scholarly journals All-optical electrophysiology with improved genetically encoded voltage indicators reveals interneuron network dynamics in vivo

2021 ◽  
Author(s):  
He Tian ◽  
Hunter C. Davis ◽  
J. David Wong-Campos ◽  
Linlin Z. Fan ◽  
Benjamin Gmeiner ◽  
...  
Keyword(s):  
Gap Junction ◽  
Signal To Noise Ratio ◽  
Voltage Imaging ◽  
All Optical ◽  
Precision Voltage ◽  
Coupling Strengths ◽  
Junction Coupling ◽  
Multiple Cells ◽  
Voltage Indicator

All-optical electrophysiology can be a powerful tool for studying neural dynamics in vivo, as it offers the ability to image and perturb membrane voltage in multiple cells simultaneously. The "Optopatch" constructs combine a red-shifted archaerhodopsin (Arch)-derived genetically encoded voltage indicator (GEVI) with a blue-shifted channelrhodopsin actuator (ChR). We used a video-based pooled screen to evolve Arch-derived GEVIs with improved signal-to-noise ratio (QuasAr6a) and kinetics (QuasAr6b). By combining optogenetic stimulation of individual cells with high-precision voltage imaging in neighboring cells, we mapped inhibitory and gap junction-mediated connections, in vivo. Optogenetic activation of a single NDNF-expressing neuron in visual cortex Layer 1 significantly suppressed the spike rate in some neighboring NDNF interneurons. Hippocampal PV cells showed near-synchronous spikes across multiple cells at a frequency significantly above what one would expect from independent spiking, suggesting that collective inhibitory spikes may play an important signaling role in vivo. By stimulating individual cells and recording from neighbors, we quantified gap junction coupling strengths. Together, these results demonstrate powerful new tools for all-optical microcircuit dissection in live mice.

scholarly journals Sensitivity optimization of a rhodopsin-based fluorescent voltage indicator

2021 ◽  
Author(s):  
Ahmed S Abdelfattah ◽  
Jihong Zheng ◽  
Daniel Reep ◽  
Getahun Tsegaye ◽  
Arthur Tsang ◽  
...  
Keyword(s):  
Saturation Mutagenesis ◽  
Voltage Sensitivity ◽  
Voltage Imaging ◽  
Neuronal Populations ◽  
Lower Baseline ◽  
Transmembrane Voltage ◽  
Automated Patch Clamp ◽  
Subthreshold Voltage ◽  
Voltage Indicator

The ability to optically image cellular transmembrane voltage at millisecond-timescale resolution can offer unprecedented insight into the function of living brains in behaving animals. The chemigenetic voltage indicator Voltron is bright and photostable, making it a favorable choice for long in vivo imaging of neuronal populations at cellular resolution. Improving the voltage sensitivity of Voltron would allow better detection of spiking and subthreshold voltage signals. We performed site saturation mutagenesis at 40 positions in Voltron and screened for increased ΔF/F0 in response to action potentials (APs) in neurons. Using a fully automated patch-clamp system, we discovered a Voltron variant (Voltron.A122D) that increased the sensitivity to a single AP by 65% compared to Voltron. This variant (named Voltron2) also exhibited approximately 3-fold higher sensitivity in response to sub-threshold membrane potential changes. Voltron2 retained the sub-millisecond kinetics and photostability of its predecessor, with lower baseline fluorescence. Introducing the same A122D substitution to other Ace2 opsin-based voltage sensors similarly increased their sensitivity. We show that Voltron2 enables improved sensitivity voltage imaging in mice, zebrafish and fruit flies. Overall, we have discovered a generalizable mutation that significantly increases the sensitivity of Ace2 rhodopsin-based sensors, improving their voltage reporting capability.

scholarly journals Bright near-infrared genetically encoded voltage indicator for all-optical electrophysiology

2019 ◽  
Author(s):  
Mikhail V. Monakhov ◽  
Mikhail E. Matlashov ◽  
Michelangelo Colavita ◽  
Chenchen Song ◽  
Daria M. Shcherbakova ◽  
...  
Keyword(s):  
Membrane Potential ◽  
Blue Light ◽  
Action Potentials ◽  
Near Infrared ◽  
Fluorescent Proteins ◽  
Voltage Imaging ◽  
All Optical ◽  
Bacterial Phytochromes ◽  
Voltage Indicator

AbstractWe developed genetically encoded voltage indicators (GEVIs) using bright near-infrared (NIR) fluorescent proteins from bacterial phytochromes. These new NIR GEVIs are optimized for combination of voltage imaging with simultaneous blue light optogenetic actuator activation. Iterative optimizations led to a GEVI here termed nirButterfly, which reliably reports neuronal activities including subthreshold membrane potential depolarization and hyperpolarization, as well as spontaneous spiking, or electrically- and optogenetically-evoked action potentials. This enables largely improved all-optical causal interrogations of physiology.

scholarly journals Voltage imaging using transgenic mouse lines expressing the GEVI ArcLight in two olfactory cell types

2020 ◽  
Author(s):  
Jelena Platisa ◽  
Hongkui Zeng ◽  
Linda Madisen ◽  
Lawrence B. Cohen ◽  
Vincent A Pieribone ◽  
...  
Keyword(s):  
Transgenic Mouse ◽  
Granule Cells ◽  
Signal To Noise Ratio ◽  
Expression System ◽  
Cell Types ◽  
Mammalian Brain ◽  
Voltage Imaging ◽  
Genetic Tool ◽  
Mouse Lines

