Talk:Developmental Mechanism - Morphodynamics
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Cite this page: Hill, M.A. (2021, August 5) Embryology Developmental Mechanism - Morphodynamics. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Talk:Developmental_Mechanism_-_Morphodynamics
Heterochromatin Morphodynamics in Late Oogenesis and Early Embryogenesis of Mammals
During the period of oocyte growth, chromatin undergoes global rearrangements at both morphological and molecular levels. An intriguing feature of oogenesis in some mammalian species is the formation of a heterochromatin ring-shaped structure, called the karyosphere or surrounded "nucleolus", which is associated with the periphery of the nucleolus-like bodies (NLBs). Morphologically similar heterochromatin structures also form around the nucleolus-precursor bodies (NPBs) in zygotes and persist for several first cleavage divisions in blastomeres. Despite recent progress in our understanding the regulation of gene silencing/expression during early mammalian development, as well as the molecular mechanisms that underlie chromatin condensation and heterochromatin structure, the biological significance of the karyosphere and its counterparts in early embryos is still elusive. We pay attention to both the changes of heterochromatin morphology and to the molecular mechanisms that can affect the configuration and functional activity of chromatin. We briefly discuss how DNA methylation, post-translational histone modifications, alternative histone variants, and some chromatin-associated non-histone proteins may be involved in the formation of peculiar heterochromatin structures intimately associated with NLBs and NPBs, the unique nuclear bodies of oocytes and early embryos.
Friction forces position the neural anlage
Nat Cell Biol. 2017 Apr;19(4):306-317. doi: 10.1038/ncb3492. Epub 2017 Mar 27.
Smutny M1, Ákos Z2, Grigolon S3, Shamipour S1, Ruprecht V4,5, Čapek D1, Behrndt M1, Papusheva E1, Tada M6, Hof B1, Vicsek T2, Salbreux G3, Heisenberg CP1.
During embryonic development, mechanical forces are essential for cellular rearrangements driving tissue morphogenesis. Here, we show that in the early zebrafish embryo, friction forces are generated at the interface between anterior axial mesoderm (prechordal plate, ppl) progenitors migrating towards the animal pole and neurectoderm progenitors moving in the opposite direction towards the vegetal pole of the embryo. These friction forces lead to global rearrangement of cells within the neurectoderm and determine the position of the neural anlage. Using a combination of experiments and simulations, we show that this process depends on hydrodynamic coupling between neurectoderm and ppl as a result of E-cadherin-mediated adhesion between those tissues. Our data thus establish the emergence of friction forces at the interface between moving tissues as a critical force-generating process shaping the embryo. PMID: 28346437 PMCID: PMC5635970 DOI: 10.1038/ncb3492
Sticking, steering, squeezing and shearing: cell movements driven by heterotypic mechanical forces
Curr Opin Cell Biol. 2018 Apr 29;54:57-65. doi: 10.1016/j.ceb.2018.04.008. [Epub ahead of print]
Labernadie A1, Trepat X2.
During development, the immune response and cancer, cells of different types interact mechanically. Here we review how such heterotypic mechanical interactions enable cell movements. We begin by analyzing the heterotypic forces that single cells use to adhere and squeeze through tight barriers, as in the case of leucocyte extravasation and cancer metastasis. We next focus on the different mechanisms by which adjacent tissues influence each other's movements, with particular emphasis on dragging forces during dorsal closure in Drosophila and shearing forces during gastrulation in zebrafish. Finally, we discuss the mechanotransduction feedback loops that enable different cell types to steer each other's migration during development and cancer. We illustrate these migration modes focusing on the combination of attractive and repulsive cues during co-migration of neural crest cells and placodes in Xenopus, and of fibroblasts and cancer cells during invasion. Throughout the review, we discuss the nature of the heterotypic contact, which may involve both homophilic and heterophilic interactions between adhesion receptors. PMID: 29719271 DOI: 10.1016/j.ceb.2018.04.008
Tissue morphodynamics shaping the early mouse embryo
Semin Cell Dev Biol. 2016 Jan 25. pii: S1084-9521(16)30033-7. doi: 10.1016/j.semcdb.2016.01.033. [Epub ahead of print]
Generation of the elongated vertebrate body plan from the initially radially symmetrical embryo requires comprehensive changes to tissue form. These shape changes are generated by specific underlying cell behaviors, coordinated in time and space. Major principles and also specifics are emerging, from studies in many model systems, of the cell and physical biology of how region-specific cell behaviors produce regional tissue morphogenesis, and how these, in turn, are integrated at the level of the embryo. New technical approaches have made it possible more recently, to examine the morphogenesis of the mouse embryo in depth, and to elucidate the underlying cellular mechanisms. This review focuses on recent advances in understanding the cellular basis for the early fundamental events that establish the basic form of the embryo. Copyright © 2016 Elsevier Ltd. All rights reserved. KEYWORDS: Axial elongation; Convergent extension; Gastrulation; Morphogenesis; Mouse; Planar cell polarity
Mechanically patterning the embryonic airway epithelium
Proc Natl Acad Sci U S A. 2015 Jul 28;112(30):9230-5. doi: 10.1073/pnas.1504102112. Epub 2015 Jul 13.
