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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 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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Yuste R. Breaking the neural code of a cnidarian: Learning principles of neuroscience from the "vulgar" Hydra. Curr Opin Neurobiol 2024; 86:102869. [PMID: 38552547 DOI: 10.1016/j.conb.2024.102869] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2023] [Revised: 02/04/2024] [Accepted: 03/07/2024] [Indexed: 06/11/2024]
Abstract
The cnidarian Hydra vulgaris is a small polyp with a nervous system of few hundred neurons belonging to a dozen cell types, organized in two nerve nets without cephalization or ganglia. Using this simple neural "chassis", Hydra can maintain a stable repertoire of behaviors, even performing complex fixed-action patterns, such as somersaulting and feeding. The ability to image the activity of Hydra's entire neural and muscle tissue has revealed that Hydra's nerve nets are divided into coactive ensembles of neurons, associated with specific movements. These ensembles can be activated by neuropeptides and interact using cross-inhibition circuits and implement integrate-to-threshold algorithms. In addition, Hydra's nervous system can self-assemble from dissociated cells in a stepwise modular architecture. Studies of Hydra and other cnidarians could enable the systematic deciphering of the neural basis of its behavior and help provide perspective on basic principles of neuroscience.
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Affiliation(s)
- Rafael Yuste
- Neurotechnology Center, Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
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3
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Wang R, Bialas AL, Goel T, Collins EMS. Mechano-Chemical Coupling in Hydra Regeneration and Patterning. Integr Comp Biol 2023; 63:1422-1441. [PMID: 37339912 DOI: 10.1093/icb/icad070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 06/07/2023] [Accepted: 06/12/2023] [Indexed: 06/22/2023] Open
Abstract
The freshwater cnidarian Hydra can regenerate from wounds, small tissue fragments and even from aggregated cells. This process requires the de novo development of a body axis and oral-aboral polarity, a fundamental developmental process that involves chemical patterning and mechanical shape changes. Gierer and Meinhardt recognized that Hydra's simple body plan and amenability to in vivo experiments make it an experimentally and mathematically tractable model to study developmental patterning and symmetry breaking. They developed a reaction-diffusion model, involving a short-range activator and a long-range inhibitor, which successfully explained patterning in the adult animal. In 2011, HyWnt3 was identified as a candidate for the activator. However, despite the continued efforts of both physicists and biologists, the predicted inhibitor remains elusive. Furthermore, the Gierer-Meinhardt model cannot explain de novo axis formation in cellular aggregates that lack inherited tissue polarity. The aim of this review is to synthesize the current knowledge on Hydra symmetry breaking and patterning. We summarize the history of patterning studies and insights from recent biomechanical and molecular studies, and highlight the need for continued validation of theoretical assumptions and collaboration across disciplinary boundaries. We conclude by proposing new experiments to test current mechano-chemical coupling models and suggest ideas for expanding the Gierer-Meinhardt model to explain de novo patterning, as observed in Hydra aggregates. The availability of a fully sequenced genome, transgenic fluorescent reporter strains, and modern imaging techniques, that enable unprecedented observation of cellular events in vivo, promise to allow the community to crack Hydra's secret to patterning.
