Effect of Solution Osmotic Pressure on Cell Fusion by Poly(Ethylene Glycol)

1995 ◽  
Vol 10 (1) ◽  
pp. 14-27 ◽  
Author(s):  
Naoki Nakajima ◽  
Yoshito Ikada
Keyword(s):  
Membrane Fusion ◽  
Osmotic Pressure ◽  
Cell Fusion ◽  
Culture Medium ◽  
Morphological Changes ◽  
Cell Swelling ◽  
Cell Incubation ◽  
Peg Treatment ◽  
Poly Ethylene ◽  
Osmotic Pressure Difference

Effects of the osmotic pressure of culture medium on the membrane fusion of L929 cells in the monolayer state were investigated using polyethylene glycol) (PEG) with the molecular weight of 3,000 at various concentrations at phosphate buffer saline (PBS). Cell incubation for fusion was performed via three stages; (1) incubation before PEG treatment (preincubation), (2) incubation in the presence of PEG (PEG incubation), and (3) incubation after PEG treatment (postincubation). The PBS concentrations half that of a isotonic solution in the pre- and postincubation stages significantly accelerated the membrane fusion, whereas cell treatment at more hypotonic or hypertonic concentrations of PBS suppressed cell fusion. This result was explained in terms of cell swelling and shrinking induced by the osmotic pressure difference, because such cell morphological changes actually occurred when the PBS concentration was varied from the isotonicity. In contrast, almost no effect of osmotic pressure on cell fusion was observed if PEG was present in the culture medium at 40 w/w% concentration, regardless of the PBS concentration.

Studies of membrane fusion. VI. Mechanism of the membrane fusion and cell swelling stages of Sendai virus-mediated cell fusion

1980 ◽  
Vol 43 (1) ◽  
pp. 103-118
Author(s):  
S. Knutton
Keyword(s):  
Membrane Fusion ◽  
Cell Fusion ◽  
Sendai Virus ◽  
Freeze Fracture ◽  
Viral Envelope ◽  
Cell Swelling ◽  
Fusion Event ◽  
Virus Envelope ◽  
Membrane Rupture ◽  
Membrane Tubules

The membrane fusion and cell swelling stages of Sendai virus-mediated cell-cell fusion have been studied by thin-section and freeze-fracture electron microscopy. Sites of membrane fusion have been detected in human erythrocytes arrested at the membrane fusion stage of cell fusion and in virtually all cases a fused viral envelope or envelope components has been identified thus providing further direct evidence that cell-viral envelope-cell bridge formation is the membrane fusion event in Sendai virus-induced cell fusion. Radial expansion of a single virus bridge connecting 2 cells is sufficient to produce a fused cell. Membrane redistribution which occurs during this cell swelling stage of the fusion process is often accompanied by the formation of a system of membrane tubules in the plane of expansion of the virus bridge. The tubules originate from points of fusion between the bridging virus envelope and the erythrocyte membrane and also expand radially as cells swell. Ultimately membrane rupture occurs and the tubules appear to break down as small vesicles. When previously observed in cross-sectioned cells these membrane tubules were interpreted as sites of direct membrane fusion. The present study indicates that this interpretation is incorrect and shows that the tubules are generated subsequent to membrane fusion when 2 cells connected by a virus bridge are induced to swell. A mechanism to explain the formation of this system of membrane tubules is proposed.

Studies of membrane fusion. V. Fusion of erythrocytes with non-haemolytic Sendai virus

1979 ◽  
Vol 36 (1) ◽  
pp. 85-96
Author(s):  
S. Knutton
Keyword(s):  
Membrane Fusion ◽  
Cell Fusion ◽  
Erythrocyte Membrane ◽  
Sendai Virus ◽  
Lateral Diffusion ◽  
Viral Envelope ◽  
Cell Swelling ◽  
Viral Membrane ◽  
Cytoplasmic Bridges ◽  
Viral Envelopes

The fusion of human erythrocytes with non-haemolytic ‘1-day’ Sendai virus has been studied by electron microscopy. The mechanism of viral envelope-cell fusion is the same as that described previously for haemolytic ‘3-day’ Sendai virus except that fusion is frequently arrested at an initial stage when 2 segments of smooth linear viral membrane fuse and become incorporated into the erythrocyte membrane. After longer periods of incubation at 37 degrees C, in addition to many partly fused virus particles, long (up to 4 micrometer) lengths of smooth linear viral membrane are seen within the erythrocyte membrane which arise by linear aggregation of shorter (approximately 0.25 micrometer long) segments of smooth linear membrane derived from individual fused viral envelopes. Cell-Cell fusion, as a result of the fusion of a viral envelope with 2 adjacent erythrocytes also occurs but, in the absence of cell swelling, fusion is arrested at this stage with cells joined by one (or more) small cytoplasmic bridges. Typical fused cells are produced if such cells are swollen with hypotonic buffer. These observations provide further evidence that membrane fusion and cell swelling are distinct events in cell fusion and that cell swelling is the driving force both for completing the incorporation of the viral envelope into the cell membrane and for expanding cells connected by small cytoplasmic bridges to form spherical fused cells. Little lateral diffusion of viral envelope components occurs in the absence of cell swelling; in fact, some aggregation of components occurs. Comparison with previous studies using haemolytic ‘3-day’ Sendai virus suggests that virally induced cell swelling perturbs membrane structure so as to allow the rapid lateral diffusion of integrated viral envelope components.

