scholarly journals Rapid patterning and zonal differentiation in a two-dimensionalDictyosteliumcell mass: the role of pH and ammonia

2002 ◽  
Vol 205 (17) ◽  
pp. 2583-2590
Author(s):  
Satoshi Sawai ◽  
Takashi Hirano ◽  
Yasuo Maeda ◽  
Yasuji Sawada
Keyword(s):  
Cell Differentiation ◽  
Outer Zone ◽  
Cell Types ◽  
Reaction Scheme ◽  
Weak Acid ◽  
Weak Base ◽  
Cytosolic Ph ◽  
Different Cell Types ◽  
Plasma Membrane Proton Pump

SUMMARYRecently it was demonstrated that a rapidly forming, self-organizing pattern that emerges within two-dimensional Dictyostelium discoideumcell cultures could later give rise to stripes of distinct zones, each comprising different cell types. Here we report physiological aspects of the initial rapid patterning and its relationship to cell differentiation. We found that as the temperature is lowered the characteristic length of the pattern increases. From this we estimated the activation energy of the patterning kinetics. Fluorescence of fluorescein-conjugated dextran revealed that the cytosolic pH of cells in the inside zone becomes lower than that in the outer zone facing the air. The patterning could be inhibited by addition of the plasma-membrane proton pump inhibitors diethystilbestrol (DES) or miconazole. Preincubation of cells with weak acid delayed the timing of the patterning, whereas weak base hastened it. A pH-indicating dye revealed localized accumulation of ammonia in the extracellular space. These results suggest that gradients of secreted metabolites may be directly responsible for the rapid patterning and its consequence on cell differentiation in a confined geometrical situation. Possible diffusible candidate molecules and a reaction scheme coupled to the imposed oxygen gradient are discussed.

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.

Effects of bafilomycin A1 on cytosolic pH of sheep alveolar and peritoneal macrophages: evaluation of the pH-regulatory role of plasma membrane V-ATPases.

1995 ◽  
Vol 198 (8) ◽  
pp. 1711-1715 ◽  
Author(s):  
T A Heming ◽  
D L Traber ◽  
F Hinder ◽  
A Bidani
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Initial Rate ◽  
Cell Types ◽  
Peritoneal Macrophages ◽  
Bafilomycin A1 ◽  
Atpase Inhibitor ◽  
Cytosolic Ph ◽  
Phi Regulation

The role of plasma membrane V-ATPase activity in the regulation of cytosolic pH (pHi) was determined for resident alveolar and peritoneal macrophages (m theta) from sheep. Cytosolic pH was measured using 2',7'-biscarboxyethyl-5,6-carboxyfluorescein (BCECF). The baseline pHi of both cell types was sensitive to the specific V-ATPase inhibitor bafilomycin A1. Bafilomycin A1 caused a significant (approximately 0.2 pH units) and rapid (within seconds) decline in baseline pHi. Further, bafilomycin A1 slowed the initial rate of pHi recovery (dpHi/dt) from intracellular acid loads. Amiloride had no effects on baseline pHi, but reduced dpHi/dt (acid-loaded pHi nadir < 6.8) by approximately 35%. Recovery of pHi was abolished by co-treatment of m theta with bafilomycin A1 and amiloride. These data indicate that plasma membrane V-ATPase activity is a major determinant of pHi regulation in resident alveolar and peritoneal m theta from sheep. Sheep m theta also appear to possess a Na+/H+ exchanger. However, Na+/H+ exchange either is inactive or can be effectively masked by V-ATPase-mediated H+ extrusion at physiological pHi values.

An Overview of the Latest Applications of Platelet-Derived Microparticles and Nanoparticles in Medical Technology 2010-2020

2021 ◽  
Vol 21 ◽  
Author(s):  
Tahereh Zadeh Mehrizi
Keyword(s):  
Drug Delivery ◽  
Cell Types ◽  
Current Status ◽  
Target Cells ◽  
Interesting Point ◽  
Large Size ◽  
Review Study ◽  
Cellular Pathways ◽  
Different Cell Types

: Today, Platelets and platelet-derived nanoparticles and microparticles have found many applications in nanomedical technology. The results of our review study show that no article has been published in this field to review the current status of applications of these platelet derivatives so far. Therefore, in present study, our goal is to compare the applications of platelet derivatives and review their latest status between 2010 and 2020 to present the latest findings to researchers. A very interesting point about the role of platelet derivatives is the presence of molecules on their surface which makes them capable of hiding from the immune system, reaching different target cells, and specifically attaching to different cell types. According to the results of this study, most of their applications include drug delivery, diagnosis of various diseases, and tissue engineering. However, their application in drug delivery is limited due to heterogeneity, large size, and the possibility of interference with cellular pathways in microparticles derived from other cells. On the other hand, platelet nanoparticles are more controllable and have been widely used for drug delivery in treatment of cancer, atherosclerosis, thrombosis, infectious diseases, repair of damaged tissue, and photothermal therapy. The results of this study show that platelet nanoparticles are more controllable than platelet microparticles and have a higher potential for use in medicine.