AbstractGenetically encoded voltage indicators (GEVIs) allow for cell-specific optical recordings of membrane potential changes in defined cell populations. One tool that would further their use in the in vivo mammalian brain is transgenic reporter animals that facilitate precise and repeatable targeting with high expression levels. The present literature on the development and use of transgenic mouse lines as vehicles for GEVI expression is limited. Here we report the first in vivo experiments using a transgenic reporter mouse for the GEVI ArcLight (Ai86(TITL-ArcLight)), which utilizes a Cre/tTA dependent expression system (TIGRE 1.0). Following pairing to appropriate Cre- and tTA transgenic mice, we report two mouse lines with ArcLight expression restricted to olfactory sensory neurons (OMP-ArcLight), and a subpopulation of interneurons that include periglomerular and granule cells (Emx1-ArcLight) in the olfactory bulb (OB). The ArcLight expression in these lines was sufficient for in vivo imaging of odorant responses in single trials. Odor responses were measured in the OB using epifluorescence and 2-photon imaging. The voltage responses were odor-specific and concentration-dependent, and confirmed earlier conclusions from calcium measurements. This study shows that the ArcLight Ai86(TITL-ArcLight) transgenic line is a flexible genetic tool that can be used to record neuronal electrical activity of a variety of cell types with a signal-to-noise ratio that is comparable to previous reports using viral transduction.

scholarly journals Role of interleukins in the pathogenesis of pulmonary fibrosis

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Yi Xin She ◽  
Qing Yang Yu ◽  
Xiao Xiao Tang
Keyword(s):  
Pulmonary Fibrosis ◽  
Therapeutic Strategy ◽  
Future Directions ◽  
Regulation Mechanisms ◽  
Underlying Mechanisms ◽  
Multiple Cells ◽  
The Relationship

AbstractInterleukins, a group of cytokines participating in inflammation and immune response, are proved to be involved in the formation and development of pulmonary fibrosis. In this article, we reviewed the relationship between interleukins and pulmonary fibrosis from the clinical, animal, as well as cellular levels, and discussed the underlying mechanisms in vivo and in vitro. Despite the effects of interleukin-targeted treatment on experimental pulmonary fibrosis, clinical applications are lacking and unsatisfactory. We conclude that intervening in one type of interleukins with similar functions in IPF may not be enough to stop the development of fibrosis as it involves a complex network of regulation mechanisms. Intervening interleukins combined with other existing therapy or targeting interleukins affecting multiple cells/with different functions at the same time may be one of the future directions. Furthermore, the intervention time is critical as some interleukins play different roles at different stages. Further elucidation on these aspects would provide new perspectives on both the pathogenesis mechanism, as well as the therapeutic strategy and drug development.

scholarly journals All-Optical Non-Inverted Parity Generator and Checker Based on Semiconductor Optical Amplifiers

2021 ◽  
Vol 11 (4) ◽  
pp. 1499
Author(s):  
Bingchen Han ◽  
Junyu Xu ◽  
Pengfei Chen ◽  
Rongrong Guo ◽  
Yuanqi Gu ◽  
...  
Keyword(s):  
Optical Amplifiers ◽  
Signal To Noise Ratio ◽  
Low Cost ◽  
Extinction Ratio ◽  
Semiconductor Optical Amplifiers ◽  
Optical Signal ◽  
Probe Light ◽  
All Optical ◽  
Negative Effect ◽  
Parity Generator

An all-optical non-inverted parity generator and checker based on semiconductor optical amplifiers (SOAs) are proposed with four-wave mixing (FWM) and cross-gain modulation (XGM) non-linear effects. A 2-bit parity generator and checker using by exclusive NOR (XNOR) and exclusive OR (XOR) gates are implemented by first SOA and second SOA with 10 Gb/s return-to-zero (RZ) code, respectively. The parity and check bits are provided by adjusting the center wavelength of the tunable optical bandpass filter (TOBPF). A saturable absorber (SA) is used to reduce the negative effect of small signal clock (Clk) probe light to improve extinction ratio (ER) and optical signal-to-noise ratio (OSNR). For Pe and Ce (even parity bit and even check bit) without Clk probe light, ER and OSNR still maintain good performance because of the amplified effect of SOA. For Po (odd parity bit), ER and OSNR are improved to 1 dB difference for the original value. For Co (odd check bit), ER is deteriorated by 4 dB without SA, while OSNR is deteriorated by 12 dB. ER and OSNR are improved by about 2 dB for the original value with the SA. This design has the advantages of simple structure and great integration capability and low cost.

scholarly journals Differential effect of subcellular localization of communication impairing gap junction protein connexin43 on tumor cell growth in vivo

Oncogene ◽  
2000 ◽  
Vol 19 (4) ◽  
pp. 505-513 ◽  
Author(s):  
V A Krutovskikh ◽  
S M Troyanovsky ◽  
C Piccoli ◽  
H Tsuda ◽  
M Asamoto ◽  
...  
Keyword(s):  
Cell Growth ◽  
Subcellular Localization ◽  
Tumor Cell ◽  
Gap Junction ◽  
Differential Effect ◽  
Tumor Cell Growth ◽  
Junction Protein ◽  
Gap Junction Protein
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