1
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Deichmann U. Contrasting philosophical and scientific views in the long history of studying the generation of form in development. Biosystems 2024; 242:105260. [PMID: 38925338 DOI: 10.1016/j.biosystems.2024.105260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2024] [Revised: 06/23/2024] [Accepted: 06/23/2024] [Indexed: 06/28/2024]
Abstract
Focusing on the opposing ways of thinking of philosophers and scientists to explain the generation of form in biological development, I show that today's controversies over explanations of early development bear fundamental similarities to the dichotomy of preformation theory versus epigenesis in Greek antiquity. They are related to the acceptance or rejection of the idea of a physical form of what today would be called information for the generating of the embryo as a necessary pre-requisite for specific development and heredity. As a recent example, I scrutinize the dichotomy of genomic causality versus self-organization in 20th and 21st century theories of the generation of form. On the one hand, the generation of patterns and form, as well as the constant outcome in development, are proposed to be causally related to something that is "preformed" in the germ cells, the nucleus of germ cells, or the genome. On the other hand, it is proposed that there is no pre-existing form or information, and development is seen as a process where genuinely new characters emerge from formless matter, either by immaterial "forces of life," or by physical-chemical processes of self-organization. I also argue that these different ways of thinking and the research practices associated with them are not equivalent, and maintain that it is impossible to explain the generation of form and constant outcome of development without the assumption of the transmission of pre-existing information in the form of DNA sequences in the genome. Only in this framework of "preformed" information can "epigenesis" in the form of physical and chemical processes of self-organization play an important role.
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Affiliation(s)
- Ute Deichmann
- Jacques Loeb Centre for the History and Philosophy of Science, Ben-Gurion University of the Negev, Beer Sheva, 8410500, Israel.
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2
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Perros T, Biquet-Bisquert A, Ben Meriem Z, Delarue M, Joseph P, Marcq P, Cochet-Escartin O. Mechanical characterization of regenerating Hydra tissue spheres. Biophys J 2024; 123:1792-1803. [PMID: 38783602 PMCID: PMC11267430 DOI: 10.1016/j.bpj.2024.05.022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 04/12/2024] [Accepted: 05/21/2024] [Indexed: 05/25/2024] Open
Abstract
Hydra vulgaris, long known for its remarkable regenerative capabilities, is also a long-standing source of inspiration for models of spontaneous patterning. Recently it became clear that early patterning during Hydra regeneration is an integrated mechanochemical process whereby morphogen dynamics is influenced by tissue mechanics. One roadblock to understanding Hydra self-organization is our lack of knowledge about the mechanical properties of these organisms. In this study, we combined microfluidic developments to perform parallelized microaspiration rheological experiments and numerical simulations to characterize these mechanical properties. We found three different behaviors depending on the applied stresses: an elastic response, a viscoelastic response, and tissue rupture. Using models of deformable shells, we quantify their Young's modulus, shear viscosity, and the critical stresses required to switch between behaviors. Based on these experimental results, we propose a description of the tissue mechanics during normal regeneration. Our results provide a first step toward the development of original mechanochemical models of patterning grounded in quantitative experimental data.
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Affiliation(s)
- Thomas Perros
- University Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, Villeurbanne, France
| | - Anaïs Biquet-Bisquert
- University Claude Bernard Lyon 1, CNRS, Institut Lumière Matière, Villeurbanne, France; Centre de Biologie Structurale, CNRS UMR5048, INSERM U1054, University of Montpellier, Montpellier, France
| | - Zacchari Ben Meriem
- Laboratory for Analysis and Architecture of Systems, Université de Toulouse-CNRS, Toulouse, France
| | - Morgan Delarue
- Laboratory for Analysis and Architecture of Systems, Université de Toulouse-CNRS, Toulouse, France
| | - Pierre Joseph
- Laboratory for Analysis and Architecture of Systems, Université de Toulouse-CNRS, Toulouse, France
| | - Philippe Marcq
- Laboratoire Physique et Mécanique des Milieux Hétérogènes, Sorbonne Université, CNRS UMR 7636, ESPCI, Université Paris Cité, Paris, France
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3
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Matas-Gil A, Endres RG. Unraveling biochemical spatial patterns: Machine learning approaches to the inverse problem of stationary Turing patterns. iScience 2024; 27:109822. [PMID: 38827409 PMCID: PMC11140185 DOI: 10.1016/j.isci.2024.109822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Revised: 03/14/2024] [Accepted: 04/24/2024] [Indexed: 06/04/2024] Open
Abstract
The diffusion-driven Turing instability is a potential mechanism for spatial pattern formation in numerous biological and chemical systems. However, engineering these patterns and demonstrating that they are produced by this mechanism is challenging. To address this, we aim to solve the inverse problem in artificial and experimental Turing patterns. This task is challenging since patterns are often corrupted by noise and slight changes in initial conditions can lead to different patterns. We used both least squares to explore the problem and physics-informed neural networks to build a noise-robust method. We elucidate the functionality of our network in scenarios mimicking biological noise levels and showcase its application using an experimentally obtained chemical pattern. The findings reveal the significant promise of machine learning in steering the creation of synthetic patterns in bioengineering, thereby advancing our grasp of morphological intricacies within biological systems while acknowledging existing limitations.
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Affiliation(s)
- Antonio Matas-Gil
- Department of Life Sciences & Centre for Integrative Systems Biology and Bioinformatics, Imperial College London, London SW7 2BU, UK
| | - Robert G. Endres
- Department of Life Sciences & Centre for Integrative Systems Biology and Bioinformatics, Imperial College London, London SW7 2BU, UK
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4
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Mousavi R, Lobo D. Automatic design of gene regulatory mechanisms for spatial pattern formation. NPJ Syst Biol Appl 2024; 10:35. [PMID: 38565850 PMCID: PMC10987498 DOI: 10.1038/s41540-024-00361-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 03/19/2024] [Indexed: 04/04/2024] Open
Abstract
Gene regulatory mechanisms (GRMs) control the formation of spatial and temporal expression patterns that can serve as regulatory signals for the development of complex shapes. Synthetic developmental biology aims to engineer such genetic circuits for understanding and producing desired multicellular spatial patterns. However, designing synthetic GRMs for complex, multi-dimensional spatial patterns is a current challenge due to the nonlinear interactions and feedback loops in genetic circuits. Here we present a methodology to automatically design GRMs that can produce any given two-dimensional spatial pattern. The proposed approach uses two orthogonal morphogen gradients acting as positional information signals in a multicellular tissue area or culture, which constitutes a continuous field of engineered cells implementing the same designed GRM. To efficiently design both the circuit network and the interaction mechanisms-including the number of genes necessary for the formation of the target spatial pattern-we developed an automated algorithm based on high-performance evolutionary computation. The tolerance of the algorithm can be configured to design GRMs that are either simple to produce approximate patterns or complex to produce precise patterns. We demonstrate the approach by automatically designing GRMs that can produce a diverse set of synthetic spatial expression patterns by interpreting just two orthogonal morphogen gradients. The proposed framework offers a versatile approach to systematically design and discover complex genetic circuits producing spatial patterns.
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Affiliation(s)
- Reza Mousavi
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA
| | - Daniel Lobo
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA.
- Greenebaum Comprehensive Cancer Center and Center for Stem Cell Biology & Regenerative Medicine, University of Maryland, Baltimore, Baltimore, MD, USA.
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5
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Di Patti F, Ugartechea Chirino Y, Arbel-Goren R, Sharon T, Castillo A, Alvarez–Buylla E, Fanelli D, Stavans J. Stochastic Turing patterns of trichomes in Arabidopsis leaves. Proc Natl Acad Sci U S A 2023; 120:e2309616120. [PMID: 37824528 PMCID: PMC10589648 DOI: 10.1073/pnas.2309616120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2023] [Accepted: 09/03/2023] [Indexed: 10/14/2023] Open
Abstract
Biological patterns that emerge during the morphogenesis of multicellular organisms can display high precision at large scales, while at cellular scales, cells exhibit large fluctuations stemming from cell-cell differences in molecular copy numbers also called demographic noise. We study the conflicting interplay between high precision and demographic noise in trichome patterns on the epidermis of wild-type Arabidopsis thaliana leaves, as a two-dimensional model system. We carry out a statistical characterization of these patterns and show that their power spectra display fat tails-a signature compatible with noise-driven stochastic Turing patterns-which are absent in power spectra of patterns driven by deterministic instabilities. We then present a theoretical model that includes demographic noise stemming from birth-death processes of genetic regulators which we study analytically and by stochastic simulations. The model captures the observed experimental features of trichome patterns.
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Affiliation(s)
- Francesca Di Patti
- Dipartimento di Matematica e Informatica, Universitá degli Studi di Perugia, Perugia06123, Italia
- Istituto Nazionale di Fisica Nucleare - Sezione di Perugia, Perugia06123, Italia
| | - Yamel Ugartechea Chirino
- Instituto de Ecología, Universidad Nacional Autónoma de México Ciudad, Universitaria 3er Circuito Interior Coyoacán, Ciudad de México04510, México
| | - Rinat Arbel-Goren
- Faculty of Physics, Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot76100, Israel
| | - Tom Sharon
- Faculty of Physics, Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot76100, Israel
| | - Aaron Castillo
- Instituto de Ecología, Universidad Nacional Autónoma de México Ciudad, Universitaria 3er Circuito Interior Coyoacán, Ciudad de México04510, México
| | - Elena Alvarez–Buylla
- Instituto de Ecología, Universidad Nacional Autónoma de México Ciudad, Universitaria 3er Circuito Interior Coyoacán, Ciudad de México04510, México
| | - Duccio Fanelli
- Dipartimento di Fisica e Astronomia, Università degli Studi di Firenze, Sesto Fiorentino, Firenze50019, Italia
- Centro Interdipartimentale per lo Studio delle Dinamiche Complesse and Istituto Nazionale di Fisica Nucleare Sezione di Firenze, Sesto Fiorentino, Firenze50019, Italia
| | - Joel Stavans
- Faculty of Physics, Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot76100, Israel
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6
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Mousavi R, Lobo D. Automatic design of gene regulatory mechanisms for spatial pattern formation. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.07.26.550573. [PMID: 37546866 PMCID: PMC10402059 DOI: 10.1101/2023.07.26.550573] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/08/2023]
Abstract
Synthetic developmental biology aims to engineer gene regulatory mechanisms (GRMs) for understanding and producing desired multicellular patterns and shapes. However, designing GRMs for spatial patterns is a current challenge due to the nonlinear interactions and feedback loops in genetic circuits. Here we present a methodology to automatically design GRMs that can produce any given spatial pattern. The proposed approach uses two orthogonal morphogen gradients acting as positional information signals in a multicellular tissue area or culture, which constitutes a continuous field of engineered cells implementing the same designed GRM. To efficiently design both the circuit network and the interaction mechanisms-including the number of genes necessary for the formation of the target pattern-we developed an automated algorithm based on high-performance evolutionary computation. The tolerance of the algorithm can be configured to design GRMs that are either simple to produce approximate patterns or complex to produce precise patterns. We demonstrate the approach by automatically designing GRMs that can produce a diverse set of synthetic spatial expression patterns by interpreting just two orthogonal morphogen gradients. The proposed framework offers a versatile approach to systematically design and discover pattern-producing genetic circuits.
