Optical Calcium Imaging Using DNA-Encoded Fluorescence Sensors in Transgenic Fruit Flies, Drosophila melanogaster
The invention of protein-based fluorescent biosensors has paved the way to target specific cells with these probes and visualize intracellular processes not only in isolated cells or tissue cultures but also in transgenic animals. In particular, DNA-encoded fluorescence proteins sensitive to Ca2+ ions are often used to monitor changes in intracellular Ca2+ concentrations. This is of particular relevance in neuroscience since the dynamics of intracellular Ca2+ concentrations represents a faithful correlate for neuronal activity, and optical Ca2+ imaging is commonly used to monitor spatiotemporal activity across populations of neurons. In this respect Drosophila provides a favorable model organism due to the sophisticated genetic tools that facilitate the targeted expression of fluorescent Ca2+ sensor proteins. Here we describe how optical Ca2+ imaging of neuronal activity in the Drosophila brain can be carried out in vivo using two-photon microscopy. We exemplify this technique by describing how to monitor odor-evoked Ca2+ dynamics in the primary olfactory center of the Drosophila brain.
Key wordsOptical Ca2+ imaging Neuronal activity Drosophila melanogaster Two-photon microscopy G-CaMP Olfactory coding
This work was supported by the Deutsche Forschungsgemeinschaft (SPP1392, FI 821/2-1, and SFB 889/B4) and the German Federal Ministry for Education and Research via the Bernstein Center for Computational Neuroscience Göttingen B01, grant number 01GQ1005A.
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