In vivo Mechanical Behavior of Drosophila Neurons
Jagannathan Rajagopalan (Arizona State University), Alireza Tofangchi (University of Illinois at Urbana-Champaign), Taher Saif (University of Illinois at Urba)
Mechanics and Physics of Biological Cells
Mon 10:45 - 12:15
Barus-Holley 166
Several in vitro experiments have shown that neurons actively respond to mechanical forces and that mechanical forces can control the initiation and growth of neurites. But there have been very few studies exploring the mechanical behavior of neurons in vivo. In this study, we used high-resolution micromechanical force sensors to study the mechanical response of neurons in live Drosophila embryos. Our experiments show that Drosophila axons have a rest tension of a few nN and respond like viscoelastic solids to externally applied deformation. But in addition to passive viscoelastic behavior, axons also exhibit an active response. When axonal tension is suddenly diminished, axons contract and recover their tension, often to a value close to their initial rest tension, in a period of few minutes. This contraction is, however, almost completely suppressed when ATP concentration is depleted, which strongly indicates that it is an active process. Preliminary results also suggest that cortical actin and myosin II are involved in restoring tension but microtubules are not. These in vivo observations are remarkably similar to results from previous in vitro studies and suggest an important role for mechanical forces in regulating neuronal function in vivo.