The function and mechanism of convergent extension during gastrulation of Xenopus laevis

Development ◽  
1985 ◽  
Vol 89 (Supplement) ◽  
pp. 185-209
Author(s):  
R. E. Keller ◽  
Michael Danilchik ◽  
Robert Gimlich ◽  
John Shih
Keyword(s):  
Marginal Zone ◽  
Cell Formation ◽  
Cell Lineage ◽  
Time Lapse ◽  
Convergent Extension ◽  
A Cell ◽  
Tissue Recombination ◽  
Migration Of Cells ◽  
Time Lapse Video

The processes thought to function in Xenopus gastrulation include bottle cell formation, migration of cells on the roof of the blastocoel, and autonomous convergent extension of the circumblastoporal region. A review of recent and classical results shows that only the last accounts for the bulk of the tissue displacement of gastrulation, including spreading of the marginal zone toward the blastopore, involution of the marginal zone, and closure of the blastopore. Microsurgical manipulation and explantation studies, analysed by time-lapse video and cine microscopy, shows that the dorsal circumblastoporal region contains two regions which show either autonomous or semiautonomous convergent extension. The dorsal involuting marginal zone (IMZ) undergoes convergence (narrowing) and extension (lengthening) after its involution, beginning at the midgastrula stage and continuing through neurulation, such that it simultaneously extends posteriorly across the yolk plug and narrows the blastoporal circumference. Concurrently, the corresponding region of the overlying non-involuting marginal zone (NIMZ) begins a complementary convergent extension, but at a greater rate, which spreads vegetally to occupy surface area vacated by the IMZ. Tissue recombination experiments show that the deep cells of the dorsal IMZ bring about convergent extension. Labelling of small populations of these cells with a cell lineage tracer shows that convergent extension involves intercalation of deep cells to form a longer, narrower array. Direct time-lapse video and cine micrography of deep cells in cultured explants show that convergent extension involves radial and circumferential intercalation. Removal of the entire blastocoel roof of the early gastrula, including all or part of the NIMZ, shows that convergent extension of the IMZ alone can bring about its involution and blastopore closure. The role of convergent extension in gastrulation of other amphibians and other metazoans and its significance to related problems in early development are discussed.

scholarly journals Computational modelling of T-cell formation kinetics: output regulated by initial proliferation-linked deferral of developmental competence

2013 ◽  
Vol 10 (78) ◽  
pp. 20120774 ◽  
Author(s):  
Erica Manesso ◽  
Vijay Chickarmane ◽  
Hao Yuan Kueh ◽  
Ellen V. Rothenberg ◽  
Carsten Peterson
Keyword(s):  
T Cell ◽  
Computational Models ◽  
Cell Formation ◽  
Computational Modelling ◽  
Cell Lineage ◽  
Developmental Competence ◽  
Yield Data ◽  
Substantial Progress ◽  
A Cell

Bone-marrow-derived progenitors must continually enter the thymus of an adult mouse to sustain T-cell homeostasis, yet only a few input cells per day are sufficient to support a yield of 5 × 10 7 immature T-cells per day and an eventual output of 1–2 × 10 6 mature cells per day. While substantial progress has been made to delineate the developmental pathway of T-cell lineage commitment, still little is known about the relationship between differentiation competence and the remarkable expansion of the earliest (DN1 stage) T-cell progenitors. To address this question, we developed computational models where the probability to progress to the next stage (DN2) is related to division number. To satisfy differentiation kinetics and overall cell yield data, our models require that adult DN1 cells divide multiple times before becoming competent to progress into DN2 stage. Our findings were subsequently tested by in vitro experiments, where putative early and later-stage DN1 progenitors from the thymus were purified and their progression into DN2 was measured. These experiments showed that the two DN1 sub-populations divided with similar rates, but progressed to the DN2 stage with different rates, thus providing experimental evidence that DN1 cells increase their commitment probability in a cell-intrinsic manner as they undergo cell division. Proliferation-linked shifts in eligibility of DN1 cells to undergo specification thus control kinetics of T-cell generation.

Experimental analysis of the extension of the dorsal marginal zone in Pleurodeles waltl gastrulae

Development ◽  
1987 ◽  
Vol 100 (1) ◽  
pp. 147-161 ◽  
Author(s):  
D.L. Shi ◽  
M. Delarue ◽  
T. Darribere ◽  
J.F. Riou ◽  
J.C. Boucaut
Keyword(s):  
Electron Microscopy ◽  
Marginal Zone ◽  
Cell Lineage ◽  
Single Layer ◽  
Gastrula Stage ◽  
Animal Pole ◽  
A Cell ◽  
Pleurodeles Waltl ◽  
Scanning Electron

