Buckling, stiffening, and negative dissipation in the dynamics of a biopolymer in an active medium.
We present a generic theory for the dynamics of a stiff filament under tension, in an active medium with orientational correlations, such as a microtubule in contractile actin. In sharp contrast to the case of a passive medium, we find the filament can stiffen, and possibly oscillate or buckle, depending on both the contractile or tensile nature of the activity and the filament-medium anchoring interaction. We also demonstrate a strong violation of the fluctuation-dissipation (FD) relation in the effective dynamics of the filament, including a negative FD ratio. Our approach is also of relevance to the dynamics of axons, and our model equations bear a remarkable formal similarity to those in recent work [Martin P, Hudspeth AJ, Juelicher F (2001) Proc Natl Acad Sci USA 98:14380-14385] on auditory hair cells. Detailed tests of our predictions can be made by using a single filament in actomyosin extracts or bacterial suspensions.
Kikuchi
Norio
N
Department of Physics, Centre for Condensed Matter Theory, Indian Institute of Science, Bangalore 560 012, India.
Ehrlicher
Allen
A
Koch
Daniel
D
Käs
Josef A
JA
Ramaswamy
Sriram
S
Rao
Madan
M
D000199:Actins / Q000737:chemistry / Q000378:metabolism; D001704:Biopolymers / Q000737:chemistry* / Q000378:metabolism; D003599:Cytoskeleton / Q000737:chemistry / Q000378:metabolism; D004548:Elasticity; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism; D008954:Models, Biological; D013314:Stress, Mechanical; D013718:Tensile Strength
D000199:Actins; D001704:Biopolymers