The hedgehog morphogen and gradients of cell affinity in the abdomen of Drosophila

Development ◽  
1999 ◽  
Vol 126 (11) ◽  
pp. 2441-2449 ◽  
Author(s):  
P.A. Lawrence ◽  
J. Casal ◽  
G. Struhl
Keyword(s):  
Positional Information ◽  
Cell Types ◽  
Direct Response ◽  
Cell Affinity ◽  
A Chain ◽  
Different Cell Types ◽  
The Relationship ◽  
P Cells ◽  
Adult Abdomen ◽  
As If

The adult abdomen of Drosophila is a chain of anterior (A) and posterior (P) compartments. The engrailed gene is active in all P compartments and selects the P state. Hedgehog enters each A compartment across both its anterior and posterior edges; within A its concentration confers positional information. The A compartments are subdivided into an anterior and a posterior domain that each make different cell types in response to Hedgehog. We have studied the relationship between Hedgehog, engrailed and cell affinity. We made twin clones and measured the shape, size and displacement of the experimental clone, relative to its control twin. We varied the perceived level of Hedgehog in the experimental clone and find that, if this level is different from the surround, the clone fails to grow normally, rounds up and sometimes sorts out completely, becoming separated from the epithelium. Also, clones are displaced towards cells that are more like themselves: for example groups of cells in the middle of the A compartment that are persuaded to differentiate as if they were at the posterior limit of A, move posteriorly. Similarly, clones in the anterior domain of the A compartment that are forced to differentiate as if they were at the anterior limit of A, move anteriorly. Quantitation of these measures and the direction of displacement indicate that there is a U-shaped gradient of affinity in the A compartment that correlates with the U-shaped landscape of Hedgehog concentration. Since affinity changes are autonomous to the clone we believe that, normally, each cell's affinity is a direct response to Hedgehog. By removing engrailed in clones we show that A and P cells also differ in affinity from each other, in a manner that appears independent of Hedgehog. Within the P compartment we found some evidence for a U-shaped gradient of affinity, but this cannot be due to Hedgehog which does not act in the P compartment.

A Convenient and Efficient Centrifugation Assay for Comparing Cell Adhesion Strength on Uncharted Surfaces

2020 ◽  
Vol 10 (4) ◽  
pp. 462-468
Author(s):  
Xuan Zhou ◽  
Xin Zhou ◽  
Yichen Du ◽  
Xiaohua Shi ◽  
Pan You ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Adhesion Strength ◽  
Population Level ◽  
Cell Types ◽  
Laboratory Equipment ◽  
Substrate Adhesion ◽  
Associated Proteins ◽  
Cell Affinity ◽  
Cell Substrate Adhesion ◽  
Different Cell Types

Regulating cell-substrate adhesion is of fundamental importance in biomaterial design and development. While an increasing number of approaches are being developed to quantify cell adhesion strength, only a fraction of these techniques provide measurements that are simple and sensitive at the living cell population level. In our previous study, the expression of adhesion-associated proteins in fibroblasts was found to change on ion-implanted silicone rubber; however, the actual effects of the modified surfaces on cellular mechanical properties remain to be probed. Here, we proposed a convenient method to compare the cell adhesion strength on various surfaces, for multiple adhesion periods and with different cell types. This method requires only common laboratory equipment. In addition, we introduced a new parameter, ECS50, which is appropriate for screening optimum centrifugal conditions when the cell affinity of the surface as a control is initially unknown. This parameter is helpful for further exploration of cell affinity on all the biomaterials of interest. The results demonstrate that this centrifugation assay is simple, efficient and adaptable in investigating the overall adhesion strength of living cells under various conditions, and therefore, it is a valid way to develop adhesion-controlled biointerface materials in the future.

scholarly journals Posttranslational modification and microtubule stability.

1987 ◽  
Vol 105 (5) ◽  
pp. 2167-2177 ◽  
Author(s):  
E Schulze ◽  
D J Asai ◽  
J C Bulinski ◽  
M Kirschner
Keyword(s):  
Posttranslational Modification ◽  
Cell Types ◽  
Fibroblast Cells ◽  
Kidney Cells ◽  
Microtubule Stability ◽  
Retinoblastoma Cells ◽  
Human Retinoblastoma ◽  
Different Cell Types ◽  
The Relationship ◽  
Total Network

We have probed the relationship between tubulin posttranslational modification and microtubule stability, using a variation of the antibody-blocking technique. In human retinoblastoma cells we find that acetylated and detyrosinated microtubules represent congruent subsets of the cells' total microtubules. We also find that stable microtubules defined as those that had not undergone polymerization within 1 h after injection of biotin-tubulin were all posttranslationally modified; furthermore dynamic microtubules were all unmodified. We therefore conclude that in these cells the stable, acetylated, and detyrosinated microtubules represent the same subset of the cells' total network. Posttranslational modification, however, is not a prerequisite for microtubule stability and vice versa. Potorous tridactylis kidney cells have no detectable acetylated microtubules but do have a sizable subset of stable ones, and chick embryo fibroblast cells are extensively modified but have few stable microtubules. We conclude that different cell types can create specific microtubule subsets by modulating the relative rates of posttranslational modification and microtubule turnover.