The capacity for extension of the dorsal marginal zone (DMZ) in Pleurodeles waltl gastrulae was studied by scanning electron microscopy and grafting experiments. At the onset of gastrulation, the cells of the animal pole (AP) undergo important changes in shape and form a single layer. As gastrulation proceeds, the arrangement of cells also changes in the noninvoluted DMZ: radial intercalation leads to a single layer of cells. Grafting experiments involving either AP or DMZ explants were performed using a cell lineage tracer. When rotated 90 degrees or 180 degrees, grafted DMZ explants were able to involute normally and there was extension according to the animal-vegetal axis of the host. In contrast, neither single nor bilayered explants from AP involutes completely, and neither extends when grafted in place of the DMZ. Furthermore, when inside of the host, these AP grafts curl up and inhibit the closure of the blastopore. Once transplanted to the AP region, the DMZ showed no obvious autonomous extension. DMZs cultured in vitro showed little extension and this only from the late gastrula stage onward. Removal of blastocoel roof blocked involution to a varied extent, depending on the developmental stage of the embryos. From these results, it is argued that differences could well exist in the mechanism of gastrulation between anuran and urodele embryos. That migrating mesodermal cells play a major role in urodele gastrulation is discussed.

scholarly journals Regional expression, pattern and timing of convergence and extension during gastrulation of Xenopus laevis

Development ◽  
1988 ◽  
Vol 103 (1) ◽  
pp. 193-209 ◽  
Author(s):  
R. Keller ◽  
M. Danilchik
Keyword(s):  
Xenopus Laevis ◽  
South African ◽  
Marginal Zone ◽  
Time Lapse ◽  
Dorsal Side ◽  
Convergent Extension ◽  
Intact Embryo ◽  
Convergence And Extension ◽  
Degree Of Convergence ◽  
Degree Of Extension

We show with time-lapse micrography that narrowing in the circumblastoporal dimension (convergence) and lengthening in the animal-vegetal dimension (extension) of the involuting marginal zone (IMZ) and the noninvoluting marginal zone (NIMZ) are the major tissue movements driving blastopore closure and involution of the IMZ during gastrulation in the South African clawed frog, Xenopus laevis. Analysis of blastopore closure shows that the degree of convergence is uniform from dorsal to ventral sides, whereas the degree of extension is greater on the dorsal side of the gastrula. Explants of the gastrula show simultaneous convergence and extension in the dorsal IMZ and NIMZ. In both regions, convergence and extension are most pronounced at their common boundary, and decrease in both animal and vegetal directions. Convergent extension is autonomous to the IMZ and begins at stage 10.5, after the IMZ has involuted. In contrast, expression of convergent extension in the NIMZ appears to be dependent on basal contact with chordamesoderm or with itself. The degree of extension decreases progressively in lateral and ventral sectors. Isolated ventral sectors show convergence without a corresponding degree of extension, perhaps reflecting the transient convergence and thickening that occurs in this region of the intact embryo. We present a detailed mechanism of how these processes are integrated with others to produce gastrulation. The significance of the regional expression of convergence and extension in Xenopus is discussed and compared to gastrulation in other amphibians.

scholarly journals C21orf91 Regulates Oligodendroglial Precursor Cell Fate—A Switch in the Glial Lineage?

2021 ◽  
Vol 15 ◽  
Author(s):  
Laura Reiche ◽  
Peter Göttle ◽  
Lydie Lane ◽  
Paula Duek ◽  
Mina Park ◽  
...  
Keyword(s):  
Cell Fate ◽  
Neuronal Development ◽  
Cognitive Impairments ◽  
Cell Lineage ◽  
Precursor Cell ◽  
Structure And Dynamics ◽  
A Cell ◽  
The Central Nervous System ◽  
Glial Lineage

Neuropathological diseases of the central nervous system (CNS) are frequently associated with impaired differentiation of the oligodendroglial cell lineage and subsequent alterations in white matter structure and dynamics. Down syndrome (DS), or trisomy 21, is the most common genetic cause for cognitive impairments and intellectual disability (ID) and is associated with a reduction in the number of neurons and oligodendrocytes, as well as with hypomyelination and astrogliosis. Recent studies mainly focused on neuronal development in DS and underestimated the role of glial cells as pathogenic players. This also relates to C21ORF91, a protein considered a key modulator of aberrant CNS development in DS. We investigated the role of C21orf91 ortholog in terms of oligodendrogenesis and myelination using database information as well as through cultured primary oligodendroglial precursor cells (OPCs). Upon modulation of C21orf91 gene expression, we found this factor to be important for accurate oligodendroglial differentiation, influencing their capacity to mature and to myelinate axons. Interestingly, C21orf91 overexpression initiates a cell population coexpressing astroglial- and oligodendroglial markers indicating that elevated C21orf91 expression levels induce a gliogenic shift towards the astrocytic lineage reflecting non-equilibrated glial cell populations in DS brains.

scholarly journals Studies of intercellular invasion in vitro using rabbit peritoneal neutrophil granulocytes (PMNS). I. Role of contact inhibition of locomotion.

