keyword
MENU ▼
Read by QxMD icon Read
search

Channelrhodopsin

keyword
https://www.readbyqxmd.com/read/28526883/openspritzer-an-open-hardware-pressure-ejection-system-for-reliably-delivering-picolitre-volumes
#1
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
#2
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
#3
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
#4
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 17, 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
#5
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
#6
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
#7
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
#8
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
#9
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
#10
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
#11
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
#12
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
#13
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
#14
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
https://www.readbyqxmd.com/read/28380331/near-infrared-fluorescent-protein-irfp713-as-a-reporter-protein-for-optogenetic-vectors-a-transgenic-cre-reporter-rat-and-other-neuronal-studies
#15
Christopher T Richie, Leslie R Whitaker, Keith W Whitaker, Julie Necarsulmer, Heather A Baldwin, Yajun Zhang, Lowella Fortuno, Josh J Hinkle, Pyry Koivula, Mark J Henderson, Wenzhi Sun, Kai Wang, Jeffrey C Smith, Jim Pickel, Na Ji, Bruce T Hope, Brandon K Harvey
BACKGROUND: The use of genetically-encoded fluorescent reporters is essential for the identification and observation of cells that express transgenic modulatory proteins. Near-infrared (NIR) fluorescent proteins have superior light penetration through biological tissue, but are not yet widely adopted. NEW METHOD: Using the near-infrared fluorescent protein, iRFP713, improves the imaging resolution in thick tissue sections or the intact brain due to the reduced light-scattering at the longer, NIR wavelengths used to image the protein...
April 2, 2017: Journal of Neuroscience Methods
https://www.readbyqxmd.com/read/28355544/complex-photochemistry-within-the-green-absorbing-channelrhodopsin-reachr
#16
Benjamin S Krause, Christiane Grimm, Joel C D Kaufmann, Franziska Schneider, Thomas P Sakmar, Franz J Bartl, Peter Hegemann
Channelrhodopsins (ChRs) are light-activated ion channels widely employed for photostimulation of excitable cells. This study focuses on ReaChR, a chimeric ChR variant with optimal properties for optogenetic applications. We combined electrophysiological recordings with infrared and UV-visible spectroscopic measurements to investigate photocurrents and photochemical properties of ReaChR. Our data imply that ReaChR is green-light activated (λmax = 532 nm) with a non-rhodopsin-like action spectrum peaking at 610 nm for stationary photocurrents...
March 28, 2017: Biophysical Journal
https://www.readbyqxmd.com/read/28350445/structural-changes-in-an-anion-channelrhodopsin-formation-of-the-k-and-l-intermediates-at-80-k
#17
Adrian Yi, Hai Li, Natalia Mamaeva, Roberto E Fernandez De Cordoba, Johan Lugtenburg, Willem J DeGrip, John L Spudich, Kenneth J Rothschild
A recently discovered natural family of light-gated anion channelrhodopsins (ACRs) from cryptophyte algae provides an effective means of optogenetically silencing neurons. The most extensively studied ACR is from Guillardia theta (GtACR1). Earlier studies of GtACR1 have established a correlation between formation of a blue-shifted L-like intermediate and the anion channel "open" state. To study structural changes of GtACR1 in the K and L intermediates of the photocycle, a combination of low-temperature Fourier transform infrared (FTIR) and ultraviolet-visible absorption difference spectroscopy was used along with stable-isotope retinal labeling and site-directed mutagenesis...
April 10, 2017: Biochemistry
https://www.readbyqxmd.com/read/28325790/dopamine-terminals-from-the-ventral-tegmental-area-gate-intrinsic-inhibition-in-the-prefrontal-cortex
#18
William C Buchta, Stephen V Mahler, Benjamin Harlan, Gary S Aston-Jones, Arthur C Riegel
Spike frequency adaptation (SFA or accommodation) and calcium-activated potassium channels that underlie after-hyperpolarization potentials (AHP) regulate repetitive firing of neurons. Precisely how neuromodulators such as dopamine from the ventral tegmental area (VTA) regulate SFA and AHP (together referred to as intrinsic inhibition) in the prefrontal cortex (PFC) remains unclear. Using whole cell electrophysiology, we measured intrinsic inhibition in prelimbic (PL) layer 5 pyramidal cells of male adult rats...
March 2017: Physiological Reports
https://www.readbyqxmd.com/read/28320275/optogenetic-stimulation-increases-level-of-antiapoptotic-protein-bcl-xl-in-neurons
#19
D A Lanshakov, U S Drozd, N N Dygalo
The antiapoptotic protein Bcl-xL is associated with several neuroplastic processes such as formation of synapses, regulation of spontaneous and evoked synaptic responses, and release of neurotransmitters. Dependence of expression on activity of neurons is characteristic for many proteins participating in regulation of neuroplasticity. Whether such property is exhibited by the Bcl-xL protein was analyzed using in vivo optogenetic stimulation of hippocampal glutamatergic neurons expressing channelrhodopsin ChR2H134 under CAMKIIa promoter in the adeno-associated viral vector, followed by immunohistochemical determination of the level of Bcl-xL protein in these neurons and surrounding cells...
March 2017: Biochemistry. Biokhimii︠a︡
https://www.readbyqxmd.com/read/28302720/adjacent-channelrhodopsin-2-residues-within-transmembranes-2-and-7-regulate-cation-selectivity-and-distribution-of-the-two-open-states
#20
Ryan Richards, Robert E Dempski
Channelrhodopsin-2 (ChR2) is a light-activated channel that can conduct cations of multiple valencies down the electrochemical gradient. Under continuous light exposure, ChR2 transitions from a high-conducting open state (O1) to a low-conducting open state (O2) with differing ion selectivity. The molecular basis for the O1 → O2 transition and how ChR2 modulates selectivity between states is currently unresolved. To this end, we used steered molecular dynamics, electrophysiology, and kinetic modeling to identify residues that contribute to gating and selectivity in discrete open states...
May 5, 2017: Journal of Biological Chemistry
keyword
keyword
12963
1
2
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read
×

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"