Membrane alterations and other morphological features associated with polyethylene glycol-induced cell fusion

1979 ◽  
Vol 40 (1) ◽  
pp. 63-75
Author(s):  
J.M. Robinson ◽  
D.S. Roos ◽  
R.L. Davidson ◽  
M.J. Karnovsky
Keyword(s):  
Polyethylene Glycol ◽  
Cell Surface ◽  
Membrane Fusion ◽  
Cell Fusion ◽  
Deleterious Effect ◽  
Freeze Fracture ◽  
Neighbouring Cell ◽  
Monolayer Cultures ◽  
Peg Treatment ◽  
Entire Cell

Polyethylene glycol (PEG) induces rapid fusion of LM cells. Membrane fusion, as detected by formation of pentalaminar membrane arrays, occurs as early as 1 min after PEG treatment. The entire cell surface arrears to be capable of fusion since fusion occurs in regions where pseudopodia make contact with each other or with a neighbouring cell body and also in areas where cells are in contact along their entire periphery. Cytoskeletal components showed no apparent deleterious effect from PEG treatment or subsequent cell fusion as determined by thin-section EM. Freeze-fracture of monolayer cultures reveals a thermotropic rearrangement of intramembranous particles following PEG treatment.

Are osmotic forces involved in influenza virus-cell fusion?

1988 ◽  
Vol 8 (1) ◽  
pp. 55-64 ◽  
Author(s):  
Cornelia Pritzen ◽  
Andreas Herrmann
Keyword(s):  
Influenza Virus ◽  
Cell Membrane ◽  
Membrane Fusion ◽  
Osmotic Pressure ◽  
Cell Fusion ◽  
Influenza Viruses ◽  
Fusion Process ◽  
Osmotic Swelling ◽  
Resealed Ghosts ◽  
Kinetics Of

The kinetics of the fusion process of unsealed and resealed erthyrocyte ghosts with influenza virus (A/PR8/34, A/Chile 1/83), were measured under hypotonic, isotonic and hypertonic conditions using a recently developed fluorescence assay (Hoekstra et al. (1984) Biochemistry23:5675–5681]. No correlation between the external osmotic pressure and kinetics and extent of fusion was observed. Influenza viruses fuse as effectively with unsealed ghosts as with resealed ghosts. It is concluded that osmotic forces as well as osmotic swelling of cells are not necessary for virus-cell membrane fusion.

Luminescence of polymer electrolytes containing europium (III)

1995 ◽  
Vol 10 (1) ◽  
pp. 202-210 ◽  
Author(s):  
L.D. Carlos ◽  
M. Assunção ◽  
L. Alcácer
Keyword(s):  
Polymer Electrolytes ◽  
Morphological Changes ◽  
Emission Spectra ◽  
Emission Lines ◽  
Hypersensitive Transition ◽  
Polymeric Matrices ◽  
Poly Ethylene Oxide ◽  
Poly Ethylene ◽  
Poly Propylene ◽  
Europium Concentration

The excitation and emission spectra of polymeric matrices—poly(ethylene oxide), PEO, and poly(propylene oxide), PPO—containing different concentrations of EuBr3 were recorded and most of the observed transitions identified. The Stark components of the 7F0−4, 5D0 levels and the corresponding barycenters were calculated based on the emission lines assignment to the 5D0,1 → 7F0−4 transitions. The spectra were discussed in terms of a C2v local Eu3+ coordination. The relative intensity of the 5D0 → 7F2 hypersensitive transition was related to the electrolyte morphological changes due to increasing europium concentration.

Studies of membrane fusion. I. Paramyxovirus-induced cell fusion, a scanning electron-microscope study

1977 ◽  
Vol 28 (1) ◽  
pp. 179-188
Author(s):  
S. Knutton ◽  
D. Jackson ◽  
M. Ford
Keyword(s):  
Cell Surface ◽  
Cell Fusion ◽  
Hela Cells ◽  
Cell Swelling ◽  
Cell Contact ◽  
Cell Agglutination ◽  
Scanning Electron Microscope Study ◽  
Virus Particles ◽  
Scanning Electron ◽  
Cell Cell

