HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Supplemental Figures and Move All Versions of this Article: 294/1/C333    most recent 00303.2007v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Nehrke, K. Articles by Mowrey, W. Search for Related Content PubMed PubMed Citation Articles by Nehrke, K. Articles by Mowrey, W.

MEMBRANE TRANSPORTERS, ION CHANNELS, AND PUMPS

Intestinal Ca²⁺ wave dynamics in freely moving C. elegans coordinate execution of a rhythmic motor program

²Departments of Anesthesiology and Pharmacology, Digestive Disease Research Center, Vanderbilt University Medical Center, Nashville, Tennessee; and ³Interdepartmental Graduate Program in Neuroscience, Center for Aging and Developmental Biology and ¹Nephrology Division, Department of Medicine, University of Rochester Medical Center, Rochester, New York

Submitted 19 July 2007 ; accepted in final form 13 October 2007

Defecation in the nematode worm Caenorhabditis elegans is a highly rhythmic behavior that is regulated by a Ca²⁺ wave generated in the 20 epithelial cells of the intestine, in part through activation of the inositol 1,4,5-trisphosphate receptor. Execution of the defecation motor program (DMP) can be modified by external cues such as nutrient availability or mechanical stimulation. To address the likelihood that environmental regulation of the DMP requires integrating distinct cellular and organismal processes, we have developed a method for studying coordinate Ca²⁺ oscillations and defecation behavior in intact, freely behaving animals. We tested this technique by examining how mutations in genes known to alter Ca²⁺ handling [including egl-8/phospholipase C (PLC)-β, kqt-3/KCNQ1, sca-1/sarco(endo)plasmic reticulum Ca²⁺ ATPase, and unc-43/Ca²⁺-CaMKII] contribute to shaping the Ca²⁺ wave and asked how Ca²⁺ wave dynamics in the mutant backgrounds altered execution of the DMP. Notably, we find that Ca²⁺ waves in the absence of PLCβ initiate ectopically, often traveling in reverse, and fail to trigger a complete DMP. These results suggest that the normal supremacy of the posterior intestinal cells is not obligatory for Ca²⁺ wave occurrence but instead helps to coordinate the DMP. Furthermore, we present evidence suggesting that an underlying pacemaker appears to oscillate at a faster frequency than the defecation cycle and that arrhythmia may result from uncoupling the pacemaker from the DMP rather than from disrupting the pacemaker itself. We also show that chronic elevations in Ca²⁺ have limited influence on the defecation period but instead alter the interval between successive steps of the DMP. Finally, our results demonstrate that it is possible to assess Ca²⁺ dynamics and muscular contractions in a completely unrestrained model organism.

calcium; oscillation; Caenorhabditis elegans; biosensor

This article has been cited by other articles:

				E. Allman, D. Johnson, and K. Nehrke Loss of the apical V-ATPase a-subunit VHA-6 prevents acidification of the intestinal lumen during a rhythmic behavior in C. elegans Am J Physiol Cell Physiol, November 1, 2009; 297(5): C1071 - C1081. [Abstract] [Full Text] [PDF]