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Affiliation(s)
- Reza Mousavi
- Department of Biological Sciences, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
| | - Daniel Lobo
- Department of Biological Sciences, University of Maryland, Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250, USA
- Greenebaum Comprehensive Cancer Center and Center for Stem Cell Biology & Regenerative Medicine, University of Maryland, School of Medicine, 22 S. Greene Street, Baltimore, MD 21201, USA
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7
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Grodstein J, McMillen P, Levin M. Closing the loop on morphogenesis: a mathematical model of morphogenesis by closed-loop reaction-diffusion. Front Cell Dev Biol 2023; 11:1087650. [PMID: 37645245 PMCID: PMC10461482 DOI: 10.3389/fcell.2023.1087650] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Accepted: 07/31/2023] [Indexed: 08/31/2023] Open
Abstract
Morphogenesis, the establishment and repair of emergent complex anatomy by groups of cells, is a fascinating and biomedically-relevant problem. One of its most fascinating aspects is that a developing embryo can reliably recover from disturbances, such as splitting into twins. While this reliability implies some type of goal-seeking error minimization over a morphogenic field, there are many gaps with respect to detailed, constructive models of such a process. A common way to achieve reliability is negative feedback, which requires characterizing the existing body shape to create an error signal-but measuring properties of a shape may not be simple. We show how cells communicating in a wave-like pattern could analyze properties of the current body shape. We then describe a closed-loop negative-feedback system for creating reaction-diffusion (RD) patterns with high reliability. Specifically, we use a wave to count the number of peaks in a RD pattern, letting us use a negative-feedback controller to create a pattern with N repetitions, where N can be altered over a wide range. Furthermore, the individual repetitions of the RD pattern can be easily stretched or shrunk under genetic control to create, e.g., some morphological features larger than others. This work contributes to the exciting effort of understanding design principles of morphological computation, which can be used to understand evolved developmental mechanisms, manipulate them in regenerative-medicine settings, or engineer novel synthetic morphology constructs with desired robust behavior.
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Affiliation(s)
- Joel Grodstein
- Department of Electrical and Computer Engineering, Tufts University, Medford, MA, United States
| | - Patrick McMillen
- Allen Discovery Center at Tufts University, Medford, MA, United States
| | - Michael Levin
- Allen Discovery Center at Tufts University, Medford, MA, United States
- Wyss Institute for Biologically Inspired Engineering at Harvard University, Boston, MA, United States
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8
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Deichmann U. Self-Organization and Genomic Causality in Models of Morphogenesis. ENTROPY (BASEL, SWITZERLAND) 2023; 25:873. [PMID: 37372217 PMCID: PMC10297450 DOI: 10.3390/e25060873] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2023] [Revised: 05/25/2023] [Accepted: 05/26/2023] [Indexed: 06/29/2023]
Abstract
The debate about what causes the generation of form and structure in embryological development goes back to antiquity. Most recently, it has focused on the divergent views as to whether the generation of patterns and form in development is a largely self-organized process or is mainly determined by the genome, in particular, complex developmental gene regulatory processes. This paper presents and analyzes pertinent models of pattern formation and form generation in a developing organism in the past and the present, with a special emphasis on Alan Turing's 1952 reaction-diffusion model. I first draw attention to the fact that Turing's paper remained, at first, without a noticeable impact on the community of biologists because purely physical-chemical models were unable to explain embryological development and often also simple repetitive patterns. I then show that from the year 2000 and onwards, Turing's 1952 paper was increasingly cited also by biologists. The model was updated to include gene products and now seemed able to account for the generation of biological patterns, though discrepancies between models and biological reality remained. I then point out Eric Davidson's successful theory of early embryogenesis based on gene-regulatory network analysis and its mathematical modeling that not only was able to provide a mechanistic and causal explanation for gene regulatory events controlling developmental cell fate specification but, unlike reaction-diffusion models, also addressed the effects of evolution and organisms' longstanding developmental and species stability. The paper concludes with an outlook on further developments of the gene regulatory network model.
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Affiliation(s)
- Ute Deichmann
- The Jacques Loeb Centre for the History and Philosophy of the Life Sciences, Ben-Gurion University of the Negev, Beer Sheva 84105, Israel
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9
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Dúzs B, Holló G, Kitahata H, Ginder E, Suematsu NJ, Lagzi I, Szalai I. Appearance and suppression of Turing patterns under a periodically forced feed. Commun Chem 2023; 6:3. [PMID: 36697882 PMCID: PMC9814632 DOI: 10.1038/s42004-022-00800-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2022] [Accepted: 12/19/2022] [Indexed: 01/04/2023] Open
Abstract
Turing instability is a general and straightforward mechanism of pattern formation in reaction-diffusion systems, and its relevance has been demonstrated in different biological phenomena. Still, there are many open questions, especially on the robustness of the Turing mechanism. Robust patterns must survive some variation in the environmental conditions. Experiments on pattern formation using chemical systems have shown many reaction-diffusion patterns and serve as relatively simple test tools to study general aspects of these phenomena. Here, we present a study of sinusoidal variation of the input feed concentrations on chemical Turing patterns. Our experimental, numerical and theoretical analysis demonstrates that patterns may appear even at significant amplitude variation of the input feed concentrations. Furthermore, using time-dependent feeding opens a way to control pattern formation. The patterns settled at constant feed may disappear, or new patterns may appear from a homogeneous steady state due to the periodic forcing.
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Affiliation(s)
- Brigitta Dúzs
- grid.5591.80000 0001 2294 6276Laboratory of Nonlinear Chemical Dynamics, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter stny. 1/A, H-1117 Budapest, Hungary ,grid.5802.f0000 0001 1941 7111Present Address: University of Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Gábor Holló
- ELKH-BME Condensed Matter Research Group, Műegyetem rkp. 3, H-1111 Budapest, Hungary
| | - Hiroyuki Kitahata
- grid.136304.30000 0004 0370 1101Graduate School of Science, Chiba University, Yayoi-cho 1-33, Inage-ku, Chiba 263-8522 Japan
| | - Elliott Ginder
- grid.411764.10000 0001 2106 7990School of Interdisciplinary Mathematical Sciences, Graduate School of Advanced Mathematical Sciences, and Meiji Institute for Advanced Study of Mathematical Sciences (MIMS), Meiji University, 4-21-1, Nakano Tokyo, 164-8525 Japan
| | - Nobuhiko J. Suematsu
- grid.411764.10000 0001 2106 7990School of Interdisciplinary Mathematical Sciences, Graduate School of Advanced Mathematical Sciences, and Meiji Institute for Advanced Study of Mathematical Sciences (MIMS), Meiji University, 4-21-1, Nakano Tokyo, 164-8525 Japan
| | - István Lagzi
- ELKH-BME Condensed Matter Research Group, Műegyetem rkp. 3, H-1111 Budapest, Hungary ,grid.6759.d0000 0001 2180 0451Department of Physics, Institute of Physics, Budapest University of Technology and Economics, Műegyetem rkp. 3, H-1111 Budapest, Hungary
| | - István Szalai
- grid.5591.80000 0001 2294 6276Laboratory of Nonlinear Chemical Dynamics, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter stny. 1/A, H-1117 Budapest, Hungary
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10
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Lam W, Oh J, Davey MG. Turing patterning and upper limb development. J Hand Surg Eur Vol 2022; 47:1085-1088. [PMID: 36165432 DOI: 10.1177/17531934221125938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- Wee Lam
- Royal Hospital for Children and Young People, Edinburgh, UK
| | - Julia Oh
- Division of Developmental Biology, The Roslin Institute, University of Edinburgh, Edinburgh, UK
| | - Megan G Davey
- Division of Developmental Biology, The Roslin Institute, University of Edinburgh, Edinburgh, UK
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11
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Escárcega-Bobadilla MV, Maldonado-Domínguez M, Romero-Ávila M, Zelada-Guillén GA. Turing patterns by supramolecular self-assembly of a single salphen building block. iScience 2022; 25:104545. [PMID: 35747384 PMCID: PMC9209723 DOI: 10.1016/j.isci.2022.104545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Revised: 05/15/2022] [Accepted: 06/02/2022] [Indexed: 11/02/2022] Open
Abstract
In the 1950s, Alan Turing showed that concerted reactions and diffusion of activating and inhibiting chemical species can autonomously generate patterns without previous positional information, thus providing a chemical basis for morphogenesis in Nature. However, access to these patterns from only one molecular component that contained all the necessary information to execute agonistic and antagonistic signaling is so far an elusive goal, since two or more participants with different diffusivities are a must. Here, we report on a single-molecule system that generates Turing patterns arrested in the solid state, where supramolecular interactions are used instead of chemical reactions, whereas diffusional differences arise from heterogeneously populated self-assembled products. We employ a family of hydroxylated organic salphen building blocks based on a bis-Schiff-base scaffold with portions responsible for either activation or inhibition of assemblies at different hierarchies through purely supramolecular reactions, only depending upon the solvent dielectric constant and evaporation as fuel.
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Affiliation(s)
- Martha V Escárcega-Bobadilla
- School of Chemistry, National Autonomous University of Mexico (UNAM), Circuito Escolar s/n, Ciudad Universitaria, 04510 Mexico City, Mexico
| | - Mauricio Maldonado-Domínguez
- School of Chemistry, National Autonomous University of Mexico (UNAM), Circuito Escolar s/n, Ciudad Universitaria, 04510 Mexico City, Mexico.,Department of Computational Chemistry, J. Heyrovský Institute of Physical Chemistry, The Czech Academy of Sciences, Dolejškova 3, 18223 Prague 8, Czech Republic
| | - Margarita Romero-Ávila
- School of Chemistry, National Autonomous University of Mexico (UNAM), Circuito Escolar s/n, Ciudad Universitaria, 04510 Mexico City, Mexico
| | - Gustavo A Zelada-Guillén
- School of Chemistry, National Autonomous University of Mexico (UNAM), Circuito Escolar s/n, Ciudad Universitaria, 04510 Mexico City, Mexico
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12
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Lu J, Şimşek E, Silver A, You L. Advances and challenges in programming pattern formation using living cells. Curr Opin Chem Biol 2022; 68:102147. [PMID: 35472832 PMCID: PMC9158282 DOI: 10.1016/j.cbpa.2022.102147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 03/15/2022] [Accepted: 03/18/2022] [Indexed: 11/29/2022]
Abstract
Spatial patterning of cell populations is a ubiquitous phenomenon in nature. Patterns occur at various length and time scales and exhibit immense diversity. In addition to offering a deeper understanding of the emergence of patterns in nature, the ability to program synthetic patterns using living cells has the potential for broad applications. To date, however, progress in engineering pattern formation has been hampered by technical challenges. In this Review, we discuss recent advances in programming pattern formation in terms of biological insights, experimental and computational tool development, and potential applications.
