Ca(2+) imaging of synaptic compartments using subcellularly targeted GCaMP8f in Drosophila.

GCaMP8f is a sensitive genetically encoded Ca(2+) indicator that enables imaging of neuronal activity. Here, we present a protocol to perform Ca(2+) imaging of the Drosophila neuromuscular junction using GCaMP8f targeted to pre- or postsynaptic compartments. We describe ratiometric Ca(2+) imaging using GCaMP8f fused to mScarlet and synaptotagmin that reveals Ca(2+) dynamics at presynaptic terminals. We then detail "quantal" imaging of miniature transmission events using GCaMP8f targeted to postsynaptic compartments by fusion to a PDZ-binding motif. For complete details on the use and execution of this protocol, please refer to Li et al.,(1) Han et al.,(2) Perry et al.,(3) and Han et al.(4).