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Results for “cell fusion”

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At least 37 records · Page 2Linked to original sources
PubMed1979

Effect of certain inhibitors of glycoprotein synthesis on cell fusion induced by vesicular stomatitis virus.

The effect of certain metabolic inhibitors on the fusion of BHK-21 cells induced by vesicular stomatitis virus (VSV) was studied. The polykaryocyte formation in infected cells and virus growth were inhibited by 2-deoxy-D-glucose and D-glucosamine. Host-cell proteins synthesis was suppressed profoundly in both BHK-21-KB and B cells infected with VSV. On the other hand, glycoprotein synthesis was significantly enhanced during the polykaryocyte formation in BHK-21-KB cells, while it was suppressed in BHK-21-B cells which were not sensitive to cell fusion by VSV.

Animals↗
PubMed1979

[Modification of a method to study cell fusion induced in vitro by viruses].

A studying method of viruses induced cell-fusion is described, using monolayers of Vero monkey cells. Nature and density of cells and infection multiplicity are studied. The sensibility is equal to 4 hemagglutining units of Sendaï and accuracy about +/- 3 % of polykaryocytosis. Quantification. comparison and kinetics study of cell-fusion are allowed by this method which may lead to systematic and routine exploration of cell-fusion ability of biological extracts from slow degenerative diseases of the human central nervous system.

Animals↗
PubMed1979

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

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.

Animals↗
PubMed1979

Cell fusion induced by invertebrate virus. Brief report.

Inoculation of invertebrate cells with Chilo Iridescent Virus (CIV) leads rapidly to massive formation of syncytia. This polykaryocytosis occurs at a high multiplicity of infection and does not require viral genome expression. Thus, cell fusion appears in non permissive conditions, and CIV suspensions rendered non infections by UV irradiation still retain the ability to produce rapid and extensive cell fusion. In the same way, some polykaryocytes could be detected in vertebrate cells (CV1 cell line). However, this process is more effective and faster in invertebrate cell systems.

Aedes↗
PubMed1978

Electron microscopic study of measles virus infection: cell fusion and hemadsorption.

Virus-induced cell fusion has been studied after infection of Vero cells with measles virus. Scanning and transmission electron microscopy were combined with immunoperoxidase labeling of measles antigens to correlate viral production and distribution of virus-induced erythrocyte binding sites with progress of fusion. Release of infectious virus started before syncytia were detected and decreased while the number and size of syncytia were increasing. Most virions were seen budding from mononucleated cells or from the periphery of syncytia where cells were being recruited. Moving inward, the surfaces of syncytia where cells were being recruited. Moving inward, the surfaces of syncytia were covered with numerous ridges containing viral antigen, but few viral buds were seen, suggesting that syncytia might be sites of defective viral formation. Hemadsorption occurred predominantly within the confines of syncytia. Erythrocytes were scattered sparsely over immature syncytia but were densely packed in the center of mature syncytia. Active binding sites for erythrocytes were located on cell villi and ridges covered with measles antigens. Hemadsorption was completely inhibited in measles virus-infected cultures pretreated with virus-specific immunoglobulin G for 1 h at 4 degrees C. However, when these cultures were shifted to 37 degrees C, hemadsorbing sites were recovered at the periphery of enlarging syncytia. Virus-induced sites for erythrocyte adsorption were found to move centripetally on syncytium membranes as fusion progressed.

Antigens, Viral↗
PubMed1978

Chromosome condensation and radiation-induced G2 arrest studied by the induction of premature chromosome condensation following cell fusion.

When mitotic and interphase cells are fused together, the chromosomes of the interphase cell sometimes condense prematurely. The phenomenon of premature chromosome condensation (PCC) was utilized in investigating the problem of whether the chromosomes of cells suffering a radiation-induced G2 delay are capable of condensation. Colcemide-arrested mitotic cells were fused with synchronized G2 cells, and with irradiated cells suffering a G2 delay. The frequency of PCC in mitotic X G2 binucleate cells was determined. This was compared to the PCC frequency in an unirradiated synchronized population rich in G2 cells after fusion with mitotic cells. Flash-labelling with 3HTdR and autoradiography allowed us to eliminate S-phase cells. The frequency of G2 PCCs was not significantly different for the irradiated G2-delayed or unirradiated cells. From these results we conclude that the chromosomes of cells suffering a G2 arrest are capable of condensation, although the involvement of the condensation process in radiation-induced G2 delay cannot be ruled out.

