Characterizing the mechanical properties of Caenorhabditis elegans using a novel micro􀄘uidic approach

Abstract

The response of an organism to mechanical stress can reveal key details of its physiology and environmental adaptation. We present a novel microfluidic technique for probing the responses of living tissues to hydrostatic pressure, and we describe a series of experiments in which this method was used to probe the mechanical properties of the model organism Caenorhabditis elegans. We observe that C. elegans exhibits an elastic regime under low applied stress, and we report a measured bulk modulus that is consistent with previous studies. This value does not strongly change when the worm is exposed to various treatments, including chemical disruption, laceration, and genetic interference. We also find an effective viscosity for the worm, which sets the timescale over which the worm can adapt its body shape to various mechanical stimuli. At higher applied stress, we observe that the worm undergoes irreversible, local jamming that results in stress hardening, in which the body deformation per unit applied stress decreases monotonically. We compare these findings to high-resolution studies of the effects of mechanical stimuli on individual organs and structures within the worm. We propose that these measurements can be used to understand various observed behaviors in the worm ranging from its environment-adaptive undulatory gait to its piecewise developmental plan. Our work represents a new means of investigating mechanics in small organisms, and it suggests that the whole-body mechanics of organisms can be a useful metric for characterizing their development and adaptation.