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Affiliation(s)
- Jia Lu
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Emrah Şimşek
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Anita Silver
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA
| | - Lingchong You
- Department of Biomedical Engineering, Duke University, Durham, NC 27708, USA; Center for Genomic and Computational Biology, Duke University, Durham, NC, 27708, USA; Department of Molecular Genetics and Microbiology, Duke University School of Medicine, Durham, NC, 27708, USA.
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13
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Camley BA. Patterning by contraction. Cell 2022; 185:1809-1810. [DOI: 10.1016/j.cell.2022.04.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 04/26/2022] [Accepted: 04/26/2022] [Indexed: 11/29/2022]
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14
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Abstract
Extracting mechanistic knowledge from the spatial and temporal phenotypes of morphogenesis is a current challenge due to the complexity of biological regulation and their feedback loops. Furthermore, these regulatory interactions are also linked to the biophysical forces that shape a developing tissue, creating complex interactions responsible for emergent patterns and forms. Here we show how a computational systems biology approach can aid in the understanding of morphogenesis from a mechanistic perspective. This methodology integrates the modeling of tissues and whole-embryos with dynamical systems, the reverse engineering of parameters or even whole equations with machine learning, and the generation of precise computational predictions that can be tested at the bench. To implement and perform the computational steps in the methodology, we present user-friendly tools, computer code, and guidelines. The principles of this methodology are general and can be adapted to other model organisms to extract mechanistic knowledge of their morphogenesis.
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Affiliation(s)
- Jason M Ko
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA
| | - Reza Mousavi
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA
| | - Daniel Lobo
- Department of Biological Sciences, University of Maryland, Baltimore County, Baltimore, MD, USA.
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15
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Van Gorder RA. Pattern formation from spatially heterogeneous reaction-diffusion systems. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2021; 379:20210001. [PMID: 34743604 DOI: 10.1098/rsta.2021.0001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
First proposed by Turing in 1952, the eponymous Turing instability and Turing pattern remain key tools for the modern study of diffusion-driven pattern formation. In spatially homogeneous Turing systems, one or a few linear Turing modes dominate, resulting in organized patterns (peaks in one dimension; spots, stripes, labyrinths in two dimensions) which repeats in space. For a variety of reasons, there has been increasing interest in understanding irregular patterns, with spatial heterogeneity in the underlying reaction-diffusion system identified as one route to obtaining irregular patterns. We study pattern formation from reaction-diffusion systems which involve spatial heterogeneity, by way of both analytical and numerical techniques. We first extend the classical Turing instability analysis to track the evolution of linear Turing modes and the nascent pattern, resulting in a more general instability criterion which can be applied to spatially heterogeneous systems. We also calculate nonlinear mode coefficients, employing these to understand how each spatial mode influences the long-time evolution of a pattern. Unlike for the standard spatially homogeneous Turing systems, spatially heterogeneous systems may involve many Turing modes of different wavelengths interacting simultaneously, with resulting patterns exhibiting a high degree of variation over space. We provide a number of examples of spatial heterogeneity in reaction-diffusion systems, both mathematical (space-varying diffusion parameters and reaction kinetics, mixed boundary conditions, space-varying base states) and physical (curved anisotropic domains, apical growth of space domains, chemicalsimmersed within a flow or a thermal gradient), providing a qualitative understanding of how spatial heterogeneity can be used to modify classical Turing patterns. This article is part of the theme issue 'Recent progress and open frontiers in Turing's theory of morphogenesis'.
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Affiliation(s)
- Robert A Van Gorder
- Department of Mathematics and Statistics, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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16
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Painter KJ, Ptashnyk M, Headon DJ. Systems for intricate patterning of the vertebrate anatomy. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2021; 379:20200270. [PMID: 34743605 PMCID: PMC8580425 DOI: 10.1098/rsta.2020.0270] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 07/11/2021] [Indexed: 05/05/2023]
Abstract
Periodic patterns form intricate arrays in the vertebrate anatomy, notably the hair and feather follicles of the skin, but also internally the villi of the gut and the many branches of the lung, kidney, mammary and salivary glands. These tissues are composite structures, being composed of adjoined epithelium and mesenchyme, and the patterns that arise within them require interaction between these two tissue layers. In embryonic development, cells change both their distribution and state in a periodic manner, defining the size and relative positions of these specialized structures. Their placement is determined by simple spacing mechanisms, with substantial evidence pointing to a variety of local enhancement/lateral inhibition systems underlying the breaking of symmetry. The nature of the cellular processes involved, however, has been less clear. While much attention has focused on intercellular soluble signals, such as protein growth factors, experimental evidence has grown for contributions of cell movement or mechanical forces to symmetry breaking. In the mesenchyme, unlike the epithelium, cells may move freely and can self-organize into aggregates by chemotaxis, or through generation and response to mechanical strain on their surrounding matrix. Different modes of self-organization may coexist, either coordinated into a single system or with hierarchical relationships. Consideration of a broad range of distinct biological processes is required to advance understanding of biological pattern formation. This article is part of the theme issue 'Recent progress and open frontiers in Turing's theory of morphogenesis'.
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Affiliation(s)
- Kevin J. Painter
- Dipartimento Interateneo di Scienze, Progetto e Politiche del Territorio, Politecnico di Torino, Torino, Italy
| | - Mariya Ptashnyk
- School of Mathematical and Computer Sciences and Maxwell Institute, Heriot-Watt University, Edinburgh, UK
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17
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Leyshon T, Tonello E, Schnoerr D, Siebert H, Stumpf MPH. The design principles of discrete turing patterning systems. J Theor Biol 2021; 531:110901. [PMID: 34530030 DOI: 10.1016/j.jtbi.2021.110901] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Revised: 08/15/2021] [Accepted: 09/06/2021] [Indexed: 10/20/2022]
Abstract
The formation of spatial structures lies at the heart of developmental processes. However, many of the underlying gene regulatory and biochemical processes remain poorly understood. Turing patterns constitute a main candidate to explain such processes, but they appear sensitive to fluctuations and variations in kinetic parameters, raising the question of how they may be adopted and realised in naturally evolved systems. The vast majority of mathematical studies of Turing patterns have used continuous models specified in terms of partial differential equations. Here, we complement this work by studying Turing patterns using discrete cellular automata models. We perform a large-scale study on all possible two-species networks and find the same Turing pattern producing networks as in the continuous framework. In contrast to continuous models, however, we find these Turing pattern topologies to be substantially more robust to changes in the parameters of the model. We also find that diffusion-driven instabilities are substantially weaker predictors for Turing patterns in our discrete modelling framework in comparison to the continuous case, in the sense that the presence of an instability does not guarantee a pattern emerging in simulations. We show that a more refined criterion constitutes a stronger predictor. The similarity of the results for the two modelling frameworks suggests a deeper underlying principle of Turing mechanisms in nature. Together with the larger robustness in the discrete case this suggests that Turing patterns may be more robust than previously thought.
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Affiliation(s)
- Thomas Leyshon
- Department of Life Sciences, Imperial College London, UK
| | - Elisa Tonello
- FB Mathematik und Informatik, Freine Universität Berlin, Germany
| | - David Schnoerr
- Department of Life Sciences, Imperial College London, UK
| | - Heike Siebert
- FB Mathematik und Informatik, Freine Universität Berlin, Germany
| | - Michael P H Stumpf
- Department of Life Sciences, Imperial College London, UK; Melbourne Integrated Genomics, University of Melbourne, Australia; School of BioScience, University of Melbourne, Australia; School of Mathematics and Statistics, University of Melbourne, Australia.
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18
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Diaz-Cuadros M, Pourquié O, El-Sherif E. Patterning with clocks and genetic cascades: Segmentation and regionalization of vertebrate versus insect body plans. PLoS Genet 2021; 17:e1009812. [PMID: 34648490 PMCID: PMC8516289 DOI: 10.1371/journal.pgen.1009812] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Oscillatory and sequential processes have been implicated in the spatial patterning of many embryonic tissues. For example, molecular clocks delimit segmental boundaries in vertebrates and insects and mediate lateral root formation in plants, whereas sequential gene activities are involved in the specification of regional identities of insect neuroblasts, vertebrate neural tube, vertebrate limb, and insect and vertebrate body axes. These processes take place in various tissues and organisms, and, hence, raise the question of what common themes and strategies they share. In this article, we review 2 processes that rely on the spatial regulation of periodic and sequential gene activities: segmentation and regionalization of the anterior-posterior (AP) axis of animal body plans. We study these processes in species that belong to 2 different phyla: vertebrates and insects. By contrasting 2 different processes (segmentation and regionalization) in species that belong to 2 distantly related phyla (arthropods and vertebrates), we elucidate the deep logic of patterning by oscillatory and sequential gene activities. Furthermore, in some of these organisms (e.g., the fruit fly Drosophila), a mode of AP patterning has evolved that seems not to overtly rely on oscillations or sequential gene activities, providing an opportunity to study the evolution of pattern formation mechanisms.
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Affiliation(s)
- Margarete Diaz-Cuadros
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Pathology, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
| | - Olivier Pourquié
- Department of Genetics, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Pathology, Brigham and Women’s Hospital, Boston, Massachusetts, United States of America
- Harvard Stem Cell Institute, Harvard University, Cambridge, Massachusetts, United States of America
| | - Ezzat El-Sherif
- Division of Developmental Biology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg, Erlangen, Germany
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19
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Zhu X, Wang Z, Teng F. A review of regulated self-organizing approaches for tissue regeneration. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2021; 167:63-78. [PMID: 34293337 DOI: 10.1016/j.pbiomolbio.2021.07.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 07/06/2021] [Accepted: 07/15/2021] [Indexed: 12/13/2022]
Abstract
Tissue and organ regeneration is the dynamic process by which a population of cells rearranges into a specific form with specific functions. Traditional tissue regeneration utilizes tissue grafting, cell implantation, and structured scaffolds to achieve clinical efficacy. However, tissue grafting methods face a shortage of donor tissue, while cell implantation may involve leakage of the implanted cells without a supportive 3D matrix. Cell migration, proliferation, and differentiation in structured scaffolds may disorganize and frustrate the artificially pre-designed structures, and sometimes involve immunogenic reactions. To overcome this limitation, the self-organizing properties and innate regenerative capability of tissue/organism formation in the absence of guidance by structured scaffolds has been investigated. This review emphasizes the growing subfield of the regulated self-organizing approach for neotissue formation and describes advances in the subfield using diverse, cutting-edge, inter-disciplinarity technologies. We cohesively summarize the directed self-organization of cells in the micro-engineered cell-ECM system and 3D/4D cell printing. Mathematical modeling of cellular self-organization is also discussed for providing rational guidance to intractable problems in tissue regeneration. It is envisioned that future self-organization approaches integrating biomathematics, micro-nano engineering, and gene circuits developed from synthetic biology will continue to work in concert with self-organizing morphogenesis to enhance rational control during self-organizing in tissue and organ regeneration.
