scholarly journals Motility-gradient induced elongation of the vertebrate embryo

2017 ◽  
Author(s):  
Ido Regev ◽  
Karine Guevorkian ◽  
Olivier Pourquie ◽  
L Mahadevan
Keyword(s):  
Cell Motility ◽  
Time Lapse ◽  
Growth Zone ◽  
The Body ◽  
Tail Bud ◽  
Fluorescent Reporters ◽  
Chemical Models ◽  
Motile Cells ◽  
Cellular Signal ◽  
Oriented Movement

The body of vertebrate embryos forms by posterior elongation from a terminal growth zone called the Tail Bud (TB). The TB produces highly motile cells forming the presomitic mesoderm (PSM), a tissue playing an important role in elongation movements. PSM cells establish an anterior-posterior cell motility gradient which parallels the degradation of a specific cellular signal (Fgf8) known to be implicated in cell motility. Here, we combine electroporation of fluorescent reporters in the PSM to time-lapse imaging in the chicken embryo to quantify cell diffusive movements along the motility gradient. We show that simple microscopic and macroscopic mechano-chemical models for tissue extension that couple Fgf activity, cell motility and tissue rheology at both the cellular and continuum levels suffice to capture the speed and extent of elongation. These observations explain how the continuous addition of cells that exhibit a gradual reduction in motility combined with lateral confinement can be converted into an oriented movement that drives body elongation. The results of the models compare well with our experimental results, with implications for other elongation processes in the embryo.

scholarly journals Region-Specific Microtubule Transport in Motile Cells

2000 ◽  
Vol 151 (5) ◽  
pp. 1003-1012 ◽  
Author(s):  
Anne-Marie C. Yvon ◽  
Patricia Wadsworth
Keyword(s):  
Growth Factor ◽  
Cell Motility ◽  
Cell Body ◽  
Dependent Manner ◽  
Retrograde Flow ◽  
Cell Locomotion ◽  
Quantitative Measurements ◽  
Motile Cells ◽  
Microtubule Transport ◽  
Hepatocyte Growth

Photoactivation and photobleaching of fluorescence were used to determine the mechanism by which microtubules (MTs) are remodeled in PtK2 cells during fibroblast-like motility in response to hepatocyte growth factor (HGF). The data show that MTs are transported during cell motility in an actomyosin-dependent manner, and that the direction of transport depends on the dominant force in the region examined. MTs in the leading lamella move rearward relative to the substrate, as has been reported in newt cells (Waterman-Storer, C.M., and E.D. Salmon. 1997. J. Cell Biol. 139:417–434), whereas MTs in the cell body and in the retraction tail move forward, in the direction of cell locomotion. In the transition zone between the peripheral lamella and the cell body, a subset of MTs remains stationary with respect to the substrate, whereas neighboring MTs are transported either forward, with the cell body, or rearward, with actomyosin retrograde flow. In addition to transport, the photoactivated region frequently broadens, indicating that individual marked MTs are moved either at different rates or in different directions. Mark broadening is also observed in nonmotile cells, indicating that this aspect of transport is independent of cell locomotion. Quantitative measurements of the dissipation of photoactivated fluorescence show that, compared with MTs in control nonmotile cells, MT turnover is increased twofold in the lamella of HGF-treated cells but unchanged in the retraction tail, demonstrating that microtubule turnover is regionally regulated.

Motility of the Limulus blood cell

1979 ◽  
Vol 37 (1) ◽  
pp. 169-180
Author(s):  
P.B. Armstrong
Keyword(s):  
Tissue Culture ◽  
Time Lapse ◽  
Coelomic Fluid ◽  
Cellular Motility ◽  
Paraffin Oil ◽  
Motile Cells ◽  
Direct Microscopic Examination ◽  
High Concentrations ◽  
Glass Surfaces