Measurements of cell adhesion

Development ◽  
1973 ◽  
Vol 30 (2) ◽  
pp. 499-509
Author(s):  
Janet E. Hornby
Keyword(s):  
Cell Types ◽  
Random Motion ◽  
Chick Embryos ◽  
Collision Efficiency ◽  
20 Nm ◽  
Kidney Liver ◽  
Different Cell Types ◽  
Laminar Shear ◽  
Lyophobic Sols

Cell suspensions were prepared from the kidney, liver and heart of chick embryos of 5 or 8 days of incubation, and from the limb-buds of chick embryos of 5, 6, 7, 8 or 9 days of incubation. When these suspensions were aggregated under laminar shear in a Couette viscometer or random motion in a reciprocating shaker they obeyed the theoretical relationships derived for flocculating lyophobic sols. The values of the collision efficiency found for the different cell types under given conditions were used to calculate the force of interaction between cells of each type. The force of interaction ranged between 9 × 10−11 N (8-day heart) and 3 × 10−9 N (8-day liver). The forces of interaction between cells appear to be responsible for aligning the membranes of adjacent cells with a 10–20 nm gap. It is possible to arrange the cell types in a hierarchy based on the forces of interaction between them. The possible role of these forces in cell specificity is considered.

scholarly journals Precancerous niche (PCN), a product of fibrosis with remodeling by incessant chronic inflammation

4open ◽  
2019 ◽  
Vol 2 ◽  
pp. 11 ◽  
Author(s):  
Björn L.D.M. Brücher ◽  
Ijaz S. Jamall
Keyword(s):  
Extracellular Matrix ◽  
Chronic Inflammation ◽  
Genetic Material ◽  
Cell Communication ◽  
Cell Types ◽  
Complex Signaling ◽  
Different Cell Types ◽  
Multiple Signaling ◽  
Extracellular Environment

Fibroblasts are actively involved in the creation of the stroma and the extracellular matrix which are important for cell adhesion, cell–cell communication, and tissue metabolism. The role of fibrosis in carcinogenesis can be examined by analogy to tissues of various cancers. The orchestration of letters in the interplay of manifold components with signaling and crosstalk is incompletely understood but available evidence suggests a hitherto underappreciated role for fibrosis in carcinogenesis. Complex signaling and crosstalk by pathogenic stimuli evoke persistent subclinical inflammation, which in turn, results in a cascade of different cell types, ubiquitous proteins and their corresponding enzymes, cytokine releases, and multiple signaling pathways promoting the onset of fibrosis. There is considerable evidence that the body's attempt to resolve such a modified extracellular environment leads to further disruption of homeostasis and the genesis of the precancerous niche as part of the six-step process that describes carcinogenesis. The precancerous niche is formed and can be understood to develop as a result of (1) pathogenic stimulus, (2) chronic inflammation, and (3) fibrosis with alterations of the extracellular matrix, stromal rigidity, and mechano-transduction. This is why carcinogenesis is not just a process of aberrant cell growth with damaged genetic material but the role of the PCN in its entirety reveals how carcinogenesis can occur without invoking the need for somatic mutations.

scholarly journals Pancreatic α and β cells are globally phase-locked

2020 ◽  
Author(s):  
Huixia Ren ◽  
Yanjun Li ◽  
Chengsheng Han ◽  
Yi Yu ◽  
Bowen Shi ◽  
...  
Keyword(s):  
Islet Cells ◽  
Cell Types ◽  
Phase Oscillators ◽  
Β Cells ◽  
Oscillation Modes ◽  
Different Types ◽  
Glucagon And Insulin ◽  
Different Cell Types

