scholarly journals Integer topological defects organize stresses driving tissue morphogenesis

2020 ◽  
Author(s):  
Pau Guillamat ◽  
Carles Blanch-Mercader ◽  
Karsten Kruse ◽  
Aurélien Roux
Keyword(s):  
Topological Defects ◽  
Self Organization ◽  
Tissue Architecture ◽  
Tissue Morphogenesis ◽  
Compressive Stresses ◽  
Cellular Forces ◽  
Stress Patterns

AbstractTissues acquire their function and shape via differentiation and morphogenesis. Both processes are driven by coordinating cellular forces and shapes at the tissue scale, but general principles governing this interplay remain to be discovered. Here, we report that self-organization of myoblasts around integer topological defects, namely spirals and asters, triggers localized differentiation and, when differentiation is inhibited, drives the growth of cylindrical multicellular protrusions. Both localized differentiation and growth require specific stress patterns. By analyzing the experimental velocity and orientation profiles through active gel theory, we show that integer topological defects can concentrate compressive stresses, which we measure by using deformable pillars. Altogether, we envision topological defects as mechanical organizational centers that control differentiation and morphogenesis to establish tissue architecture.

scholarly journals Self-organized cytoskeletal alignment during Drosophila mesoderm invagination

2020 ◽  
Vol 375 (1809) ◽  
pp. 20190551 ◽  
Author(s):  
Adam C. Martin
Keyword(s):  
Self Organization ◽  
Mechanical Forces ◽  
Feedback Process ◽  
Wild Type ◽  
Tissue Morphogenesis ◽  
Cell Behaviour ◽  
Feedback Mechanisms ◽  
Self Organized ◽  
Actomyosin Cytoskeleton ◽  
Shape Changes

During tissue morphogenesis, mechanical forces are propagated across tissues, resulting in tissue shape changes. These forces in turn can influence cell behaviour, leading to a feedback process that can be described as self-organizing. Here, I discuss cytoskeletal self-organization and point to evidence that suggests its role in directing force during morphogenesis. During Drosophila mesoderm invagination, the shape of the region of cells that initiates constriction creates a mechanical pattern that in turn aligns the cytoskeleton with the axis of greatest resistance to contraction. The wild-type direction of the force controls the shape and orientation of the invaginating mesoderm. Given the ability of the actomyosin cytoskeleton to self-organize, these types of feedback mechanisms are likely to play important roles in a range of different morphogenetic events. This article is part of the discussion meeting issue ‘Contemporary morphogenesis'.

scholarly journals Tunable two-dimensional polarization grating using a self-organized micropixelated liquid crystal structure

RSC Advances ◽  
2018 ◽  
Vol 8 (72) ◽  
pp. 41472-41479 ◽  
Author(s):  
Reo Amano ◽  
Péter Salamon ◽  
Shunsuke Yokokawa ◽  
Fumiaki Kobayashi ◽  
Yuji Sasaki ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Liquid Crystal ◽  
Nematic Liquid Crystal ◽  
Topological Defects ◽  
Self Organization ◽  
Two Dimensional ◽  
Self Organized ◽  
Optical Grating ◽  
Liquid Crystal Structure ◽  
Polarization Grating

A micro-pixelated pattern of a nematic liquid crystal formed by self-organization of topological defects is shown to work as a tunable two-dimensional optical grating.

scholarly journals Surface tension determines tissue shape and growth kinetics

2019 ◽  
Vol 5 (9) ◽  
pp. eaav9394 ◽  
Author(s):  
S. Ehrig ◽  
B. Schamberger ◽  
C. M. Bidan ◽  
A. West ◽  
C. Jacobi ◽  
...  
Keyword(s):  
Physical Environment ◽  
Constant Mean Curvature ◽  
Three Dimensional ◽  
Feedback Mechanism ◽  
Self Organization ◽  
Biological Feedback ◽  
Cell Contractility ◽  
Mechanical Signaling ◽  
Fluid Behavior ◽  
Cellular Forces

The collective self-organization of cells into three-dimensional structures can give rise to emergent physical properties such as fluid behavior. Here, we demonstrate that tissues growing on curved surfaces develop shapes with outer boundaries of constant mean curvature, similar to the energy minimizing forms of liquids wetting a surface. The amount of tissue formed depends on the shape of the substrate, with more tissue being deposited on highly concave surfaces, indicating a mechano-biological feedback mechanism. Inhibiting cell-contractility further revealed that active cellular forces are essential for generating sufficient surface stresses for the liquid-like behavior and growth of the tissue. This suggests that the mechanical signaling between cells and their physical environment, along with the continuous reorganization of cells and matrix is a key principle for the emergence of tissue shape.

scholarly journals Mechanical control of tissue shape and morphogenetic flows during vertebrate body axis elongation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Samhita P. Banavar ◽  
Emmet K. Carn ◽  
Payam Rowghanian ◽  
Georgina Stooke-Vaughan ◽  
Sangwoo Kim ◽  
...  
Keyword(s):  
Topological Defects ◽  
Body Axis ◽  
Physical Factors ◽  
Anteroposterior Axis ◽  
Solid Tissue ◽  
Embryonic Tissues ◽  
Quantitative Measurements ◽  
Theoretical Predictions ◽  
Axis Elongation ◽  
Cellular Forces

