scholarly journals Emergence of a geometric pattern of cell fates from tissue-scale mechanics in the Drosophila eye

2021 ◽  
Author(s):  
Kevin D. Gallagher ◽  
Madhav Mani ◽  
Richard W. Carthew
Keyword(s):  
Spatial Configuration ◽  
Reaction Diffusion ◽  
Self Organization ◽  
Triangular Grid ◽  
Regular Pattern ◽  
Geometric Pattern ◽  
Cell Fates ◽  
Biochemical Model ◽  
Different Types ◽  
Drosophila Eye

Pattern formation of biological structures involves the arrangement of different types of cells in an ordered spatial configuration. In this study, we investigate the mechanism of patterning the Drosophila eye into a precise triangular grid of photoreceptor clusters called ommatidia. Previous studies had led to a long-standing biochemical model whereby a reaction-diffusion process is templated by recently formed ommatidia to propagate a molecular prepattern across the eye epithelium. Here, we find that the templating mechanism is instead, mechanical in origin; newly born columns of ommatidia serve as a template to spatially pattern cell flows that move the cells in the epithelium into position to form each new column of ommatidia. Cell flow is generated by a pressure gradient that is caused by a narrow zone of cell dilation precisely positioned behind the growing wavefront of ommatidia. The newly formed lattice grid of ommatidia cells are immobile, deflecting and focusing the flow of other cells. Thus, the self-organization of a regular pattern of cell fates in an epithelium is mechanically driven.

scholarly journals Multiscale modeling of glioma pseudopalisades: contributions from the tumor microenvironment

2021 ◽  
Vol 82 (6) ◽  
Author(s):  
Pawan Kumar ◽  
Jing Li ◽  
Christina Surulescu
Keyword(s):  
Multiscale Modeling ◽  
Reaction Diffusion ◽  
Tumor Grade ◽  
Invasive Potential ◽  
Macroscopic System ◽  
Active Particles ◽  
Reaction Diffusion Model ◽  
Different Types ◽  
Parabolic Scaling ◽  
Parameter Ranges

AbstractGliomas are primary brain tumors with a high invasive potential and infiltrative spread. Among them, glioblastoma multiforme (GBM) exhibits microvascular hyperplasia and pronounced necrosis triggered by hypoxia. Histological samples showing garland-like hypercellular structures (so-called pseudopalisades) centered around the occlusion site of a capillary are typical for GBM and hint on poor prognosis of patient survival. We propose a multiscale modeling approach in the kinetic theory of active particles framework and deduce by an upscaling process a reaction-diffusion model with repellent pH-taxis. We prove existence of a unique global bounded classical solution for a version of the obtained macroscopic system and investigate the asymptotic behavior of the solution. Moreover, we study two different types of scaling and compare the behavior of the obtained macroscopic PDEs by way of simulations. These show that patterns (not necessarily of Turing type), including pseudopalisades, can be formed for some parameter ranges, in accordance with the tumor grade. This is true when the PDEs are obtained via parabolic scaling (undirected tissue), while no such patterns are observed for the PDEs arising by a hyperbolic limit (directed tissue). This suggests that brain tissue might be undirected - at least as far as glioma migration is concerned. We also investigate two different ways of including cell level descriptions of response to hypoxia and the way they are related .

scholarly journals Self-organization of nanoparticles and molecules in periodic Liesegang-type structures

2021 ◽  
Vol 7 (16) ◽  
pp. eabe3801
Author(s):  
Amanda J. Ackroyd ◽  
Gábor Holló ◽  
Haridas Mundoor ◽  
Honghu Zhang ◽  
Oleg Gang ◽  
...  
Keyword(s):  
Constant Velocity ◽  
Periodic Structures ◽  
Reaction Diffusion ◽  
Self Organization ◽  
Reaction Diffusion Systems ◽  
Structural Hierarchy ◽  
Preparation Conditions ◽  
Diffusion Systems ◽  
Film Preparation ◽  
Self Organizing

Chemical organization in reaction-diffusion systems offers a strategy for the generation of materials with ordered morphologies and structural hierarchy. Periodic structures are formed by either molecules or nanoparticles. On the premise of new directing factors and materials, an emerging frontier is the design of systems in which the precipitation partners are nanoparticles and molecules. We show that solvent evaporation from a suspension of cellulose nanocrystals (CNCs) and l-(+)-tartaric acid [l-(+)-TA] causes phase separation and precipitation, which, being coupled with a reaction/diffusion, results in rhythmic alternation of CNC-rich and l-(+)-TA–rich rings. The CNC-rich regions have a cholesteric structure, while the l-(+)-TA–rich bands are formed by radially aligned elongated bundles. The moving edge of the pattern propagates with a finite constant velocity, which enables control of periodicity by varying film preparation conditions. This work expands knowledge about self-organizing reaction-diffusion systems and offers a strategy for the design of self-organizing materials.

