Abstract
A characteristic posture is considered one of the behavioral hallmarks of sleep, and typically includes functional features such as support for the limbs and shielding of sensory organs. The nematode C. elegans exhibits a sleep-like state during a stage termed lethargus, which precedes ecdysis at the transition between larval stages. A hockey-stick-like posture is commonly observed during lethargus. What might its function be? It was previously noted that during lethargus, C. elegans nematodes abruptly rotate about their longitudinal axis. Plausibly, these “flips” facilitate ecdysis by assisting the disassociation of the old cuticle from the new one. We found that body-posture during lethargus was established using a stereotypical motor program and that body bends during lethargus quiescence were actively maintained. Moreover, flips occurred almost exclusively when the animals exhibited a single body bend, preferentially in the anterior or mid section of the body. We describe a simple biomechanical model that imposes the observed lengths of the longitudinally directed body-wall muscles on an otherwise passive elastic rod. We show that this minimal model is sufficient for generating a rotation about the anterior-posterior body axis. Our analysis suggests that posture during lethargus quiescence may serve a developmental role in facilitating flips and that the control of body wall muscles in anterior and posterior body regions are distinct.
Highlights
The identification of sleep by researchers most commonly employs electrophysiological criteria [1,2,3]
We found that the newly quiescent angles were initially larger than the average body-angle, indicating that animals preferentially initiated the transition into a quiescence bout by freezing positions along the body where the curvature was high
These stereotypical dynamics ended with 1–2 body bends that persisted throughout the quiescence bout
Summary
The identification of sleep by researchers most commonly employs electrophysiological criteria [1,2,3] These criteria were originally developed in mammalian species, relying on the observed close interdependence between electrophysiological brain activity and behavioral indicators of sleep, but they were not found to be generally applicable across phyla [4]. Sleep-postures have been described for numerous vertebrate and invertebrate species, and in many cases have been shown to correlate with elevated arousal thresholds [4]. They include functionally beneficial features such as support of a substrate for the limbs and the head, a hunched (protective) body posture, and shielding of sensory organs. A distinctive posture is considered a behavioral hallmark sleep
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
