scholarly journals Isotropic expansion of external environment induces tissue elongation and collective cell alignment

2019 ◽  
Author(s):  
H. Koyama ◽  
T. Fujimori
Keyword(s):  
Cell Movement ◽  
Cell Alignment ◽  
Standard Type ◽  
Cell Clusters ◽  
Asymmetric Structures ◽  
Frictional Forces ◽  
Isotropic Expansion ◽  
Multicellular Organisms ◽  
Theoretical Analyses ◽  
Insight Into

AbstractCell movement is crucial for morphogenesis in multicellular organisms. Growing embryos or tissues often expand isotropically, i.e., uniformly, in all dimensions. On the surfaces of these expanding environments, which we call “fields,” cells are subjected to frictional forces and move passively in response. However, the potential roles of isotropically expanding fields in morphogenetic events have not been investigated well. In this study, we mathematically analyzed the effect of isotropically expanding fields using a vertex model, a standard type of multi-cellular model. We found that cells located on fields were elongated along a similar direction each other. Simultaneously, the cell clusters were also elongated, even though field expansion was absolutely isotropic. We then investigated the mechanism underlying these counterintuitive phenomena. In particular, we asked whether elongation was caused by the properties of the field, the cell cluster, or both. Theoretical analyses involving simplification of the model revealed that cell clusters have an intrinsic ability to asymmetrically deform, leading to their elongation. Importantly, this ability is effective only under the non-equilibrium conditions provided by field expansion. This may explain the elongation of the notochord, located on the surface of the growing mouse embryo. We established that passive cell movement induced by isotropically expanding external environments can contribute to both cell and tissue elongation, as well as collective cell alignment, providing key insight into morphogenesis involving multiple adjacent tissues.Statement of SignificanceIt is a central question of developmental biology how the symmetric shapes of eggs can develop the asymmetric structures of embryos. Embryos expand through their growth. Simultaneously, elongation of tissues such as the notochord occurs, which is fundamental phenomena of morphogenesis. However, possible relationships between tissue elongation and the expansion of embryos have not been investigated well. Here we mathematically present that, even if the expansion is isotropic, tissues located on the embryos are asymmetrically deformed by the expansion, resulting in elongation. We generalize the effect of expanding environments on tissue elongation through model reduction and uncover the mechanism underlying elongation. This process can be a novel key piece for symmetry breaking of embryos, together with previously established morphogenetic processes.

Cell movement within aggregates of the slime mould Dictyostelium discoideum revealed by surface markers

Development ◽  
1965 ◽  
Vol 13 (1) ◽  
pp. 97-117
Author(s):  
B. M. Shaffer
Keyword(s):  
Dictyostelium Discoideum ◽  
Cell Movement ◽  
Surface Markers ◽  
Slime Mould ◽  
Culture Plate ◽  
Multicellular Organisms

Earlier workers examined the behaviour of foreign particles placed as markers on aggregates of D. discoideum that were migrating over the surface of the culture plate (Bonner, 1959; Francis, 1959, 1962). Comparable observations, made on aggregates in other conditions and at other stages, have now provided further information about the movement of individual cells within the aggregates. Before reporting them, the course of development must be described in some detail. During aggregation on an ordinary culture plate, D. discoideum amoebae crawl towards centres, in which they pack themselves together, forming rounded aggregates of no fixed shape. Papillae develop on the side of the aggregates away from the agar, and by extension, roughly perpendicular to the substratum, transform them into cylindrical multicellular organisms with tapered tips (Text-fig. 1, A—E). Such an organism, which contains from a dozen to a few hundred thousand cells, has been named a grex (Shaffer, 1962) because ‘aggregation’ is derived from the Latin aggregare, to form a grex.

scholarly journals How cells determine the number of polarity sites

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Jian-geng Chiou ◽  
Kyle D Moran ◽  
Daniel J Lew
Keyword(s):  
Design Principle ◽  
Fundamental Question ◽  
Yeast Cells ◽  
Regulatory Mechanisms ◽  
Saturation Point ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
Theoretical Analyses ◽  
Novel Design ◽  
Insight Into

The diversity of cell morphologies arises, in part, through regulation of cell polarity by Rho-family GTPases. A poorly understood but fundamental question concerns the regulatory mechanisms by which different cells generate different numbers of polarity sites. Mass-conserved activator-substrate (MCAS) models that describe polarity circuits develop multiple initial polarity sites, but then those sites engage in competition, leaving a single winner. Theoretical analyses predicted that competition would slow dramatically as GTPase concentrations at different polarity sites increase towards a 'saturation point', allowing polarity sites to coexist. Here, we test this prediction using budding yeast cells, and confirm that increasing the amount of key polarity proteins results in multiple polarity sites and simultaneous budding. Further, we elucidate a novel design principle whereby cells can switch from competition to equalization among polarity sites. These findings provide insight into how cells with diverse morphologies may determine the number of polarity sites.

