The geometry and motion of nematode sperm cells

Demekhin, E. A.; Haugen, Nicole; Ibanez, Brian; Lederman, Jerome; Murphy, Kaitlyn M.; Verzi, D. W.; Witczak, Debra

doi:10.1002/cm.20362

Cited by 4 publications

(5 citation statements)

References 22 publications

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“…Constitutive relations include graded radial polymerization and depolymerization in both distance from the cell body interface, and arc length from the direction of motion. Since polar radii intersect the cell boundary at right angles, this approach is consistent with GRE [15,7] for nematode sperm cell motility.…”

Section: Introductionmentioning

confidence: 68%

“…New in this work are 2-D functions, graded from the direction of motion, for the rates of polymerization (protrusion), and depolymerization, and stress associated with dragging the cell body forward. Since polar radii intersect the cell's boundary at right angles, this approach is consistent with GRE [7,15], applied to nematode sperm cell motility. /s e c m 1 65 n A central feature of the model is energy turnover in conservation laws, as MSP cycles between the states of free and bundled fi bers.…”

Section: Discussionmentioning

confidence: 92%

“…Mogilner and Oster [19] have shown that thermal undulation of fi lament tips can accommodate intercalation and drive protrusion, given an optimal angle of "attack" to the edge of the cell. For the polar model, radii intersect the cell boundary at right angles, consistent with GRE [15] and circumferential motion [7]. Consider a fi lament incorporated into a fi ber complex, or bundle, with a tip that is growing at a rate .…”

Section: Protrusionmentioning

confidence: 95%

“…However, computer simulations in multiple dimensions are time consuming, and fi nite-element methods preclude the important localized view of MSP dynamics. Demekin et al, [7] developed a pseudo 2-D model in curvilinear coordinates for a discrete number of MSP fi ber complexes to study how bundle protrusion orthogonal to the cell boundary could result in bundle bending observed in laboratory videos [23,26]. This work applied the graded radial extension model (GRE) and circumferential motion (CM) for cell-shape maintenance in keratocytes [15] to the geometry of A. summ.…”

Section: Introductionmentioning

confidence: 97%

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A two-dimensional continuum model for the crawling nematode sperm cell

Verzi

2013

Journal of Interdisciplinary Mathematics

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Migration of animal cells is the most striking process underlying the phenomena of wound healing, morphogenesis and cancerogenesis. Despite radical advances in cell biology and biophysics, we still do not have a complete picture of how animal cells move across surfaces. Motility for many of these cells involves a multitude of molecular mechanisms, and we do not yet know how they are integrated at the cellular level. Because of this, simple and specialized cells, like the sperm of Ascaris suum (A. suum) have attracted the attention of researchers. They appear to be dedicated solely to migration, and the locomotion machinery has been dramatically simplifi ed. Nematode sperm cells recycle major sperm protein from dimers into fi lament networks, as their hydrophobic patches come into contact with each other. These cells look and move much like similarly shaped actin-based cells, so that understanding their locomotion will elucidate general principles of migrating animal cells.This paper develops a two-dimensional (2-D) model of motility for the sperm of A. suum, in a polar coordinate system, for a continuous density of bundled fi laments, free dimers and crosslinks. Simulations recover bundle densities, crawling speeds and cell shapes observed in recent experiments for both turning and steady-state motion.

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Section: Introductionmentioning

confidence: 68%

Section: Discussionmentioning

confidence: 92%

Section: Protrusionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 97%

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A two-dimensional continuum model for the crawling nematode sperm cell

Verzi

2013

Journal of Interdisciplinary Mathematics

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“…There are patches on the individual filaments of MSP which cross-link filaments into "bundles". Ideas similar to "tethered ratchet", developed originally for actin filaments, could be adapted to explain the mechanism of cell protrusion by MSP filament bundles in the leading edge of the nematode sperm [965,966,967,968]. However, in the absence of myosin and analogous motor proteins, an altogether different mechanism had to be invoked for the observed retraction of the rear of the nematode sperm [969].…”

Section: •Force Generated By Depolymerizing Msp In Nematodesmentioning

confidence: 99%

Stochastic mechano-chemical kinetics of molecular motors: a multidisciplinary enterprise from a physicist's perspective

Chowdhury

2012

Preprint

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A molecular motor is made of either a single macromolecule or a macromolecular complex. Just like their macroscopic counterparts, molecular motors "transduce" input energy into mechanical work. All the nanomotors considered here operate under isothermal conditions far from equilibrium. Moreover, one of the possible mechanisms of energy transduction, called Brownian ratchet, does not even have any macroscopic counterpart. But, molecular motor is not synonymous with Brownian ratchet; a large number of molecular motors execute a noisy power stroke, rather than operating as Brownian ratchet. We review not only the structural design and stochastic kinetics of individual single motors, but also their coordination, cooperation and competition as well as the assembly of multimodule motors in various intracellular kinetic processes. Although all the motors considered here execute mechanical movements, efficiency and power output are not necessarily good measures of performance of some motors. Among the intracellular nano-motors, we consider the porters, sliders and rowers, pistons and hooks, exporters, importers, packers and movers as well as those that also synthesize, manipulate and degrade "macromolecules of life". We review mostly the quantitative models for the kinetics of these motors. We also describe several of those motordriven intracellular stochastic processes for which quantitative models are yet to be developed. In part I, we discuss mainly the methodology and the generic models of various important classes of molecular motors. In part II, we review many specific examples emphasizing the unity of the basic mechanisms as well as diversity of operations arising from the differences in their detailed structure and kinetics. Multi-disciplinary research is presented here from the perspective of physicists.

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Moving Life

Ohki¹,

Miyata²

2018

Biological and Medical Physics, Biomedical Engineering

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The geometry and motion of nematode sperm cells

Cited by 4 publications

References 22 publications

A two-dimensional continuum model for the crawling nematode sperm cell

A two-dimensional continuum model for the crawling nematode sperm cell

Stochastic mechano-chemical kinetics of molecular motors: a multidisciplinary enterprise from a physicist's perspective

Moving Life

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