Ca imaging of synaptic compartments using subcellularly targeted GCaMP8f in Drosophila.

GCaMP8f is a sensitive genetically encoded Ca indicator that enables imaging of neuronal activity. Here, we present a protocol to perform Ca imaging of the Drosophila neuromuscular junction using GCaMP8f targeted to pre- or postsynaptic compartments. We describe ratiometric Ca imaging using GCaMP8f fused to mScarlet and synaptotagmin that reveals Ca 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., Han et al., Perry et al., and Han et al..