Protocadherins and diversity of the cadherin superfamily

1996 ◽  
Vol 109 (11) ◽  
pp. 2609-2611 ◽  
Author(s):  
S.T. Suzuki
Keyword(s):  
Cell Adhesion ◽  
Circumstantial Evidence ◽  
Biological Role ◽  
Classical Cadherins ◽  
Adhesion Role ◽  
Multicellular Organisms ◽  
Related Proteins ◽  
Insight Into ◽  
Cadherin Superfamily

Recent cadherin studies have revealed that many cadherins and cadherin-related proteins are expressed in various tissues of different multicellular organisms. These proteins are characterized by the multiple repeats of the cadherin motif in their extracellular domains. The members of the cadherin superfamily are divided into two groups: classical cadherin type and protocadherin type. The current cadherins appear to have evolved from a protocadherin type. Recent studies have proved the cell adhesion role of classical cadherins in embryogenesis. In contrast, the biological role of protocadherins is elusive. Circumstantial evidence, however, suggests that protocadherins are involved in a variety of cell-cell interactions. Since protocadherins, and many other new cadherins as well, have unique properties, studies of these cadherins may provide insight into the structure and biological role of the cadherin superfamily.

scholarly journals Microtubule-dependent ribosome localization in C. elegans neurons

eLife ◽  
2017 ◽  
Vol 6 ◽  
Author(s):  
Kentaro Noma ◽  
Alexandr Goncharov ◽  
Mark H Ellisman ◽  
Yishi Jin
Keyword(s):  
Cell Biology ◽  
Neuronal Development ◽  
Ultrastructural Level ◽  
Synthesis Methods ◽  
Tissue Specific ◽  
C Elegans ◽  
Multicellular Organisms ◽  
Axonal Trafficking ◽  
Insight Into

Subcellular localization of ribosomes defines the location and capacity for protein synthesis. Methods for in vivo visualizing ribosomes in multicellular organisms are desirable in mechanistic investigations of the cell biology of ribosome dynamics. Here, we developed an approach using split GFP for tissue-specific visualization of ribosomes in Caenorhabditis elegans. Labeled ribosomes are detected as fluorescent puncta in the axons and synaptic terminals of specific neuron types, correlating with ribosome distribution at the ultrastructural level. We found that axonal ribosomes change localization during neuronal development and after axonal injury. By examining mutants affecting axonal trafficking and performing a forward genetic screen, we showed that the microtubule cytoskeleton and the JIP3 protein UNC-16 exert distinct effects on localization of axonal and somatic ribosomes. Our data demonstrate the utility of tissue-specific visualization of ribosomes in vivo, and provide insight into the mechanisms of active regulation of ribosome localization in neurons.

scholarly journals Compatibility of the movement protein and the coat protein of cucumoviruses is required for cell-to-cell movement

2004 ◽  
Vol 85 (4) ◽  
pp. 1039-1048 ◽  
Author(s):  
Katalin Salánki ◽  
Ákos Gellért ◽  
Emese Huppert ◽  
Gábor Náray-Szabó ◽  
Ervin Balázs
Keyword(s):  
Coat Protein ◽  
Movement Protein ◽  
Point Mutations ◽  
Cell Movement ◽  
Virus Movement ◽  
Tomato Aspermy Virus ◽  
Sequence Encoding ◽  
Surface Electrostatic Potential ◽  
Test Plants ◽  
Insight Into

