff base. Both states will lead to a functional channel opening, but the route is different as reflected in the photochemical states observed spectroscopically...
May 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28484220/electrophysiological-properties-and-viability-of-neonatal-rat-ventricular-myocyte-cultures-with-inducible-chr2-expression
#13
Qince Li, Rong Ruby Ni, Huixian Hong, Kah Yong Goh, Michael Rossi, Vladimir G Fast, Lufang Zhou
Channelrhodopsin-2 (ChR2)-based optogenetic technique has been increasingly applied to cardiovascular research. However, the potential effects of ChR2 protein overexpression on cardiomyocytes are not completely understood. The present work aimed to examine how the doxycycline-inducible lentiviral-mediated ChR2 expression may affect cell viability and electrophysiological property of neonatal rat ventricular myocyte (NRVM) cultures. Primary NVRMs were infected with lentivirus containing ChR2 or YFP gene and subjected to cytotoxicity analysis...
May 8, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28477350/protonation-state-coupled-conformational-dynamics-in-reaction-mechanisms-of-channel-and-pump-rhodopsins
#14
Ana-Nicoleta Bondar, Jeremy C Smith
Channel and pump rhodopsins use energy from light absorbed by a covalently bound retinal chromophore to transport ions across membranes of microbial cells. Ion transfer steps, including proton transfer, can couple to changes in protein conformational dynamics and water positions. Although general principles of how microbial rhodopsins function are largely understood, key issues pertaining to reaction mechanisms remain unclear. In this review, we compare the protonation-coupled dynamics of pump and channel rhodopsins, highlighting the roles that water dynamics, protein electrostatics, and protein flexibility can have in ion transport mechanisms...
May 6, 2017: Photochemistry and Photobiology
https://www.readbyqxmd.com/read/28442946/optogenetic-rescue-of-locomotor-dysfunction-and-dopaminergic-degeneration-caused-by-alpha-synuclein-and-eko-genes
#15
Cheng Qi, Scott Varga, Soo-Jin Oh, C Justin Lee, Daewoo Lee
α-Synuclein (α-Syn) is a small presynaptic protein and its mutant forms (e.g. A53T) are known to be directly associated with Parkinson's disease (PD). Pathophysiological mechanisms underlying α-Syn-mediated neurodegeneration in PD still remain to be explored. However, several studies strongly support that overexpression of mutant α-Syn causes reduced release of dopamine (DA) in the brain, and contributes to motor deficits in PD. Using a favorable genetic model Drosophila larva, we examined whether reduced DA release is enough to induce key PD symptoms (i...
April 2017: Experimental Neurobiology
https://www.readbyqxmd.com/read/28435858/flexible-and-stretchable-nanowire-coated-fibers-for-optoelectronic-probing-of-spinal-cord-circuits
#16
Chi Lu, Seongjun Park, Thomas J Richner, Alexander Derry, Imogen Brown, Chong Hou, Siyuan Rao, Jeewoo Kang, Chet T Mortiz, Yoel Fink, Polina Anikeeva
Studies of neural pathways that contribute to loss and recovery of function following paralyzing spinal cord injury require devices for modulating and recording electrophysiological activity in specific neurons. These devices must be sufficiently flexible to match the low elastic modulus of neural tissue and to withstand repeated strains experienced by the spinal cord during normal movement. We report flexible, stretchable probes consisting of thermally drawn polymer fibers coated with micrometer-thick conductive meshes of silver nanowires...
