Periodic traction in migrating large amoeba of<i>Physarum polycephalum</i>

Rieu, Jean Paul; Delanoë-Ayari, Hélène; Takagi, Seiji; Takai, Yoshimi; Nakagaki, Toshiyuki

doi:10.1098/rsif.2015.0099

Cited by 35 publications

(51 citation statements)

References 23 publications

(42 reference statements)

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“…We also observe a second mode of deformation which we call 'amphistaltic' due to the fact that the front and rear contract and relax in an anti-phase manner. The amphistaltic amoeboid mode could be the precursor of the contractile dumbbells found by Rieu et al in the companion paper [10]. Of the 21 cells we study, 10 of them clearly exhibit the peristaltic behaviour, while six are amphistaltic.…”

Section: Cell Behaviourmentioning

confidence: 75%

Coordination of contractility, adhesion and flow in migratingPhysarumamoebae

Lewis

Zhang

Guy

et al. 2015

J. R. Soc. Interface.

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This work examines the relationship between spatio-temporal coordination of intracellular flow and traction stress and the speed of amoeboid locomotion of microplasmodia of Physarum polycephalum. We simultaneously perform particle image velocimetry and traction stress microscopy to measure the velocity of cytoplasmic flow and the stresses applied to the substrate by migrating Physarum microamoebae. In parallel, we develop a mathematical model of a motile cell which includes forces from the viscous cytosol, a poro-elastic, contractile cytoskeleton and adhesive interactions with the substrate. Our experiments show that flow and traction stress exhibit back-to-front-directed waves with a distinct phase difference. The model demonstrates that the direction and speed of locomotion are determined by this coordination between contraction, flow and adhesion. Using the model, we identify forms of coordination that generate model predictions consistent with experiments. We demonstrate that this coordination produces near optimal migration speed and is insensitive to heterogeneity in substrate adhesiveness. While it is generally thought that amoeboid motility is robust to changes in extracellular geometry and the nature of extracellular adhesion, our results demonstrate that coordination of adhesive forces is essential to producing robust migration.

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Section: Cell Behaviourmentioning

confidence: 75%

Coordination of contractility, adhesion and flow in migratingPhysarumamoebae

Lewis

Zhang

Guy

et al. 2015

J. R. Soc. Interface.

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“…Experiments have shown that the tension in the tube wall of P. polycephalum oscillates with a well-defined frequency (24,25). A typical period is around 120 s. Oscillations seem independent of cytoplasmic flows because they persist if cytoplasm is replaced by air (26), even though they become spatially uncorrelated if flows are stalled (26,27).…”

Section: P Polycephalum Responds To a Stimulus With A Propagating Chmentioning

confidence: 99%

Mechanism of signal propagation in Physarum polycephalum

Alim

Andrew

Pringle

et al. 2017

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

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Complex behaviors are typically associated with animals, but the capacity to integrate information and function as a coordinated individual is also a ubiquitous but poorly understood feature of organisms such as slime molds and fungi. Plasmodial slime molds grow as networks and use flexible, undifferentiated body plans to forage for food. How an individual communicates across its network remains a puzzle, but Physarum polycephalum has emerged as a novel model used to explore emergent dynamics. Within P. polycephalum, cytoplasm is shuttled in a peristaltic wave driven by cross-sectional contractions of tubes. We first track P. polycephalum's response to a localized nutrient stimulus and observe a front of increased contraction. The front propagates with a velocity comparable to the flow-driven dispersion of particles. We build a mathematical model based on these data and in the aggregate experiments and model identify the mechanism of signal propagation across a body: The nutrient stimulus triggers the release of a signaling molecule. The molecule is advected by fluid flows but simultaneously hijacks flow generation by causing local increases in contraction amplitude as it travels. The molecule is initiating a feedback loop to enable its own movement. This mechanism explains previously puzzling phenomena, including the adaptation of the peristaltic wave to organism size and P. polycephalum's ability to find the shortest route between food sources. A simple feedback seems to give rise to P. polycephalum's complex behaviors, and the same mechanism is likely to function in the thousands of additional species with similar behaviors. acellular slime mold | transport network | behavior | Taylor dispersion O ne of the great challenges of unraveling biological complexity is understanding what kind of and how much computational power is required for an organism to generate sophisticated behaviors. Behaviors are typically associated with a nervous system, but many organisms without nervous systems integrate information and function as coordinated individuals (1); examples range from the ability of Escherichia coli to move up chemical gradients (2) to the ability of a multicellular fungus to sense and precisely explore unoccupied space (3). A recently published and striking example of a complex behavior involves bacteria within a biofilm: When a Bacillus subtilis biofilm is deprived of nutrients, bacteria are able to grow networks of channels and evaporatively pump flows, creating intricate structures that benefit the entire community (4).Perhaps the archetypal example of an apparently simple organism able to generate sophisticated behaviors is the slime mold Physarum polycephalum, whose behaviors are repeatedly characterized as "intelligent." This slime mold is able to navigate mazes by finding the shortest route between different food sources (5) and has used its ability to reconstruct the transportation maps of major cities (6). The organism can structure its connections to different nutrient sources to optimize its diet...

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“…Very recently, models based on the poroelastic nature of Physarum cell have been proposed to rationalize the mechanism of locomotion of migrating microplasmodia [27,28]. The concept of Physarum cells as being poroelastic media was used previously in a series of studies aiming at understanding the dynamics of the reorganization of protoplasmic droplets and the related deformation patterns [3,44,45].…”

Section: Introductionmentioning

confidence: 99%

“…The morphology of such networks is analyzed from the point of view of the physiology [14,16,17,18] as well as in the frame of graph theory [19,20,21,22,23]. On the other hand, the scientific focus also lies on small cellular structures of about 50 -800 µm length, where the amoeboid motility of migrating microplasmodia [24,25,26,27,28,29,30] is currently intensively investigated.…”

Section: Introductionmentioning

confidence: 99%