Collective motion of driven semiflexible filaments tuned by soft repulsion and stiffness

Moore, Jeffrey M.; Thompson, Tyler N.; Glaser, Matthew A.; Betterton, Meredith D.

doi:10.1039/d0sm01036g

Cited by 22 publications

(28 citation statements)

References 54 publications

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“…These results support the conclusion that active bundling is promoted by the lipid bilayer and therefore that the bilayer supports formation of an active nematic phase. We note, however, that crossings are not completely suppressed by the presence of the bilayer and that further suppression of crossings may lead to additional collective phases, such as the polar phases observed or predicted in previous works (24,25,(29)(30)(31).…”

Section: Significancementioning

confidence: 38%

“…Brownian Dynamics Simulation. Brownian dynamics was used to simulate MTs, represented as active bead-spring chains (29,53) gliding in the presence of a static, spatially nonuniform distribution of kinesin motors represented as point particles. The motor distributions were generated probabilistically using Gaussian or uniform spatial distributions.…”

Section: Methodsmentioning

confidence: 99%

“…At high enough concentrations, global nematic order can emerge in the MT or actin layer, purely due to lateral steric interactions and activity, creating an active nematic system of self-propelled filaments (23)(24)(25). These experimental results have recently been explored theoretically with agent-based simulations producing polar and apolar nematics and motile polar clusters (26)(27)(28)(29).…”

Section: Significancementioning

confidence: 99%

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Active nematic order and dynamic lane formation of microtubules driven by membrane-bound diffusing motors

Memarian

Lopes

Schwarzendahl

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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Dynamic lane formation and long-range active nematic alignment are reported using a geometry in which kinesin motors are directly coupled to a lipid bilayer, allowing for in-plane motor diffusion during microtubule gliding. We use fluorescence microscopy to image protein distributions in and below the dense two-dimensional microtubule layer, revealing evidence of diffusion-enabled kinesin restructuring within the fluid membrane substrate as microtubules collectively glide above. We find that the lipid membrane acts to promote filament–filament alignment within the gliding layer, enhancing the formation of a globally aligned active nematic state. We also report the emergence of an intermediate, locally ordered state in which apolar dynamic lanes of nematically aligned microtubules migrate across the substrate. To understand this emergent behavior, we implement a continuum model obtained from coarse graining a collection of self-propelled rods, with propulsion set by the local motor kinetics. Tuning the microtubule and kinesin concentrations as well as active propulsion in these simulations reveals that increasing motor activity promotes dynamic nematic lane formation. Simulations and experiments show that, following fluid bilayer substrate mediated spatial motor restructuring, the total motor concentration becomes enriched below the microtubule lanes that they drive, with the feedback leading to more dynamic lanes. Our results have implications for membrane-coupled active nematics in vivo as well as for engineering dynamic and reconfigurable materials where the structural elements and power sources can dynamically colocalize, enabling efficient mechanical work.

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Section: Significancementioning

confidence: 38%

Section: Methodsmentioning

confidence: 99%

Section: Significancementioning

confidence: 99%

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Active nematic order and dynamic lane formation of microtubules driven by membrane-bound diffusing motors

Memarian

Lopes

Schwarzendahl

et al. 2021

Proc. Natl. Acad. Sci. U.S.A.

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“…Active matter is composed of energy-consuming units that generate activity through motility. Emergent behavior, like global contraction, collective motion, and turbulent flow underpin active matter systems [1][2][3][4]. Self-organization in active matter can form structures orders of magnitude larger than the size of a single particle [5][6][7].…”

Section: Introductionmentioning

confidence: 99%

Active Condensation of Filaments Under Spatial Confinement

et al. 2022

Self Cite

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Living systems exhibit self-organization, a phenomenon that enables organisms to perform functions essential for life. The interior of living cells is a crowded environment in which the self-assembly of cytoskeletal networks is spatially constrained by membranes and organelles. Cytoskeletal filaments undergo active condensation in the presence of crosslinking motor proteins. In past studies, confinement has been shown to alter the morphology of active condensates. Here, we perform simulations to explore systems of filaments and crosslinking motors in a variety of confining geometries. We simulate spatial confinement imposed by hard spherical, cylindrical, and planar boundaries. These systems exhibit non-equilibrium condensation behavior where crosslinking motors condense a fraction of the overall filament population, leading to coexistence of vapor and condensed states. We find that the confinement lengthscale modifies the dynamics and condensate morphology. With end-pausing crosslinking motors, filaments self-organize into half asters and fully-symmetric asters under spherical confinement, polarity-sorted bilayers and bottle-brush-like states under cylindrical confinement, and flattened asters under planar confinement. The number of crosslinking motors controls the size and shape of condensates, with flattened asters becoming hollow and ring-like for larger motor number. End pausing plays a key role affecting condensate morphology: systems with end-pausing motors evolve into aster-like condensates while those with non-end-pausing crosslinking motor proteins evolve into disordered clusters and polarity-sorted bundles.

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“…Self-propelled particles self-organize into macroscopic structures with collective dynamics like clustering, swarming, and swirling. This type of dynamical pattern formation has been subject to intensive research in recent years, both from a theoretical or computational viewpoint [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] and experimentally [26][27][28][29][30][31][32][33], often using systems of bacteria either swimming in a solution or gliding on surfaces as well as synthetic self-propelled particles systems [34].…”

Section: Introductionmentioning

confidence: 99%

Effects of direction reversals on patterns of active filaments

Abbaspour¹,

Malek²,

Karpitschka³

et al. 2021

Preprint

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Active matter systems provide fascinating examples of pattern formation and collective motility without counterpart in equilibrium systems. Here, we employ Brownian dynamics simulations to study the collective motion and self-organization in systems of self-propelled semiflexible filaments, inspired by the gliding motility of filamentous Cyanobacteria. Specifically, we investigate the influence of stochastic direction reversals on the patterns. We explore pattern formation and dynamics by modulating three relevant physical parameters, the bending stiffness, the activity, and the reversal rate. In the absence of reversals, our results show rich dynamical behavior including spiral formation and collective motion of aligned clusters of various sizes, depending on the bending stiffness and self-propulsion force. The presence of reversals diminishes spiral formation and reduces the sizes of clusters or suppresses clustering entirely. This homogenizing effect of direction reversals can be understood as reversals providing an additional mechanism to either unwind spirals or to resolve clusters.

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Collective motion of driven semiflexible filaments tuned by soft repulsion and stiffness

Abstract: In active matter systems, self-propelled particles can self-organize to undergo collective motion, leading to persistent dynamical behavior out of equilibrium. In cells, cytoskeletal filaments and motor proteins self-organize into complex...

Cited by 22 publications

References 54 publications

Active nematic order and dynamic lane formation of microtubules driven by membrane-bound diffusing motors

Active nematic order and dynamic lane formation of microtubules driven by membrane-bound diffusing motors

Active Condensation of Filaments Under Spatial Confinement

Effects of direction reversals on patterns of active filaments

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