The sole cell type (the amoebocyte) found in the coelomic fluid of the horseshoe crab, Limulus polyphemus can be stimulated to become motile by extravasation or trauma. Motility was studied using time-lapse microcinematography and direct microscopic examination of cells in tissue culture and in gill leaflets isolated from young animals. Phase-contrast and Nomarski differential-interference contrast optics were employed. Both in culture and in the gills, motile cells showed 2 interconvertible morphological types: the contracted cell, which was compact and rounded and had a relatively small area of contact with the substratum, and a flattened from with a larger area of contact. In both morphological types, motility involved the protrusion of hyaline pseudopods followed by flow of granular endoplasm forward in the pseudoplod. Cellular motility in vivo (in the gill leaflet) was morphologically identical to that displayed in tissue culture. In culture, motility was unaffected by the nature of the substratum: cells were indistinguishable on fluid (paraffin oil) or solid (glass) substrata or on hydrophobic (paraffin oil, siliconized glass) or hydrophilic (clean glass) surfaces. Cells migrated and spread on agar surfaces. Cell motility was unaffected by high concentrations (100 micrograms/ml) of the microtubule-depolymerizing agent colcemid and was abolished by cytochalasin B at 1 microgram/ml.

scholarly journals The Role of Cell Motility in Metastatic Cell Dominance Phenomenon: Analysis by a Mathematical Model

2000 ◽  
Vol 3 (1) ◽  
pp. 63-77 ◽  
Author(s):  
A. V. Kolobov ◽  
A. A. Polezhaev ◽  
G. I. Solyanik
Keyword(s):  
Mathematical Model ◽  
Cell Motility ◽  
Threshold Value ◽  
Experimental Investigations ◽  
Metastatic Cell ◽  
Metastatic Cells ◽  
Motile Cells ◽  
Cell Subpopulations ◽  
Cell Motion ◽  
Slow Growing

Metastasis is the outcome of several selective sequential steps where one of the first and necessary steps is the progressive overgrowth or dominance of a small number of metastatic cells in a tumour. In spite of numerous experimental investigations concerning the growth advantage of metastatic cells, the mechanisms resulting in their dominance are still unknown. Metastatic cell overgrowth occurs even if doubling time of the metastatic subpopulation is shorter than that of all others subpopulations in a heterogeneous tumour. In order to examine the hypothesis that under conditions of competition of cell subpopulations for common substrata cell motility of the slow-growing subpopulation can result in its dominance in a heterogeneous tumour, a mathematical model of heterogeneous tumour growth is suggested. The model describes two cell subpopulations which can grow with different rates and transform into the resting state depending on the concentration of the substrate consumed by both subpopulations. The slow-growing subpopulation is assumed to be motile. In numerical simulations it is shown that this subpopulation is able to overgrow the other one. The dominance phenomenon (resulting from random cell motion) depends on the motility coefficient in a threshold manner: in a heterogeneous tumour the slow-dividing motile subpopulation is able to overgrow its non-motile counterparts if its motility coefficient exceeds a certain threshold value. Computations demonstrate independence of the motile cells overgrowth from the initial tumour composition.

Cell number in relation to primary pattern formation in the embryo of Xenopus laevis

Development ◽  
1979 ◽  
Vol 53 (1) ◽  
pp. 269-289
Author(s):  
Jonathan Cooke
Keyword(s):  
Cell Cycle ◽  
Pattern Formation ◽  
Cell Cycle Control ◽  
Cell Number ◽  
The Body ◽  
Morphological Evidence ◽  
Tail Bud ◽  
Cell Cycle Time ◽  
Mesodermal Cell ◽  
Body Pattern

Morphological evidence is presented that definitive mesoderm formation in Xenopus is best understood as extending to the end of the neurula phase of development. A process of recruitment of cells from the deep neurectoderm layers into mesodermal position and behaviour, strictly comparable with that already agreed to occur around the internal blastoporal ‘lip’ during gastrula stages, can be shown to continue at the posterior end of the presumptive body pattern up to stage 20 (earliest tail bud). Spatial patterns of incidence of mitosis are described for the fifteen hours of development between the late gastrula and stage 20–22. These are related to the onset of new cell behaviours and overt cyto-differentiations characterizing the dorsal axial pattern,which occur in cranio-caudal and then medio-lateral spatial sequence as development proceeds. A relatively abrupt cessation of mitosis, among hitherto asynchronously cycling cells,precedes the other changes at each level in the presumptive axial pattern. The widespread incidence of cells still in DNA synthesis, anterior to the last mitoses in the posterior-to-anteriordevelopmental sequence of axial tissue, strongly suggests that cells of notochord and somites in their prolonged, non-cycling phase are G2-arrested, and thus tetraploid. This is discussed in relation to what is known of cell-cycle control in other situations. Best estimates for cell-cycle time in the still-dividing, posterior mesoderm of the neurula lie between 10 and 15 h. The supposition of continuing recruitment from neurectoderm can resolve an apparent discrepancy whereby total mesodermal cell number nevertheless contrives to double over a period of approximately 12 h during neurulation when most of the cells are leaving the cycle. Because of pre-existing evidence that cells maintain their relative positions (despite distortion)during the movements that form the mesodermal mantle, the patterns presented in this paper can be understood in two ways: as a temporal sequence of developmental events undergone by individual, posteriorly recruited cells as they achieve their final positions in the body pattern, or alternatively as a succession of wavefronts with respect to changes of cellstate, passing obliquely across the presumptive body pattern in antero-posterior direction. These concepts are discussed briefly in relation to recent ideas about pattern formation in growing systems.

