Successive patterns of clonal cell dispersion in relation to neuromeric subdivision in the mouse neuroepithelium

Development ◽  
1999 ◽  
Vol 126 (18) ◽  
pp. 4095-4106 ◽  
Author(s):  
L. Mathis ◽  
J. Sieur ◽  
O. Voiculescu ◽  
P. Charnay ◽  
J.F. Nicolas
Keyword(s):  
Major Change ◽  
Positional Information ◽  
Cell Labelling ◽  
Morphological Segmentation ◽  
Cell Dispersion ◽  
Interesting Possibility ◽  
Cell Organization ◽  
A Cell ◽  
Anterior Posterior ◽  
Epithelial Growth

We made use of the laacz procedure of single-cell labelling to visualize clones labelled before neuromere formation, in 12.5-day mouse embryos. This allowed us to deduce two successive phases of cell dispersion in the formation of the rhombencephalon: an initial anterior-posterior (AP) cell dispersion, followed by an asymmetrical dorsoventral (DV) cell distribution during which AP cell dispersion occurs in territories smaller than one rhombomere. We conclude that the general arrest of AP cell dispersion precedes the onset of morphological segmentation and is not imposed by the interface between adjacent rhombomeres. This demonstrates a major change in the mode of epithelial growth that precedes or accompanies the formation of neuromeres. We also deduced that the period of DV cell dispersion in the neuroepithelium is followed by a coherent growth phase. These results suggest a cell organization on a Cartesian grid, the coordinates of which correspond to the AP and DV axis of the neural tube. A similar sequence of AP cell dispersion followed by an arrest of AP cell dispersion, a preferential DV cell dispersion and then by a coherent neuroepithelial growth, is also observed in the spinal cord and mesencephalon. This demonstrates that a similar cascade of cell events occurs in these different domains of the CNS. In the prosencephalon, differences in spatial constraints may explain the variability in the orientation of cell clusters. Genetic and clonal patterning in the AP and DV dimensions follow the same spatial sequence. An interesting possibility is that these successive patterns of cell growth facilitate the acquisition of positional information.

Morphogenesis in the cellular slime mould Dictyostelium discoideum; the formation and regulation of aggregate tips and the specification of developmental axes

Development ◽  
1973 ◽  
Vol 29 (2) ◽  
pp. 253-266
Author(s):  
P. Farnsworth
Keyword(s):  
Morphological Changes ◽  
Cell Mass ◽  
Staging System ◽  
Positional Information ◽  
Cell Labelling ◽  
Slime Mould ◽  
Impermeable Barrier ◽  
A Cell ◽  
Cellular Slime

A general discussion of ‘organizing regions’ and the specification of biological patterns is followed by introducing the idea that the tip of the slime mould cell mass is such an ‘organizer’. This view is supported by a discussion of the developmental ubiquity of the tip and its effects. A staging system is described which assigns numbers to sequential morphological changes during development. A set of experiments investigating the role of the tip are described, using techniques of cell labelling, grafting and bisection of cell masses with barriers, and the manufacture and use of cylindrical barriers of permeable cellulose. The results of such experiments show: (1) That the tip of the cell mass is made of the same group of cells from stage 10 (late aggregate) to stage 20+ (culmination). (2) That a stage 10 aggregate will regenerate a new tip in an average time of 32 min. (3) That if a stage 10 aggregate is bisected by an impermeable barrier two tips, indicating two new developmental axes, develop in an average time of 34 min. (4) That if a stage 10 aggregate is bisected for 40 min, the barrier removed and one of the tips removed, the remaining tip inhibits the re-formation of the second tip, and the polarity of the aggregate is again reorganized with respect to the remaining tip. (5) That if experiments (3), (4) and (5) are repeated with a stage 9 aggregate, which is an hour younger, all the regulation times are increased by about 60 min. Similarly a stage 8 aggregate takes over 120 min longer to show the effect. (6) That if part or all of a cell mass from any stage is placed inside a cellulose tube, all the enclosed cells differentiate into stalk cells. These results are then discussed in relation to pattern formation and the role of the tip in polarization and the specification of new developmental axes in cell masses. A model for culmination in the slime mould is proposed which takes account of the above results. The essence of this model is that at no time are stalk and spore cells ‘determined’ in the classical sense, and that, by a non-signalling positional information system, the size invariance of the ratio of stalk to spore cells seen in the fruiting body is a result of the mechanical process of culmination.

scholarly journals The use of a slide spinner in the analysis of cell dispersion.