Fusion of erythrocytes and HeLa cells with Sendai and Newcastle disease viruses has been studied by scanning electron microscopy. Most virus particles are spherical but vary in diameter from approximately 200 to approximately 600 nm. At 4 degrees C virus particles bind randomly to the cell surface and at high cell densities cross-linking of adjacent cells by virus particles results in cell agglutination. Cell-cell fusion takes place when the agglutinated cell suspension is warmed to 37 degrees C. Fusion is initiated at sites of cell-cell contact and is accompanied in all cases by cell swelling. In the case of suspension HeLa cells, virally mediated cell swelling involves an ‘unfolding’ of cell surface microvilli and results in the formation of smooth-surfaced single or fused cells. With erythrocytes, swelling results in haemolysis. There is a dramatic reduction in the numbers of virus particles bound to cells following fusion.

scholarly journals Effect of Lignocaine Concentration on Human Fibroblasts Growth in Eyes Undergoing Trabeculectomy: An in vitro Study

2018 ◽  
Vol 3 (3) ◽  
pp. 1-10 ◽  
Author(s):  
Madhuravasal Krishnan Janani ◽  
Venkatakrishnan Jaichandran ◽  
Hajib Narahari Rao Madhavan ◽  
Lingam Vijaya ◽  
Ronnie Jacob George ◽  
...  
Keyword(s):  
Culture Medium ◽  
In Vitro Model ◽  
Morphological Changes ◽  
Human Fibroblasts ◽  
Annexin V ◽  
In Vitro Study ◽  
Tenon’S Capsule ◽  
Tenon's Capsule ◽  
Vitro Model

Purpose: To evaluate the effect of lignocaine on growth and apoptosis indication of primary human Tenon’s capsule fibroblast (HTFs) in an in vitro model. Patients and Methods: Tenon’s capsule tissue obtained from patients undergoing trabeculectomy were grown in cell culture medium. The effect of different concentrations of lignocaine (0.5, 1.0, 1.5, and 2%) on the morphology and growth of the fibroblasts was studied using microscopy, cell viability, and proliferation assay, and apoptosis was detected using the FITC Annexin V Apoptosis Kit. Results: Morphological changes similar to those of apoptotic cells, including cytoplasmic vacuolation, shrinkage, and rounding were visualized in the cells treated with concentrations greater than 1.0% (i.e., 1.5, 2.0%). Though proliferation inhibition was found with all four concentrations (0.5–2.0%), the viability of cells decreased from 1.0% lignocaine. Conclusion: 0.5% lignocaine prevents proliferation of fibroblasts without causing apoptosis in vitro.

scholarly journals Experimental conversion of virulent RH Toxoplasma gondii tachyzoites in vitro

2001 ◽  
Vol 7 (1-2) ◽  
pp. 181-188
Author(s):  
N. A. Hammouda ◽  
I. R. Ibrahim ◽  
E. D. Elkerdany ◽  
A. Y. Negm ◽  
S. R. Allam
Keyword(s):  
Toxoplasma Gondii ◽  
Culture Medium ◽  
Dna Analysis ◽  
Morphological Changes ◽  
Control Group ◽  
Image Analyser

We aimed to induce conversion of RH-stain tachyzoites to bradyzoites by changing the pH of the culture medium. Alkalization of the medium to pH 8 induced morphological changes in the cultured tachyzoites. The majority of the organism increased in size and changed from a regular crescent shape to a rounded or ovoid shape. Cyst-like structures were formed. Using a computerized image analyser, significant differences in the size of the whole organisms and in their nuclei were observed compared to the control group. The converted organisms also showed significant differences from the control group by quantitative DNA analysis, and did not infect mice.

Paracrystalline bundles of large tubules, induced in vitro by Mebendazole in Cysticercus cellulosae

Parasitology ◽  
1981 ◽  
Vol 83 (3) ◽  
pp. 513-518 ◽  
Author(s):  
J. P. Laclette ◽  
Marie Therese Merchant ◽  
Kaethe Willms ◽  
L. Cañedo
Keyword(s):  
Electron Microscopy ◽  
Culture Medium ◽  
Morphological Changes ◽  
Bladder Wall ◽  
Secretory Cells ◽  
External Diameter ◽  
Nematode Larvae ◽  
Transmission Electron ◽  
Cysticercus Cellulosae

SUMMARYThe effect of the anthelmintic Mebendazole on Cysticercus cellulosae maintained in culture medium was studied by transmission electron microscopy. In addition to the well-known morphological changes induced by Mebendazole in other cestode and nematode larvae, it also induced the cytoplasmic appearance of paracrystalline bundles in the secretory cells of the bladder wall. These bundles were formed by groups of large parallel tubules arranged in a hexagonal-like pattern. The tubules, which had an external diameter of about 50 nm and a length that might exceed 5 μm, were surrounded by a matrix and a distance between neighbouring tubules of 80–120 nm centre to centre was estimated. The tubules were stable to colchicine and low temperature. The temporary appearance of bundles is described and some alternative explanations on their origin are advanced.

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