scholarly journals Trait-specific dispersal of bacteria in heterogeneous porous environments: from pore to porous medium scale

2020 ◽  
Vol 17 (164) ◽  
pp. 20200046 ◽  
Author(s):  
David Scheidweiler ◽  
Filippo Miele ◽  
Hannes Peter ◽  
Tom J. Battin ◽  
Pietro de Anna
Keyword(s):  
Preferential Flow ◽  
Cell Attachment ◽  
Flow Direction ◽  
Time Lapse ◽  
Breakthrough Curves ◽  
Porous System ◽  
Dispersal Patterns ◽  
Multi Scale ◽  
Motile Cells ◽  
Hydrodynamic Shear

The dispersal of organisms controls the structure and dynamics of populations and communities, and can regulate ecosystem functioning. Predicting dispersal patterns across scales is important to understand microbial life in heterogeneous porous environments such as soils and sediments. We developed a multi-scale approach, combining experiments with microfluidic devices and time-lapse microscopy to track individual bacterial trajectories and measure the overall breakthrough curves and bacterial deposition profiles: we, then, linked the two scales with a novel stochastic model. We show that motile cells of Pseudomonas putida disperse more efficiently than non-motile mutants through a designed heterogeneous porous system. Motile cells can evade flow-imposed trajectories, enabling them to explore larger pore areas than non-motile cells. While transported cells exhibited a rotation in response to hydrodynamic shear, motile cells were less susceptible to the torque, maintaining their body oriented towards the flow direction and thus changing the population velocity distribution with a significant impact on the overall transport properties. We also found, in a separate set of experiments, that if the suspension flows through a porous system already colonized by a biofilm, P. putida cells are channelled into preferential flow paths and the cell attachment rate is increased. These two effects were more pronounced for non-motile than for motile cells. Our findings suggest that motility coupled with heterogeneous flows can be beneficial to motile bacteria in confined environments as it enables them to actively explore the space for resources or evade regions with unfavourable conditions. Our study also underlines the benefit of a multi-scale approach to the study of bacterial dispersal in porous systems.

scholarly journals Real-time imaging reveals that noninvasive mammary epithelial acini can contain motile cells

2007 ◽  
Vol 179 (7) ◽  
pp. 1555-1567 ◽  
Author(s):  
Gray W. Pearson ◽  
Tony Hunter
Keyword(s):  
Basement Membrane ◽  
Cell Motility ◽  
Real Time ◽  
Light Chain ◽  
Myosin Light Chain ◽  
Cell Monolayer ◽  
Branching Morphogenesis ◽  
Time Behavior ◽  
Mesenchymal Transition ◽  
Motile Cells

To determine how extracellular signal–regulated kinases (ERK) 1/2 promote mammary tumorigenesis, we examined the real-time behavior of cells in an organotypic culture of the mammary glandular epithelium. Inducible activation of ERK1/2 in mature acini elicits cell motility and disrupts epithelial architecture in a manner that is reminiscent of ductal carcinoma in situ; however, motile cells do not invade through the basement membrane and branching morphogenesis does not take place. ERK1/2-induced motility causes cells to move both within the cell monolayer that contacts the basement membrane surrounding the acinus and through the luminal space of the acinus. E-cadherin expression is reduced after ERK1/2 activation, but motility does not involve an epithelial–mesenchymal transition. Cell motility and the disruption of epithelial architecture require a Rho kinase– and myosin light chain kinase–dependent increase in the phosphorylation of myosin light chain 2. Our results identify a new mechanism for the disruption of architecture in epithelial acini and suggest that ERK1/2 can promote noninvasive motility in preinvasive mammary tumors.