Models for positional signalling, the threefold subdivision of segments and the pigmentation pattern of molluscs

Development ◽  
1984 ◽  
Vol 83 (Supplement) ◽  
pp. 289-311
Author(s):  
Hans Meinhardt
Keyword(s):  
Pattern Formation ◽  
Long Range ◽  
Positional Information ◽  
Pigmentation Pattern ◽  
Intercalary Regeneration ◽  
Biological Pattern Formation ◽  
Appendage Formation ◽  
Triggering Events ◽  
A Chain ◽  
P Cells

Models of biological pattern formation are discussed. The regulatory features expected from the models are compared to those observed experimentally. It will be shown that: (i) Stable gradients appropriate to supply positional information can be produced by local autocatalysis and long-range inhibition. (ii) Spatially ordered sequences of differentiated cell states can emerge if these cell states mutually activate each other on long range but exclude each other locally. Segmentation results from the repetition of three such cell states, S, A and P (and not of only two, as is usually assumed). With a repetition of three states, each segment has a defined polarity. The confrontation of P cells and S cells lead to the formation of a segment border (…P/SAP/SAP/S…) while the A—P confrontation is a prerequisite for appendage formation. Mutations of Drosophila affecting larval segmentation are discussed in terms of this model. (iii) The two models for the generation of sequences of structures in space (positional information including interpretation versus mutual activation) lead to different predictions with respect to intercalary regeneration. This allows a distinction between the two models on the basis of experiments. (iv) The pigmentation patterns of certain molluscs emerge from a coupled oscillation of cells (that is, a lateral inhibition in time, instead of space). The oblique lines result from a chain of triggering events.

scholarly journals Anthracyclins Increase PUFAs: Potential Implications in ER Stress and Cell Death

Cells ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 1163
Author(s):  
David Balgoma ◽  
Fredrik Kullenberg ◽  
Carlemi Calitz ◽  
Maria Kopsida ◽  
Femke Heindryckx ◽  
...  
Keyword(s):  
Cell Death ◽  
Er Stress ◽  
Cell Lines ◽  
De Novo ◽  
Primary Liver Cancer ◽  
Cell Types ◽  
De Novo Lipogenesis ◽  
The Individual ◽  
Different Cell Types ◽  
The Relationship

Metabolic and personalized interventions in cancer treatment require a better understanding of the relationship between the induction of cell death and metabolism. Consequently, we treated three primary liver cancer cell lines with two anthracyclins (doxorubicin and idarubin) and studied the changes in the lipidome. We found that both anthracyclins in the three cell lines increased the levels of polyunsaturated fatty acids (PUFAs) and alkylacylglycerophosphoethanolamines (etherPEs) with PUFAs. As PUFAs and alkylacylglycerophospholipids with PUFAs are fundamental in lipid peroxidation during ferroptotic cell death, our results suggest supplementation with PUFAs and/or etherPEs with PUFAs as a potential general adjuvant of anthracyclins. In contrast, neither the markers of de novo lipogenesis nor cholesterol lipids presented the same trend in all cell lines and treatments. In agreement with previous research, this suggests that modulation of the metabolism of cholesterol could be considered a specific adjuvant of anthracyclins depending on the type of tumor and the individual. Finally, in agreement with previous research, we found a relationship across the different cell types between: (i) the change in endoplasmic reticulum (ER) stress, and (ii) the imbalance between PUFAs and cholesterol and saturated lipids. In the light of previous research, this imbalance partially explains the sensitivity to anthracyclins of the different cells. In conclusion, our results suggest that the modulation of different lipid metabolic pathways may be considered for generalized and personalized metabochemotherapies.

Neurosecretory innervation of the pituitary of the eels anguilla and conger II. The structure and innervation of the pars distalis at different stages of the life-cycle

1966 ◽  
Vol 250 (768) ◽  
pp. 329-342 ◽  
Keyword(s):  
Life Cycle ◽  
Endocrine Cells ◽  
Functional Relationship ◽  
Cell Types ◽  
Intermediate Lobe ◽  
Special Importance ◽  
Pars Distalis ◽  
Distinct Cell ◽  
Different Cell Types ◽  
The Relationship