1976 ◽  
Vol 24 (1) ◽  
pp. 11-15 ◽  
Author(s):  
R C Wolley ◽  
H M Dembitzer ◽  
F Herz ◽  
K Schreiber ◽  
L G Koss
Keyword(s):  
Cell Suspension ◽  
Single Cells ◽  
Cell Loss ◽  
Optimum Conditions ◽  
Isolated Cells ◽  
Cell Dispersion ◽  
Cervical Cancer Cells ◽  
A Cell ◽  
Human Cervical Cancer Cells ◽  
Human Cervical Cancer

A simple and reliable method of determining the degree of dispersion of a cell suspension has been developed using the Perkin-Elmer Uni-Smear Spinner. Optimum conditions regarding rate and duration of spin, etc., were first ascertained using dispersed cell cultures including human cervical cancer cells as well as gynecologic samples. After spinning, single cells in suspension appeared as isolated cells on the slides. Cell aggregates, on the other hand, remained together. Therefore, the distribution of cells in various sized aggregates could be easily quantitated and the slides retained for future review. This method was used to evaluate the dispersing effects of trypsin, ethylenediaminetetraacetate and and syringing human on human gynecology samples obtained by routine cervical scrapes. None of the dispersion methods has, so far, produced an adequate monodispersed cell suspension without unacceptable cell loss.

Non-genic inheritance of cellular handedness

Development ◽  
1989 ◽  
Vol 105 (3) ◽  
pp. 447-456 ◽  
Author(s):  
E.M. Nelsen ◽  
J. Frankel ◽  
L.M. Jenkins
Keyword(s):  
Positional Information ◽  
Regulatory Elements ◽  
Genetic Change ◽  
Surface Structures ◽  
Phenotypic Alteration ◽  
Left Handed ◽  
A Cell ◽  
Usual Order ◽  
Genic Control ◽  
Rule Out

Ciliates exhibit an asymmetry in arrangement of surface structures around the cell which could be termed handedness. If the usual order of placement of structures defines a ‘right-handed’ (RH) cell, then a cell with this order reversed would be ‘left-handed’ (LH). Such LH forms appear to be produced in Tetrahymena thermophila through aberrant reorganization of homopolar doublets back to the singlet condition. Four clones of LH forms were selected and subjected to genetic analysis to test whether this drastic phenotypic alteration resulted from a nuclear genetic change. The results of this analysis indicate that the change in handedness is not due to a genetic change in either the micronucleus or macronucleus. The LH form can, under certain circumstances, revert to the RH form, but typically it propagates itself across both vegetative and sexual generations with similar fidelity. While this analysis does not formally rule out certain possibilities of nuclear genic control involving regulatory elements transmitted through the cytoplasm, when the circumstances of origin and propagation of the LH condition are taken into account direct cortical perpetuation seems far more likely. Here we outline a conceptual framework centred on the idea of longitudinally propagated positional information; the positive evidence supporting this idea as well as further application of the idea itself are presented in the accompanying paper.

Mutant expression of male copulatory bursa surface markers in Caenorhabditis elegans

Development ◽  
1988 ◽  
Vol 103 (3) ◽  
pp. 485-495 ◽  
Author(s):  
C.D. Link ◽  
C.W. Ehrenfels ◽  
W.B. Wood
Keyword(s):  
Positional Information ◽  
Surface Expression ◽  
Surface Markers ◽  
Adult Males ◽  
Vulval Development ◽  
Altered Expression ◽  
C Elegans ◽  
Isolation And Characterization ◽  
Cuticle Development ◽  
Anterior Posterior

In a search for molecular markers of male tail morphogenesis in C. elegans, we have detected two surface markers that are specifically observed in the copulatory bursa of adult males and the vulva of adult hermaphrodites. These markers are defined by binding of a monoclonal antibody (Ab117) and the lectin wheat germ agglutinin (WGA) to live intact animals. Expression of these markers is dependent on sex, stage and anterior-posterior position in the animal. Four of ten mutants with specific defects in bursal development show altered expression of one or both markers. Because the WGA marker can be expressed in intersexual animals with very little bursal development, posterior surface expression of this marker can serve as an indication of subtle masculinization of hermaphrodites. The timing of expression of these markers is not affected by heterochronic mutations that cause larval animals to express adult cuticles or adult animals to express larval cuticles, indicating that marker expression can be uncoupled from general cuticle development. Mutant lin-22 males, which have an anterior-to-posterior transformation of cell fates in the lateral hypodermis, ectopically express both markers in a manner consistent with a ‘posteriorization’ of positional information in these animals. These markers should be useful for the isolation and characterization of mutants defective in bursal and vulval development, sex determination and expression of anterior-posterior positional information.

scholarly journals The next frontier: using space as management strategy - an exploratory study

2020 ◽  
Vol 33 (3) ◽  
pp. 217-229
Author(s):  
Pia Storvang ◽  
Bang Nguyen
Keyword(s):  
Management Strategy ◽  
Design Methodology ◽  
Physical Space ◽  
Organizational Strategy ◽  
University Campus ◽  
Content Type ◽  
Industrial Setting ◽  
Cell Organization ◽  
A Cell ◽  
The University

Purpose More and more companies use physical space as a way to enhance creativity, create change and stimulate interaction. The purpose of this paper is to investigate how space affects this interrelationship and explores how space can support organizational strategy. Design/methodology/approach Using a qualitative approach, this study explores three cases from an educational, a cultural and an industrial setting to illustrate how space can be used to support an organization’s policy and help its strategic intentions. Findings The findings demonstrate how space can be used to enhance organizational strategy and demonstrate how closely the creation of space can be related to the development of that strategy. Specifically, the study finds that the “’space-organizational strategy’ link has three uses: “Space as an organizational meeting place” in the University campus, (2) “Space as a network organization” in the culture and production center and (3) “Space as a cell organization” in the private manufacturing company. Originality/value The study will show that the design and operationalization of spaces can influence management and organizational strategy because space influences relations between people and that organizations can use space to support their strategic intentions seems to have been overlooked in the literature.

