The molting cycle of C. elegans includes specialized animal behaviors. We seek to understand how endocrine and neuroendocrine circuits regulate these idiosyncratic behaviors, and coordinate them with episodes of tissue remodeling.
C. elegans cease locomotion and feeding at the end of each larval stage, while the cuticle is remade. This period of quiescence, called lethargus, is similar to human sleep. Larvae in lethargus move in response to adverse stimuli, as the behavioral state is reversible. Animals must resume physical activity in order to escape from the old cuticle. The accompanying film shows a quiescent animal, provoked by UV light at the 1:36 mark.
C. elegans break out of the old cuticle, or ecdyse, using a series of idiosyncratic movements including regurgitation of part of the pharyngeal cuticle; longitudinal rotation, which loosens the cuticle from the body; contraction and expansion along the anterior-posterior axis; and forward thrusts. The signaling pathways that orchestrate these behaviors have not yet been characterized, but likely include communication among various neurons, muscles, and epidermal cells. Animals typically ecdyse quickly. However, this movie shows a mutant larva that struggled, and failed, to escape its prior cuticle.