For the cell-to-cell movement of cucumoviruses both the movement protein (MP) and the coat protein (CP) are required. These are not reversibly exchangeable between Cucumber mosaic virus (CMV) and Tomato aspermy virus (TAV). The MP of CMV is able to function with the TAV CP (chimera RT), but TAV MP is unable to promote the cell-to-cell movement in the presence of CMV CP (chimera TR). To gain further insight into the non-infectious nature of the TR recombinant, RNA 3 chimeras were constructed with recombinant MPs and CPs. The chimeric MP and one of the CP recombinants were infectious. The other recombinant CP enabled virus movement only after the introduction of two point mutations (Glu→Lys and Lys→Arg at aa 62 and 65, respectively). The mutations served to correct the CP surface electrostatic potential that was altered by the recombination. The infectivity of the TR virus on different test plants was restored by replacing the sequence encoding the C-terminal 29 aa of the MP with the corresponding sequence of the CMV MP gene or by exchanging the sequence encoding the C-terminal 15 aa of the CP with the same region of TAV. The analysis of the recombinant clones suggests a requirement for compatibility between the C-terminal 29 aa of the MP and the C-terminal two-thirds of the CP for cell-to-cell movement of cucumoviruses.

scholarly journals The evolution of organellar metabolism in unicellular eukaryotes

2010 ◽  
Vol 365 (1541) ◽  
pp. 693-698 ◽  
Author(s):  
Michael L. Ginger ◽  
Geoffrey I. McFadden ◽  
Paul A. M. Michels
Keyword(s):  
Drug Targets ◽  
Oxygenic Photosynthesis ◽  
Geological Time ◽  
Unicellular Eukaryotes ◽  
Niche Adaptation ◽  
History Of ◽  
Critical Insight ◽  
Multicellular Organisms ◽  
Gradual Transformation ◽  
Insight Into

Metabolic innovation has facilitated the radiation of microbes into almost every niche environment on the Earth, and over geological time scales transformed the planet on which we live. A notable example of innovation is the evolution of oxygenic photosynthesis which was a prelude to the gradual transformation of an anoxic Earth into a world with oxygenated oceans and an oxygen-rich atmosphere capable of supporting complex multicellular organisms. The influence of microbial innovation on the Earth's history and the timing of pivotal events have been addressed in other recent themed editions of Philosophical Transactions of Royal Society B ( Cavalier-Smith et al . 2006 ; Bendall et al . 2008 ). In this issue, our contributors provide a timely history of metabolic innovation and adaptation within unicellular eukaryotes. In eukaryotes, diverse metabolic portfolios are compartmentalized across multiple membrane-bounded compartments (or organelles). However, as a consequence of pathway retargeting, organelle degeneration or novel endosymbiotic associations, the metabolic repertoires of protists often differ extensively from classic textbook descriptions of intermediary metabolism. These differences are often important in the context of niche adaptation or the structure of microbial communities. Fundamentally interesting in its own right, the biochemical, cell biological and phylogenomic investigation of organellar metabolism also has wider relevance. For instance, in some pathogens, notably those causing some of the most significant tropical diseases, including malaria, unusual organellar metabolism provides important new drug targets. Moreover, the study of organellar metabolism in protists continues to provide critical insight into our understanding of eukaryotic evolution.

scholarly journals Insights into viral community composition of the cnidarian model metaorganism Aiptasia using RNA-Seq data

2017 ◽  
Author(s):  
Jan D Brüwer ◽  
Christian R Voolstra
Keyword(s):  
Community Composition ◽  
Well Being ◽  
Rna Seq ◽  
Viral Origin ◽  
Viral Community ◽  
Coral Reef Ecosystems ◽  
Algal Endosymbiont ◽  
Endosymbiotic Algae ◽  
Multicellular Organisms ◽  
Insight Into

