scholarly journals Strain maps characterize the symmetry of convergence and extension patterns during zebrafish gastrulation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Dipanjan Bhattacharya ◽  
Jun Zhong ◽  
Sahar Tavakoli ◽  
Alexandre Kabla ◽  
Paul Matsudaira
Keyword(s):  
Large Scale ◽  
Zebrafish Embryo ◽  
Mechanical Strain ◽  
Tissue Level ◽  
Lateral Compression ◽  
Linear Strain ◽  
Convergence And Extension ◽  
Wnt Inhibitor ◽  
Spherical Domains ◽  
Anterior Posterior

AbstractDuring gastrulation of the zebrafish embryo, the cap of blastoderm cells organizes into the axial body plan of the embryo with left–right symmetry and head–tail, dorsal–ventral polarities. Our labs have been interested in the mechanics of early development and have investigated whether these large-scale cell movements can be described as tissue-level mechanical strain by a tectonics-based approach. The first step is to image the positions of all nuclei from mid-epiboly to early segmentation by digital sheet light microscopy, organize the surface of the embryo into multi-cell spherical domains, construct velocity fields from the movements of these domains and extract strain rate maps from the change in density of the domains. During gastrulation, tensile/expansive and compressive strains in the axial and equatorial directions are detected as anterior and posterior expansion along the anterior–posterior axis and medial–lateral compression across the dorsal–ventral axis and corresponds to the well characterized morphological movements of convergence and extension. Following gastrulation strain is represented by localized medial expansion at the onset of segmentation and anterior expansion at the onset of neurulation. In addition to linear strain, symmetric patterns of rotation/curl are first detected in the animal hemispheres at mid-epiboly and then the vegetal hemispheres by the end of gastrulation. In embryos treated with C59, a Wnt inhibitor that inhibits head and tail extension, the axial extension and vegetal curl are absent. By analysing the temporal sequence of large-scale movements, deformations across the embryo can be attributed to a combination of epiboly and dorsal convergence-extension.

scholarly journals Strain maps characterize the symmetry of convergence and extension patterns during Zebrafish gastrulation

2018 ◽  
Author(s):  
Dipanjan Bhattacharya ◽  
Jun Zhong ◽  
Sahar Tavakoli ◽  
Alexandre Kabla ◽  
Paul Matsudaira
Keyword(s):  
Plate Tectonics ◽  
Large Scale ◽  
Zebrafish Embryo ◽  
Mechanical Strain ◽  
Tissue Level ◽  
Body Plan ◽  
Major Step ◽  
Mechanical Coupling ◽  
Convergence And Extension ◽  
Anterior Posterior

AbstractDuring gastrulation of the zebrafish embryo, the cap of blastoderm cells organizes into the axial body plan of the embryo with left-right symmetry and head-tail, dorsal-ventral polarities. Our labs have been interested in the mechanics of early development and have investigated whether these large-scale cells movements can be described as tissue-level mechanical strain by a tectonics-based approach. The first step is to image the positions of all nuclei from mid-epiboy to early segmentation by digital sheet light microscopy (DSLM), organize the surface of the embryo into multi-cell spherical domains, construct velocity fields from the movements of these domains and extract 3D strain rate maps. Tensile/expansive and compressive strains in the axial and equatorial directions are detected during gastrulation as anterior and posterior expansion along the anterior-posterior axis and medial-lateral compression across the dorsal-ventral axis corresponding to convergence and extension. In later stages in development are represented by localized medial expansion at the onset of segmentation and anterior expansion at the onset of neurulation. Symmetric patterns of rotation are first detected in the animal hemispheres at mid-epiboly and then the vegetal hemispheres by the end of gastrulation. By analysing the temporal sequence of large scale movements, deformations across the embryo can be attributed to a combination of epiboly and dorsal convergence-extension.SignificanceStrain is an emergent property of tissues that originates from the mechanical coupling of cell-cell and cell-substrate interactions, individual cell shape changes, and cell level forces. By imaging the positions of nuclei from mid-epiboly to early segmentation of the zebrafish embryo we are able to calculate three types of strain maps by a plate tectonics based method. The regions of expansive and compressive axial and equatorial strain correspond to areas undergoing convergence and extension, a major step in the formation of the embryonic body plan as well as the formation of somite and head structures. The most striking signatures of strain are: 1. the bilateral symmetry of linear strain across the anterior-posterior, dorsal-ventral axis during gastrulation, 2. the complementary counter-rotational strains or curl in the animal hemisphere at mid epiboly, and 3. a divergence or saddle point in the region of the dorsal organizer, head-trunk boundary. These strains represent a general method to describe large-scale tissue-level mechanics not only of embryonic development but also tissue homeostasis and disease.