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Affiliation(s)
- Rui Wang
- Department of Bioengineering, University of California San Diego, 9500 Gilman Drive, La Jolla, 92093 CA, USA
| | - April L Bialas
- Department of Biology, Swarthmore College, 500 College Ave, Swarthmore, 19081 PA, USA
| | - Tapan Goel
- School of Biological Sciences, Georgia Institute of Technology, Atlanta, 30332 GA, USA
- Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, 92093 CA, USA
| | - Eva-Maria S Collins
- Department of Biology, Swarthmore College, 500 College Ave, Swarthmore, 19081 PA, USA
- Department of Physics, University of California San Diego, 9500 Gilman Drive, La Jolla, 92093 CA, USA
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, 19104 PA, USA
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4
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Abstract
The remarkable regenerative abilities of the small cnidarian Hydra vulgaris include the capacity to reassemble itself after dissociation into individual cells. Here, we present a robust protocol for the dissociation and reaggregation of Hydra tissue that addresses many common challenges encountered during the preparation and execution of the dissociation, as well as the formation and care of regenerating cellular aggregates. Analysis of the process provides insight into the mechanisms of nervous system self-organization. For complete details on the use and execution of this protocol, please refer to Lovas and Yuste (2021). Amplify experimental Hydra and prepare for the animal’s dissociation Dissociate Hydra into individual cells, aggregate, and monitor their reassembly Follow Hydra’s epithelial layer segregation and neural circuit formation A new polyp emerges from the cellular aggregate after one week of development
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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Sun SY, Feng XQ. Fluid-solid coupling dynamic model for oscillatory growth of multicellular lumens. J Biomech 2021; 131:110937. [PMID: 34972017 DOI: 10.1016/j.jbiomech.2021.110937] [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: 05/12/2021] [Revised: 12/18/2021] [Accepted: 12/20/2021] [Indexed: 11/15/2022]
Abstract
The development of multicellular lumens involves the interplay of cell proliferation, oscillation, and fluid transport. In this paper, a fluid-solid coupling dynamic model is proposed to investigate the physical mechanisms underlying the oscillatory growth of lumens. On the basis of experimental observations, the periodic oscillation of a lumen is interpreted by the fracturing-healing mechanism of cell-cell contacts, which induces a hydraulic-controlled outward flow switch. This model reproduces the oscillations of lumen sizes, in agreement with the experimental results of Hydra regeneration. It is found that the overall change trend of the lumen volume is determined by the tissue development induced by cell proliferation and the fluid transport induced by the osmotic pressure, while the outward flow due to the fracturing of cell-cell contacts regulates the oscillatory volume and the stress level in an appropriate scope. This work not only deepens our understanding of biomechanical mechanisms under the development of fluid-containing lumens, but also provides a theoretical framework to rationalize the dynamics of lumen-like tissues.
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Affiliation(s)
- Shu-Yi Sun
- Institute of Biomechanics and Medical Engineering, AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China
| | - Xi-Qiao Feng
- Institute of Biomechanics and Medical Engineering, AML, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China; State Key Lab of Tribology, Department of Engineering Mechanics, Tsinghua University, Beijing 100084, China.
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6
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Ferenc J, Papasaikas P, Ferralli J, Nakamura Y, Smallwood S, Tsiairis CD. Mechanical oscillations orchestrate axial patterning through Wnt activation in Hydra. SCIENCE ADVANCES 2021; 7:eabj6897. [PMID: 34890235 PMCID: PMC8664257 DOI: 10.1126/sciadv.abj6897] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2021] [Accepted: 10/21/2021] [Indexed: 05/25/2023]
Abstract
Mechanical input shapes cell fate decisions during development and regeneration in many systems, yet the mechanisms of this cross-talk are often unclear. In regenerating Hydra tissue spheroids, periodic osmotically driven inflation and deflation cycles generate mechanical stimuli in the form of tissue stretching. Here, we demonstrate that tissue stretching during inflation is important for the appearance of the head organizer—a group of cells that secrete the Wnt3 ligand. Exploiting time series RNA expression profiles, we identify the up-regulation of Wnt signaling as a key readout of the mechanical input. In this system, the levels of Wnt3 expression correspond to the levels of stretching, and Wnt3 overexpression alone enables successful regeneration in the absence of mechanical stimulation. Our findings enable the incorporation of mechanical signals in the framework of Hydra patterning and highlight the broad significance of mechanochemical feedback loops for patterning epithelial lumens.
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Affiliation(s)
- Jaroslav Ferenc
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- University of Basel, Petersplatz 1, 4001 Basel, Switzerland
| | - Panagiotis Papasaikas
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
- SIB Swiss Institute of Bioinformatics, 4058 Basel, Switzerland
| | - Jacqueline Ferralli
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Yukio Nakamura
- Institute of Medical Sciences, University of Aberdeen, AB25 2ZD Aberdeen, UK
| | - Sebastien Smallwood
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
| | - Charisios D. Tsiairis
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, 4058 Basel, Switzerland
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7
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Badhiwala KN, Primack AS, Juliano CE, Robinson JT. Multiple neuronal networks coordinate Hydra mechanosensory behavior. eLife 2021; 10:e64108. [PMID: 34328079 PMCID: PMC8324302 DOI: 10.7554/elife.64108] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2020] [Accepted: 06/17/2021] [Indexed: 12/11/2022] Open
Abstract
Hydra vulgaris is an emerging model organism for neuroscience due to its small size, transparency, genetic tractability, and regenerative nervous system; however, fundamental properties of its sensorimotor behaviors remain unknown. Here, we use microfluidic devices combined with fluorescent calcium imaging and surgical resectioning to study how the diffuse nervous system coordinates Hydra's mechanosensory response. Mechanical stimuli cause animals to contract, and we find this response relies on at least two distinct networks of neurons in the oral and aboral regions of the animal. Different activity patterns arise in these networks depending on whether the animal is contracting spontaneously or contracting in response to mechanical stimulation. Together, these findings improve our understanding of how Hydra's diffuse nervous system coordinates sensorimotor behaviors. These insights help reveal how sensory information is processed in an animal with a diffuse, radially symmetric neural architecture unlike the dense, bilaterally symmetric nervous systems found in most model organisms.
