jYCaMP: An optimized calcium indicator for two-photon imaging at fiber laser wavelengths

State-of-the-art GFP-based calcium indicators do not undergo efficient two-photon excitation at wavelengths above 1000 nm, for which inexpensive and powerful industrial femtosecond lasers are available. Here we report jYCaMP1, a yellow variant of jGCaMP7 that outperforms its parent in mice and flies at excitation wavelengths above 1000 nm and enables improved two-color calcium imaging with RFP-based indicators.