Intracellular Ca2+ imaging in C. elegans.

Optical methods provide a noninvasive way to monitor calcium transients in Caenorhabditis elegans. Imaging techniques are particularly appealing in C. elegans because worms are optically transparent and can be imaged while fully intact. Furthermore, a variety of genetically encoded calcium indicators are available that can be targeted to cells of interest with appropriate tissue-specific promoters. Here, we describe a specific protocol, suitable for monitoring neuronal activity, for rapid calcium imaging in C. elegans using the cameleon indicator. Notes are provided to assist with adapting this protocol for use with other indicators and slower time scales.