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Affiliation(s)
| | - Abby S Primack
- Department of Molecular and Cellular BiologyUniversity of California, DavisUnited States
| | - Celina E Juliano
- Department of Molecular and Cellular BiologyUniversity of California, DavisUnited States
| | - Jacob T Robinson
- Department of Bioengineering, Rice UniversityHoustonUnited States
- Department of Electrical and Computer Engineering, Rice UniversityHoustonUnited States
- Department of Neuroscience, Baylor College of MedicineHoustonUnited States
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8
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Whole-Body Imaging of Neural and Muscle Activity during Behavior in Hydra vulgaris: Effect of Osmolarity on Contraction Bursts. eNeuro 2020; 7:ENEURO.0539-19.2020. [PMID: 32699071 PMCID: PMC7452734 DOI: 10.1523/eneuro.0539-19.2020] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 04/28/2020] [Accepted: 05/11/2020] [Indexed: 11/21/2022] Open
Abstract
The neural code relates the activity of the nervous system to the activity of the muscles to the generation of behavior. To decipher it, it would be ideal to comprehensively measure the activity of the entire nervous system and musculature in a behaving animal. As a step in this direction, we used the cnidarian Hydra vulgaris to explore how physiological and environmental conditions alter simple contractile behavior and its accompanying neural and muscle activity. We used whole-body calcium imaging of neurons and muscle cells and studied the effect of temperature, media osmolarity, nutritional state, and body size on contractile behavior. In mounted Hydra preparations, changes in temperature, nutrition state, or body size did not have a major effect on neural or muscle activity, or on contractile behavior. But changes in media osmolarity systematically altered contractile behavior and foot detachments, increasing their frequency in hypo-osmolar media solutions and decreasing it in hyperosmolar media. Similar effects were seen in ectodermal, but not in endodermal muscle. Osmolarity also bidirectionally changed the activity of contraction burst (CB) neurons, but did not affect the network of rhythmic potential (RP) neurons in the ectoderm. These findings show osmolarity-dependent changes in the activity of CB neurons and ectodermal muscle, consistent with the hypothesis that CB neurons respond to media hypo-osmolarity, activating ectodermal muscle to generate CBs. This dedicated reflex could serve as an excretory system to prevent osmotic injury. This work demonstrates the feasibility of studying an entire neuronal and muscle activity in a behaving animal.
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Abstract
The freshwater polyp Hydra provides a potent model system for investigating the conditions that promote wound healing, reactivation of a developmental process and, ultimately, regeneration of an amputated body part. Hydra polyps can also be dissociated to the single cell level and can regenerate a complete body axis from aggregates, behaving as natural organoids. In recent years, the ability to exploit Hydra has been expanded with the advent of new live-imaging approaches, genetic manipulations that include stable transgenesis, gene silencing and genome editing, and the accumulation of high-throughput omics data. In this Primer, we provide an overview of Hydra as a model system for studying regeneration, highlighting recent results that question the classical self-enhancement and long-range inhibition model supposed to drive Hydra regeneration. We underscore the need for integrative explanations incorporating biochemical as well as mechanical signalling.
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Affiliation(s)
- Matthias C Vogg
- Department of Genetics and Evolution, Institute of Genetics and Genomics in Geneva (iGE3), Faculty of Sciences, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Brigitte Galliot
- Department of Genetics and Evolution, Institute of Genetics and Genomics in Geneva (iGE3), Faculty of Sciences, University of Geneva, 30 Quai Ernest Ansermet, CH-1211 Geneva 4, Switzerland
| | - Charisios D Tsiairis
- Friedrich Miescher Institute for Biomedical Research, Maulbeerstrasse 66, CH-4058 Basel, Switzerland
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10
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Arcaro MJ, Schade PF, Livingstone MS. Universal Mechanisms and the Development of the Face Network: What You See Is What You Get. Annu Rev Vis Sci 2019; 5:341-372. [PMID: 31226011 PMCID: PMC7568401 DOI: 10.1146/annurev-vision-091718-014917] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Our assignment was to review the development of the face-processing network, an assignment that carries the presupposition that a face-specific developmental program exists. We hope to cast some doubt on this assumption and instead argue that the development of face processing is guided by the same ubiquitous rules that guide the development of cortex in general.