A number of distinct cell types may be recognized in the pituitary of the eel at the level of ultra-­structure by reason of the specificity of the size and electron-density of the granules they contain. The size of the granules and changes in the different cell types at different stages of the life-cycle permit a tentative identification in terms of function. The pars distalis of the eel pituitary receives the greater part of its innervation from the nucleus lateralis tuberis by Type B neurosecretory fibres (Knowles 1965 a ), which do not stain with the so-called neurosecretory stains, but which nevertheless contain elementary neurosecretory vesicles. Type A, or classical, neurosecretory innervation is also present and seems to be of special importance at certain stages of the life-cycle. The possible function of these two forms of neurosecretory inner­- vation is discussed. The relationship between the intrinsic endocrine cells of the pars distalis and their neurosecretory innervation is fundamentally similar, at the level of ultrastructure, to that of the neuro-intermediate lobe. There are no direct contacts between the neurosecretory fibres and the intrinsic endocrine cells, but the proximity of the fibre terminals ( ca. 2000 to 4000 A) to endocrine cells indicates a functional relationship between these two elements of the pituitary of the eel.

Heterogeneity of acid secretion induced by carbachol and histamine along the gastric gland axis and its relationship to [Ca2+]i

2008 ◽  
Vol 295 (4) ◽  
pp. G671-G681 ◽  
Author(s):  
Jose Francisco Perez-Zoghbi ◽  
Adriana Mayora ◽  
Marie Christine Ruiz ◽  
Fabian Michelangeli
Keyword(s):  
Acid Secretion ◽  
Slow Component ◽  
Gastric Gland ◽  
Cell Types ◽  
Gastric Fluid ◽  
Cholinergic Stimulation ◽  
Gastric Glands ◽  
Alkali Ions ◽  
Different Cell Types ◽  
The Relationship

The gastric glands of the mammalian fundic mucosa are constituted by different cell types. Gastric fluid is a mixture of acid, alkali, ions, enzymes, and mucins secreted by parietal, chief, and mucous cells. We studied activation of acid secretion using LysoSensor Yellow/Blue in conjunction with fluo 3 to measure changes in pH and Ca2+ in isolated rabbit gastric glands. We evidenced a spatial heterogeneity in the amplitude of acid response along the gland axis under histamine and cholinergic stimulation. Carbachol induced a transitory pH increase before acidification. This relative alkalinization may be related to granule release from other cell types. Omeprazole inhibited the acid component but not the rise in pH. Histamine stimulated acid secretion without increase of lumen pH. We studied the relationship between Ca2+ release and/or entry and H+ secretion in glands stimulated by carbachol. Ca2+ release was associated with a fast and transient components of H+ secretion. We found a linear relationship between Ca2+ release and H+ secretion. Ca2+ entry was associated with a second slow and larger component of acid secretion. The fast component may be the result of activation of Cl− and K+ channels and hence H+/K+ pumps already present in the membrane, whereas the slow component might be associated with translocation of H+/K+ pumps to the canaliculi. In conclusion, with cholinergic stimulation, gastric glands secrete a mixture of acid and other product(s) with a pH above 4.2, both triggered by Ca2+ release. Maintenance of acid secretion depends on Ca2+ entry and perhaps membrane fusion.

Models for positional signalling with application to the dorsoventral patterning of insects and segregation into different cell types

Development ◽  
1989 ◽  
Vol 107 (Supplement) ◽  
pp. 169-180 ◽  
Author(s):  
Hans Meinhardt
Keyword(s):  
Positional Information ◽  
Cell Types ◽  
Ventral Side ◽  
Homogeneous Distribution ◽  
Dorsoventral Patterning ◽  
High Concentration ◽  
Low Concentrations ◽  
Homogeneous Cell ◽  
Pattern Forming ◽  
Different Cell Types

Models of pattern formation and possible molecular realizations are discussed and compared with recent experimental observations. In application to the dorsoventral patterning of insects, it is shown that a superposition of two pattern-forming reactions is required. The first system generates the overall dorsoventral polarity of the oocyte, the second generates the positional information proper with a stripe-like region of high concentration along the ventral side of the embryo. A single reaction would be insufficient since the two reactions require different parameters. The model accounts for the orientation of the DV axes of the oocytes in the ovary of Musca domestica and Sarcophaga, independent of the DV axis of the mother, for the formation of several ventral furrows in the absence of the primary gurken/torpedo system in Drosophila, as well as for the good size regulation of the dorsoventral axis as observed in some insect species. Segregation of a homogeneous cell population into different cell types requires autocatalytic processes that saturate at relatively low concentrations and nondiffusible substances responsible for the autocatalytic feedback loops. Thus, these loops can be realized directly on the gene level via their gene products, for instance, by the mutual repression of two genes. A balance of the two cell types is achieved by a long-ranging substance interfering with the self-enhancing process. This substance is expected to have a more or less homogeneous distribution. This model accounts for the reestablishment of the correct proportion after an experimental interference and the change of determination after transplantation. Applications to the segregation of prestalk and prespore cells in Dictyostelium and of neuroblast cells from the ventral ectoderm in Drosophila are provided.

