Optical calcium imaging in the nervous system of Drosophila melanogaster

BackgroundDrosophila melanogaster is one of the best-studied model organisms in biology, mainly because of the versatility of methods by which heredity and specific expression of genes can be traced and manipulated. Sophisticated genetic tools have been developed to express transgenes in selected cell types, and these techniques can be utilized to target DNA-encoded fluorescence probes to genetically defined subsets of neurons. Neuroscientists make use of this approach to monitor the activity of restricted types or subsets of neurons in the brain and the peripheral nervous system. Since membrane depolarization is typically accompanied by an increase in intracellular calcium ions, calcium-sensitive fluorescence proteins provide favorable tools to monitor the spatio-temporal activity across groups of neurons.Scope of reviewHere we describe approaches to perform optical calcium imaging in Drosophila in consideration of various calcium sensors and expression systems. In addition, we outline by way of examples for which particular neuronal systems in Drosophila optical calcium imaging have been used. Finally, we exemplify briefly how optical calcium imaging in the brain of Drosophila can be carried out in practice.Major conclusions and general significanceDrosophila provides an excellent model organism to combine genetic expression systems with optical calcium imaging in order to investigate principles of sensory coding, neuronal plasticity, and processing of neuronal information underlying behavior. This article is part of a Special Issue entitled Biochemical, Biophysical and Genetic Approaches to Intracellular Calcium Signaling.

► Drosophila provides a unique system to investigate defined neurons within a brain. ► DNA-encoded Ca2+ sensors can be used to monitor the activity of defined neurons. ► Progress in Ca2+ sensor development and genetic expression systems is summarized. ► Applications of Ca2+ imaging in Drosophila neurobiology are exemplified. ► Information on how in vivo Ca2+ imaging is performed in Drosophila is provided.