ABSTRACTThe Ca2+ modulated pulsatile secretions of glucagon and insulin by pancreatic α and β cells play a key role in glucose metabolism and homeostasis. However, how different types of islet cells couple and coordinate via paracrine interactions to produce various Ca2+ oscillation patterns are still elusive. By designing a microfluidic device to facilitate long-term recording of islet Ca2+ activity at single cell level and simultaneously identifying different cell types in live islet imaging, we show heterogeneous but intrinsic Ca2+ oscillation patterns of islets upon glucose stimulation. The α and β cells oscillate in antiphase and are globally phase locked to various phase delays, causing fast, slow or mixed oscillations. A mathematical model of coupled phase oscillators quantitatively agrees with experiments and reveals the essential role of paracrine regulations in tuning the oscillation modes. Our study highlights the importance of cell-cell interactions to generate stable but tunable islet oscillation patterns.

Immunofluorescence studies on deoxyribonuclease from mouse teratocarcinoma cells during cell differentiation

Development ◽  
1979 ◽  
Vol 54 (1) ◽  
pp. 37-46
Author(s):  
L. Soriano ◽  
D. Paulin
Keyword(s):  
Cell Differentiation ◽  
Embryonal Carcinoma ◽  
Cell Types ◽  
Carcinoma Cells ◽  
Nuclear Staining ◽  
Fluorescence Staining ◽  
Immunofluorescence Method ◽  
Teratocarcinoma Cells ◽  
Different Cell Types ◽  
Mouse Teratocarcinoma

Specific anti-DNase-I IgG have been used to detect deoxyribonuclease in teratocarcinoma cells by an indirect immunofluorescence method. All the cells studied show fluorescence staining. However, the patterns are quite different in embryonal carcinoma cells (amorphous cytoplasmic fluorescence and absence of nuclear staining) as compared to differentiated cell lines (diffuse, bright granular nuclear and fibrillar cytoplasmic fluorescence). It is possible by this method to distinguish different cell types derived from the same origin. Deoxyribonuclease from teratocarcinoma cells can therefore be considered as a marker of cell differentiation in this system.

Hedgehog organises the pattern and polarity of epidermal cells in the Drosophila abdomen

Development ◽  
1997 ◽  
Vol 124 (11) ◽  
pp. 2143-2154 ◽  
Author(s):  
G. Struhl ◽  
D.A. Barbash ◽  
P.A. Lawrence
Keyword(s):  
Anterior Part ◽  
Posterior Part ◽  
Cell Types ◽  
Epidermal Cells ◽  
Concentration Gradients ◽  
Cell Pattern ◽  
Different Cell Types ◽  
Adult Drosophila

The abdomen of adult Drosophila, like that of other insects, is formed by a continuous epithelium spanning several segments. Each segment is subdivided into an anterior (A) and posterior (P) compartment, distinguished by activity of the selector gene engrailed (en) in P but not A compartment cells. Here we provide evidence that Hedgehog (Hh), a protein secreted by P compartment cells, spreads into each A compartment across the anterior and the posterior boundaries to form opposing concentration gradients that organize cell pattern and polarity. We find that anteriorly and posteriorly situated cells within the A compartment respond in distinct ways to Hh: they express different combinations of genes and form different cell types. They also form polarised structures that, in the anterior part, point down the Hh gradient and, in the posterior part, point up the gradient - therefore all structures point posteriorly. Finally, we show that ectopic Hh can induce cells in the middle of each A compartment to activate en. Where this happens, A compartment cells are transformed into an ectopic P compartment and reorganise pattern and polarity both within and around the transformed tissue. Many of these results are unexpected and lead us to reassess the role of gradients and compartments in patterning insect segments.

Infection and immunity

2021 ◽  
pp. 853-920
Keyword(s):  
Major Histocompatibility Complex ◽  
Immune System ◽  
Cell Types ◽  
The Body ◽  
Acquired Immunity ◽  
Histocompatibility Complex ◽  
Repair Mechanisms ◽  
Antigen Presenting ◽  
Different Cell Types

‘Infection and immunity’ considers the response of the body to pathogens, such as bacteria, viruses, prions, fungi, and parasites, which are discussed in terms of their nature, life cycle, and modes of infection. The role of the immune system in defence against infection is discussed, including innate and adaptive (acquired) immunity, antigens, the major histocompatibility complex, and the different cell types involved (antigen-presenting cells, T-cells, and B-cells). The mechanisms and cellular basis of inflammation are considered, as are post-infection repair mechanisms, and pathologies of the immune system such as hypersensitivity, autoimmunity and transplantations, and immunodeficiency (both primary and secondary to other diseases).

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