scholarly journals Travelling colourful patterns in self-organized cellulose-based liquid crystalline structures

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Pedro E. S. Silva ◽  
Ricardo Chagas ◽  
Susete N. Fernandes ◽  
Pawel Pieranski ◽  
Robin L. B. Selinger ◽  
...  
Keyword(s):  
Simple Model ◽  
Temporal Variation ◽  
Liquid Crystalline ◽  
Diffusion Mechanism ◽  
Reaction Diffusion ◽  
Self Organization ◽  
Spatial And Temporal Variation ◽  
Living Matter ◽  
Equilibrium Conditions ◽  
Self Organized

AbstractCellulose-based systems are useful for many applications. However, the issue of self-organization under non-equilibrium conditions, which is ubiquitous in living matter, has scarcely been addressed in cellulose-based materials. Here, we show that quasi-2D preparations of a lyotropic cellulose-based cholesteric mesophase display travelling colourful patterns, which are generated by a chemical reaction-diffusion mechanism being simultaneous with the evaporation of solvents at the boundaries. These patterns involve spatial and temporal variation in the amplitude and sign of the helix´s pitch. We propose a simple model, based on a reaction-diffusion mechanism, which simulates the observed spatiotemporal colour behaviour.

scholarly journals Suitability of Self-Organization for Different Types of Production

2021 ◽  
Vol 54 ◽  
pp. 124-129
Author(s):  
Martin Krockert ◽  
Marvin Matthes ◽  
Torsten Munkelt
Keyword(s):  
Self Organization ◽  
Different Types

scholarly journals Switching cell fates in the developing Drosophila eye

Development ◽  
2013 ◽  
Vol 140 (21) ◽  
pp. 4353-4361 ◽  
Author(s):  
Y. E. Mavromatakis ◽  
A. Tomlinson
Keyword(s):  
Cell Fates ◽  
Drosophila Eye

scholarly journals Collision patterns on mollusc shells

1997 ◽  
Vol 1 (1) ◽  
pp. 57-76 ◽  
Author(s):  
P. J. Plath ◽  
J. K. Plath ◽  
J. Schwietering
Keyword(s):  
Reaction Diffusion ◽  
Growth Front ◽  
Cell System ◽  
One Dimensional ◽  
Reaction Diffusion Systems ◽  
Diffusion Systems ◽  
Different Types ◽  
Classical Waves ◽  
Cellular Behaviour ◽  
Mollusc Shells

On mollusc shells one can find famous patterns. Some of them show a great resemblance to the soliton patterns in one-dimensional systems. Other look like Sierpinsky triangles or exhibit very irregular patterns. Meinhardt has shown that those patterns can be well described by reaction–diffusion systems [1]. However, such a description neglects the discrete character of the cell system at the growth front of the mollusc shell.We have therefore developed a one-dimensional cellular vector automaton model which takes into account the cellular behaviour of the system [2]. The state of the mathematical cell is defined by a vector with two components. We looked for the most simple transformation rules in order to develop quite different types of waves: classical waves, chemical waves and different types of solitons. Our attention was focussed on the properties of the system created through the collision of two waves.

scholarly journals An Advanced Galerkin Approach to Solve the Nonlinear \\[6pt]Reaction-Diffusion Equations With Different Boundary Conditions

2022 ◽  
Vol 14 (1) ◽  
pp. 30
Author(s):  
Hazrat Ali ◽  
Md. Kamrujjaman ◽  
Md. Shafiqul Islam
Keyword(s):  
Boundary Conditions ◽  
Reaction Diffusion ◽  
Reaction Diffusion Equations ◽  
Parabolic Partial Differential Equations ◽  
Galerkin Finite Element Method ◽  
Galerkin Finite Element ◽  
Nonlinear Parabolic ◽  
Comparison Results ◽  
Different Types ◽  
Convergence And Stability Analysis

This study proposed a scheme originated from the Galerkin finite element method (GFEM) for solving nonlinear parabolic partial differential equations (PDEs) numerically with initial and different types of boundary conditions. The scheme is applied generally handling the nonlinear terms in a simple way and throwing over restrictive assumptions. The convergence and stability analysis of the method are derived. The error of the method is estimated. In the series, eminent problems are solved, such as  Fisher's equation, Newell-Whitehead-Segel equation, Burger's equation, and  Burgers-Huxley equation to demonstrate the validity, efficiency, accuracy, simplicity and applicability of this scheme. In each example, the comparison results are presented both numerically and graphically

Patterning of angiogenesis in the zebrafish embryo

Development ◽  
2002 ◽  
Vol 129 (4) ◽  
pp. 973-982 ◽  
Author(s):  
Sarah Childs ◽  
Jau-Nian Chen ◽  
Deborah M. Garrity ◽  
Mark C. Fishman
Keyword(s):  
Zebrafish Embryo ◽  
Regular Pattern ◽  
Wild Type ◽  
Cell Fates ◽  
Mutagenesis Screen ◽  
The Third ◽  
Shaped Cell ◽  
Vessel Growth ◽  
Lateral Posterior ◽  
Lineage Analysis