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Affiliation(s)
- Xiaolu Zhu
- College of Mechanical & Electrical Engineering, Hohai University, Changzhou, Jiangsu, 213022, China; Changzhou Key Laboratory of Digital Manufacture Technology, Hohai University, Changzhou, Jiangsu, 213022, China; Jiangsu Key Laboratory of Special Robot Technology, Hohai University, Changzhou, Jiangsu, 213022, China.
| | - Zheng Wang
- College of Mechanical & Electrical Engineering, Hohai University, Changzhou, Jiangsu, 213022, China
| | - Fang Teng
- Department of Gynaecology and Obstetrics, Nanjing Maternity and Child Health Care Hospital Affiliated to Nanjing Medical University, Nanjing, Jiangsu, 210004, China.
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20
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Jaeger J, Monk N. Dynamical modules in metabolism, cell and developmental biology. Interface Focus 2021; 11:20210011. [PMID: 34055307 PMCID: PMC8086940 DOI: 10.1098/rsfs.2021.0011] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/10/2021] [Indexed: 02/06/2023] Open
Abstract
Modularity is an essential feature of any adaptive complex system. Phenotypic traits are modules in the sense that they have a distinguishable structure or function, which can vary (quasi-)independently from its context. Since all phenotypic traits are the product of some underlying regulatory dynamics, the generative processes that constitute the genotype-phenotype map must also be functionally modular. Traditionally, modular processes have been identified as structural modules in regulatory networks. However, structure only constrains, but does not determine, the dynamics of a process. Here, we propose an alternative approach that decomposes the behaviour of a complex regulatory system into elementary activity-functions. Modular activities can occur in networks that show no structural modularity, making dynamical modularity more widely applicable than structural decomposition. Furthermore, the behaviour of a regulatory system closely mirrors its functional contribution to the outcome of a process, which makes dynamical modularity particularly suited for functional decomposition. We illustrate our approach with numerous examples from the study of metabolism, cellular processes, as well as development and pattern formation. We argue that dynamical modules provide a shared conceptual foundation for developmental and evolutionary biology, and serve as the foundation for a new account of process homology, which is presented in a separate contribution by DiFrisco and Jaeger to this focus issue.
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Affiliation(s)
- Johannes Jaeger
- Complexity Science Hub (CSH) Vienna, Josefstädter Strasse 39, 1080 Vienna, Austria
| | - Nick Monk
- School of Mathematics and Statistics, University of Sheffield, Hicks Building, Sheffield S3 7RH, UK
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21
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Morales JS, Raspopovic J, Marcon L. From embryos to embryoids: How external signals and self-organization drive embryonic development. Stem Cell Reports 2021; 16:1039-1050. [PMID: 33979592 PMCID: PMC8185431 DOI: 10.1016/j.stemcr.2021.03.026] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Revised: 03/19/2021] [Accepted: 03/22/2021] [Indexed: 12/15/2022] Open
Abstract
Embryonic development has been traditionally seen as an inductive process directed by exogenous maternal inputs and extra-embryonic signals. Increasing evidence, however, is showing that, in addition to exogenous signals, the development of the embryo involves endogenous self-organization. Recently, this self-organizing potential has been highlighted by a number of stem cell models known as embryoids that can recapitulate different aspects of embryogenesis in vitro. Here, we review the self-organizing behaviors observed in different embryoid models and seek to reconcile this new evidence with classical knowledge of developmental biology. This analysis leads to reexamine embryonic development as a guided self-organizing process, where patterning and morphogenesis are controlled by a combination of exogenous signals and endogenous self-organization. Finally, we discuss the multidisciplinary approach required to investigate the genetic and cellular basis of self-organization.
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Affiliation(s)
- J Serrano Morales
- Andalusian Center for Developmental Biology (CABD), CSIC - UPO - JA, Seville, Spain
| | - Jelena Raspopovic
- Andalusian Center for Developmental Biology (CABD), CSIC - UPO - JA, Seville, Spain.
| | - Luciano Marcon
- Andalusian Center for Developmental Biology (CABD), CSIC - UPO - JA, Seville, Spain.
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22
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Abstract
Reaction-diffusion systems are an intensively studied form of partial differential equation, frequently used to produce spatially heterogeneous patterned states from homogeneous symmetry breaking via the Turing instability. Although there are many prototypical "Turing systems" available, determining their parameters, functional forms, and general appropriateness for a given application is often difficult. Here, we consider the reverse problem. Namely, suppose we know the parameter region associated with the reaction kinetics in which patterning is required-we present a constructive framework for identifying systems that will exhibit the Turing instability within this region, whilst in addition often allowing selection of desired patterning features, such as spots, or stripes. In particular, we show how to build a system of two populations governed by polynomial morphogen kinetics such that the: patterning parameter domain (in any spatial dimension), morphogen phases (in any spatial dimension), and even type of resulting pattern (in up to two spatial dimensions) can all be determined. Finally, by employing spatial and temporal heterogeneity, we demonstrate that mixed mode patterns (spots, stripes, and complex prepatterns) are also possible, allowing one to build arbitrarily complicated patterning landscapes. Such a framework can be employed pedagogically, or in a variety of contemporary applications in designing synthetic chemical and biological patterning systems. We also discuss the implications that this freedom of design has on using reaction-diffusion systems in biological modelling and suggest that stronger constraints are needed when linking theory and experiment, as many simple patterns can be easily generated given freedom to choose reaction kinetics.
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Affiliation(s)
- Thomas E Woolley
- Cardiff School of Mathematics, Cardiff University, Senghennydd Road, Cardiff, CF24 4AG, UK.
| | - Andrew L Krause
- Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, UK
| | - Eamonn A Gaffney
- Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, UK
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23
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Van Gorder RA, Klika V, Krause AL. Turing conditions for pattern forming systems on evolving manifolds. J Math Biol 2021; 82:4. [PMID: 33475826 DOI: 10.1007/s00285-021-01552-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 07/29/2020] [Accepted: 10/16/2020] [Indexed: 12/18/2022]
Abstract
The study of pattern-forming instabilities in reaction-diffusion systems on growing or otherwise time-dependent domains arises in a variety of settings, including applications in developmental biology, spatial ecology, and experimental chemistry. Analyzing such instabilities is complicated, as there is a strong dependence of any spatially homogeneous base states on time, and the resulting structure of the linearized perturbations used to determine the onset of instability is inherently non-autonomous. We obtain general conditions for the onset and structure of diffusion driven instabilities in reaction-diffusion systems on domains which evolve in time, in terms of the time-evolution of the Laplace-Beltrami spectrum for the domain and functions which specify the domain evolution. Our results give sufficient conditions for diffusive instabilities phrased in terms of differential inequalities which are both versatile and straightforward to implement, despite the generality of the studied problem. These conditions generalize a large number of results known in the literature, such as the algebraic inequalities commonly used as a sufficient criterion for the Turing instability on static domains, and approximate asymptotic results valid for specific types of growth, or specific domains. We demonstrate our general Turing conditions on a variety of domains with different evolution laws, and in particular show how insight can be gained even when the domain changes rapidly in time, or when the homogeneous state is oscillatory, such as in the case of Turing-Hopf instabilities. Extensions to higher-order spatial systems are also included as a way of demonstrating the generality of the approach.
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Affiliation(s)
- Robert A Van Gorder
- Department of Mathematics and Statistics, University of Otago, P.O. Box 56, Dunedin, 9054, New Zealand.
| | - Václav Klika
- Department of Mathematics FNSPE, Czech Technical University in Prague, Trojanova 13, 12000, Prague, Czech Republic
| | - Andrew L Krause
- Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, UK
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24
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Slavkov I, Carrillo-Zapata D, Carranza N, Diego X, Jansson F, Kaandorp J, Hauert S, Sharpe J. Morphogenesis in robot swarms. Sci Robot 2021; 3:3/25/eaau9178. [PMID: 33141694 DOI: 10.1126/scirobotics.aau9178] [Citation(s) in RCA: 54] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 11/14/2018] [Indexed: 12/31/2022]
Abstract
Morphogenesis allows millions of cells to self-organize into intricate structures with a wide variety of functional shapes during embryonic development. This process emerges from local interactions of cells under the control of gene circuits that are identical in every cell, robust to intrinsic noise, and adaptable to changing environments. Constructing human technology with these properties presents an important opportunity in swarm robotic applications ranging from construction to exploration. Morphogenesis in nature may use two different approaches: hierarchical, top-down control or spontaneously self-organizing dynamics such as reaction-diffusion Turing patterns. Here, we provide a demonstration of purely self-organizing behaviors to create emergent morphologies in large swarms of real robots. The robots achieve this collective organization without any self-localization and instead rely entirely on local interactions with neighbors. Results show swarms of 300 robots that self-construct organic and adaptable shapes that are robust to damage. This is a step toward the emergence of functional shape formation in robot swarms following principles of self-organized morphogenetic engineering.
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Affiliation(s)
- I Slavkov
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - D Carrillo-Zapata
- University of Bristol, Bristol, UK.,University of the West of England, Bristol, UK.,Bristol Robotics Laboratory, Bristol, UK
| | - N Carranza
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain
| | - X Diego
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain.,Universitat Pompeu Fabra (UPF), Barcelona, Spain.,EMBL Barcelona, Barcelona, Spain
| | - F Jansson
- Centrum Wiskunde & Informatica (CWI), Amsterdam, Netherlands.,University of Amsterdam, Amsterdam, Netherlands
| | - J Kaandorp
- University of Amsterdam, Amsterdam, Netherlands
| | - S Hauert
- University of Bristol, Bristol, UK.,Bristol Robotics Laboratory, Bristol, UK
| | - J Sharpe
- Centre for Genomic Regulation (CRG), Barcelona Institute of Science and Technology, Barcelona, Spain. .,Universitat Pompeu Fabra (UPF), Barcelona, Spain.,EMBL Barcelona, Barcelona, Spain.,Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
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25
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Symmetry Breaking as an Interdisciplinary Concept Unifying Cell and Developmental Biology. Cells 2021; 10:cells10010086. [PMID: 33430209 PMCID: PMC7825676 DOI: 10.3390/cells10010086] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 12/25/2020] [Indexed: 12/16/2022] Open
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26
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Ledesma-Durán A, Ortiz-Durán EA, Aragón JL, Santamaría-Holek I. Eckhaus selection: The mechanism of pattern persistence in a reaction-diffusion system. Phys Rev E 2020; 102:032214. [PMID: 33076036 DOI: 10.1103/physreve.102.032214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Accepted: 09/01/2020] [Indexed: 11/07/2022]
Abstract
In this work, we show theoretically and numerically that a one-dimensional reaction-diffusion system, near the Turing bifurcation, produces different number of stripes when, in addition to random noise, the Fourier mode of a prepattern used to initialize the system changes. We also show that the Fourier modes that persist are inside the Eckhaus stability regions, while those outside this region follow a wave number selection process not predicted by the linear analysis. To test our results, we use the Brusselator reaction-diffusion system obtaining an excellent agreement between the weakly nonlinear predictions of the real Ginzburg-Landau equations and the numerical solutions near the bifurcation. Although the persistence of patterns is not relevant as a simple generating mechanism of self-organization, it is crucial to understand the formation of patterns that occurs in multiple stages. In this work, we discuss the relevance of our results on the robustness and diversity of solutions in multiple-steps mechanisms of biological pattern formation and auto-organization in growing domains.