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Affiliation(s)
- Michael J Arcaro
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA;
| | - Peter F Schade
- Department of Neurobiology, Harvard Medical School, Boston, Massachusetts 02115, USA;
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11
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The Sialic Acid-Dependent Nematocyst Discharge Process in Relation to Its Physical-Chemical Properties Is A Role Model for Nanomedical Diagnostic and Therapeutic Tools. Mar Drugs 2019; 17:md17080469. [PMID: 31409009 PMCID: PMC6722915 DOI: 10.3390/md17080469] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 08/01/2019] [Accepted: 08/06/2019] [Indexed: 12/13/2022] Open
Abstract
Formulas derived from theoretical physics provide important insights about the nematocyst discharge process of Cnidaria (Hydra, jellyfishes, box-jellyfishes and sea-anemones). Our model description of the fastest process in living nature raises and answers questions related to the material properties of the cell- and tubule-walls of nematocysts including their polysialic acid (polySia) dependent target function. Since a number of tumor-cells, especially brain-tumor cells such as neuroblastoma tissues carry the polysaccharide chain polySia in similar concentration as fish eggs or fish skin, it makes sense to use these findings for new diagnostic and therapeutic approaches in the field of nanomedicine. Therefore, the nematocyst discharge process can be considered as a bionic blue-print for future nanomedical devices in cancer diagnostics and therapies. This approach is promising because the physical background of this process can be described in a sufficient way with formulas presented here. Additionally, we discuss biophysical and biochemical experiments which will allow us to define proper boundary conditions in order to support our theoretical model approach. PolySia glycans occur in a similar density on malignant tumor cells than on the cell surfaces of Cnidarian predators and preys. The knowledge of the polySia-dependent initiation of the nematocyst discharge process in an intact nematocyte is an essential prerequisite regarding the further development of target-directed nanomedical devices for diagnostic and therapeutic purposes. The theoretical description as well as the computationally and experimentally derived results about the biophysical and biochemical parameters can contribute to a proper design of anti-tumor drug ejecting vessels which use a stylet-tubule system. Especially, the role of nematogalectins is of interest because these bridging proteins contribute as well as special collagen fibers to the elastic band properties. The basic concepts of the nematocyst discharge process inside the tubule cell walls of nematocysts were studied in jellyfishes and in Hydra which are ideal model organisms. Hydra has already been chosen by Alan Turing in order to figure out how the chemical basis of morphogenesis can be described in a fundamental way. This encouraged us to discuss the action of nematocysts in relation to morphological aspects and material requirements. Using these insights, it is now possible to discuss natural and artificial nematocyst-like vessels with optimized properties for a diagnostic and therapeutic use, e.g., in neurooncology. We show here that crucial physical parameters such as pressure thresholds and elasticity properties during the nematocyst discharge process can be described in a consistent and satisfactory way with an impact on the construction of new nanomedical devices.
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12
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Wang R, Goel T, Khazoyan K, Sabry Z, Quan HJ, Diamond PH, Collins EMS. Mouth Function Determines the Shape Oscillation Pattern in Regenerating Hydra Tissue Spheres. Biophys J 2019; 117:1145-1155. [PMID: 31443907 DOI: 10.1016/j.bpj.2019.07.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 06/25/2019] [Accepted: 07/30/2019] [Indexed: 12/12/2022] Open
Abstract
Hydra is a small freshwater polyp capable of regeneration from small tissue pieces and from aggregates of cells. During regeneration, a hollow bilayered sphere is formed that undergoes osmotically driven shape oscillations of inflation and rupture. These oscillations are necessary for successful regeneration. Eventually, the oscillating sphere breaks rotational symmetry along the future head-foot axis of the animal. Notably, the shape oscillations show an abrupt shift from large-amplitude, long-period oscillations to small-amplitude, short-period oscillations. It has been widely accepted that this shift in oscillation pattern is linked to symmetry breaking and axis formation, and current theoretical models of Hydra symmetry breaking use this assumption as a model constraint. However, a mechanistic explanation for the shift in oscillation pattern is lacking. Using in vivo manipulation and imaging, we quantified the shape oscillation dynamics and dissected the timing and triggers of the pattern shift. Our experiments demonstrate that the shift in the shape oscillation pattern in regenerating Hydra tissue pieces is caused by the formation of a functional mouth and not by shape symmetry breaking as previously assumed. Thus, model assumptions must be revised in light of these new experimental data, which can be used to constrain and validate improved theoretical models of pattern formation in Hydra.