Varner VD1, Gleghorn JP1, Miller E2, Radisky DC2, Nelson CM3.
Collections of cells must be patterned spatially during embryonic development to generate the intricate architectures of mature tissues. In several cases, including the formation of the branched airways of the lung, reciprocal signaling between an epithelium and its surrounding mesenchyme helps generate these spatial patterns. Several molecular signals are thought to interact via reaction-diffusion kinetics to create distinct biochemical patterns, which act as molecular precursors to actual, physical patterns of biological structure and function. Here, however, we show that purely physical mechanisms can drive spatial patterning within embryonic epithelia. Specifically, we find that a growth-induced physical instability defines the relative locations of branches within the developing murine airway epithelium in the absence of mesenchyme. The dominant wavelength of this instability determines the branching pattern and is controlled by epithelial growth rates. These data suggest that physical mechanisms can create the biological patterns that underlie tissue morphogenesis in the embryo. KEYWORDS: buckling; instability; mechanical stress; morphodynamics; morphogenesis
Open source software for quantification of cell migration, protrusions, and fluorescence intensities
J Cell Biol. 2015 Apr 13;209(1):163-80. doi: 10.1083/jcb.201501081. Epub 2015 Apr 6.
Barry DJ1, Durkin CH1, Abella JV1, Way M2.
Cell migration is frequently accompanied by changes in cell morphology (morphodynamics) on a range of spatial and temporal scales. Despite recent advances in imaging techniques, the application of unbiased computational image analysis methods for morphodynamic quantification is rare. For example, manual analysis using kymographs is still commonplace, often caused by lack of access to user-friendly, automated tools. We now describe software designed for the automated quantification of cell migration and morphodynamics. Implemented as a plug-in for the open-source platform, ImageJ, ADAPT is capable of rapid, automated analysis of migration and membrane protrusions, together with associated fluorescently labeled proteins, across multiple cells. We demonstrate the ability of the software by quantifying variations in cell population migration rates on different extracellular matrices. We also show that ADAPT can detect and morphologically profile filopodia. Finally, we have used ADAPT to compile an unbiased description of a "typical" bleb formed at the plasma membrane and quantify the effect of Arp2/3 complex inhibition on bleb retraction. © 2015 Barry et al.
Apical constriction initiates new bud formation during monopodial branching of the embryonic chicken lung
Development. 2013 Aug;140(15):3146-55. doi: 10.1242/dev.093682. Epub 2013 Jul 3.
Kim HY, Varner VD, Nelson CM. Source Department of Chemical and Biological Engineering, Princeton University, Princeton, NJ 08544, USA.
Abstract Branching morphogenesis sculpts the airway epithelium of the lung into a tree-like structure to conduct air and promote gas exchange after birth. In the avian lung, a series of buds emerges from the dorsal surface of the primary bronchus via monopodial branching to form the conducting airways; anatomically, these buds are similar to those formed by domain branching in the mammalian lung. Here, we show that monopodial branching is initiated by apical constriction of the airway epithelium, and not by differential cell proliferation, using computational modeling and quantitative imaging of embryonic chicken lung explants. Both filamentous actin and phosphorylated myosin light chain were enriched at the apical surface of the airway epithelium during monopodial branching. Consistently, inhibiting actomyosin contractility prevented apical constriction and blocked branch initiation. Although cell proliferation was enhanced along the dorsal and ventral aspects of the primary bronchus, especially before branch formation, inhibiting proliferation had no effect on the initiation of branches. To test whether the physical forces from apical constriction alone are sufficient to drive the formation of new buds, we constructed a nonlinear, three-dimensional finite element model of the airway epithelium and used it to simulate apical constriction and proliferation in the primary bronchus. Our results suggest that, consistent with the experimental results, apical constriction is sufficient to drive the early stages of monopodial branching whereas cell proliferation is dispensable. We propose that initial folding of the airway epithelium is driven primarily by apical constriction during monopodial branching of the avian lung. KEYWORDS: Biomechanics, Mechanical stress, Morphodynamics, Patterning