On the unity and diversity of cilia

Wan, Kirsty Y.; Jékely, Gáspár

doi:10.1098/rstb.2019.0148

Cited by 19 publications

(18 citation statements)

References 66 publications

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“…2d), implying that the state sequences are either stochastic, or generated by complex deterministic processes. This lack of periodicity or fixed phase relationships between appendage movements is different from the gaits of most animals or those reported for various flagellates 57–59 . Autocorrelation analysis confirmed the observed lack of clear periodicity (Fig.…”

Section: Resultscontrasting

confidence: 94%

“…Walking locomotion in Euplotes represents a departure from many of the best studied appendage-based locomotor systems. For example, limbed locomotion in animals tends to proceed by highly stereotyped, determinate patterns of activity 57,58 , and many small, aquatic animals exhibit periodic movements of appendages, often cilia, during locomotion 7,59,80 . Many forms of unicellular locomotion involve such dynamics as well including in sperm cells 81 , diverse flagellates with various numbers of flagella 59 , and ciliates 59,82,83 .…”

Section: Discussionmentioning

confidence: 99%

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A unicellular walker controlled by a microtubule-based finite state machine

Larson¹,

Garbus

Pollack

et al. 2021

Preprint

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Cells are complex biochemical systems whose behavior emerges from interactions among myriad molecular components. The idea that cells execute computational processes is often invoked as a general framework for understanding cellular complexity. However, the manner in which cells might embody computational processes in a way that the powerful theories of computation, such as finite state machine models, could be productively applied, remains to be seen. Here we demonstrate finite state machine-like processing embodied in cells, using the walking behavior of Euplotes eurystomus, a ciliate that walks across surfaces using fourteen motile appendages called cirri. We found that cellular walking entails a discrete set of gait states. Transitions between these states are highly regulated, with distinct breaking of detailed balance and only a small subset of possible transitions actually observed. The set of observed transitions decomposes into a small group of high-probability unbalanced transitions forming a cycle and a large group of low-probability balanced transitions, thus revealing stereotypy in sequential patterns of state transitions. Taken together these findings implicate a machine-like process. Cirri are connected by microtubule bundles, and we find an association between the involvement of cirri in different state transitions and the pattern of attachment to the microtubule bundle system, suggesting a mechanical basis for the regularity of state transitions. We propose a model where the actively controlled, unbalanced transitions establish strain in certain cirri, the release of which from the substrate causes the cell to advance forward along a linear trajectory. This demonstration of a finite state machine embodied in a living cell opens up new links between theoretical computer science and cell biology and may provide a general framework for understanding and predicting cell behavior at a super-molecular level.

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Section: Resultscontrasting

confidence: 94%

Section: Discussionmentioning

confidence: 99%

A unicellular walker controlled by a microtubule-based finite state machine

Larson¹,

Garbus

Pollack

et al. 2021

Preprint

View full text Add to dashboard Cite

show abstract

“…We then define the sliding σ j (s) as the difference of the two arc lengths s and Π j (s). More formally, Figure A1 illustrates the geometric idea of definition (33). Figure A1.…”

Section: A Model Detailsmentioning

confidence: 99%

“…where F j (s) are the sliding forces on the j-th MT exerted by the dyneins on the (j − 1)-th MT, and F j are the singular sliding forces (on the j-th MT exerted by the dyneins on the (j − 1)-th MT) concentrated at the distal end of the Ax. Taylor expanding (33) in ρ a we have, at the leading order,…”

Section: A Model Detailsmentioning

confidence: 99%

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The biomechanical role of extra-axonemal structures in shaping the flagellar beat of Euglena

Cicconofri

Noselli

DeSimone

2020

Preprint

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We propose and discuss a model for flagellar mechanics in Euglena gracilis. We show that the peculiar non-planar shapes of its beating flagellum, dubbed "spinning lasso", arise from the mechanical interactions between two of its inner components, namely, the axoneme and the paraflagellar rod. The spontaneous shape of the axoneme and the resting shape of the paraflagellar rod are incompatible. The complex non-planar configurations of the coupled system emerge as the energetically optimal compromise between the two antagonistic components. The model is able to reproduce the experimentally observed flagellar beats and their characteristic spinning lasso geometric signature, namely, travelling waves of torsion with alternating sing along the length of the flagellum.

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Neurofluids—Deep inspiration, cilia and preloading of the astrocytic network

Ludwig

Dreha-Kulaczewski

Bock

2021

J of Neuroscience Research

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With the advent of real‐time MRI, the motion and passage of cerebrospinal fluid can be visualized without gating and exclusion of low‐frequency waves. This imaging modality gives insights into low‐volume, rapidly oscillating cardiac‐driven movement as well as sustained, high‐volume, slowly oscillating inspiration‐driven movement. Inspiration means a spontaneous or artificial increase in the intrathoracic dimensions independent of body position. Alterations in thoracic diameter enable the thoracic and spinal epidural venous compartments to be emptied and filled, producing an upward surge of cerebrospinal fluid inside the spine during inspiration; this surge counterbalances the downward pooling of venous blood toward the heart. Real‐time MRI, as a macroscale in vivo observation method, could expand our knowledge of neurofluid dynamics, including how astrocytic fluid preloading is adjusted and how brain buoyancy and turgor are maintained in different postures and zero gravity. Along with these macroscale findings, new microscale insights into aquaporin‐mediated fluid transfer, its sensing by cilia, and its tuning by nitric oxide will be reviewed. By incorporating clinical knowledge spanning several disciplines, certain disorders—congenital hydrocephalus with Chiari malformation, idiopathic intracranial hypertension, and adult idiopathic hydrocephalus—are interpreted and reviewed according to current concepts, from the basics of the interrelated systems to their pathology.

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On the unity and diversity of cilia

Cited by 19 publications

References 66 publications

A unicellular walker controlled by a microtubule-based finite state machine

A unicellular walker controlled by a microtubule-based finite state machine

The biomechanical role of extra-axonemal structures in shaping the flagellar beat of Euglena

Neurofluids—Deep inspiration, cilia and preloading of the astrocytic network

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