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1.D.239.  The Optogenetic Activator Channel/Optogenetic Indicator Sensor (OAC/OIS) Family 

Optogenetics utilizes light-reactive proteins to manipulate tissue activity, particularlly important to the field of cardiac electrophysiology. Marchal et al. 2023 provided an overview of light-activated transmembrane channels (optogenetic actuators) applied in strategies to modulate cardiac activity. The authors discuss genetically encoded indicators (optogenetic sensors) and fluorescent dyes to monitor tissue activity, including cardiac transmembrane potential and ion homeostasis. The combination of the two allows for all-optical approaches to monitor and manipulate the heart without physical contact. Optogenetic proteins and fluorescent dyes must be carefully selected to avoid optical crosstalk and consequent disruptions in readouts. The authors presented a novel approach to simultaneously monitor transmembrane potential and cytosolic calcium, while also performing optogenetic manipulations. For this, they used a novel voltage-sensitive dye ElectroFluor 730p and the cytosolic calcium indicator X-Rhod-1 in mouse hearts expressing channelrhodopsin-2 (ChR2). By exploiting the isosbestic point of ElectroFluor 730p and avoiding the ChR2 activation spectrum, they introduced novel optical imaging with minimal crosstalk. 

References associated with 1.D.239 family:

Marchal, G.A., V. Biasci, P. Yan, C. Palandri, M. Campione, E. Cerbai, L.M. Loew, and L. Sacconi. (2023). Recent advances and current limitations of available technology to optically manipulate and observe cardiac electrophysiology. Pflugers Arch. [Epub: Ahead of Print] 37770585