Force-extension curves of bacterial flagella

Vogel, Reinhard; Stark, Holger

doi:10.1140/epje/i2010-10664-5

Cited by 45 publications

(82 citation statements)

References 44 publications

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“…In this first modelling approach, we did not include the dynamics of bond formation and breakage [59]. In addition, the models did not include variability between the agents.…”

Section: Looking Aheadmentioning

confidence: 99%

Collective navigation of cargo-carrying swarms

et al. 2012

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Much effort has been devoted to the study of swarming and collective navigation of microorganisms, insects, fish, birds and other organisms, as well as multi-agent simulations and to the study of real robots. It is well known that insect swarms can carry cargo. The studies here are motivated by a less well-known phenomenon: cargo transport by bacteria swarms. We begin with a concise review of how bacteria swarms carry natural, micrometre-scale objects larger than the bacteria (e.g. fungal spores) as well as man-made beads and capsules (for drug delivery). A comparison of the trajectories of virtual beads in simulations (using different putative coupling between the virtual beads and the bacteria) with the observed trajectories of transported fungal spores implies the existence of adaptable coupling. Motivated by these observations, we devised new, multi-agent-based studies of cargo transport by agent swarms. As a first step, we extended previous modelling of collective navigation of simple bacteriainspired agents in complex terrain, using three putative models of agent-cargo coupling. We found that cargo-carrying swarms can navigate efficiently in a complex landscape. We further investigated how the stability, elasticity and other features of agent-cargo bonds influence the collective motion and the transport of the cargo, and found sharp phase shifts and dual successful strategies for cargo delivery. Further understanding of such mechanisms may provide valuable clues to understand cargo-transport by smart swarms of other organisms as well as by man-made swarming robots.

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“…In this first modelling approach, we did not include the dynamics of bond formation and breakage [59]. In addition, the models did not include variability between the agents.…”

Section: Looking Aheadmentioning

confidence: 99%

Collective navigation of cargo-carrying swarms

et al. 2012

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“…Although much research has been performed on the mechanical properties of a prokaryotic or bacterial flagellum and how these properties are related to the overall bacterial dynamics, [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] still our understanding of the complex aspects of bacterial locomotion, such as tumbling of an E. coli, remains incomplete. 14,[17][18][19] The locomotion of bacteria involves rich and complex physics.…”

Section: Introductionmentioning

confidence: 99%

“…2,17 The flagellum can exist in different stable polymorphic forms, transitions among which are induced mechanically, either by the reverse rotation of the flagellum, 14,17,18 by the application of stretching forces, 3,12 or by external flows. 7,34 Rotation induced polymorphic transitions occur during the locomotion of the bacterium and affect the overall bacterial dynamics.…”

Section: Introductionmentioning

confidence: 99%

“…35 A number of approaches using the Kirchhoff free energy density and extended versions of it, were proposed to deal with the flagellar multistability. [6][7][8]12 In ref.…”

Section: Introductionmentioning

confidence: 99%

“…In our study here, we explore the flagellar dynamics in the full free energy landscape by studying the impact of the ground state energies. Changes in their values affect the heights of the transition barriers between the local minima, 6,8,12 which the flagellum has to pass to locally transform from one polymorphic state to the other. Thus the full landscape of the free energy determines the flagellar dynamics during reverse rotation including possible transient and final steady states.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of a bacterial flagellum under reverse rotation

Adhyapak

Stark

2016

Soft Matter

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To initiate tumbling of an E. coli, one of the helical flagella reverses its sense of rotation. It then transforms from its normal form first to the transient semicoiled state and subsequently to the curly-I state. The dynamics of polymorphism is effectively modeled by describing flagellar elasticity through an extended Kirchhoff free energy. However, the complete landscape of the free energy remains undetermined because the ground state energies of the polymorphic forms are not known. We investigate how variations in these ground state energies affect the dynamics of a reversely rotated flagellum of a swimming bacterium. We find that the flagellum exhibits a number of distinct dynamical states and comprehensively summarize them in a state diagram. As a result, we conclude that tuning the landscape of the extended Kirchhoff free energy alone cannot generate the intermediate full-length semicoiled state. However, our model suggests an ad hoc method to realize the sequence of polymorphic states as observed for a real bacterium. Since the elastic properties of bacterial flagella are similar, our findings can easily be extended to other peritrichous bacteria.

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Flow Effects in Supramolecular Chirality

Arteaga¹,

Canillas²,

Crusats³

et al. 2011

Israel Journal of Chemistry

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There are an increasing number of reports on the emergence of circular dichroic signals when solutions of J‐aggregates are vortex‐stirred. Some authors claim that the transfer of chirality from the macroscopic stirring vortex occurs at the level of electronic transitions. Others argue that the signal observed is not due to true circular dichroism (CD), but rather that it is an artifact due to combinations of linear polarization contributions. For both interpretations it is necessary to assume that the alignment by effect of flows dominates over the Brownian dynamics. Therefore, the topic belongs to supramolecular chemistry because the alignment in current flows can only occur for relatively large particles with an appropriate shape. The phenomenon is detected by CD spectroscopy, which itself is also the main hindrance, even controversial, in its study and interpretation. However, modern Mueller matrix polarimetry can solve some of the problems. The phenomenon has been explained using different scenarios; however, in some of the systems the experimental evidence only supports the model in which deformation (folding/torsion) of elastic soft‐matter yields true CD. Here we discuss the role of the gradient of shear rates in the deformation of nano particles of soft matter to give chiral supramolecular structures, as the first step to explaining the phenomenon.

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Force-extension curves of bacterial flagella

Cited by 45 publications

References 44 publications

Collective navigation of cargo-carrying swarms

Collective navigation of cargo-carrying swarms

Dynamics of a bacterial flagellum under reverse rotation

Flow Effects in Supramolecular Chirality

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