GCaMP3 is converted from green to red fluorescence after exposure to blue light.

(A-B) Fluorescent micrographs of dissected Drosophila brains expressing UAS-GCaMP3; IR8a-GAL4 (A) or UAS-GCaMP6s; NP225-GAL4 (B). The dissected brains were exposed to blue light (mercury arc light passed through a Zeiss 63x oil-immersion objective) for different durations as indicated at the top of each panel. Green (top) and red (bottom) fluorescence micrographs were captured using a confocal microscope. Scale bar: 20μm. (C) Green-to-red photoconversion of GCaMP3 as quantified by the ratio of red-to-green fluorescence intensity (y-axis) following exposure to light from a Xenon lamp (x-axis).