1975 ◽  
Vol 65 (2) ◽  
pp. 439-462 ◽  
Author(s):  
P B Armstrong ◽  
J M Lackie
Keyword(s):  
Monolayer Culture ◽  
Time Lapse ◽  
Cell Types ◽  
Host Tissue ◽  
Necessary Condition ◽  
Neutrophil Granulocytes ◽  
Cell Type ◽  
A Cell

Intercellular invasion is the active migration of cells on one type into the interiors of tissues composed of cells of dissimilar cell types. Contact paralysis of locomotion is the cessation of forward extension of the pseudopods of a cell as a result of its collision with another cell. One hypothesis to account for intercellular invasion proposes that a necessary condition for a cell type to be invasive to a given host tissue is that it lack contact paralysis of locomotion during collision with cells of that host tissue. The hypothesis has been tested using rabbit peritoneal neutrophil granulocytes (PMNs) as the invasive cell type and chick embryo fibroblasts as the host tissue. In organ culture, PMNs rapidly invade aggregates of fibroblasts. The behavior of the pseudopods of PMNs during collision with fibroblasts was analyzed for contact paralysis by a study of time-lapse films of cells in mixed monolayer culture. In monolayer culture, PMNs show little sign of paralysis of the pseudopods upon collision with fibroblasts and thus conform in their behavior to that predicted by the hypothesis.

scholarly journals The micropyle: a sperm guidance system in teleost fertilization

Development ◽  
1990 ◽  
Vol 109 (2) ◽  
pp. 495-500 ◽  
Author(s):  
D. Amanze ◽  
A. Iyengar
Keyword(s):  
Time Lapse ◽  
Guidance System ◽  
Vitro Fertilization ◽  
Video Microscope ◽  
Computer Aided Analysis ◽  
Sperm Entry ◽  
Fertilization Experiments ◽  
Time Lapse Video

The micropylar region of the Rosy barb, Barbus conchonius, egg consists of 7–10 grooves and ridges, which drain directly into a funnel-shaped vestibule, the only point on the chorion through which sperm-egg contact is achieved during fertilization. Results of time-lapse video microscope study and computer-aided analysis of sperm motility pattern in the micropylar region showed that the fertilizing sperm, usually the first to enter the micropylar region, always travelled preferentially along the grooves into the micropylar pit. Subsequently, 86% of sperm arriving the micropylar region within 30 s travelled preferentially along the grooves into the immediate vicinity of the micropylar pit. The sperm guidance role of the micropylar region was calculated to enhance chances of egg penetration/fertilization by as much as 99.7% once sperm were within the micropylar region, possibly in response to some form of chemo-attractant(s) from the egg. Sperm agglutination post-fertilization was also found to occur preferentially along the grooves. Results of our in vitro fertilization experiments showed association between point of sperm entry and blastodisc formation: the blastodisc formed directly beneath the micropyle in all undisturbed eggs.

PDGF signalling is required for gastrulation of Xenopus laevis

Development ◽  
1995 ◽  
Vol 121 (9) ◽  
pp. 3099-3110 ◽  
Author(s):  
P. Ataliotis ◽  
K. Symes ◽  
M.M. Chou ◽  
L. Ho ◽  
M. Mercola
Keyword(s):  
Growth Factor ◽  
Marginal Zone ◽  
Platelet Derived Growth Factor ◽  
Pdgf Receptor ◽  
Convergent Extension ◽  
Mesodermal Cell ◽  
Point Mutant ◽  
Receptor Alpha

During Xenopus gastrulation, platelet-derived growth factor (PDGF) receptor-alpha is expressed in involuting marginal zone cells which migrate over ectodermal cells expressing PDGF-A. To investigate the role of PDGF signalling during this process, we have generated a novel point mutant of PDGF receptor-alpha analogous to the W37 mutation of c-kit. This molecule is a specific, potent, dominant inhibitor of PDGF signalling in vivo. Injection of RNA encoding this protein into Xenopus embryos prevents closure of the blastopore, leads to abnormal gastrulation and a loss of anterior structures. Convergent extension is not inhibited in these embryos, but rather, involuting mesodermal cells fail to adhere to the overlying ectoderm. PDGF may therefore be required for mesodermal cell-substratum interaction.

scholarly journals The Role of PI3K/AKT and MAPK Signaling Pathways in Erythropoietin Signalization

2021 ◽  
Vol 22 (14) ◽  
pp. 7682
Author(s):  
Zuzana Tóthová ◽  
Martina Šemeláková ◽  
Zuzana Solárová ◽  
Jana Tomc ◽  
Nataša Debeljak ◽  
...  
Keyword(s):  
Signaling Pathways ◽  
Cell Formation ◽  
Cell Lineage ◽  
Cell Types ◽  
Mapk Signaling ◽  
The Novel ◽  
Current State ◽  
State Of Research ◽  
Specific Tissue

Erythropoietin (EPO) is a glycoprotein cytokine known for its pleiotropic effects on various types of cells and tissues. EPO and its receptor EPOR trigger signaling cascades JAK2/STAT5, MAPK, and PI3K/AKT that are interconnected and irreplaceable for cell survival. In this article, we describe the role of the MAPK and PI3K/AKT signaling pathways during red blood cell formation as well as in non-hematopoietic tissues and tumor cells. Although the central framework of these pathways is similar for most of cell types, there are some stage-specific, tissue, and cell-lineage differences. We summarize the current state of research in this field, highlight the novel members of EPO-induced PI3K and MAPK signaling, and in this respect also the differences between erythroid and non-erythroid cells.

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