Pharmacotherapeuetic Options for the Treatment of Multiple Sclerosis

2012 ◽  
Vol 4 ◽  
pp. CMT.S8661 ◽  
Author(s):  
Alan M. Palmer
Keyword(s):  
Multiple Sclerosis ◽  
Immune Cells ◽  
Cell Adhesion Molecule ◽  
Major Change ◽  
Clinical Development ◽  
Immunomodulatory Drugs ◽  
Amino Acid Peptide ◽  
A Cell ◽  
Patent Life ◽  
Neuro Inflammation

Multiple sclerosis is the most common progressive and disabling neurological condition in young adults. Neuro-inflammation is an early and persistent change and forms the basis of most pharmacotherapy for this disease. Immunomodulatory drugs are mainly biologies (β-interferons, a four amino acid peptide, and a monoclonal antibody to a cell adhesion molecule on the blood-CNS barrier) that either attenuate the inflammatory response or block the movement of immune cells into the CNS. They reduce the rate of relapse, but have little or no effect on the progression of disability. The market landscape for MS drugs is in the midst of major change because the patent life of many of these medicines will soon expire, which will lead to the emergence of biosimilars. In addition, new small molecule immunomodulatory and palliative drugs have entered the market, with more in the pipeline; a number of monoclonal antibodies and other immunomodulatory drugs are also in clinical development.

scholarly journals The yeast centrosome translates the positional information of the anaphase spindle into a cell cycle signal

2007 ◽  
Vol 179 (3) ◽  
pp. 423-436 ◽  
Author(s):  
Hiromi Maekawa ◽  
Claire Priest ◽  
Johannes Lechner ◽  
Gislene Pereira ◽  
Elmar Schiebel
Keyword(s):  
Spindle Pole Body ◽  
Coiled Coil ◽  
Positional Information ◽  
Spindle Pole ◽  
Mitotic Exit ◽  
Spindle Orientation ◽  
Additional Function ◽  
A Cell ◽  
Cytoplasmic Microtubules ◽  
Guanosine Triphosphatase

The spindle orientation checkpoint (SPOC) of budding yeast delays mitotic exit when cytoplasmic microtubules (MTs) are defective, causing the spindle to become misaligned. Delay is achieved by maintaining the activity of the Bfa1–Bub2 guanosine triphosphatase–activating protein complex, an inhibitor of mitotic exit. In this study, we show that the spindle pole body (SPB) component Spc72, a transforming acidic coiled coil–like molecule that interacts with the γ-tubulin complex, recruits Kin4 kinase to both SPBs when cytoplasmic MTs are defective. This allows Kin4 to phosphorylate the SPB-associated Bfa1, rendering it resistant to inactivation by Cdc5 polo kinase. Consistently, forced targeting of Kin4 to both SPBs delays mitotic exit even when the anaphase spindle is correctly aligned. Moreover, we present evidence that Spc72 has an additional function in SPOC regulation that is independent of the recruitment of Kin4. Thus, Spc72 provides a missing link between cytoplasmic MT function and components of the SPOC.

scholarly journals Mechanisms Underlying Hox-Mediated Transcriptional Outcomes

2021 ◽  
Vol 9 ◽  
Author(s):  
Brittany Cain ◽  
Brian Gebelein
Keyword(s):  
Transcription Factors ◽  
Differentially Express ◽  
Target Genes ◽  
Cell Type ◽  
Cell Fates ◽  
Specific Manner ◽  
A Cell ◽  
Cell Type Specific ◽  
Anterior Posterior ◽  
Anterior Posterior Axis

Metazoans differentially express multiple Hox transcription factors to specify diverse cell fates along the developing anterior-posterior axis. Two challenges arise when trying to understand how the Hox transcription factors regulate the required target genes for morphogenesis: First, how does each Hox factor differ from one another to accurately activate and repress target genes required for the formation of distinct segment and regional identities? Second, how can a Hox factor that is broadly expressed in many tissues within a segment impact the development of specific organs by regulating target genes in a cell type-specific manner? In this review, we highlight how recent genomic, interactome, and cis-regulatory studies are providing new insights into answering these two questions. Collectively, these studies suggest that Hox factors may differentially modify the chromatin of gene targets as well as utilize numerous interactions with additional co-activators, co-repressors, and sequence-specific transcription factors to achieve accurate segment and cell type-specific transcriptional outcomes.

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