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Affiliation(s)
- Aldo Ledesma-Durán
- Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla, 76230 Querétaro, Mexico
| | - E A Ortiz-Durán
- Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla, 76230 Querétaro, Mexico
| | - J L Aragón
- Centro de Física Aplicada y Tecnología Avanzada, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla, 76230 Querétaro, Mexico
| | - Iván Santamaría-Holek
- Unidad Multidiciplinaria de Docencia e Investigación, Facutad de Ciencias, Universidad Nacional Autónoma de México, Boulevard Juriquilla 3001, Juriquilla, 76230 Querétaro, Mexico
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27
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Goryachev AB, Leda M. Compete or Coexist? Why the Same Mechanisms of Symmetry Breaking Can Yield Distinct Outcomes. Cells 2020; 9:E2011. [PMID: 32882972 PMCID: PMC7563139 DOI: 10.3390/cells9092011] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2020] [Revised: 08/27/2020] [Accepted: 08/28/2020] [Indexed: 12/22/2022] Open
Abstract
Cellular morphogenesis is governed by the prepattern based on the symmetry-breaking emergence of dense protein clusters. Thus, a cluster of active GTPase Cdc42 marks the site of nascent bud in the baker's yeast. An important biological question is which mechanisms control the number of pattern maxima (spots) and, thus, the number of nascent cellular structures. Distinct flavors of theoretical models seem to suggest different predictions. While the classical Turing scenario leads to an array of stably coexisting multiple structures, mass-conserved models predict formation of a single spot that emerges via the greedy competition between the pattern maxima for the common molecular resources. Both the outcome and the kinetics of this competition are of significant biological importance but remained poorly explored. Recent theoretical analyses largely addressed these questions, but their results have not yet been fully appreciated by the broad biological community. Keeping mathematical apparatus and jargon to the minimum, we review the main conclusions of these analyses with their biological implications in mind. Focusing on the specific example of pattern formation by small GTPases, we speculate on the features of the patterning mechanisms that bypass competition and favor formation of multiple coexisting structures and contrast them with those of the mechanisms that harness competition to form unique cellular structures.
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Affiliation(s)
- Andrew B. Goryachev
- SynthSys, Centre for Synthetic and Systems Biology, Institute for Cell Biology, University of Edinburgh, Edinburg EH9 3BD, UK;
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28
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How MJ, Gonzales D, Irwin A, Caro T. Zebra stripes, tabanid biting flies and the aperture effect. Proc Biol Sci 2020; 287:20201521. [PMID: 32811316 PMCID: PMC7482270 DOI: 10.1098/rspb.2020.1521] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Abstract
Of all hypotheses advanced for why zebras have stripes, avoidance of biting fly attack receives by far the most support, yet the mechanisms by which stripes thwart landings are not yet understood. A logical and popular hypothesis is that stripes interfere with optic flow patterns needed by flying insects to execute controlled landings. This could occur through disrupting the radial symmetry of optic flow via the aperture effect (i.e. generation of false motion cues by straight edges), or through spatio-temporal aliasing (i.e. misregistration of repeated features) of evenly spaced stripes. By recording and reconstructing tabanid fly behaviour around horses wearing differently patterned rugs, we could tease out these hypotheses using realistic target stimuli. We found that flies avoided landing on, flew faster near, and did not approach as close to striped and checked rugs compared to grey. Our observations that flies avoided checked patterns in a similar way to stripes refutes the hypothesis that stripes disrupt optic flow via the aperture effect, which critically demands parallel striped patterns. Our data narrow the menu of fly-equid visual interactions that form the basis for the extraordinary colouration of zebras.
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Affiliation(s)
- Martin J How
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Dunia Gonzales
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Alison Irwin
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Tim Caro
- School of Biological Sciences, University of Bristol, 24 Tyndall Avenue, Bristol BS8 1TQ, UK.,Center for Population Biology, University of California, Davis, CA 95616, USA
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29
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Abstract
The Turing instability is one of the most commonly studied mechanisms leading to pattern formation in reaction–diffusion systems, yet there are still many open questions on the applicability of the Turing mechanism. Although experiments on pattern formation using chemical systems have shown that temperature differences play a role in pattern formation, there is far less theoretical work concerning the interplay between temperature and spatial instabilities. We consider a thermodynamically extended reaction–diffusion system, consisting of a pair of reaction–diffusion equations coupled to an energy equation for temperature, and use this to obtain a natural extension of the Turing instability accounting for temperature. We show that thermal contributions can restrict or enlarge the set of unstable modes possible under the instability, and in some cases may be used to completely shift the set of unstable modes, strongly modifying emergent Turing patterns. Spatial heterogeneity plays a role under several experimentally feasible configurations, and we give particular consideration to scenarios involving thermal gradients, thermodynamics of chemicals transported within a flow, and thermodiffusion. Control of Turing patterns is also an area of active interest, and we also demonstrate how patterns can be modified using time-dependent control of the boundary temperature.
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Affiliation(s)
- Robert A. Van Gorder
- Department of Mathematics and Statistics, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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30
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Giffin JL, Franz-Odendaal TA. Quantitative gene expression dynamics of key placode signalling factors in the embryonic chicken scleral ossicle system. Gene Expr Patterns 2020; 38:119131. [PMID: 32755633 DOI: 10.1016/j.gep.2020.119131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2020] [Revised: 06/25/2020] [Accepted: 07/29/2020] [Indexed: 10/23/2022]
Abstract
Development of the scleral ossicles, a ring of bony elements within the sclera, is directed by a series of papillae that arise from placodes in the conjunctival epithelium over a 1.5-day induction period in the chicken embryo. The regular spacing of the papillae around the corneal-scleral limbus suggests that their induction may be regulated by a reaction-diffusion mechanism, similar to other epithelial appendages. Some key placode signalling molecules, including β-catenin, are known to be expressed throughout the induction period. However, others have been studied only at certain stages or have not been successfully detected. Here we use qPCR to study the gene expression patterns of the wingless integration (WNT)/β-catenin, bone morphogenetic protein (BMP), ectodysplasin (EDA), fibroblast growth factor (FGF) and hedgehog (HH) signalling families in discrete regions of the eye throughout the complete conjunctival placode and papillae induction period. This comprehensive analysis revealed a variable level of gene expression within specific eye regions, with some genes exhibiting high, moderate or low changes. Most genes exhibited an initial increase in gene expression, followed by a decrease or plateau as development proceeded, suggesting that some genes are important for a brief initial period whilst the sustained elevated expression level of other genes is needed for developmental progression. The timing or magnitude of these changes, and/or the overall gene expression trend differed in the temporal, nasal and/or dorsal eye regions for some, but not all genes, demonstrating that gene expression may vary across different eye regions. Temporal and nasal EDA receptor (EDAR) had the greatest number of strong correlations (r > 0.700) with other genes and β-catenin had the greatest number of moderate correlations (r = 0.400-0.700), while EDA had the greatest range in correlation strengths. Among the strongly correlated genes, two distinct signalling modules were identified, connected by some intermediate genes. The dynamic gene expression patterns of the five signalling pathways studied here from conjunctival placode formation through to papillae development is consistent with other epithelial appendages and confirms the presence of a conserved induction and patterning signalling network. Two unique gene expression patterns and corresponding gene interaction modules suggest functionally distinct roles throughout placode development. Furthermore, spatial differences in gene expression patterns among the temporal, nasal and dorsal regions of the eye may indicate that the expression of certain genes is influenced by mechanical forces exerted throughout development. Therefore, this study identifies key placode signalling factors and their interactions, as well as some potential region-specific features of gene expression in the scleral ossicle system and provides a basis for further exploration of the spatial expression of these genes and the patterning mechanism(s) active throughout conjunctival placode and papillae formation.
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Affiliation(s)
- Jennifer L Giffin
- Department of Biology, Mount Saint Vincent University, 166 Bedford Highway, Halifax, NS, B3M 2J6, Canada.
| | - Tamara A Franz-Odendaal
- Department of Biology, Mount Saint Vincent University, 166 Bedford Highway, Halifax, NS, B3M 2J6, Canada.
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31
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Cornwall Scoones J, Banerjee DS, Banerjee S. Size-Regulated Symmetry Breaking in Reaction-Diffusion Models of Developmental Transitions. Cells 2020; 9:E1646. [PMID: 32659915 PMCID: PMC7407810 DOI: 10.3390/cells9071646] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 07/03/2020] [Accepted: 07/06/2020] [Indexed: 12/26/2022] Open
Abstract
The development of multicellular organisms proceeds through a series of morphogenetic and cell-state transitions, transforming homogeneous zygotes into complex adults by a process of self-organisation. Many of these transitions are achieved by spontaneous symmetry breaking mechanisms, allowing cells and tissues to acquire pattern and polarity by virtue of local interactions without an upstream supply of information. The combined work of theory and experiment has elucidated how these systems break symmetry during developmental transitions. Given that such transitions are multiple and their temporal ordering is crucial, an equally important question is how these developmental transitions are coordinated in time. Using a minimal mass-conserved substrate-depletion model for symmetry breaking as our case study, we elucidate mechanisms by which cells and tissues can couple reaction-diffusion-driven symmetry breaking to the timing of developmental transitions, arguing that the dependence of patterning mode on system size may be a generic principle by which developing organisms measure time. By analysing different regimes of our model, simulated on growing domains, we elaborate three distinct behaviours, allowing for clock-, timer- or switch-like dynamics. Relating these behaviours to experimentally documented case studies of developmental timing, we provide a minimal conceptual framework to interrogate how developing organisms coordinate developmental transitions.
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Affiliation(s)
- Jake Cornwall Scoones
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA;
| | - Deb Sankar Banerjee
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA;
| | - Shiladitya Banerjee
- Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA;
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32
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Shapira AZ, Uecker H, Yochelis A. Stripes on finite domains: Why the zigzag instability is only a partial story. CHAOS (WOODBURY, N.Y.) 2020; 30:073104. [PMID: 32752648 DOI: 10.1063/5.0006126] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/15/2020] [Indexed: 06/11/2023]
Abstract
Stationary periodic patterns are widespread in natural sciences, ranging from nano-scale electrochemical and amphiphilic systems to mesoscale fluid, chemical, and biological media and to macro-scale vegetation and cloud patterns. Their formation is usually due to a primary symmetry breaking of a uniform state to stripes, often followed by secondary instabilities to form zigzag and labyrinthine patterns. These secondary instabilities are well studied under idealized conditions of an infinite domain; however, on finite domains, the situation is more subtle since the unstable modes depend also on boundary conditions. Using two prototypical models, the Swift-Hohenberg equation and the forced complex Ginzburg-Landau equation, we consider finite size domains with no flux boundary conditions transversal to the stripes and reveal a distinct mixed-mode instability that lies in between the classical zigzag and the Eckhaus lines. This explains the stability of stripes in the mildly zigzag unstable regime and, after crossing the mixed-mode line, the evolution of zigzag stripes in the bulk of the domain and the formation of defects near the boundaries. The results are of particular importance for problems with large timescale separation, such as bulk-heterojunction deformations in organic photovoltaic and vegetation in semi-arid regions, where early temporal transients may play an important role.
