Pharyngeal timing and particle transport defects in Caenorhabditis elegans feeding mutants

The nematode C. elegans uses rhythmic muscle contractions (pumps) of the pharynx, a tubular feeding organ, to filter, transport, and crush food particles. A number of feeding mutants have been identified, including those with slow pharyngeal pumping rate, weak muscle contraction, defective muscle relaxation, and defective grinding of bacteria. Many aspects of these pharyngeal behavioral defects and how they affect pharyngeal function are not well understood. For example, the behavioral deficits underlying inefficient particle transport in ‘slippery’ mutants have been unclear. Here we use high speed video microscopy to describe pharyngeal pumping behaviors and particle transport in wild-type animals and in feeding mutants. Different ‘slippery’ mutants exhibit distinct defects including weak isthmus contraction, failure to trap particles in the anterior isthmus, and abnormal timing of contraction and relaxation in pharyngeal compartments. Our results show that multiple deficits in pharyngeal timing or contraction can cause defects in particle transport.