Calcium Transients in the Pharyngeal Muscle of C. elgans



Calcium imaging has potential for both investigating the molecular mechanisms that underlie calcium flux and regulation and visualizing the activity of excitable cells by monitoring the calcium responses.  Cameleon (Miyawaki et al., 1997), a genetically encoded calcium indicator, facilitates calcium imaging in experimental organisms with powerful genetics.  We are using cameleon in C. elegans to study the molecular mechanisms involved in muscular calcium transients and are working to extend the technique to the visualization of neural activity.  For details, see (Kerr et al., 2000).  Shown here is a movie illustrating the visualization of calcium transients in the C. elegans pharyngeal muscle.


C. elegans expressing yellow cameleon 2.1 was imaged at 20Hz using a Princeton Instruments PentaMAX CCD camera.  The image of the worm was split, filtered through two separate filters, and recombined with an offset on the CCD chip to provide a simultaneous image of two wavelengths.  This image was then split and recombined into the ratio image shown using MetaView (Universal Imaging).  See (Kerr et al., 2000) for details.


Pseudocolor movie of calcium transients in the pharyngeal muscle of an intact Caenorhabditis elegans.  The calcium indicator is cameleon (Miaywaki et al., Nature 388:882), a ratiometric fluorescent calcium sensor containing CFP and YFP.  An increase in calcium increases the YFP emission while decreasing the CFP emission.   Color indicates calcium level on a rainbow scale: red hues correspond to high calcium (high YFP/CFP intensity ratio), while blue hues correspond to low calcium (low ratio).  The graph displays average ratio (y axis) vs. frame number (x axis; 20 frames/sec). During contraction, the terminal bulb of the pharynx opens to let in food; note the simultaneous increase in calcium (red in images, upwards on graph).   Details of the recording method have been published (Kerr et al. 2000. Neuron 26:583-94).