Current research posits that all multicellular organisms live in symbioses with associated microorganisms and form so-called metaorganisms or holobionts. Cnidarian metaorganisms are of specific interest given that stony corals provide the foundation of the globally threatened coral reef ecosystems and their well-being strongly relies on forming mutualistic relationships with endosymbiotic algae of the genus Symbiodinium. So far, only few studies characterized viral diversity and the potential underlying functional importance to coral holobionts. Here we analyzed an existing RNA-Seq dataset of the coral model metaorganism Aiptasia CC7 (sensu Exaiptasia pallida) associated with aposymbiotic, partially populated, and fully symbiotic anemones with Symbiodinium to gain further insight into viral community composition and the relation to the algal endosymbiosis. Our approach included the selective removal of anemone host and algal endosymbiont sequences and subsequent microbial sequence annotation. Of a total of 297 million raw sequence reads, 8.6 million (~ 3%) remained after host and endosymbiont sequence removal. Of these, 3,293 sequences (paired-end read pairs) could be assigned as of viral origin. Taxonomic annotation shows that Aiptasia is associated with a diverse viral community consisting of 116 viral taxa covering 40 families. The viral community was dominated by viruses from the families Herpesviridae (12.00%), Partitiviridae (9.93%), and Picornaviridae (9.87%). Despite an overall stable viral community, we found that some viral taxa significantly changed in relative abundance when Aiptasia engage in a symbiotic relationship with Symbiodinium. Elucidation of viral taxa consistently present in all samples revealed an Aiptasia core virome of 15 viral taxa from 11 viral families that was comprised of many viruses previously reported in coral viromes. Our study provides a first insight into the viral community of Aiptasia. Aiptasia seem to harbor a diverse and overall stable viral community, although certain members change in abundance when the anemone host associates with its algal endosymbiont. However, the functional significance of this remains to be determined.

scholarly journals Quantitative Analysis of Plasmodesmata Permeability using Cultured Tobacco BY-2 Cells Entrapped in Microfluidic Chips

2021 ◽  
Author(s):  
Kazunori Shimizu ◽  
Masahiro Kikkawa ◽  
Ryo Tabata ◽  
Daisuke Kurihara ◽  
Ken-ichi Kurotani ◽  
...  
Keyword(s):  
Real Time ◽  
Microfluidic Device ◽  
Cultured Cells ◽  
Cell Movement ◽  
Flow Channel ◽  
Microfluidic Chips ◽  
Isolated Cells ◽  
Cell Clusters ◽  
A Cell ◽  
Channel Structures

AbstractPlasmodesmata are unique channel structures in plants that link the fluid cytoplasm between adjacent cells. Plants have evolved these microchannels to allow trafficking of nutritious substances as well as signaling molecules for intercellular communication. However, tracking the behavior of plasmodesmata in real time is difficult because they are located inside tissues. Hence, we developed a microfluidic device that traps cultured cells and fixes their positions to allow testing of plasmodesmata permeability. The device has 112 tandemly aligned trap zones in the flow channel. Cells of the tobacco line BY-2 were cultured for 7 days and filtered using a sieve and a cell strainer before use to isolate short cell clusters consisting of only a few cells. The isolated cells were introduced into the flow channel, resulting in entrapment of cell clusters at 25 out of 112 trap zones (22.3%). Plasmodesmata permeability was tested from 1 to 4 days after trapping the cells. During this period, the cell numbers increased through cell division. Fluorescence recovery after photobleaching experiments using a transgenic marker line expressing nuclear-localized H2B-GFP demonstrated that cell-to-cell movement of H2B-GFP protein occurred within 200 min of photobleaching. The transport of H2B-GFP protein was not observed when sodium chloride, a compound known to cause plasmodesmata closure, was present in the microfluid channel. Thus, this microfluidic device and one-dimensional plant cell samples allowed us to observe plasmodesmata behavior in real time under controllable conditions.

scholarly journals Synthetic mammalian signaling circuits for robust cell population control

2020 ◽  
Author(s):  
Yitong Ma ◽  
Mark W. Budde ◽  
Michaëlle N. Mayalu ◽  
Junqin Zhu ◽  
Richard M. Murray ◽  
...  
Keyword(s):  
Quorum Sensing ◽  
Circuit Design ◽  
Population Control ◽  
Cell Communication ◽  
Limited Growth ◽  
Cell Therapies ◽  
Population Sizes ◽  
Multicellular Organisms ◽  
And Control ◽  
Insight Into

SummaryIn multicellular organisms, cells actively sense, respond to, and control their own population density. Synthetic mammalian quorum sensing circuits could provide insight into principles of population control and improve cell therapies. However, a key challenge is avoiding their inherent sensitivity to “cheater” mutations that evade control. Here, we repurposed the plant hormone auxin to enable orthogonal mammalian cell-cell communication and quorum sensing. Further, we show that a “paradoxical” circuit design, in which auxin stimulates and inhibits net cell growth at different concentrations, achieves population control that is robust to cheater mutations, controlling growth for 43 days of continuous culture. By contrast, a non-paradoxical control circuit limited growth but was susceptible to mutations. These results establish a foundation for future cell therapies that can respond to and control their own population sizes.

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