scholarly journals Anterior expansion and posterior addition to the notochord mechanically coordinate embryo axis elongation

2021 ◽  
Author(s):  
Susannah B.P. McLaren ◽  
Benjamin J. Steventon
Keyword(s):  
Cell Expansion ◽  
Zebrafish Embryo ◽  
Volumetric Growth ◽  
Cell Ablation ◽  
Notochord Cell ◽  
Convergence And Extension ◽  
Axis Elongation ◽  
Notochord Cells ◽  
The Impact ◽  
Anterior Posterior

AbstractDuring development the embryo body progressively elongates from head-to-tail along the anterior-posterior (AP) axis. Multiple tissues contribute to this elongation through a combination of convergence and extension and/or volumetric growth. How force generated by the morphogenesis of one tissue impacts the morphogenesis of other axial tissues to achieve an elongated axis is not well understood. The notochord, a rod-shaped tissue possessed by all vertebrates, runs across the entire length of the somitic compartment and is flanked on either side by the developing somites in the segmented region of the axis and presomitic mesoderm in the posterior. Cells in the notochord undergo an expansion that is constrained by a stiff sheath of extracellular matrix, that increases the internal pressure in the notochord allowing it to straighten and elongate. Therefore, it is appropriately positioned to play a role in mechanically elongating the somitic compartment. Here, we use multi-photon mediated cell ablation to remove specific regions of the developing notochord and quantify the impact on axis elongation. We show that anterior notochord cell expansion generates a force that displaces notochord cells posteriorly relative to adjacent axial tissues and contributes to the elongation of segmented tissue during post-tailbud stages of development. Crucially, unexpanded cells derived from progenitors at the posterior end of the notochord provide resistance to anterior notochord cell expansion, allowing for force generation across the AP axis. Therefore, notochord cell expansion beginning in the anterior, and addition of cells to the posterior notochord, act as temporally coordinated morphogenetic events that shape the zebrafish embryo AP axis.

The Utah paradigm of skeletal physiology: what is it?

2001 ◽  
Vol 14 (04) ◽  
pp. 179-184 ◽  
Author(s):  
H. M. Frost
Keyword(s):  
Muscle Strength ◽  
Mechanical Strain ◽  
Postnatal Growth ◽  
Tissue Level ◽  
Second Step ◽  
Load Bearing ◽  
Salient Features ◽  
Utah Paradigm ◽  
Strain Dependent

SummaryAn elegant design stratagem for an organ intended to carry loads for life without fracturing, rupturing or wearing out would make those loads determine the organ's strength. It seems load-bearing mammalian bones, joints, fascia, ligaments and tendons do exactly that. Physiologists begin to understand how they do it, and that led to the Utah paradigm of skeletal physiology. Those adaptations occur in two major steps. The first step creates the genetically predetermined newborn skeleton with its anatomical relationships and biologic machinery. The second step adds to the first one all postnatal adaptations to mechanical and other challenges that would affect an organ's strength, size, architecture and composition. During postnatal growth, increasing loads make tissue-level biologic mechanisms correspondingly increase the strength of such organs. Mechanical strain-dependent signals help to control that process, which muscle strength, muscle anatomy and neuromuscular physiology strongly influence. Its problems seem to cause or help to cause numerous skeletal and some extraskeletal disorders. A Table in the article lists examples of them.This article summarizes salient features of the Utah paradigm, which includes both facts and some meanings inferred from them. Other times and people must resolve any questions about those meanings and about the devils that can lie in the details. Parenthetically, instead of the accuracy of the facts on which that paradigm stands, the above questions usually concern the different meanings people can infer from facts, and whether particular facts and ideas would be relevant to a particular issue.

scholarly journals Are the Somatic Mutation and Tissue Organization Field Theories of Carcinogenesis Incompatible?

