title: Direct measurements of drag forces in C. elegans crawling locomotion.
abstract: With a simple and versatile microcantilever-based force measurement technique, we have probed the drag forces involved in Caenorhabditis elegans locomotion. As a worm crawls on an agar surface, we found that substrate viscoelasticity introduces nonlinearities in the force-velocity relationships, yielding nonconstant drag coefficients that are not captured by original resistive force theory. A major contributing factor to these nonlinearities is the formation of a shallow groove on the agar surface. We measured both the adhesion forces that cause the worm's body to settle into the agar and the resulting dynamics of groove formation. Furthermore, we quantified the locomotive forces produced by C. elegans undulatory motions on a wet viscoelastic agar surface. We show that an extension of resistive force theory is able to use the dynamics of a nematode's body shape along with the measured drag coefficients to predict the forces generated by a crawling nematode.
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada; Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada.
authors.forename: Yegor
authors.initials: Y
authors.lastname: Rabets
authors.affiliation: Department of Physics & Astronomy and the Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Matilda
authors.initials: M
authors.lastname: Backholm
authors.affiliation: Department of Physics & Astronomy and the Brockhouse Institute for Materials Research, McMaster University, Hamilton, Ontario, Canada; Laboratoire de Physico-Chimie Théorique, UMR Centre National de la Recherche Scientifique 7083 GULLIVER, ESPCI, Paris, France.
authors.forename: Kari
authors.initials: K
authors.lastname: Dalnoki-Veress
authors.affiliation: Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Ontario, Canada; Donnelly Centre for Cellular and Biomolecular Research, University of Toronto, Toronto, Ontario, Canada; Department of Physics, University of Toronto, Toronto, Ontario, Canada. Electronic address: wryu@physics.utoronto.ca.
authors.forename: William S
authors.initials: WS
authors.lastname: Ryu
mesh_terms: D000818:Animals; D001696:Biomechanical Phenomena; D017173:Caenorhabditis elegans / Q000502:physiology*; D008124:Locomotion