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

Area of Science:

• Neuroscience
• Developmental Biology
• Genetics

Background:

• Defecation in *Caenorhabditis elegans* is a rhythmic behavior regulated by intestinal calcium (Ca2+) waves.
• The defecation motor program (DMP) is influenced by environmental factors.

Purpose of the Study:

• To develop a method for studying Ca2+ oscillations and defecation in freely behaving *C. elegans*.
• To investigate how mutations affecting Ca2+ handling impact Ca2+ waves and DMP execution.

Main Methods:

• Developed a novel technique to observe Ca2+ dynamics and defecation in unrestrained *C. elegans*.
• Analyzed mutant strains with altered Ca2+ handling (e.g., *egl-8*/PLC-beta, *kqt-3*/KCNQ1, *sca-1*/SERCA, *unc-43*/Ca2+-CaMKII).

Main Results:

• Absence of PLCbeta leads to ectopic and reversed Ca2+ waves, failing to trigger a complete DMP.
• A faster underlying pacemaker may exist, with arrhythmias arising from pacemaker-DMP uncoupling.
• Chronic Ca2+ elevation alters DMP step intervals rather than the defecation period.

Conclusions:

• Posterior intestinal cell dominance is crucial for DMP coordination, not Ca2+ wave initiation.
• Pacemaker function appears intact, but its coupling to the DMP is critical for rhythmic defecation.
• The developed method allows simultaneous assessment of Ca2+ dynamics and muscle contractions in a dynamic model organism.