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Affiliation(s)
- Rui Wang
- Department of Bioengineering, University of California San Diego, La Jolla, California; Biology Department, Swarthmore College, Swarthmore, Pennsylvania
| | - Tapan Goel
- Department of Physics, University of California San Diego, La Jolla, California; Biology Department, Swarthmore College, Swarthmore, Pennsylvania
| | - Kate Khazoyan
- Department of Bioengineering, University of California San Diego, La Jolla, California
| | - Ziad Sabry
- Biology Department, Swarthmore College, Swarthmore, Pennsylvania
| | - Heng J Quan
- Department of Physics, University of California San Diego, La Jolla, California; Department of Mathematics, University of California San Diego, La Jolla, California
| | - Patrick H Diamond
- Department of Physics, University of California San Diego, La Jolla, California
| | - Eva-Maria S Collins
- Department of Physics, University of California San Diego, La Jolla, California; Biology Department, Swarthmore College, Swarthmore, Pennsylvania.
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Brinkmann F, Mercker M, Richter T, Marciniak-Czochra A. Post-Turing tissue pattern formation: Advent of mechanochemistry. PLoS Comput Biol 2018; 14:e1006259. [PMID: 29969460 PMCID: PMC6047832 DOI: 10.1371/journal.pcbi.1006259] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 07/16/2018] [Accepted: 06/01/2018] [Indexed: 12/22/2022] Open
Abstract
Chemical and mechanical pattern formation is fundamental during embryogenesis and tissue development. Yet, the underlying molecular and cellular mechanisms are still elusive in many cases. Most current theories assume that tissue development is driven by chemical processes: either as a sequence of chemical patterns each depending on the previous one, or by patterns spontaneously arising from specific chemical interactions (such as “Turing-patterns”). Within both theories, mechanical patterns are usually regarded as passive by-products of chemical pre-patters. However, several experiments question these theories, and an increasing number of studies shows that tissue mechanics can actively influence chemical patterns during development. In this study, we thus focus on the interplay between chemical and mechanical processes during tissue development. On one hand, based on recent experimental data, we develop new mechanochemical simulation models of evolving tissues, in which the full 3D representation of the tissue appears to be critical for obtaining a realistic mechanochemical behaviour. The presented modelling approach is flexible and numerically studied using state of the art finite element methods. Thus, it may serve as a basis to combine simulations with new experimental methods in tissue development. On the other hand, we apply the developed approach and demonstrate that even simple interactions between tissue mechanics and chemistry spontaneously lead to robust and complex mechanochemical patterns. Especially, we demonstrate that the main contradictions arising in the framework of purely chemical theories are naturally and automatically resolved using the mechanochemical patterning theory. During embryogenesis, biological tissues gradually increase their complexity by self-organised creation of diverse chemical and mechanical patterns. Detailed mechanisms driving and controlling these patterns are not well understood. Previous theories mostly assume that these patterns are driven by chemical processes. Based on these theories, mechanical patterns are usually considered being mainly determined by chemical pre-patterns. However, experimental evidence for these theories is sparse, and several inconsistencies have been discovered. Furthermore, an increasing amount of data shows that tissue mechanics plays an important role in pattern formation. In this study, we present 3D computer simulations of evolving tissues to investigate the capacity of mechanochemical interactions for pattern formation. We show that even simple interactions between tissue mechanics and tissue chemistry spontaneously lead to robust chemical and mechanical pattern formation. We additionally demonstrate that main contradictions arising in the framework of purely chemical theories are naturally and automatically resolved using the mechanochemical patterning theory. The presented modelling approach can be used to combine simulations with recent experimental developments, to help unravel one of the big mysteries in biology: The mechanisms of self-organised pattern formation during embryogenesis.
