Biophysical Journal
Volume 100, Issue 8, 20 April 2011, Pages 1977-1985
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Article
Caenorhabditis elegans Body Mechanics Are Regulated by Body Wall Muscle Tone

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Abstract

Body mechanics in the nematode Caenorhabditis elegans are central to both mechanosensation and locomotion. Previous work revealed that the mechanics of the outer shell, rather than internal hydrostatic pressure, dominates stiffness. This shell is comprised of the cuticle and the body wall muscles, either of which could contribute to the body mechanics. Here, we tested the hypothesis that the muscles are an important contributor by modulating muscle tone using optogenetic and pharmacological tools, and measuring animal stiffness using piezoresistive microcantilevers. As a proxy for muscle tone, we measured changes in animal length under the same treatments. We found that treatments that induce muscle contraction generally resulted in body shortening and stiffening. Conversely, methods to relax the muscles more modestly increased length and decreased stiffness. The results support the idea that body wall muscle activation contributes significantly to and can modulate C. elegans body mechanics. Modulation of body stiffness would enable nematodes to tune locomotion or swimming gaits and may have implications in touch sensation.

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Sung-Jin Park's present address is the Disease Biophysics Group, School of Engineering and Applied Sciences, Harvard University, Cambridge, MA.

Chloé Powell's present address is Biomedical Engineering Program, University of Michigan, Ann Arbor, MI.