Zebrafish are an excellent model organism to study many aspects of vertebrate sensory encoding and behavior. Their escape responses begin with a C-shaped body bend followed by several swimming bouts away from the potentially threatening stimulus. This highly stereotyped motor behavior provides a model for studying startle reflexes and the neural circuitry underlying multisensory encoding and locomotion. Channelrhodopsin (ChR2) can be expressed in the lateral line and ear hair cells of zebrafish and can be excited in vivo to elicit these rapid forms of escape. Here we review our methods for studying transgenic ChR2-expressing zebrafish larvae, including screening for positive expression of ChR2 and recording field potentials and high-speed videos of optically evoked escape responses. We also highlight important features of the acquired data and provide a brief review of other zebrafish research that utilizes or has the potential to benefit from ChR2 and optogenetics.Channelrhodopsin (ChR)-based optogenetics is one promising approach to restore vision in photoreceptor degenerative diseases such as retinitis pigmentosa (RP) and age-related macular degeneration (AMD). Currently, a large number of ChRs from different alga species as well as engineered variants are available. They vary with their light response properties like peak sensitive wavelength (λmax), current amplitude, and kinetics. Therefore, it is important to choose an appropriate ChR for practical applications, such as vision restoration. Here we describe a standard laboratory protocol for characterizing properties of ChRs in in vitro in human embryonic kidney (HEK) cells. Based on such characterization, we also discuss the criteria for selecting optimal ChRs for optogenetic vision restoration.Optical manipulation is a powerful way to control neural activity in vitro and in vivo with millisecond precision. Patterning of light provides the remarkable ability to simultaneously target spatially segregated neurons from a population. Commercially available projectors provide one of the simplest and most economical ways of achieving spatial light modulation at millisecond timescales. Here, we describe the protocol for constructing a projector-based spatio-temporal light patterning system integrated with a microscope on a typical electrophysiology rig. The set-up is well suited for applications requiring rapid, distinct, and combinatorial inputs, akin to brain activity. https://www.selleckchem.com/products/iberdomide.html This equipment involved is fairly economical ( less then $5000 including all optical and mechanical components), and the set-up is easy to assemble and program.The delivery of cells into damaged myocardium induces limited cardiac regeneration due to extensive cell death. In an effort to limit cell death, our lab formulates three-dimensional matrices as a delivery system for cell therapy. Our primary work has been focused on the formation of engineered cardiac tissues (ECTs) from human-induced pluripotent stem cell-derived engineered cardiac cells. However, ECT immaturity hinders ability to fully recover damaged myocardium. Various conditioning regimens such as mechanical stretch and/or electric pacing have been used to activate maturation pathways. To improve ECT maturity, we use non-contacting chronic light stimulation using heterologously expressed light-sensitive channelrhodopsin ion channels. We transduce ECTs with an AAV packaged channelrhodopsin and chronically optically pace (C-OP) ECTs for 1 week above the intrinsic beat rate, resulting in increased ECT electrophysiological properties.In just over 10 years, the use of optogenetic technologies in neuroscience has become widespread, having today a tremendous impact on our understanding of brain function. An extensive number of studies have implemented a variety of tools allowing for the manipulation of neurons with light, including light-activated ion channels or G protein-coupled receptors, among other innovations. In this context, the proper calibration of photostimulation in vivo remains crucial to dissect brain circuitry or investigate the effect of neuronal activity on specific subpopulations of neurons and glia. Depending on the scientific question, the design of specific stimulation protocols must consider from the choice of the animal model to the light stimulation pattern to be delivered. In this chapter, we describe a detailed framework to investigate neuron-glia interactions in both mouse pups and adults using an optogenetic approach.Optogenetics provides a powerful approach for investigating neuronal electrophysiology at the scale required for drug discovery applications. Probing synaptic function with high throughput using optogenetics requires robust tools that enable both precise stimulation of and facile readout of synaptic activity. Here we describe two functional assays to achieve this end (1) a pre-synaptic calcium assay that utilizes the channelrhodopsin, CheRiff, patterned optogenetic stimulus, and the pre-synaptically targeted calcium reporter jRGECO1a to monitor pre-synaptic changes in calcium influx and (2) a synaptic transmission assay in which CheRiff and cytosolic jRGECO1a are expressed in non-overlapping sets of neurons, enabling pre-synaptic stimulation and post-synaptic readout of activity. This chapter describes the methodology and practical considerations for implementation of these two assays.Optogenetics enables experimental control over neural activity using light. Channelrhodopsin and its variants are typically activated using visible light excitation but can also be activated using infrared two-photon excitation. Two-photon excitation can improve the spatial precision of stimulation in scattering tissue but has several practical limitations that need to be considered before use. Here we describe the methodology and best practices for using two-photon optogenetic stimulation of neurons within the brain of the fruit fly, Drosophila melanogaster, with an emphasis on projection neurons of the antennal lobe.Photoelectric recording from populations of phototactic flagellate algae provides a means to study channelrhodopsin functions in vivo. Technical simplicity, versatility, high sensitivity, and reproducibility are the advantages of this assay over recording from individual algal cells by the suction pipette technique. Here we describe the principles and procedures of this assay.