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Affiliation(s)
- Felix Brinkmann
- Institute of Applied Mathematics, BioQuant and Interdisciplinary Center of Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
| | - Moritz Mercker
- Institute of Applied Mathematics, BioQuant and Interdisciplinary Center of Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
- * E-mail:
| | - Thomas Richter
- Magdeburg University, Institute for Analysis and Numerics, Magdeburg, Germany
| | - Anna Marciniak-Czochra
- Institute of Applied Mathematics, BioQuant and Interdisciplinary Center of Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
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14
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Braun E, Keren K. HydraRegeneration: Closing the Loop with Mechanical Processes in Morphogenesis. Bioessays 2018; 40:e1700204. [DOI: 10.1002/bies.201700204] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2017] [Revised: 04/29/2018] [Indexed: 12/17/2022]
Affiliation(s)
- Erez Braun
- Department of Physics & Network Biology Research LaboratoriesTechnion – Israel Institute of TechnologyHaifaIsrael
| | - Kinneret Keren
- Department of Physics & Network Biology Research LaboratoriesTechnion – Israel Institute of TechnologyHaifaIsrael
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15
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Chiou K, Collins EMS. Why we need mechanics to understand animal regeneration. Dev Biol 2017; 433:155-165. [PMID: 29179947 DOI: 10.1016/j.ydbio.2017.09.021] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2017] [Revised: 08/31/2017] [Accepted: 09/17/2017] [Indexed: 12/19/2022]
Abstract
Mechanical forces are an important contributor to cell fate specification and cell migration during embryonic development in animals. Similarities between embryogenesis and regeneration, particularly with regards to pattern formation and large-scale tissue movements, suggest similarly important roles for physical forces during regeneration. While the influence of the mechanical environment on stem cell differentiation in vitro is being actively exploited in the fields of tissue engineering and regenerative medicine, comparatively little is known about the role of stresses and strains acting during animal regeneration. In this review, we summarize published work on the role of physical principles and mechanical forces in animal regeneration. Novel experimental techniques aimed at addressing the role of mechanics in embryogenesis have greatly enhanced our understanding at scales from the subcellular to the macroscopic - we believe the time is ripe for the field of regeneration to similarly leverage the tools of the mechanobiological research community.
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Affiliation(s)
- Kevin Chiou
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Eva-Maria S Collins
- Physics Department, UC San Diego, La Jolla, CA 92093, USA; Section of Cell&Developmental Biology, UC San Diego, La Jolla, CA 92093, USA.
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16
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Naganathan SR, Oates AC. Mechanochemical coupling and developmental pattern formation. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/j.coisb.2017.09.007] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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17
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Livshits A, Shani-Zerbib L, Maroudas-Sacks Y, Braun E, Keren K. Structural Inheritance of the Actin Cytoskeletal Organization Determines the Body Axis in Regenerating Hydra. Cell Rep 2017; 18:1410-1421. [DOI: 10.1016/j.celrep.2017.01.036] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 12/11/2016] [Accepted: 01/13/2017] [Indexed: 01/04/2023] Open
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Mercker M, Brinkmann F, Marciniak-Czochra A, Richter T. Beyond Turing: mechanochemical pattern formation in biological tissues. Biol Direct 2016; 11:22. [PMID: 27145826 PMCID: PMC4857296 DOI: 10.1186/s13062-016-0124-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 04/20/2016] [Indexed: 01/03/2023] Open
Abstract
Background During embryogenesis, chemical (morphogen) and mechanical patterns develop within tissues in a self-organized way. More than 60 years ago, Turing proposed his famous reaction-diffusion model for such processes, assuming chemical interactions as the main driving force in tissue patterning. However, experimental identification of corresponding molecular candidates is still incomplete. Recent results suggest that beside morphogens, also tissue mechanics play a significant role in these patterning processes. Results Combining continuous finite strain with discrete cellular tissue models, we present and numerically investigate mechanochemical processes, in which morphogen dynamics and tissue mechanics are coupled by feedback loops. We consider three different mechanical cues involved in such feedbacks: strain, stress, and compression. Based on experimental results, for each case, we present a feedback loop spontaneously creating robust mechanochemical patterns. In contrast to Turing-type models, simple mechanochemical interaction terms are sufficient to create de novo patterns. Conclusions Our results emphasize mechanochemical processes as possible candidates controlling different steps of embryogenesis. To motivate further experimental research discovering related mechanisms in living tissues, we also present predictive in silicio experiments. Reviewers Reviewer 1 - Marek Kimmel; Reviewer 2 - Konstantin Doubrovinski (nominated by Ned Wingreen); Reviewer 3 - Jun Allard (nominated by William Hlavacek).
