Pech, U. et al. Cell Rep. 10, 2083–2095 (2015).

Genetically encoded calcium indicators are popular tools for monitoring neural activity in Drosophila. However, these sensors are usually expressed throughout the neuron and do not report localized calcium signals. Pech et al. generated calcium sensors that are targeted to pre- or postsynaptic compartments in Drosophila. The researchers fused the calcium sensor GCaMP3 either to the postsynaptically localized protein dHomer or to synaptophysin, which resides in vertebrate presynapses and localizes correctly when expressed in Drosophila. Furthermore, fusing synaptophysin to the pH sensor pHTomato yielded a reporter for synaptic vesicle fusion. The researchers applied these tools to analyze synaptic plasticity in the Drosophila olfactory system using two-photon imaging.