2013 ◽  
Vol 12 ◽  
pp. CIN.S13013 ◽  
Author(s):  
Simon Rosenfeld
Keyword(s):  
Somatic Mutation ◽  
Large Scale ◽  
Control Cell ◽  
Tissue Level ◽  
Dna Mutations ◽  
Tissue Organization ◽  
Tissue Organization Field Theory ◽  
Wide Range ◽  
Carcinogenic Agents ◽  
Successful Resolution

Two drastically different approaches to understanding the forces driving carcinogenesis have crystallized through years of research. These are the somatic mutation theory (SMT) and the tissue organization field theory (TOFT). The essence of SMT is that cancer is derived from a single somatic cell that has successively accumulated multiple DNA mutations, and that those mutations occur on genes which control cell proliferation and cell cycle. Thus, according to SMT, neoplastic lesions are the results of DNA-level events. Conversely, according to TOFT, carcinogenesis is primarily a problem of tissue organization: carcinogenic agents destroy the normal tissue architecture thus disrupting cell-to-cell signaling and compromising genomic integrity. Hence, in TOFT the DNA mutations are the effect, and not the cause, of the tissue-level events. Cardinal importance of successful resolution of the TOFT versus SMT controversy dwells in the fact that, according to SMT, cancer is a unidirectional and mostly irreversible disease; whereas, according to TOFT, it is curable and reversible. In this paper, our goal is to outline a plausible scenario in which TOFT and SMT can be reconciled using the framework and concepts of the self-organized criticality (SOC), the principle proven to be extremely fruitful in a wide range of disciplines pertaining to natural phenomena, to biological communities, to large-scale social developments, to technological networks, and to many other subjects of research.

scholarly journals Integration of contractile forces during tissue invagination

2010 ◽  
Vol 188 (5) ◽  
pp. 735-749 ◽  
Author(s):  
Adam C. Martin ◽  
Michael Gelbart ◽  
Rodrigo Fernandez-Gonzalez ◽  
Matthias Kaschube ◽  
Eric F. Wieschaus
Keyword(s):  
Cell Shape ◽  
Control Cell ◽  
Adherens Junction ◽  
Tissue Level ◽  
Epithelial Morphogenesis ◽  
Apical Constriction ◽  
Contractile Forces ◽  
Actomyosin Cytoskeleton ◽  
Cellular Forces ◽  
Anterior Posterior

Contractile forces generated by the actomyosin cytoskeleton within individual cells collectively generate tissue-level force during epithelial morphogenesis. During Drosophila mesoderm invagination, pulsed actomyosin meshwork contractions and a ratchet-like stabilization of cell shape drive apical constriction. Here, we investigate how contractile forces are integrated across the tissue. Reducing adherens junction (AJ) levels or ablating actomyosin meshworks causes tissue-wide epithelial tears, which release tension that is predominantly oriented along the anterior–posterior (a-p) embryonic axis. Epithelial tears allow cells normally elongated along the a-p axis to constrict isotropically, which suggests that apical constriction generates anisotropic epithelial tension that feeds back to control cell shape. Epithelial tension requires the transcription factor Twist, which stabilizes apical myosin II, promoting the formation of a supracellular actomyosin meshwork in which radial actomyosin fibers are joined end-to-end at spot AJs. Thus, pulsed actomyosin contractions require a supracellular, tensile meshwork to transmit cellular forces to the tissue level during morphogenesis.

scholarly journals QuickStitch for seamless stitching of confocal mosaics through high-pass filtering and recursive normalization

2016 ◽  
Author(s):  
Pavel A. Brodskiy ◽  
Paulina M. Eberts ◽  
Cody Narciso ◽  
Jochen Kursawe ◽  
Alexander Fletcher ◽  
...  
Keyword(s):  
Open Source ◽  
Large Scale ◽  
Imaging System ◽  
Tissue Level ◽  
Cellular Level ◽  
Specific Information ◽  
Open Source Tool ◽  
The Individual ◽  
User Friendly ◽  
High Pass