AbstractShaping embryonic tissues into their functional morphologies requires cells to control the physical state of the tissue in space and time. While regional variations in cellular forces or cell proliferation have been typically assumed to be the main physical factors controlling tissue morphogenesis, recent experiments have revealed that spatial variations in the tissue physical (fluid/solid) state play a key role in shaping embryonic tissues. Here we theoretically study how the regional control of fluid and solid tissue states guides morphogenetic flows to shape the extending vertebrate body axis. Our results show that both the existence of a fluid-to-solid tissue transition along the anteroposterior axis and the tissue surface tension determine the shape of the tissue and its ability to elongate unidirectionally, with large tissue tensions preventing unidirectional elongation and promoting blob-like tissue expansions. We predict both the tissue morphogenetic flows and stresses that enable unidirectional axis elongation. Our results show the existence of a sharp transition in the structure of morphogenetic flows, from a flow with no vortices to a flow with two counter-rotating vortices, caused by a transition in the number and location of topological defects in the flow field. Finally, comparing the theoretical predictions to quantitative measurements of both tissue flows and shape during zebrafish body axis elongation, we show that the observed morphogenetic events can be explained by the existence of a fluid-to-solid tissue transition along the anteroposterior axis. These results highlight the role of spatiotemporally-controlled fluid-to-solid transitions in the tissue state as a physical mechanism of embryonic morphogenesis.

A Three-Dimensional Autowave Turbulence

1998 ◽  
Vol 08 (04) ◽  
pp. 677-684 ◽  
Author(s):  
V. N. Biktashev
Keyword(s):  
Three Dimensional ◽  
Topological Defects ◽  
Self Organization ◽  
Time Behavior ◽  
Long Time Behavior ◽  
Vortex Filaments ◽  
Principal Role ◽  
Cardiac Fibrillation ◽  
Internal Instability ◽  
Long Time

Autowave vortices are topological defects in autowave fields in nonlinear active media of various natures and serve as centers of self-organization in the medium. In three-dimensional media, the topological defects are lines, called vortex filaments. Evolution of three-dimensional vortices, in certain conditions, can be described in terms of evolution of their filaments, analogously to that of hydrodynamical vortices in LIA approximation. In the motion equation for the filament, a coefficient called filament tension, plays a principal role, and determines qualitative long-time behavior. While vortices with positive tension tend to shrink and so either collapse or stabilize to a straight shape, depending on boundary conditions, vortices with negative tension show internal instability of shape. This is an essentially three-dimensional effect, as two-dimensional media with the same parameters do not possess any peculiar properties. In large volumes, the instability of filaments can lead to propagating, nondecremental activity composed of curved vortex filaments that multiply and annihilate in an apparently chaotic manner. This may be related to a mechanism of cardiac fibrillation.

scholarly journals Four-dimensional hydrogel-in-hydrogel bioprinting for the spatiotemporal control of organoid and organotypic cultures

2021 ◽  
Author(s):  
Nicola Elvassore ◽  
Anna Urciuolo ◽  
Giovanni Giobbe ◽  
Yixiao Dong ◽  
Federica Michielin ◽  
...  
Keyword(s):  
Ex Vivo ◽  
Morphological Changes ◽  
Three Dimensional ◽  
Culture Conditions ◽  
Developmental Trajectory ◽  
Self Organization ◽  
Tissue Architecture ◽  
Initial Culture ◽  
Spatiotemporal Control

Abstract Tissue architecture is a driving force for morphogenetic processes during development as well as for several physiological and regenerative responses. Far from being a passive static environment, tissue architecture is highly dynamic. Hydrogel technology reproduces in vitro geometrical and mechanical constrains that control the three-dimensional self-organization of (3D) organoids and organ-like cultures. This control is restricted to the initial culture conditions and cannot be adapted to the dynamic morphological changes of complex 3D cultures during their developmental trajectory. Here, we developed a method that overcomes this spatiotemporal limit. Using 2P crosslinking approach, high resolution 3D hydrogel structures can be fabricated within pre-existing hydrogel with spatiotemporal (four-dimensional, 4D) control relative to ex-vivo organotypic or organoid culture. This hydrogel-in-hydrogel bioprinting approach enables to continuously instruct the self-organization of the evolving 3D organ-like cultures.

scholarly journals Filamentous active matter: Band formation, bending, buckling, and defects

2020 ◽  
Vol 6 (30) ◽  
pp. eaaw9975 ◽  
Author(s):  
Gerard A. Vliegenthart ◽  
Arvind Ravichandran ◽  
Marisol Ripoll ◽  
Thorsten Auth ◽  
Gerhard Gompper
Keyword(s):  
Molecular Motors ◽  
Persistence Length ◽  
Topological Defects ◽  
Domain Size ◽  
Self Organization ◽  
Design Strategies ◽  
Band Formation ◽  
Microscopic Interactions ◽  
Large Length ◽  
Microscopy Techniques

Motor proteins drive persistent motion and self-organization of cytoskeletal filaments. However, state-of-the-art microscopy techniques and continuum modeling approaches focus on large length and time scales. Here, we perform component-based computer simulations of polar filaments and molecular motors linking microscopic interactions and activity to self-organization and dynamics from the filament level up to the mesoscopic domain level. Dynamic filament cross-linking and sliding and excluded-volume interactions promote formation of bundles at small densities and of active polar nematics at high densities. A buckling-type instability sets the size of polar domains and the density of topological defects. We predict a universal scaling of the active diffusion coefficient and the domain size with activity, and its dependence on parameters like motor concentration and filament persistence length. Our results provide a microscopic understanding of cytoplasmic streaming in cells and help to develop design strategies for novel engineered active materials.

Self-Organization of Topological Defects due to Applied Constraints

2008 ◽  
Vol 101 (25) ◽  
Author(s):  
Jonathan H. McCoy ◽  
Will Brunner ◽  
Werner Pesch ◽  
Eberhard Bodenschatz
Keyword(s):  
Topological Defects ◽  
Self Organization
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