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Affiliation(s)
- Alon Z Shapira
- Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion 8499000, Israel
| | - Hannes Uecker
- Institute for Mathematics, Carl von Ossietzky University of Oldenburg, PF 2503, 26111 Oldenburg, Germany
| | - Arik Yochelis
- Department of Solar Energy and Environmental Physics, Swiss Institute for Dryland Environmental and Energy Research, Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion 8499000, Israel
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33
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Van Gorder RA. Turing and Benjamin–Feir instability mechanisms in non-autonomous systems. Proc Math Phys Eng Sci 2020. [DOI: 10.1098/rspa.2020.0003] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The Turing and Benjamin–Feir instabilities are two of the primary instability mechanisms useful for studying the transition from homogeneous states to heterogeneous spatial or spatio-temporal states in reaction–diffusion systems. We consider the case when the underlying reaction–diffusion system is non-autonomous or has a base state which varies in time, as in this case standard approaches, which rely on temporal eigenvalues, break down. We are able to establish respective criteria for the onset of each instability using comparison principles, obtaining inequalities which involve the in general time-dependent model parameters and their time derivatives. In the autonomous limit where the base state is constant in time, our results exactly recover the respective Turing and Benjamin–Feir conditions known in the literature. Our results make the Turing and Benjamin–Feir analysis amenable for a wide collection of applications, and allow one to better understand instabilities emergent due to a variety of non-autonomous mechanisms, including time-varying diffusion coefficients, time-varying reaction rates, time-dependent transitions between reaction kinetics and base states which change in time (such as heteroclinic connections between unique steady states, or limit cycles), to name a few examples.
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Affiliation(s)
- Robert A. Van Gorder
- Department of Mathematics and Statistics, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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34
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On the problem of biological form. Theory Biosci 2020; 139:299-308. [PMID: 32418121 DOI: 10.1007/s12064-020-00317-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 05/05/2020] [Indexed: 10/24/2022]
Abstract
Embryonic development, which inspired the first theories of biological form, was eventually excluded from the conceptual framework of the Modern Synthesis as irrelevant. A major question during the last decades has centred on understanding whether new advances in developmental biology are compatible with the standard view or whether they compel a new theory. Here, I argue that the answer to this question depends on which concept of morphogenesis is held. Morphogenesis can be conceived as (1) a chemically driven or (2) a mechanically driven process. According to the first option, genetic regulatory networks drive morphogenesis. According to the second, morphogenesis results from an invariant tendency of embryonic tissues to restore changes in mechanical stress. While chemically driven morphogenesis allows an extension of the standard view, mechanically driven morphogenesis would deeply transform it. Which of these hypotheses has wider explanatory power is unknown. At present, the problem of biological form remains unsolved.
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35
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Landge AN, Jordan BM, Diego X, Müller P. Pattern formation mechanisms of self-organizing reaction-diffusion systems. Dev Biol 2020; 460:2-11. [PMID: 32008805 PMCID: PMC7154499 DOI: 10.1016/j.ydbio.2019.10.031] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2019] [Revised: 10/29/2019] [Accepted: 10/29/2019] [Indexed: 01/26/2023]
Abstract
Embryonic development is a largely self-organizing process, in which the adult body plan arises from a ball of cells with initially nearly equal potency. The reaction-diffusion theory first proposed by Alan Turing states that the initial symmetry in embryos can be broken by the interplay between two diffusible molecules, whose interactions lead to the formation of patterns. The reaction-diffusion theory provides a valuable framework for self-organized pattern formation, but it has been difficult to relate simple two-component models to real biological systems with multiple interacting molecular species. Recent studies have addressed this shortcoming and extended the reaction-diffusion theory to realistic multi-component networks. These efforts have challenged the generality of previous central tenets derived from the analysis of simplified systems and guide the way to a new understanding of self-organizing processes. Here, we discuss the challenges in modeling multi-component reaction-diffusion systems and how these have recently been addressed. We present a synthesis of new pattern formation mechanisms derived from these analyses, and we highlight the significance of reaction-diffusion principles for developmental and synthetic pattern formation.
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Affiliation(s)
- Amit N Landge
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, 72076, Tübingen, Germany
| | - Benjamin M Jordan
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, 02143, USA
| | - Xavier Diego
- European Molecular Biology Laboratory, Barcelona Outstation, 08003 Barcelona, Spain
| | - Patrick Müller
- Systems Biology of Development Group, Friedrich Miescher Laboratory of the Max Planck Society, 72076, Tübingen, Germany; Modeling Tumorigenesis Group, Translational Oncology Division, Eberhard Karls University Tübingen, 72076, Tübingen, Germany.
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36
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Ding B, Patterson EL, Holalu SV, Li J, Johnson GA, Stanley LE, Greenlee AB, Peng F, Bradshaw HD, Blinov ML, Blackman BK, Yuan YW. Two MYB Proteins in a Self-Organizing Activator-Inhibitor System Produce Spotted Pigmentation Patterns. Curr Biol 2020; 30:802-814.e8. [PMID: 32155414 PMCID: PMC7156294 DOI: 10.1016/j.cub.2019.12.067] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Revised: 11/24/2019] [Accepted: 12/20/2019] [Indexed: 11/19/2022]
Abstract
Many organisms exhibit visually striking spotted or striped pigmentation patterns. Developmental models predict that such spatial patterns can form when a local autocatalytic feedback loop and a long-range inhibitory feedback loop interact. At its simplest, this self-organizing network only requires one self-activating activator that also activates a repressor, which inhibits the activator and diffuses to neighboring cells. However, the molecular activators and inhibitors fully fitting this versatile model remain elusive in pigmentation systems. Here, we characterize an R2R3-MYB activator and an R3-MYB repressor in monkeyflowers (Mimulus). Through experimental perturbation and mathematical modeling, we demonstrate that the properties of these two proteins correspond to an activator-inhibitor pair in a two-component, reaction-diffusion system, explaining the formation of dispersed anthocyanin spots in monkeyflower petals. Notably, disrupting this pattern impacts pollinator visitation. Thus, subtle changes in simple activator-inhibitor systems are likely essential contributors to the evolution of the remarkable diversity of pigmentation patterns in flowers.
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Affiliation(s)
- Baoqing Ding
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 North Eagleville Road, Unit 3043, Storrs, CT 06269, USA
| | - Erin L Patterson
- Department of Plant and Microbial Biology, University of California, Berkeley, 111 Koshland Hall #3102, Berkeley, CA 94720, USA; Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, VA 22904, USA
| | - Srinidhi V Holalu
- Department of Plant and Microbial Biology, University of California, Berkeley, 111 Koshland Hall #3102, Berkeley, CA 94720, USA; Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, VA 22904, USA
| | - Jingjian Li
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 North Eagleville Road, Unit 3043, Storrs, CT 06269, USA; College of Forestry and Landscape Architecture, South China Agricultural University, Guangzhou 510642, China
| | - Grace A Johnson
- Department of Plant and Microbial Biology, University of California, Berkeley, 111 Koshland Hall #3102, Berkeley, CA 94720, USA
| | - Lauren E Stanley
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 North Eagleville Road, Unit 3043, Storrs, CT 06269, USA
| | - Anna B Greenlee
- Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, VA 22904, USA
| | - Foen Peng
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195, USA
| | - H D Bradshaw
- Department of Biology, University of Washington, Box 351800, Seattle, WA 98195, USA
| | - Michael L Blinov
- Center for Cell Analysis and Modeling, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030, USA
| | - Benjamin K Blackman
- Department of Plant and Microbial Biology, University of California, Berkeley, 111 Koshland Hall #3102, Berkeley, CA 94720, USA; Department of Biology, University of Virginia, P.O. Box 400328, Charlottesville, VA 22904, USA.
| | - Yao-Wu Yuan
- Department of Ecology and Evolutionary Biology, University of Connecticut, 75 North Eagleville Road, Unit 3043, Storrs, CT 06269, USA; Institute for Systems Genomics, University of Connecticut, 67 North Eagleville Road, Storrs, CT 06269, USA.
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37
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Mathematical modeling of chondrogenic pattern formation during limb development: Recent advances in continuous models. Math Biosci 2020; 322:108319. [PMID: 32001201 DOI: 10.1016/j.mbs.2020.108319] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 01/17/2020] [Accepted: 01/17/2020] [Indexed: 11/20/2022]
Abstract
The phenomenon of chondrogenic pattern formation in the vertebrate limb is one of the best studied examples of organogenesis. Many different models, mathematical as well as conceptual, have been proposed for it in the last fifty years or so. In this review, we give a brief overview of the fundamental biological background, then describe in detail several models which aim to describe qualitatively and quantitatively the corresponding biological phenomena. We concentrate on several new models that have been proposed in recent years, taking into account recent experimental progress. The major mathematical tools in these approaches are ordinary and partial differential equations. Moreover, we discuss models with non-local flux terms used to account for cell-cell adhesion forces and a structured population model with diffusion. We also include a detailed list of gene products and potential morphogens which have been identified to play a role in the process of limb formation and its growth.
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38
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Herath S, Lobo D. Cross-inhibition of Turing patterns explains the self-organized regulatory mechanism of planarian fission. J Theor Biol 2020; 485:110042. [DOI: 10.1016/j.jtbi.2019.110042] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2019] [Revised: 09/24/2019] [Accepted: 10/10/2019] [Indexed: 12/13/2022]
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Abstract
Two phrases attributed to Lewis Wolpert - 'positional information' and 'The French Flag Model' - have become so intertwined that they are now used almost interchangeably. Here, I argue that this represents an unfortunate oversimplification of Wolpert's ideas that arose gradually in the developmental biology community, some significant time after his key papers were published. In contrast to common belief, Wolpert did not use the phrase French Flag 'Model' but instead introduced the French Flag 'Problem'. This famous metaphor was not a proposal of how patterning works, but rather an abstraction of the question to be addressed. More specifically, the French flag metaphor was an attempt to de-couple the problem from the multiple possible models that could solve it. In this spirit, Wolpert's first article on this topic also proposed (in addition to the well-known gradient model) an alternative solution to the French Flag Problem that was self-organising and had no gradients, and in which each cell 'cannot compute where it is in the system', i.e. there is no positional information. I discuss the history and evolution of these terms, and how they influence the way we study patterning.