ABSTRACTFluorescence micrographs naturally exhibit darkening around their edges (vignetting), which makes seamless stitching challenging. If vignetting is not corrected for, a stitched image will have visible seams where the individual images (tiles) overlap, introducing a systematic error into any quantitative analysis of the image. Although multiple vignetting correction methods exist, there remains no open-source tool that robustly handles large 2D immunofluorescence-based mosaic images. Here, we develop and validate QuickStitch, a tool that applies a recursive normalization algorithm to stitch large-scale immunofluorescence-based mosaics without incurring vignetting seams. We demonstrate how the tool works successfully for tissues of differing size, morphology, and fluorescence intensity. QuickStitch requires no specific information about the imaging system. It is provided as an open-source tool that is both user friendly and extensible, allowing straightforward incorporation into existing image processing pipelines. This enables studies that require accurate segmentation and analysis of high-resolution datasets when parameters of interest include both cellular-level phenomena and larger tissue-level regions of interest.

scholarly journals Self-organised symmetry breaking in zebrafish reveals feedback from morphogenesis to pattern formation

2019 ◽  
Author(s):  
Vikas Trivedi ◽  
Timothy Fulton ◽  
Andrea Attardi ◽  
Kerim Anlas ◽  
Chaitanya Dingare ◽  
...  
Keyword(s):  
Pattern Formation ◽  
Symmetry Breaking ◽  
Embryonic Stem ◽  
Break Symmetry ◽  
Early Embryo ◽  
Beta Catenin ◽  
Embryonic Cells ◽  
Convergence And Extension ◽  
Extensive Cell ◽  
Anterior Posterior

A fundamental question in developmental biology is how the early embryo breaks initial symmetry to establish the spatial coordinate system later important for the organisation of the embryonic body plan. In zebrafish, this is thought to depend on the inheritance of maternal mRNAs [1–3], cortical rotation to generate a dorsal pole of beta-catenin activity [4–8] and the release of Nodal signals from the yolk syncytial layer (YSL) [9–12]. Recent work aggregating mouse embryonic stem cells has shown that symmetry breaking can occur in the absence of extra-embryonic tissue [19,20]. To test whether this is also true in zebrafish, we separated embryonic cells from the yolk and allowed them to develop as aggregates. These aggregates break symmetry autonomously to form elongated structures with an anterior-posterior pattern. Extensive cell mixing shows that any pre-existing asymmetry is lost prior to the breaking morphological symmetry, revealing that the maternal pre-pattern is not strictly required for early embryo patterning. Following early signalling events after isolation of embryonic cells reveals that a pole of Nodal activity precedes and is required for elongation. The blocking of PCP-dependent convergence and extension movements disrupts the establishment of opposing poles of BMP and Wnt/TCF activity and the patterning of anterior-posterior neural tissue. These results lead us to suggest that convergence and extension plays a causal role in the establishment of morphogen gradients and pattern formation during zebrafish gastrulation.

scholarly journals Manganese distribution in the Mn-hyperaccumulator Grevillea meisneri from New Caledonia

2021 ◽  
Author(s):  
Camille Bihanic ◽  
Eddy Petit ◽  
Roseline Perrot ◽  
Lucie Cases ◽  
Armelle Garcia ◽  
...  
Keyword(s):  
Large Scale ◽  
New Caledonia ◽  
Tissue Level ◽  
Cluster Roots ◽  
Transport Pathways ◽  
X Ray ◽  
Mining Sites ◽  
Rehabilitation Programs ◽  
Primary Roots ◽  
Preferential Uptake

Abstract • Grevillea meisneri, an endemic New Caledonian Mn-hyperaccumulator, is used in rehabilitation of degraded mining sites on the island. Large-scale programs require transplanting nursery-grown seedlings, but effects of the nursery environment on Mn tolerance of transplants and their capacity to hyper-accumulate Mn are unknown, slowing rehabilitation efforts.• We studied tissue-level distribution of Mn and other elements in different tissues of G. meisneri using micro-X-Ray Fluorescence spectroscopy (μXRF), comparing nursery-grown plants transplanted into the site and sampled seven years later, and similar-sized plants that had grown spontaneously in the site. • Mirroring patterns in other Mn-hyperaccumulators, Mn was preferentially accumulated in leaves but was also present in roots. Concentrations were highest in leaf epidermal tissues, in cortex and vascular tissues of stems and primary roots, and in phloem and pericycle-endodermis of parent cluster roots. Although abundant in soil, Ni was absent from all tissues of G. meisneri. Ca was always co-localised with Mn. Preferential uptake of Mn vs Ni in roots implies as-yet-uncharacterized specific Mn-transporters, while Ca and Mn co-localisation suggests shared transport pathways. • No differences were observed in concentration and distribution of Mn in transplanted and spontaneously-growing plants. Nursery-grown transplants should be highly suitable for large-scale, high-throughput rehabilitation programs.