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Affiliation(s)
- Moritz Mercker
- Institute of Applied Mathematics, BioQuant and Interdisciplinary Center of Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany.
| | - Felix Brinkmann
- Institute of Applied Mathematics, BioQuant and Interdisciplinary Center of Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany.,Department Mathematik, FAU Erlangen-Nürnberg, Erlangen, Germany
| | - Anna Marciniak-Czochra
- Institute of Applied Mathematics, BioQuant and Interdisciplinary Center of Scientific Computing (IWR), Heidelberg University, Heidelberg, Germany
| | - Thomas Richter
- Department Mathematik, FAU Erlangen-Nürnberg, Erlangen, Germany
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Mercker M, Köthe A, Marciniak-Czochra A. Mechanochemical symmetry breaking in Hydra aggregates. Biophys J 2016; 108:2396-407. [PMID: 25954896 PMCID: PMC4423050 DOI: 10.1016/j.bpj.2015.03.033] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 03/01/2015] [Accepted: 03/20/2015] [Indexed: 11/25/2022] Open
Abstract
Tissue morphogenesis comprises the self-organized creation of various patterns and shapes. Although detailed underlying mechanisms are still elusive in many cases, an increasing amount of experimental data suggests that chemical morphogen and mechanical processes are strongly coupled. Here, we develop and test a minimal model of the axis-defining step (i.e., symmetry breaking) in aggregates of the Hydra polyp. Based on previous findings, we combine osmotically driven shape oscillations with tissue mechanics and morphogen dynamics. We show that the model incorporating a simple feedback loop between morphogen patterning and tissue stretch reproduces a wide range of experimental data. Finally, we compare different hypothetical morphogen patterning mechanisms (Turing, tissue-curvature, and self-organized criticality). Our results suggest the experimental investigation of bigger (i.e., multiple head) aggregates as a key step for a deeper understanding of mechanochemical symmetry breaking in Hydra.
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Affiliation(s)
- Moritz Mercker
- Institute of Applied Mathematics, University of Heidelberg, Heidelberg, Germany; BioQuant, University of Heidelberg, Heidelberg, Germany; Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Heidelberg, Germany.
| | - Alexandra Köthe
- Institute of Applied Mathematics, University of Heidelberg, Heidelberg, Germany
| | - Anna Marciniak-Czochra
- Institute of Applied Mathematics, University of Heidelberg, Heidelberg, Germany; BioQuant, University of Heidelberg, Heidelberg, Germany; Interdisciplinary Center for Scientific Computing (IWR), University of Heidelberg, Heidelberg, Germany
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A mechanochemical model for embryonic pattern formation: coupling tissue mechanics and morphogen expression. PLoS One 2013; 8:e82617. [PMID: 24376555 PMCID: PMC3869727 DOI: 10.1371/journal.pone.0082617] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2013] [Accepted: 10/23/2013] [Indexed: 11/19/2022] Open
Abstract
Motivated by recent experimental findings, we propose a novel mechanism of embryonic pattern formation based on coupling of tissue curvature with diffusive signaling by a chemical factor. We derive a new mathematical model using energy minimization approach and show that the model generates a variety of morphogen and curvature patterns agreeing with experimentally observed structures. The mechanism proposed transcends the classical Turing concept which requires interactions between two morphogens with a significantly different diffusivity. Our studies show how biomechanical forces may replace the elusive long-range inhibitor and lead to formation of stable spatially heterogeneous structures without existence of chemical prepatterns. We propose new experimental approaches to decisively test our central hypothesis that tissue curvature and morphogen expression are coupled in a positive feedback loop.