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Affiliation(s)
- James Sharpe
- EMBL Barcelona, Carrer Dr. Aiguader 88, Barcelona 08003, Spain
- ICREA Research Professor, Catalan Institute for Research and Advanced Studies, Passeig Lluís Companys 23, 08010 Barcelona, Spain
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40
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Carrillo-Zapata D, Sharpe J, Winfield AFT, Giuggioli L, Hauert S. Toward Controllable Morphogenesis in Large Robot Swarms. IEEE Robot Autom Lett 2019. [DOI: 10.1109/lra.2019.2926961] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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41
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Gross P, Kumar KV, Goehring NW, Bois JS, Hoege C, Jülicher F, Grill SW. Guiding self-organized pattern formation in cell polarity establishment. NATURE PHYSICS 2019; 15:293-300. [PMID: 31327978 PMCID: PMC6640039 DOI: 10.1038/s41567-018-0358-7] [Citation(s) in RCA: 62] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 10/23/2018] [Indexed: 05/25/2023]
Abstract
Spontaneous pattern formation in Turing systems relies on feedback. Patterns in cells and tissues however often do not form spontaneously, but are under control of upstream pathways that provide molecular guiding cues. The relationship between guiding cues and feedback in controlled biological pattern formation remains unclear. We explored this relationship during cell polarity establishment in the one-cell-stage C. elegans embryo. We quantified the strength of two feedback systems that operate during polarity establishment, feedback between polarity proteins and the actomyosin cortex, and mutual antagonism amongst polarity proteins. We characterized how these feedback systems are modulated by guiding cues from the centrosome. By coupling a mass-conserved Turing-like reaction-diffusion system for polarity proteins to an active gel description of the actomyosin cortex, we reveal a transition point beyond which feedback ensures self-organized polarization even when cues are removed. Notably, the baton is passed from a guide-dominated to a feedback-dominated regime significantly beyond this transition point, which ensures robustness. Together, this reveals a general criterion for controlling biological pattern forming systems: feedback remains subcritical to avoid unstable behaviour, and molecular guiding cues drive the system beyond a transition point for pattern formation.
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Affiliation(s)
- Peter Gross
- BIOTEC, TU Dresden, Tatzberg 47/49, 01307, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics,
Pfotenhauerstrasse 108, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems,
Nöthnitzer Strasse 38, 01187 Dresden, Germany
| | - K. Vijay Kumar
- Max Planck Institute for the Physics of Complex Systems,
Nöthnitzer Strasse 38, 01187 Dresden, Germany
- International Centre for Theoretical Sciences, Tata Institute of
Fundamental Research, Bengaluru 560089, India
| | - Nathan W. Goehring
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT,
UK
- Medical Research Council Laboratory for Molecular Cell Biology,
Gower Street, University College London, London WC1E 6BT, UK
| | - Justin S. Bois
- California Institute of Technology, 1200 E California Blvd,
Pasadena, CA 91125, USA
| | - Carsten Hoege
- Max Planck Institute of Molecular Cell Biology and Genetics,
Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Frank Jülicher
- Max Planck Institute for the Physics of Complex Systems,
Nöthnitzer Strasse 38, 01187 Dresden, Germany
| | - Stephan W. Grill
- BIOTEC, TU Dresden, Tatzberg 47/49, 01307, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics,
Pfotenhauerstrasse 108, 01307 Dresden, Germany
- Max Planck Institute for the Physics of Complex Systems,
Nöthnitzer Strasse 38, 01187 Dresden, Germany
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42
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Yuan YW. Monkeyflowers (Mimulus): new model for plant developmental genetics and evo-devo. THE NEW PHYTOLOGIST 2019; 222:694-700. [PMID: 30471231 DOI: 10.1111/nph.15560] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/18/2018] [Indexed: 06/09/2023]
Abstract
Contents Summary 694 I. Introduction 694 II. The system 695 III. Regulation of carotenoid pigmentation 695 IV. Formation of periodic pigmentation patterns 696 V. Developmental genetics of corolla tube formation and elaboration 697 VI. Molecular basis of floral trait variation underlying pollinator shift 698 VII. Outlook 699 Acknowledgements 699 References 699 SUMMARY: Monkeyflowers (Mimulus) have long been recognized as a classic ecological and evolutionary model system. However, only recently has it been realized that this system also holds great promise for studying the developmental genetics and evo-devo of important plant traits that are not found in well-established model systems such as Arabidopsis. Here, I review recent progress in four different areas of plant research enabled by this new model, including transcriptional regulation of carotenoid biosynthesis, formation of periodic pigmentation patterns, developmental genetics of corolla tube formation and elaboration, and the molecular basis of floral trait divergence underlying pollinator shift. These examples suggest that Mimulus offers ample opportunities to make exciting discoveries in plant development and evolution.
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Affiliation(s)
- Yao-Wu Yuan
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA
- Institute for Systems Genomics, University of Connecticut, Storrs, CT, 06269, USA
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43
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Sadier A, Twarogowska M, Steklikova K, Hayden L, Lambert A, Schneider P, Laudet V, Hovorakova M, Calvez V, Pantalacci S. Modeling Edar expression reveals the hidden dynamics of tooth signaling center patterning. PLoS Biol 2019; 17:e3000064. [PMID: 30730874 PMCID: PMC6382175 DOI: 10.1371/journal.pbio.3000064] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Revised: 02/20/2019] [Accepted: 01/24/2019] [Indexed: 12/31/2022] Open
Abstract
When patterns are set during embryogenesis, it is expected that they are straightly established rather than subsequently modified. The patterning of the three mouse molars is, however, far from straight, likely as a result of mouse evolutionary history. The first-formed tooth signaling centers, called MS and R2, disappear before driving tooth formation and are thought to be vestiges of the premolars found in mouse ancestors. Moreover, the mature signaling center of the first molar (M1) is formed from the fusion of two signaling centers (R2 and early M1). Here, we report that broad activation of Edar expression precedes its spatial restriction to tooth signaling centers. This reveals a hidden two-step patterning process for tooth signaling centers, which was modeled with a single activator-inhibitor pair subject to reaction-diffusion (RD). The study of Edar expression also unveiled successive phases of signaling center formation, erasing, recovering, and fusion. Our model, in which R2 signaling center is not intrinsically defective but erased by the broad activation preceding M1 signaling center formation, predicted the surprising rescue of R2 in Edar mutant mice, where activation is reduced. The importance of this R2-M1 interaction was confirmed by ex vivo cultures showing that R2 is capable of forming a tooth. Finally, by introducing chemotaxis as a secondary process to RD, we recapitulated in silico different conditions in which R2 and M1 centers fuse or not. In conclusion, pattern formation in the mouse molar field relies on basic mechanisms whose dynamics produce embryonic patterns that are plastic objects rather than fixed end points.
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Affiliation(s)
- Alexa Sadier
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, Lyon, France
| | - Monika Twarogowska
- Unité de Mathématiques Pures et Appliquées, project team Inria NUMED, Université de Lyon, ENS de Lyon, CNRS UMR 5669, Lyon, France
| | - Klara Steklikova
- Institute of Experimental Medicine, The Czech Academy of Sciences, Prague, Czech Republic
- Department of Cell Biology, Faculty of Science, Charles University, Prague, Czech Republic
| | - Luke Hayden
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, Lyon, France
| | - Anne Lambert
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, Lyon, France
| | - Pascal Schneider
- Department of Biochemistry, University of Lausanne, CH-1066 Epalinges, Switzerland
| | - Vincent Laudet
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, Lyon, France
| | - Maria Hovorakova
- Institute of Experimental Medicine, The Czech Academy of Sciences, Prague, Czech Republic
| | - Vincent Calvez
- Institut Camille Jordan, Université de Lyon, Université Claude Bernard, CNRS UMR 5208, Lyon, France
| | - Sophie Pantalacci
- Laboratoire de Biologie et Modélisation de la Cellule, Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, INSERM U1210, Lyon, France
- Institut de Génomique Fonctionnelle de Lyon, Université de Lyon, ENS de Lyon, Univ Claude Bernard, CNRS UMR 5239, Lyon, France
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44
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Horváth J, Szalai I, De Kepper P. Designing Stationary Reaction-Diffusion Patterns in pH Self-Activated Systems. Acc Chem Res 2018; 51:3183-3190. [PMID: 30412377 DOI: 10.1021/acs.accounts.8b00441] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Since Alan Turing's 1952 pioneering work, reaction-diffusion (RD) processes are regarded as prototype mechanisms for pattern formation in living systems. Though suspected in many aspects of morphogenetic development, pure RD patterns have not yet been demonstrated in living organisms. The first observations of an autonomous development of stationary chemical patterns were made in the early 1990s. In this Account, we discuss the recent developments for producing stationary pH RD patterns in open spatial reactors. The theoretical analysis of the early experiments anticipated the possibility of finding Turing patterns in a wide range of oscillatory reactions if one could control the kinetic and diffusional rate of some key species. However, no experimentally effective method to produce stationary Turing patterns was attained before 2009, and the number of systems stagnated at two until then. The two precursor reaction systems benefited from unplanned favorable chemical properties of the RD media. Theoretical studies point out that appropriate diffusion rate differences are necessary to produce stationary patterns since a competition between an effective short distance self-activation and a long distance inhibitory process is required. This differential diffusion would naturally lead to differential exchange rates between the RD system and its feed environment, an aspect somewhat overlooked in theoretical and in primal experimental approaches. Our pattern design method takes this aspect into account. A slower diffusion of a self-activated species (here, protons), produced in the RD part of the spatial reactor, generates the accumulation of this species compared to the other species. This accumulation has to be at least partly compensated by an independent scavenging reaction. The above requirement naturally brought us to focus on two-substrate pH oscillatory reactions. Stationary RD patterns are now well documented in six pH driven reaction systems. Furthermore, the coupling with a pH dependent metal ion complexing agent led to stationary patterns in calcium ion concentration. Our effective semiempirical design method does not require a detailed knowledge of the reaction kinetics; thus it is applicable to a broad spectrum of reactions and even to synthetic biological systems. It is based on simple dynamic arguments and on general topological characteristics of a nonequilibrium phase diagram. We first illustrate our method with numerical simulations, based on a realistic but idealized general model of the two-substrate pH-oscillator reaction family, and provide a refined view of the topology of the resulting phase diagrams. Then, we exemplify its effectiveness by observations made in distinct pH self-activated systems. Analogies and differences between experiments and the model calculations are pointed out. Besides standard hexagonal arrays of spots and parallel stripes, hitherto undocumented dynamic phenomena, such as randomly blinking areas and complex dynamic and stationary filamentous structures, were observed. The main challenge, to find low-mobility complexing agents that would selectively and reversibly bind a species controlling the self-activatory kinetic path of the reaction, was readily overcome in multiple ways by anions of weak acids: not only by polymeric substances but in some cases by a pH color indicator or even smaller molecules, depending on their proton binding affinity.
