Protoplasmic movement in slime mold plasmodia: The diffusion drag force hypothesis

Stewart, Peter A.; Stewart, Babette Taylor

doi:10.1016/0014-4827(59)90151-x

Cited by 48 publications

(16 citation statements)

References 14 publications

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“…The network consists of tubes made of a gel-like outer layer enclosing the cytoplasmic fluid, and the fluid oscillates forth and back across a network with a period of about 100 s (11). The most natural hypothesis to explain flow suggests it is caused by observed cross-sectional contractions of the tubes generated by the actin cytoskeleton in the outer gel layer (12).…”

mentioning

confidence: 99%

Random network peristalsis in Physarum polycephalum organizes fluid flows across an individual

Alim¹,

Amselem

Peaudecerf³

et al. 2013

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

150

167

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Individuals can function as integrated organisms only when information and resources are shared across a body. Signals and substrates are commonly moved using fluids, often channeled through a network of tubes. Peristalsis is one mechanism for fluid transport and is caused by a wave of cross-sectional contractions along a tube. We extend the concept of peristalsis from the canonical case of one tube to a random network. Transport is maximized within the network when the wavelength of the peristaltic wave is of the order of the size of the network. The slime mold Physarum polycephalum grows as a random network of tubes, and our experiments confirm peristalsis is used by the slime mold to drive internal cytoplasmic flows. Comparisons of theoretically generated contraction patterns with the patterns exhibited by individuals of P. polycephalum demonstrate that individuals maximize internal flows by adapting patterns of contraction to size, thus optimizing transport throughout an organism. This control of fluid flow may be the key to coordinating growth and behavior, including the dynamic changes in network architecture seen over time in an individual.

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mentioning

confidence: 99%

Random network peristalsis in Physarum polycephalum organizes fluid flows across an individual

Alim¹,

Amselem

Peaudecerf³

et al. 2013

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

150

167

View full text Add to dashboard Cite

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“…Networks connecting multiple food sources are a good compromise between efficiency, reliability, and cost, comparable to human transport networks [29]. Fluid cytoplasm enclosed in the tubular network exhibits nonstationary shuttle flows [30][31][32] driven by a peristaltic wave of contractions spanning the entire organism [33]. Investigations of transport in these networks are so far limited to estimates based on the minimal distance between tubes [29,34,35].…”

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confidence: 99%

Pruning to Increase Taylor Dispersion inPhysarum polycephalumNetworks

et al. 2016

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How do the topology and geometry of a tubular network affect the spread of particles within fluid flows? We investigate patterns of effective dispersion in the hierarchical, biological transport network formed by Physarum polycephalum. We demonstrate that a change in topology -pruning in the foraging state -causes a large increase in effective dispersion throughout the network. By comparison, changes in the hierarchy of tube radii result in smaller and more localized differences. Pruned networks capitalize on Taylor dispersion to increase the dispersion capability.PACS numbers: 87.18. Vf, 87.16.Wd Transport due to fluid flowing through tubular networks is of great interest, because it has technological applications to biomimetic microfluidic devices [1][2][3], foams [4], fuel cells [5], and other filtration systems [6] and lies at the heart of extended organisms that rely on transport networks to function: animal vasculature [7,8], fungal mycelia [9], and plant tubes [10][11][12]. A big challenge regarding transport networks is to understand how network architecture changes the efficiency of particle spread throughout a network. While it is experimentally tedious to map particle transport in a network, predicting the spread of particles is also a theoretical challenge [13][14][15][16][17][18][19][20]. Attempts to understand how the network topology and geometry affect the transport of particles are scarce [17]. Alternatively, we can study the dynamic changes of tubular network architecture in living beings. Organisms spontaneously reorganize their transport networks, including tube pruning [21][22][23][24]. Examples are vessel development in zebra fish brain development [21], or growth of a large foraging fungal body [22]. Here, we study the slime mold Physarum polycephalum which emerged as an inspiring and yet puzzling model for 'intelligent' living transport networks.P. polycephalum like foraging fungi, actively adapts its network to environmental cues [25][26][27][28][29]. Networks connecting multiple food sources are a good compromise between efficiency, reliability, and cost, comparable to human transport networks [29]. Fluid cytoplasm enclosed in the tubular network exhibits nonstationary shuttle flows [30][31][32] driven by a peristaltic wave of contractions spanning the entire organism [33]. Investigations of transport in these networks are so far limited to estimates based on the minimal distance between tubes [29,34,35]. We tracked a well-reticulated individual trimmed from a larger network (Fig. 1). After several hours, the thin central tubes were abandoned in favor of a few large central tubes and globular structures at the periphery. How does this radical change of topology affect the transport capabilities of the individual? What role do hierarchical tube radii play? We present a method to efficiently map the effective dispersion of particles from any initiation site throughout any network with nonstationary but periodic fluid flows. We use this method to study the change in dispersion patterns ...

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“…Although protoplasmic gels are more stable at higher temperatures within the range of viability, the stopping of Brownian motion suggests an actual change in state and not just an increased stability. Reversible stoppage of Brownian motion has also been seen in plasmodia subjected to physical agitation (7) or cutting (30). Stewart and Stewart (30) called this state type III gel, distinguished from normal stream and tube by the absence of Brownian movement.…”

Section: Discussionmentioning

confidence: 99%

“…(a) At the lowest energies causing a change, the "least response" was an endoplasmic gelation that diverted or blocked streams briefly and dispersed within a few seconds to a few minutes. The normal Brownian motion of cytoplasmic particles (7,30) was stopped. (b) At higher energies, the "intermediate response" was a localized contraction of part of the gelled material to produce a slowly reversible, more dense, gelled region surrounded by rapidly reversible gelation.…”

Section: Light Microscopic Observationsmentioning

confidence: 99%

LASER MICROSCOPE IRRADIATION OF PHYSARUM POLYCEPHALUM: DYNAMIC AND ULTRASTRUCTURAL EFFECTS

Griffin

Stein

Stowell

1969

The Journal of Cell Biology

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Streaming plasmodia of Physarum polycephalum were irradiated with a microscope-mounted ruby laser and the resulting changes were recorded by cinemicrography or streak photographs. Some lesions were processed for electron microscopy. By varying the incident energy, three levels of response were detected. Two transient responses, a gelation briefly blocking streams and a more severe gelation with contraction, changed movement patterns but not organelle ultrastructure. At higher energies, a permanently coagulated lesion was rapidly segregated from normal and transiently altered cytoplasm by formation of new membranes. Within the coagulum, pigment granules were destroyed, membranes were disrupted, and cytoplasm was flocculent. Nuclei and mitochondria were compact in the center and swollen in a peripheral space left by contraction of the coagulum.These changes are probably caused by heat produced by the interaction between the laser beam and the pigment granules of the plasmodium. Many of the changes seem to be secondary responses that follow the primary capture of energy during irradiation.

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Protoplasmic movement in slime mold plasmodia: The diffusion drag force hypothesis

Cited by 48 publications

References 14 publications

Random network peristalsis in Physarum polycephalum organizes fluid flows across an individual

Random network peristalsis in Physarum polycephalum organizes fluid flows across an individual

Pruning to Increase Taylor Dispersion inPhysarum polycephalumNetworks

LASER MICROSCOPE IRRADIATION OF PHYSARUM POLYCEPHALUM: DYNAMIC AND ULTRASTRUCTURAL EFFECTS

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