Dynamic instability in the hook-flagellum system that triggers bacterial flicks

Jabbarzadeh, Mehdi; Fu, Henry

doi:10.1103/physreve.97.012402

Cited by 20 publications

(20 citation statements)

References 42 publications

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“…For hydrodynamic signals at high enough frequencies, such as those due to the beating of swimming appendages, the unsteady Stokes equations must be used to calculate the setal bending flows, which will be attenuated by unsteady effects at ranges larger than the viscous dissipation length. Last, our model used Euler beam theory, applicable for small setal deformations, but for larger deflections could be improved by using Kirchhoff rod theories coupled to hydrodynamics (Jabbarzadeh and Fu ).…”

Section: Resultsmentioning

confidence: 99%

How the bending mechanics of setae modulate hydrodynamic sensing in copepods

Shen

Marcos

2019

Limnology & Oceanography

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Copepods sense the hydrodynamic disturbances induced by swimming planktonic prey, potential mates, and predators through the bending of setae on their first antennae and other appendages. While the flows induced by these sources have been studied and are crucial for the mechanoreception of copepods, there is little knowledge on how these flows cause the deformation of the copepod's mechanoreceptional seta. In this article, we present a mechanical model to address how the mechanics of setal deformation by hydrodynamic signals determines the sensing capabilities of copepods. We represent a generic flow around a copepod as a combination of a uniform plus shear flow, and demonstrate that the detailed geometry of the first antenna has nonnegligible effects on the flow profile across the seta. We then proceed to evaluate the setal deformations induced by such a flow oscillating at frequencies relevant for copepod sensing, and find that lower frequency signals lead to larger setal bending and are more easily detected. We investigate the effects of setal length, signal amplitude, and signal frequency on setal bending. Finally, we investigate the response time of setal bending to hydrodynamic signals, and find short response time consistent with the rapid behavioral and neurological response of copepods.

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Section: Resultsmentioning

confidence: 99%

How the bending mechanics of setae modulate hydrodynamic sensing in copepods

Shen

Marcos

2019

Limnology & Oceanography

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“…Our study shows that an assembly of the flagellar filament by one or two different flagellins affects its mechanistic properties, which has significant consequences for several aspects of flagellar function in different environments. Directional changes of many monopolarly flagellated bacteria are mediated by combined bending of flagellar filament and hook, the structure which joins filament and motor, during the typical run-reverse-flick movement 25,33–35 . Thus, the proximal FlaA segment in S. putrefaciens likely has a positive effect on robust directional changes at high and fast swimming at normal viscosity.…”

Section: Discussionmentioning

confidence: 99%

Spatial arrangement of several flagellins within bacterial flagella improves motility in different environments

et al. 2018

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Bacterial flagella are helical proteinaceous fibers, composed of the protein flagellin, that confer motility to many bacterial species. The genomes of about half of all flagellated species include more than one flagellin gene, for reasons mostly unknown. Here we show that two flagellins (FlaA and FlaB) are spatially arranged in the polar flagellum of Shewanella putrefaciens, with FlaA being more abundant close to the motor and FlaB in the remainder of the flagellar filament. Observations of swimming trajectories and numerical simulations demonstrate that this segmentation improves motility in a range of environmental conditions, compared to mutants with single-flagellin filaments. In particular, it facilitates screw-like motility, which enhances cellular spreading through obstructed environments. Similar mechanisms may apply to other bacterial species and may explain the maintenance of multiple flagellins to form the flagellar filament.

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“…In this study we assume a constant motor torque applied towards the normal to the cell-body surface, (Shum & Gaffney 2012; Shimogonya et al. 2015; Jabbarzadeh & Fu 2018).…”

Section: Bacterial Hydrodynamicsmentioning

confidence: 99%

“…Compared with the flagellar filament consisting of helical polymers, the short flagellar hook ( in length) is a flexible structure so that it acts like a universal joint, and can be buckled during the swimming motion (Son, Guasto & Stocker 2013), generating a rich diversity of bacterial behaviours (Shum & Gaffney 2012; Nguyen & Graham 2017, 2018; Jabbarzadeh & Fu 2018). Riley, Das & Lauga (2018) considered the hook elasticity for peritrichous bacteria and numerically demonstrated that the elastohydrodynamic instability enables their swimming.…”

Section: Introductionmentioning

confidence: 99%

Bacterial spinning top

Ishimoto

2019

J. Fluid Mech.

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We have investigated the dynamics of a monotrichous bacteria cell near a wall boundary, taking elastic hook flexibility into consideration. Combining theoretical linear stability analysis and direct numerical computations via the boundary element method, we have found that the elastohydrodynamic coupling between the hook elasticity and cell rotational motion enables a stable vertical spinning behaviour like a low-Reynolds-number spinning top. The forwardly rotated flagellum, which generates the force exertion pushing towards the cell body, typically destabilizes the vertical upright position and leads to a boundary-following motion. In contrast, the backward rotation of the flagellum, generating a force pulling the cell body, contributes to stable upright behaviour in a large range of hook rigidity. Further numerical investigations have demonstrated that the non-spherical geometry of the cell body and boundary adhesive interactions affect the bacterial dynamics, leading to complex behaviours such as horizontal spinning and unstable vertical spinning motions, both of which are experimentally observed in Pseudomonas aeruginosa bacteria. These results highlight the rich diversity of bacterial surface motility emerging from mechanical boundary interactions coupled with the cell swimming and hook flexibility.

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Dynamic instability in the hook-flagellum system that triggers bacterial flicks

Cited by 20 publications

References 42 publications

How the bending mechanics of setae modulate hydrodynamic sensing in copepods

How the bending mechanics of setae modulate hydrodynamic sensing in copepods

Spatial arrangement of several flagellins within bacterial flagella improves motility in different environments

Bacterial spinning top

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