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Affiliation(s)
- Judit Horváth
- Institute of Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518 Budapest 112, Hungary
| | - István Szalai
- Institute of Chemistry, Eötvös Loránd University, P.O. Box 32, H-1518 Budapest 112, Hungary
| | - Patrick De Kepper
- Centre de Recherche Paul Pascal, CNRS, University of Bordeaux, 115, avenue Schweitzer, F-33600 Pessac, France
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Erkurt M. Emergence of form in embryogenesis. J R Soc Interface 2018; 15:20180454. [PMID: 30429261 PMCID: PMC6283983 DOI: 10.1098/rsif.2018.0454] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 10/12/2018] [Indexed: 11/23/2022] Open
Abstract
The development of form in an embryo is the result of a series of topological and informational symmetry breakings. We introduce the vector-reaction-diffusion-drift (VRDD) system where the limit cycle of spatial dynamics is morphogen concentrations with Dirac delta-type distributions. This is fundamentally different from the Turing reaction-diffusion system, as VRDD generates system-wide broken symmetry. We developed 'fundamental forms' from spherical blastula with a single organizing axis (rotational symmetry), double axis (mirror symmetry) and triple axis (no symmetry operator in three dimensions). We then introduced dynamics for cell differentiation, where genetic regulatory states are modelled as a finite-state machine (FSM). The state switching of an FSM is based on local morphogen concentrations as epigenetic information that changes dynamically. We grow complicated forms hierarchically in spatial subdomains using the FSM model coupled with the VRDD system. Using our integrated simulation model with four layers (topological, physical, chemical and regulatory), we generated life-like forms such as hydra. Genotype-phenotype mapping was investigated with continuous and jump mutations. Our study can have applications in morphogenetic engineering, soft robotics and biomimetic design.
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Affiliation(s)
- Murat Erkurt
- Department of Mathematics, Centre for Complexity Science, Imperial College London, London SW7 2AZ, UK
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Elhai J, Khudyakov I. Ancient association of cyanobacterial multicellularity with the regulator HetR and an RGSGR pentapeptide-containing protein (PatX). Mol Microbiol 2018; 110:931-954. [PMID: 29885033 DOI: 10.1111/mmi.14003] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/04/2018] [Indexed: 12/14/2022]
Abstract
One simple model to explain biological pattern postulates the existence of a stationary regulator of differentiation that positively affects its own expression, coupled with a diffusible suppressor of differentiation that inhibits the regulator's expression. The first has been identified in the filamentous, heterocyst-forming cyanobacterium, Anabaena PCC 7120 as the transcriptional regulator, HetR and the second as the small protein, PatS, which contains a critical RGSGR motif that binds to HetR. HetR is present in almost all filamentous cyanobacteria, but only a subset of heterocyst-forming strains carry proteins similar to PatS. We identified a third protein, PatX that also carries the RGSGR motif and is coextensive with HetR. Amino acid sequences of PatX contain two conserved regions: the RGSGR motif and a hydrophobic N-terminus. Within 69 nt upstream from all instances of the gene is a DIF1 motif correlated in Anabaena with promoter induction in developing heterocysts, preceded in heterocyst-forming strains by an apparent NtcA-binding site, associated with regulation by nitrogen-status. Consistent with a role in the simple model, PatX is expressed dependent on HetR and acts to inhibit differentiation. The acquisition of the PatX/HetR pair preceded the appearance of both PatS and heterocysts, dating back to the beginnings of multicellularity.
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Affiliation(s)
- Jeff Elhai
- Center for the Study of Biological Complexity, Virginia Commonwealth University, Richmond, VA, 23284, USA
| | - Ivan Khudyakov
- All-Russia Research Institute for Agricultural Microbiology, Saint-Petersburg, 196608, Russia
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Sánchez-Garduño F, Krause AL, Castillo JA, Padilla P. Turing-Hopf patterns on growing domains: The torus and the sphere. J Theor Biol 2018; 481:136-150. [PMID: 30266461 DOI: 10.1016/j.jtbi.2018.09.028] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Revised: 09/18/2018] [Accepted: 09/24/2018] [Indexed: 10/28/2022]
Abstract
This paper deals with the study of spatial and spatio-temporal patterns in the reaction-diffusion FitzHugh-Nagumo model on growing curved domains. This is carried out on two exemplar cases: a torus and a sphere. We compute bifurcation boundaries for the homogeneous steady state when the homogeneous system is monostable. We exhibit Turing and Turing-Hopf bifurcations, as well as additional patterning outside of these bifurcation regimes due to the multistability of patterned states. We consider static and growing domains, where the growth is slow, isotropic, and exponential in time, allowing for a simple analytical calculation of these bifurcations in terms of model parameters. Numerical simulations allow us to discuss the role played by the growth and the curvature of the domains on the pattern selection on the torus and the sphere. We demonstrate parameter regimes where the linear theory can successfully predict the kind of pattern (homogeneous and heterogeneous oscillations and stationary spatial patterns) but not their detailed nonlinear structure. We also find parameter regimes where the linear theory fails, such as Hopf regimes which give rise to spatial patterning (depending on geometric details), where we suspect that multistability plays a key role in the departure from homogeneity. Finally we also demonstrate effects due to the evolution of nonuniform patterns under growth, suggesting important roles for growth in reaction-diffusion systems beyond modifying instability regimes.
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Affiliation(s)
- Faustino Sánchez-Garduño
- Departamento de Matemáticas, Facultad de Ciencias, Universidad Nacional Autónoma de México (UNAM), Ciudad Universitaria. Circuito Exterior, Ciudad de México, Delegación Coyoacán CP 04510, México.
| | - Andrew L Krause
- Wolfson Centre for Mathematical Biology, Mathematical Institute, University of Oxford, Andrew Wiles Building, Radcliffe Observatory Quarter, Woodstock Rd, Oxford OX2 6GG, United Kingdom.
| | - Jorge A Castillo
- Facultad de Matemáticas, Universidad Autónoma de Guerrero, Carlos E. Adame # 54, Col. Garita, Acapulco, Guerrero CP 39650, México.
| | - Pablo Padilla
- IIMAS-UNAM, Apartado Postal 20-726, Admon. No. 20, Delegación Álvaro Obregón, Ciudad de México CP 01000, México.
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Videau P, Rivers OS, Tom SK, Oshiro RT, Ushijima B, Swenson VA, Philmus B, Gaylor MO, Cozy LM. The hetZ gene indirectly regulates heterocyst development at the level of pattern formation in Anabaena sp. strain PCC 7120. Mol Microbiol 2018; 109:91-104. [PMID: 29676808 DOI: 10.1111/mmi.13974] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/18/2018] [Indexed: 01/08/2023]
Abstract
Multicellular development requires the careful orchestration of gene expression to correctly create and position specialized cells. In the filamentous cyanobacterium Anabaena sp. strain PCC 7120, nitrogen-fixing heterocysts are differentiated from vegetative cells in a reproducibly periodic and physiologically relevant pattern. While many genetic factors required for heterocyst development have been identified, the role of HetZ has remained unclear. Here, we present evidence to clarify the requirement of hetZ for heterocyst production and support a model where HetZ functions in the patterning stage of differentiation. We show that a clean, nonpolar deletion of hetZ fails to express the developmental genes hetR, patS, hetP and hetZ correctly and fails to produce heterocysts. Complementation and overexpression of hetZ in a hetP mutant revealed that hetZ was incapable of bypassing hetP, suggesting that it acts upstream of hetP. Complementation and overexpression of hetZ in a hetR mutant, however, demonstrated bypass of hetR, suggesting that it acts downstream of hetR and is capable of bypassing the need for hetR for differentiation irrespective of nitrogen status. Finally, protein-protein interactions were observed between HetZ and HetR, Alr2902 and HetZ itself. Collectively, this work suggests a regulatory role for HetZ in the patterning phase of cellular differentiation in Anabaena.
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Affiliation(s)
- Patrick Videau
- Department of Biology, College of Arts and Sciences, Dakota State University, Madison, SD, USA
| | - Orion S Rivers
- Department of Microbiology, University of Hawaii, Honolulu, HI, USA
| | - Sasa K Tom
- Department of Microbiology, University of Hawaii, Honolulu, HI, USA
| | - Reid T Oshiro
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Blake Ushijima
- Department of Microbiology, University of Hawaii, Honolulu, HI, USA
| | - Vaille A Swenson
- Department of Biology, College of Arts and Sciences, Dakota State University, Madison, SD, USA
- Department of Chemistry, College of Arts and Sciences, Dakota State University, Madison, SD, USA
| | - Benjamin Philmus
- Department of Pharmaceutical Sciences, Oregon State University, Corvallis, OR, USA
| | - Michael O Gaylor
- Department of Chemistry, College of Arts and Sciences, Dakota State University, Madison, SD, USA
| | - Loralyn M Cozy
- Department of Biology, Illinois Wesleyan University, Bloomington, IL, USA
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Affiliation(s)
- Patrick L. Ferree
- Department of Cell Biology; Duke University Medical Center; Durham NC USA
| | - Stefano Di Talia
- Department of Cell Biology; Duke University Medical Center; Durham NC USA
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Zhu X, Yang H. Turing Instability-Driven Biofabrication of Branching Tissue Structures: A Dynamic Simulation and Analysis Based on the Reaction⁻Diffusion Mechanism †. MICROMACHINES 2018; 9:E109. [PMID: 30424043 PMCID: PMC6187743 DOI: 10.3390/mi9030109] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/01/2018] [Revised: 02/20/2018] [Accepted: 03/01/2018] [Indexed: 12/17/2022]
Abstract
Four-dimensional (4D) biofabrication techniques aim to dynamically produce and control three-dimensional (3D) biological structures that would transform their shapes or functionalities with time, when a stimulus is imposed or cell post-printing self-assembly occurs. The evolution of 3D branching patterns via self-assembly of cells is critical for the 4D biofabrication of artificial organs or tissues with branched geometry. However, it is still unclear how the formation and evolution of these branching patterns are biologically encoded. Here, we study the biofabrication of lung branching structures utilizing a simulation model based on Turing instability that raises a dynamic reaction⁻diffusion (RD) process of the biomolecules and cells. The simulation model incorporates partial differential equations of four variables, describing the tempo-spatial distribution of the variables in 3D over time. The simulation results present the formation and evolution process of 3D branching patterns over time and also interpret both the behaviors of side-branching and tip-splitting as the stalk grows and the fabrication style under an external concentration gradient of morphogen, through 3D visualization. This provides a theoretical framework for rationally guiding the 4D biofabrication of lung airway grafts via cellular self-organization, which would potentially reduce the complexity of future experimental research and number of trials.
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Affiliation(s)
- Xiaolu Zhu
- College of Mechanical & Electrical Engineering, Hohai University, Changzhou 213022, Jiangsu, China.
- Changzhou Key Laboratory of Digital Manufacture Technology, Hohai University, Changzhou 213022, Jiangsu, China.
| | - Hao Yang
- College of Mechanical & Electrical Engineering, Hohai University, Changzhou 213022, Jiangsu, China.
- Jiangsu Key Laboratory of Special Robot Technology, Hohai University, Changzhou 213022, Jiangsu, China.
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