Oscillatory transepithelial H(+) flux regulates a rhythmic behavior in C. elegans

Area of Science:

• Cellular biology
• Physiology
• Developmental biology

Background:

• Rhythmic defecation in C. elegans is regulated by calcium signaling in the intestine.
• The precise mechanisms coordinating defecation timing and intestinal function require further elucidation.

Purpose of the Study:

• To investigate the role of intestinal pH oscillations and proton flux in regulating C. elegans defecation.
• To identify the specific ion exchangers involved in proton transport during defecation.

Main Methods:

• Utilized fluorescent biosensors in live, unrestrained C. elegans to monitor intestinal pH dynamics.
• Employed RNA interference (RNAi) to study the function of Na+/H+ exchangers (NHX-2 and NHX-7).
• Measured changes in intestinal pH, pseudocoelomic acidification, and posterior body wall muscle contractions.

Main Results:

• Demonstrated that intestinal pH oscillates during defecation, coupled with transepithelial proton movement.
• Identified NHX-7 (PBO-4) as essential for basolateral proton extrusion, pseudocoelomic acidification, and muscle contractions.
• Showed that NHX-2 regulates apical proton movement, influencing basal intestinal pH and defecation period.

Conclusions:

• Intestinal pH oscillations and proton flux are integral components of the defecation timing mechanism.
• Na+/H+ exchangers play critical roles in mediating proton signaling between the intestine and muscles.
• The C. elegans defecation cycle serves as a valuable model for studying transepithelial proton flux and acid-base balance.