March 2017: Science Advances
https://www.readbyqxmd.com/read/28431249/macrophages-facilitate-electrical-conduction-in-the-heart
#17
Maarten Hulsmans, Sebastian Clauss, Ling Xiao, Aaron D Aguirre, Kevin R King, Alan Hanley, William J Hucker, Eike M Wülfers, Gunnar Seemann, Gabriel Courties, Yoshiko Iwamoto, Yuan Sun, Andrej J Savol, Hendrik B Sager, Kory J Lavine, Gregory A Fishbein, Diane E Capen, Nicolas Da Silva, Lucile Miquerol, Hiroko Wakimoto, Christine E Seidman, Jonathan G Seidman, Ruslan I Sadreyev, Kamila Naxerova, Richard N Mitchell, Dennis Brown, Peter Libby, Ralph Weissleder, Filip K Swirski, Peter Kohl, Claudio Vinegoni, David J Milan, Patrick T Ellinor, Matthias Nahrendorf
Organ-specific functions of tissue-resident macrophages in the steady-state heart are unknown. Here, we show that cardiac macrophages facilitate electrical conduction through the distal atrioventricular node, where conducting cells densely intersperse with elongated macrophages expressing connexin 43. When coupled to spontaneously beating cardiomyocytes via connexin-43-containing gap junctions, cardiac macrophages have a negative resting membrane potential and depolarize in synchrony with cardiomyocytes. Conversely, macrophages render the resting membrane potential of cardiomyocytes more positive and, according to computational modeling, accelerate their repolarization...
April 20, 2017: Cell
https://www.readbyqxmd.com/read/28409086/kinetic-characteristics-of-chimeric-channelrhodopsins-implicate-the-molecular-identity-involved-in-desensitization
#18
Alemeh Zamani, Shigeo Sakuragi, Toru Ishizuka, Hiromu Yawo
Channelrhodopsin (ChR)-1 and ChR2 were the first-identified members of ChRs which are a growing subfamily of microbial-type rhodopsins. Light absorption drives the generation of a photocurrent in cell membranes expressing ChR2. However, the photocurrent amplitude attenuates and becomes steady-state during prolonged irradiation. This process, called desensitization or inactivation, has been attributed to the accumulation of intermediates less conductive to cations. Here we provided evidence that the dark-adapted (DA) photocurrent before desensitization is kinetically different from the light-adapted (LA) one after desensitization, that is, the deceleration of both basal-to-conductive and conductive-to-basal transitions...
2017: Biophysics and Physicobiology
https://www.readbyqxmd.com/read/28395022/optogenetic-manipulation-of-anatomical-re-entry-by-light-guided-generation-of-a-reversible-local-conduction-block
#19
Masaya Watanabe, Iolanda Feola, Rupamanjari Majumder, Wanchana Jangsangthong, Alexander S Teplenin, Dirk L Ypey, Martin J Schalij, Katja Zeppenfeld, Antoine A F de Vries, Daniël A Pijnappels
Aims: Anatomical re-entry is an important mechanism of ventricular tachycardia, characterized by circular electrical propagation in a fixed pathway. It's current investigative and therapeutic approaches are non-biological, rather unspecific (drugs), traumatizing (electrical shocks), or irreversible (ablation). Optogenetics is a new biological technique that allows reversible modulation of electrical function with unmatched spatiotemporal precision using light-gated ion channels. We therefore investigated optogenetic manipulation of anatomical re-entry in ventricular cardiac tissue...
March 1, 2017: Cardiovascular Research
https://www.readbyqxmd.com/read/28381675/alternative-formation-of-red-shifted-channelrhodopsins-noncovalent-incorporation-with-retinal-based-enamine-type-schiff-bases-and-mutated-channelopsin
#20
Takashi Okitsu, Take Matsuyama, Takahiro Yamashita, Toru Ishizuka, Hiromu Yawo, Yasushi Imamoto, Yoshinori Shichida, Akimori Wada
Red-shifted channelrhodopsins (ChRs) are attractive for optogenetic tools. We developed a new type of red-shifted ChRs that utilized noncovalent incorporation of retinal and 3,4-dehydroretinal-based enamine-type Schiff bases and mutated channelopsin, C1C2-K296G. These ChRs exhibited absorption maxima that were shifted 10-30 nm toward longer wavelengths than that of C1C2-ChR regenerated with all-trans-retinal.
2017: Chemical & Pharmaceutical Bulletin
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