scholarly journals Individual cell motility studied by time-lapse video recording: Influence of experimental conditions

Cytometry ◽  
2000 ◽  
Vol 40 (4) ◽  
pp. 260-270 ◽  
Author(s):  
Rasmus Hartmann-Petersen ◽  
Peter S. Walmod ◽  
Anton Berezin ◽  
Vladimir Berezin ◽  
Elisabeth Bock
Keyword(s):  
Cell Motility ◽  
Individual Cell ◽  
Video Recording ◽  
Time Lapse ◽  
Experimental Conditions ◽  
Time Lapse Video

scholarly journals Virus-Induced Cell Motility

1998 ◽  
Vol 72 (2) ◽  
pp. 1235-1243 ◽  
Author(s):  
Christopher M. Sanderson ◽  
Michael Way ◽  
Geoffrey L. Smith
Keyword(s):  
Cell Migration ◽  
Cell Motility ◽  
Uv Light ◽  
Cell Metabolism ◽  
Cell Movement ◽  
Time Lapse ◽  
Late Gene Expression ◽  
Infected Cells ◽  
And Function

ABSTRACT Many viruses induce profound changes in cell metabolism and function. Here we show that vaccinia virus induces two distinct forms of cell movement. Virus-induced cell migration was demonstrated by an in vitro wound healing assay in which infected cells migrated independently into the wound area while uninfected cells remained relatively static. Time-lapse microscopy showed that the maximal rate of migration occurred between 9 and 12 h postinfection. Virus-induced cell migration was inhibited by preinactivation of viral particles with trioxsalen and UV light or by the addition of cycloheximide but not by addition of cytosine arabinoside or rifampin. The expression of early viral genes is therefore necessary and sufficient to induce cell migration. Following migration, infected cells developed projections up to 160 μm in length which had growth-cone-like structures and were frequently branched. Time-lapse video microscopy showed that these projections were formed by extension and condensation of lamellipodia from the cell body. Formation of extensions was dependent on late gene expression but not the production of intracellular enveloped (IEV) particles. The requirements for virus-induced cell migration and for the formation of extensions therefore differ from each other and are distinct from the polymerization of actin tails on IEV particles. These data show that poxviruses encode genes which control different aspects of cell motility and thus represent a useful model system to study and dissect cell movement.

scholarly journals Fused dorsal-ventral cerebral organoids model human cortical interneuron migration

2017 ◽  
Author(s):  
Joshua A Bagley ◽  
Daniel Reumann ◽  
Shan Bian ◽  
Juergen A Knoblich
Keyword(s):  
Time Lapse ◽  
Brain Regions ◽  
Model Systems ◽  
Gabaergic Interneuron ◽  
Cxcr4 Antagonist ◽  
Cortical Interneuron ◽  
Fluorescent Reporters ◽  
Complex Interactions ◽  
Neuropsychiatric Diseases ◽  
Model Complex

AbstractDevelopment of the forebrain involves the migration of GABAergic interneurons over long distances from ventral into dorsal regions. Although defects in interneuron migration are implicated in neuropsychiatric diseases such as Epilepsy, Autism, and Schizophrenia, model systems to study this process in humans are currently lacking. Here, we describe a method for analyzing human interneuron migration using 3D organoid culture. By fusing cerebral organoids specified toward dorsal and ventral forebrain, we generate a continuous dorsal-ventral axis. Using fluorescent reporters, we demonstrate robust directional GABAergic interneuron migration from ventral into dorsal forebrain. We describe methodology for time lapse imaging of human interneuron migration that is inhibited by the CXCR4 antagonist AMD3100. Our results demonstrate that cerebral organoid fusion cultures can model complex interactions between different brain regions. Combined with reprogramming technology, fusions offer a possibility to analyze complex neurodevelopmental defects using cells from neuropsychiatric disease patients, and to test potential therapeutic compounds.

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