Pharyngeal Pumping Variability Assessment Reveals Subtle Mutant and Treatment Effects in the Nematode C. elegans

Abstract

In C. elegans, feeding is achieved through a well characterized behavior, pharyngeal pumping. This pumping is controlled by two pairs of pharyngeal motor neurons (MC and M3). Each pump cycle corresponds to the propagation of a single pharyngeal muscle action potential, initiated by MC and transmitted across a single cholinergic neuromuscular junction. The eat‐2 gene is required for nicotinic neurotransmission at the pharynx. We assessed pumping patterns exhibited by wild type (N2) and a series of eat‐2 mutant strains, each identified as possessing deficits in pumping, including: (Strain: genotype) DA465: eat‐2(ad465) II; DA1113: eat‐2(ad1113) II; DA1116: eat‐2(ad1116) II. We also assessed pumping patterns in N2 strain animals incubated in the anthelmintic and acetylcholine receptor antagonist Levamisole ((−)‐Tetramisole hydrochloride; 0 – 50 uM). All studies we done in animals incubated in 10mM serotonin in M9 buffer. We recorded electropharyngeograms (EPG) using the recently developed ScreenChip system (NemaMetrix) to detect individual pump events, and analyzed recordings using an algorithm (WormBeat) to distinguish and quantify neuromuscular fidelity of the pharynx and pharyngeal pumping pace variation. As expected, mutant strains and Levamisole‐exposed N2 worms each illustrated pump pattern defects. Results show that the WormBeat algorithm can identify subtle treatment effects and distinguish phenotypic variation between mutant strains. Pump pattern assessment distinguished individual strains and allowed comparison of defect to the Levamisole dose‐responses of N2s.Support or Funding InformationWork reported in this publication was supported by the National Heart Lung and Blood Institute and National Institute of General Medical Sciences of the National Institutes of Health under Award Numbers 1R15HL126105, 1SC2GM112570, UL1GM118979, TL4GM118980, and RL5GM118978. The work is solely the responsibility of the authors and does not necessarily represent the official view of the National Institutes of Health or any other funding body.