title: Motor-driven dynamics in actin-myosin networks.
abstract: The effect of myosin motor protein activity on the filamentous actin (F-actin) rheological response is studied using diffusing wave spectroscopy. Under conditions of saturating motor activity, we find an enhancement of longitudinal filament fluctuations corresponding to a scaling of the viscoelastic shear modulus G(d)(omega) approximately omega(7/8). As the adenosine tri-phosphate reservoir sustaining motor activity is depleted, we find an abrupt transient to a passive, "rigor state" and a return to dissipation dominated by transverse filament modes. Single-filament measurements of the apparent persistence length support the notion that motor activity leads to an increase in the effective temperature for tangential motion.
authors.affiliation: Institut Curie, Physico-Chimie Curie, UMR CNRS/IC 168, 26 rue d'Ulm, 75248 Paris Cedex 05, France.
authors.forename: Loïc
authors.initials: L
authors.lastname: Le Goff
authors.forename: François
authors.initials: F
authors.lastname: Amblard
authors.forename: Eric M
authors.initials: EM
authors.lastname: Furst
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000502:physiology*; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002645:Chickens; D008856:Microscopy, Fluorescence; D009043:Motor Activity / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000378:metabolism / Q000502:physiology; D018482:Muscle, Skeletal / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D009218:Myosins / Q000737:chemistry* / Q000502:physiology*; D012212:Rheology
chemical_list: D000199:Actins; D000255:Adenosine Triphosphate; D009218:Myosins