Spiral Defects in Motility Assays: A Measure of Motor Protein Force

Bourdieu, Laurent; Duke, Thomas; Elowitz, Michael B.; Winkelmann, Donald A.; Leibler, Stanislas; Libchaber, Albert

doi:10.1103/physrevlett.75.176

Cited by 98 publications

(124 citation statements)

References 14 publications

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“…In particular, recent efforts to manipulate connected passive colloids by electrical fields [29], microfluidics [30], lock-and-key type interactions [31] and heat [29] have been quite successful in yielding externally actuated filaments with controllable bending stiffness. Extension of such techniques using diffusophoretic Janus particles as templates should yield internally controlled self-propelling filaments, just as a small variation of the motility assay for rotating filaments [27], by clamping an end, will lead to beating. However, the quantitative experiments to check our predictions remain to be done.…”

Section: Discussionmentioning

confidence: 99%

Flagellar dynamics of a connected chain of active, polar, Brownian particles

Chelakkot

Gopinath

Mahadevan

et al. 2014

J. R. Soc. Interface.

116

152

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We show that active, self-propelled particles that are connected together to form a single chain that is anchored at one end can produce the graceful beating motions of flagella. Changing the boundary condition from a clamp to a pivot at the anchor leads to steadily rotating tight coils. Strong noise in the system disrupts the regularity of the oscillations. We use a combination of detailed numerical simulations, mean-field scaling analysis and first passage time theory to characterize the phase diagram as a function of the filament length, passive elasticity, propulsion force and noise. Our study suggests minimal experimental tests for the onset of oscillations in an active polar chain.

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Section: Discussionmentioning

confidence: 99%

Flagellar dynamics of a connected chain of active, polar, Brownian particles

Chelakkot

Gopinath

Mahadevan

et al. 2014

J. R. Soc. Interface.

116

152

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“…The tensile forces only contribute at subleading orders, and hence T(s,t) % 0. In the absence of internal shear, equations (2.1) and (2.4) describe the elastohydrodynamics of a passive filament in a viscous fluid and have already been studied analytically (Machin 1958;Bourdieu et al 1995;Goldstein & Langer 1995;Goldstein et al 1998;Wiggins et al 1998;Wolgemuth et al 2000;Fu et al 2008) and experimentally (Bourdieu et al 1995;Wiggins et al 1998;Yu et al 2006). Despite the relative simplicity of the linearized formulation equation (2.4), there has not been a study of its accuracy compared with the full nonlinear framework equation (2.1) given the variation of parameters such as the shear force wavenumber k, shear force amplitude A and the sperm compliance Sp.…”

Section: Parallels With the Linear Theorymentioning

confidence: 99%

Nonlinear instability in flagellar dynamics: a novel modulation mechanism in sperm migration?

Gadêlha

Gaffney

Smith

et al. 2010

J. R. Soc. Interface.

109

148

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Throughout biology, cells and organisms use flagella and cilia to propel fluid and achieve motility. The beating of these organelles, and the corresponding ability to sense, respond to and modulate this beat is central to many processes in health and disease. While the mechanics of flagellum -fluid interaction has been the subject of extensive mathematical studies, these models have been restricted to being geometrically linear or weakly nonlinear, despite the high curvatures observed physiologically. We study the effect of geometrical nonlinearity, focusing on the spermatozoon flagellum. For a wide range of physiologically relevant parameters, the nonlinear model predicts that flagellar compression by the internal forces initiates an effective buckling behaviour, leading to a symmetry-breaking bifurcation that causes profound and complicated changes in the waveform and swimming trajectory, as well as the breakdown of the linear theory. The emergent waveform also induces curved swimming in an otherwise symmetric system, with the swimming trajectory being sensitive to head shape-no signalling or asymmetric forces are required. We conclude that nonlinear models are essential in understanding the flagellar waveform in migratory human sperm; these models will also be invaluable in understanding motile flagella and cilia in other systems.

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“…Recent experiments on molecular motor assays revealed formation of spiral defects and loops of actively moving filaments driven by motor proteins [22,31]. In gliding assays, one end of motor proteins are irreversibly attached to a two dimensional substrate.…”

Section: Introductionmentioning

confidence: 99%

Forced desorption of semiflexible polymers, adsorbed and driven by molecular motors

Chaudhuri

2016

Soft Matter

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We formulate and characterize a model to describe dynamics of semiflexible polymers in the presence of activity due to motor proteins attached irreversibly to a substrate, and a transverse pulling force acting on one end of the filament. The stochastic binding-unbinding of the motor proteins and their ability to move along the polymer, generates active forces. As the pulling force reaches a threshold value, the polymer eventually desorbs from the substrate. Performing molecular dynamics simulations of the polymer in presence of a Langevin heat bath, and stochastic motor activity, we obtain desorption phase diagrams. The correlation time for fluctuations in desorbed fraction increases as one approaches complete desorption, captured quantitatively by a power law spectral density. We present theoretical analysis of the phase diagram using mean field approximations in the weakly bending limit of the polymer and performing linear stability analysis. This predicts increase in the desorption force with the polymer bending rigidity, active velocity and processivity of the motor proteins to capture the main features of the simulation results.PACS numbers: 05.20.-y, 36.20.-r, 87.15.-v

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Spiral Defects in Motility Assays: A Measure of Motor Protein Force

Cited by 98 publications

References 14 publications

Flagellar dynamics of a connected chain of active, polar, Brownian particles

Flagellar dynamics of a connected chain of active, polar, Brownian particles

Nonlinear instability in flagellar dynamics: a novel modulation mechanism in sperm migration?

Forced desorption of semiflexible polymers, adsorbed and driven by molecular motors

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