Little is known about how vascular patterns are generated in the embryo. The vasculature of the zebrafish trunk has an extremely regular pattern. One intersegmental vessel (ISV) sprouts from the aorta, runs between each pair of somites, and connects to the dorsal longitudinal anastomotic vessel (DLAV). We now define the cellular origins, migratory paths and cell fates that generate these metameric vessels of the trunk. Additionally, by a genetic screen we define one gene, out of bounds (obd), that constrains this angiogenic growth to a specific path. We have performed lineage analysis, using laser activation of a caged dye and mosaic construction to determine the origin of cells that constitute the ISV. Individual angioblasts destined for the ISVs arise from the lateral posterior mesoderm (LPM), and migrate to the dorsal aorta, from where they migrate between somites to their final position in the ISVs and dorsal longitudinal anastomotic vessel (DLAV). Cells of each ISV leave the aorta only between the ventral regions of two adjacent somites, and migrate dorsally to assume one of three ISV cell fates. Most dorsal is a T-shaped cell, based in the DLAV and branching ventrally; the second constitutes a connecting cell; and the third an inverted T-shaped cell, based in the aorta and branching dorsally. The ISV remains between somites during its ventral course, but changes to run mid-somite dorsally. This suggests that the pattern of ISV growth ventrally and dorsally is guided by different cues. We have also performed an ENU mutagenesis screen of 750 mutagenized genomes and identified one mutation, obd that disrupts this pattern. In obd mutant embryos, ISVs sprout precociously at abnormal sites and migrate anomalously in the vicinity of ventral somite. The dorsal extent of the ISV is less perturbed. Precocious sprouting can be inhibited in a VEGF morphant, but the anomalous site of origin of obd ISVs remains. In mosaic embryos, obd somite causes adjacent wild-type endothelial cells to assume the anomalous ISV pattern of obd embryos. Thus, the launching position of the new sprout and its initial trajectory are directed by inhibitory signals from ventral somites. Zebrafish ISVs are a tractable system for defining the origins and fates of vessels, and for dissecting elements that govern patterns of vessel growth.

Self-Organization in Multiplex Networks

2018 ◽  
pp. 148-158
Author(s):  
Nikos E. Kouvaris ◽  
Albert Díaz-Guilera
Keyword(s):  
Complex Systems ◽  
Network Structure ◽  
Reaction Diffusion ◽  
Reaction Diffusion Equations ◽  
Diffusion Equations ◽  
Self Organization ◽  
Multiplex Networks ◽  
The Way

The chapter “Self-Organization in Multiplex Networks” discusses the use of multiplex networks in studying complex systems and synchronization. An important question in the research of complex systems concerns the way the network structure shapes the hosted dynamics and leads to a plethora of self-organization phenomena. Complex systems consist of nodes having some intrinsic dynamics, usually nonlinear, and are connected through the links of the network. Such systems can be studied by means of discrete reaction–diffusion equations; reaction terms account for the dynamics in the nodes, whereas diffusion terms describe the coupling between them. This chapter discusses how multiplex networks are suitable for studying such systems by providing two illustrative examples of self-organization phenomena occurring in them.

Contrastive Studies of Asphalt Pavement on Suction Exothermic Properties and Cooling Measures

2011 ◽  
Vol 97-98 ◽  
pp. 290-296
Author(s):  
Wei Guang Li ◽  
Zhi Dong Han ◽  
Zhen Bei Lv ◽  
Yan Hong Duan
Keyword(s):  
Heat Storage ◽  
Asphalt Pavement ◽  
Asphalt Mixture ◽  
Heat Island ◽  
Regular Pattern ◽  
Island Effect ◽  
Different Types ◽  
Urban Heat ◽  
Pavement Structure ◽  
Quantity Of Heat

It is important to reduce asphalt mixture strong absorption characteristics to improve anti-rutting ability and reduce the urban heat island effect. This paper firstly studies the suction and exothermic regular pattern of existing three types, five kinds of asphalt pavement structure. It turns out that there are differences in suction and exothermic characteristics of different types of pavement structure. Suspension close-grained type structure has higher adiabatic heating; gap-type skeleton has faster speed of suction and exothermic; and dense skeleton has more total quantity of heat storage. Accordingly, test and analysis of cooling effect of Gap-type skeleton asphalt pavement has conducted by adopting smear reflective materials to reduce reflectance and surface adding insulation materials, The results show that reducing reflectivity is the best way which can reduce by 5 centigrade around. In addition , improving effectiveness has also been studied by adding light-colored stone partly replacing mineral aggregate, and substituting busing mullite for aggregate below2.36 mm is the best cooling way ,which can reduce by 3.3 centigrade.

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