scholarly journals The patterning and functioning of protrusive activity during convergence and extension of the Xenopus organiser

Development ◽  
1992 ◽  
Vol 116 (Supplement) ◽  
pp. 81-91 ◽  
Author(s):  
Ray Keller ◽  
John Shih ◽  
Carmen Domingo
Keyword(s):  
Spinal Cord ◽  
Nervous System ◽  
Marginal Zone ◽  
Tissue Differentiation ◽  
Tissue Interactions ◽  
Dorsal Mesoderm ◽  
Convergence And Extension ◽  
Early Gastrula ◽  
Ventral Explants ◽  
Anterior Posterior

We discuss the cellular basis and tissue interactions regulating convergence and extension of the vertebrate body axis in early embryogenesls of Xenopus. Convergence and extension occur in the dorsal mesoderm (prospective notochord and somite) and in the posterior nervous system (prospective hindbrain and spinal cord) by sequential cell intercalations. Several layers of cells intercalate to form a thinner, longer array (radial intercalation) and then cells intercalate in the mediolateral orientation to form a longer, narrower array (mediolateral intercalation). Fluorescence microscopy of labeled mesodermal cells in explants shows that protrusive activity is rapid and randomly directed until the midgastrula stage, when it slows and is restricted to the medial and lateral ends of the cells. This bipolar protrusive activity results in elongation, alignment and mediolateral intercalation of the cells. Mediolateral intercalation behavior (MIB) is expressed in an anterior-posterior and lateral-medial progression in the mesoderm. MIB is first expressed laterally in both somitic and notochordal mesoderm. From its lateral origins in each tissue, MIB progresses medially. If convergence does not bring the lateral boundaries of the tissues closer to the medial cells in the notochordal and somitic territories, these cells do not express MIB. Expression of tissue-specific markers follows and parallels the expression of MIB. These facts argue that MIB and some aspects of tissue differentiation are induced by signals emanating from the lateral boundaries of the tissue territories and that convergence must bring medial cells and boundaries closer together for these signals to be effective. Grafts of dorsal marginal zone epithelium to the ventral sides of other embryos, to ventral explants and to UV-ventralized embryos show that it has a role in organising convergence and extension, and dorsal tissue differentiation among deep mesodermal cells. Grafts of involuting marginal zone to animal cap tissue of the early gastrula shows that convergence and extension of the hindbrain-spinal cord are induced by planar signals from the involuting marginal zone.

scholarly journals Convergence of cortical types and functional motifs in the human mesiotemporal lobe

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Casey Paquola ◽  
Oualid Benkarim ◽  
Jordan DeKraker ◽  
Sara Larivière ◽  
Stefan Frässle ◽  
...  
Keyword(s):  
High Resolution ◽  
Cognitive Processes ◽  
Large Scale ◽  
Effective Connectivity ◽  
Brain Disorders ◽  
Neuronal Density ◽  
Functional Organisation ◽  
Large Scale Networks ◽  
Anterior Posterior

The mesiotemporal lobe (MTL) is implicated in many cognitive processes, is compromised in numerous brain disorders, and exhibits a gradual cytoarchitectural transition from six-layered parahippocampal isocortex to three-layered hippocampal allocortex. Leveraging an ultra-high-resolution histological reconstruction of a human brain, our study showed that the dominant axis of MTL cytoarchitectural differentiation follows the iso-to-allocortical transition and depth-specific variations in neuronal density. Projecting the histology-derived MTL model to in-vivo functional MRI, we furthermore determined how its cytoarchitecture underpins its intrinsic effective connectivity and association to large-scale networks. Here, the cytoarchitectural gradient was found to underpin intrinsic effective connectivity of the MTL, but patterns differed along the anterior-posterior axis. Moreover, while the iso-to-allocortical gradient parametrically represented the multiple-demand relative to task-negative networks, anterior-posterior gradients represented transmodal versus unimodal networks. Our findings establish that the combination of micro- and macrostructural features allow the MTL to represent dominant motifs of whole-brain functional organisation.

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