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Brigandt I. Systems biology and the integration of mechanistic explanation and mathematical explanation. STUDIES IN HISTORY AND PHILOSOPHY OF BIOLOGICAL AND BIOMEDICAL SCIENCES 2013; 44:477-492. [PMID: 23863399 DOI: 10.1016/j.shpsc.2013.06.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Revised: 06/12/2013] [Accepted: 06/14/2013] [Indexed: 06/02/2023]
Abstract
The paper discusses how systems biology is working toward complex accounts that integrate explanation in terms of mechanisms and explanation by mathematical models-which some philosophers have viewed as rival models of explanation. Systems biology is an integrative approach, and it strongly relies on mathematical modeling. Philosophical accounts of mechanisms capture integrative in the sense of multilevel and multifield explanations, yet accounts of mechanistic explanation (as the analysis of a whole in terms of its structural parts and their qualitative interactions) have failed to address how a mathematical model could contribute to such explanations. I discuss how mathematical equations can be explanatorily relevant. Several cases from systems biology are discussed to illustrate the interplay between mechanistic research and mathematical modeling, and I point to questions about qualitative phenomena (rather than the explanation of quantitative details), where quantitative models are still indispensable to the explanation. Systems biology shows that a broader philosophical conception of mechanisms is needed, which takes into account functional-dynamical aspects, interaction in complex networks with feedback loops, system-wide functional properties such as distributed functionality and robustness, and a mechanism's ability to respond to perturbations (beyond its actual operation). I offer general conclusions for philosophical accounts of explanation.
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Affiliation(s)
- Ingo Brigandt
- Department of Philosophy, University of Alberta, 2-40 Assiniboia Hall, Edmonton, AB T6G2E7, Canada.
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Schötz EM, Lanio M, Talbot JA, Manning ML. Glassy dynamics in three-dimensional embryonic tissues. J R Soc Interface 2013; 10:20130726. [PMID: 24068179 DOI: 10.1098/rsif.2013.0726] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Many biological tissues are viscoelastic, behaving as elastic solids on short timescales and fluids on long timescales. This collective mechanical behaviour enables and helps to guide pattern formation and tissue layering. Here, we investigate the mechanical properties of three-dimensional tissue explants from zebrafish embryos by analysing individual cell tracks and macroscopic mechanical response. We find that the cell dynamics inside the tissue exhibit features of supercooled fluids, including subdiffusive trajectories and signatures of caging behaviour. We develop a minimal, three-parameter mechanical model for these dynamics, which we calibrate using only information about cell tracks. This model generates predictions about the macroscopic bulk response of the tissue (with no fit parameters) that are verified experimentally, providing a strong validation of the model. The best-fit model parameters indicate that although the tissue is fluid-like, it is close to a glass transition, suggesting that small changes to single-cell parameters could generate a significant change in the viscoelastic properties of the tissue. These results provide a robust framework for quantifying and modelling mechanically driven pattern formation in tissues.
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Affiliation(s)
- Eva-Maria Schötz
- 170 Carl Icahn Laboratory, Lewis-Sigler Institute, Princeton University, , Princeton, NJ 08544, USA
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Gamba A, Nicodemi M, Soriano J, Ott A. Critical behavior and axis defining symmetry breaking in Hydra embryonic development. PHYSICAL REVIEW LETTERS 2012; 108:158103. [PMID: 22587289 DOI: 10.1103/physrevlett.108.158103] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2011] [Indexed: 05/31/2023]
Abstract
The formation of a hollow cellular sphere is often one of the first steps of multicellular embryonic development. In the case of Hydra, the sphere breaks its initial symmetry to form a foot-head axis. During this process a gene, ks1, is increasingly expressed in localized cell domains whose size distribution becomes scale-free at the axis-locking moment. We show that a physical model based solely on the production and exchange of ks1-promoting factors among neighboring cells robustly reproduces the scaling behavior as well as the experimentally observed spontaneous and temperature-directed symmetry breaking.
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Affiliation(s)
- Andrea Gamba
- Politecnico di Torino and CNISM, 10129 Torino, Italy.
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Abstract
Cells can polarize in response to external signals, such as chemical gradients, cell-cell contacts, and electromagnetic fields. However, cells can also polarize in the absence of an external cue. For example, a motile cell, which initially has a more or less round shape, can lose its symmetry spontaneously even in a homogeneous environment and start moving in random directions. One of the principal determinants of cell polarity is the cortical actin network that underlies the plasma membrane. Tension in this network generated by myosin motors can be relaxed by rupture of the shell, leading to polarization. In this article, we discuss how simplified model systems can help us to understand the physics that underlie the mechanics of symmetry breaking.
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Affiliation(s)
- Jasper van der Gucht
- Laboratory of Physical Chemistry and Colloid Science, Wageningen University, Wageningen, The Netherlands
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