Study of the Molecular Architecture of Keratin Filaments by Electron Microscopy

1982 ◽  
Vol 40 ◽  
pp. 118-119
Author(s):  
U. Aebi ◽  
P. Rew ◽  
T.-T. Sun
Keyword(s):  
Electron Microscopy ◽  
Structural Organization ◽  
Cell Types ◽  
Structural Features ◽  
Molecular Architecture ◽  
The Past ◽  
Keratin Filaments ◽  
Different Types ◽  
10 Nm Filaments ◽  
Different Cell Types

Various types of intermediate-sized (10-nm) filaments have been found and described in many different cell types during the past few years. Despite the differences in the chemical composition among the different types of filaments, they all yield common structural features: they are usually up to several microns long and have a diameter of 7 to 10 nm; there is evidence that they are made of several 2 to 3.5 nm wide protofilaments which are helically wound around each other; the secondary structure of the polypeptides constituting the filaments is rich in ∞-helix. However a detailed description of their structural organization is lacking to date.

Processing and Characterization of Recombinant von Willebrand Factor Expressed in Different Cell Types Using a Vaccinia Virus Vector

1992 ◽  
Vol 67 (01) ◽  
pp. 154-160 ◽  
Author(s):  
P Meulien ◽  
M Nishino ◽  
C Mazurier ◽  
K Dott ◽  
G Piétu ◽  
...  
Keyword(s):  
Vaccinia Virus ◽  
Von Willebrand Factor ◽  
Human Fibroblasts ◽  
Active Form ◽  
Cell Types ◽  
Biologically Active ◽  
L Cells ◽  
Von Willebrand ◽  
Different Cell Types ◽  
Willebrand Factor

SummaryThe cloning of the cDNA encoding von Willebrand factor (vWF) has revealed that it is synthesized as a large precursor (pre-pro-vWF) molecule and it is now clear that the prosequence or vWAgll is responsible for the intracellular multimerization of vWF. We have cloned the complete vWF cDNA and expressed it using a recombinant vaccinia virus as vector. We have characterized the structure and function of the recombinant vWF (rvWF) secreted from five different cell types: baby hamster kidney (BHK), Chinese hamster ovary (CHO), human fibroblasts (143B), mouse fibroblasts (L) and primary embryonic chicken cells. Forty-eight hours after infection, the quantity of vWF antigen found in the cell supernatant varied from 3 to 12 U/dl depending on the cell type. By SDS-agarose gel electrophoresis, the percentage of high molecular weight forms of vWF varied from 39 to 49% relative to normal plasma for BHK, CHO, 143B and chicken cells but was less than 10% for L cells. In all cell types, the two anodic subbands of each multimer were missing. The two cathodic subbands were easily detected only in BHK and L cells. By SDS-PAGE of reduced samples, pro-vWF was present in similar quantity to the fully processed vWF subunit in L cells, present in moderate amounts in BHK and CHO and in very low amounts in 143B and chicken cells. rvWF from all cells bound to collagen and to platelets in the presence of ristocetin, the latter showing a high correlation between binding efficiency and degree of multimerization. rvWF from all cells was also shown to bind to purified FVIII and in this case binding appeared to be independent of the degree of multimerization. We conclude that whereas vWF is naturally synthesized only by endothelial cells and megakaryocytes, it can be expressed in a biologically active form from various other cell types.

Role of Transcriptional Read-Through in PRE Activity in Drosophila melanogaster

Acta Naturae ◽  
2016 ◽  
Vol 8 (2) ◽  
pp. 79-86 ◽  
Author(s):  
P. V. Elizar’ev ◽  
D. V. Lomaev ◽  
D. A. Chetverina ◽  
P. G. Georgiev ◽  
M. M. Erokhin
Keyword(s):  
Dna Sequences ◽  
Cell Types ◽  
Transcription Terminator ◽  
Response Elements ◽  
Polycomb Response Elements ◽  
The Individual ◽  
Multicellular Organisms ◽  
Different Cell Types ◽  
Main Factor

Maintenance of the individual patterns of gene expression in different cell types is required for the differentiation and development of multicellular organisms. Expression of many genes is controlled by Polycomb (PcG) and Trithorax (TrxG) group proteins that act through association with chromatin. PcG/TrxG are assembled on the DNA sequences termed PREs (Polycomb Response Elements), the activity of which can be modulated and switched from repression to activation. In this study, we analyzed the influence of transcriptional read-through on PRE activity switch mediated by the yeast activator GAL4. We show that a transcription terminator inserted between the promoter and PRE doesnt prevent switching of PRE activity from repression to activation. We demonstrate that, independently of PRE orientation, high levels of transcription fail to dislodge PcG/TrxG proteins from PRE in the absence of a terminator. Thus, transcription is not the main factor required for PRE activity switch.

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