Cell Cycle↗
PubMed1978

A hypotetraploid human T lymphoid cell line established by cell fusion.

A human T lymphoid cell line was established by cell hybridization technique from peripheral blood leucocytes of a patient with Sezary syndrome. The cells beared the surface antigens of human T lymphocyte specificity as demonstrated by immune cytolysis tests, but did not form E rosettes with sheep red blood cells. Isozyme patterns of enzymes in this line such as lactate dehydrogenase, glucose 6-phosphate dehydrogenase and esterase were of human type. The line had 79 chromosomes in modal number. This case supports the proposal that the production of tetraploids is favourable for establishment of cell lines.

Antigens↗
PubMed1978

Redistribution of intramembrane particles of human erythrocytes induced by HVJ (Sendai virus): a prerequisite for the virus-induced cell fusion.

Aggregation of intramembrane particles of human erythrocytes was found to be induced by HVJ (Sendai virus) under conditions which lead to cell fusion. Degree of polyerythrocyte formation was compared under a variety of conditions with extent of cluster formation observed with the same preparations. Both structural changes of the membranes, ie, fusion and clustering of the particles, behaved very similarly under widely different virus-to-cell ratios and over the time course of cell fusion. Furthermore, by inclusion of high concentrations of antispectrin antibodies within the ghosts, inhibition of clustering of intramembrane particles and hindrance of virus-induced cell fusion were found to occur simultaneously. Antibodies by themselves did not induce aggregation of particles under isotonic conditions, whereas particle clustering could be induced under hypotonic conditions at antibody concentrations causing partial cross-linking of spectrin molecules. In conclusion, clustering of intramembrane particles seems to be required for virus-induced fusion of human erythrocytes.

Antigen-Antibody Reactions↗
PubMed1978

[Bioligical aspects of cell fusion induced in vitro by sheep Visna virus].

Visna virus induced cell fusion of sheep choroid plexus cells was explored in vitro. Fusion is early rapid, and of exogenous origin for multiplicities of infection equal to or greater than 2 UFP per cell; whereas fusion is slow, late-occurring and of endogenous origin for multiplicities of infection less than or equal to 0.75 UFP per cell.

Animals↗
PubMed1977

Reconstitution of catecholamine-sensitive adenylate cyclase activity: interaction of components following cell-cell and membrane-cell fusion.

Heterokaryons formed by the fusion of adenylate cyclase-deficient S49 cells and beta-adrenergic receptor-deficient B82 cells in the presence of cycloheximide display a catecholamine-sensitive adenylate cyclase activity. Similar complementation can be observed when receptor-replete membranes from the cyclase-deficient cell are fused with intact B82 cells. Using the cell fusion technique it can be demonstrated that the uncoupled S49 cell variant has a functional beta-adrenergic receptor but that this variant and the adenylate cyclase-deficient variant are not complementary. Hypothetically, both clones may share a common defect in regulatory components of adenylate cyclase or both may lack a specific coupling factor.

Adenylyl Cyclases↗
PubMed1977

[Ultrastructural aspects of the cell fusion induced by Visna virus on sheep choroid plexus cell in culture].

Sheep choroid plexus cells infected with low multiplicities of infection of Visna Virus were stellate and had long and thin processes containing filaments and forming cytoplasmic bridges between adjacent cells. Enlargement of the bridges resulted in the formation of multinucleated cells. Some glycoproteins were clustered on filaments outside the cell. The cytoplasmic changes showed : an intensive protein synthesis; numerous mitochondria closely associated with filaments and some lysosomes and numerous vesicules near the plasma membrane.

Animals↗
PubMed1979

Somatic cell fusion in the study of glucocorticoid action.

The basic phenomena of cell fusion and hybrid cell formation are briefly described and the potential of somatic cell hybridization in studies on the expression of differentiated cellular functions is discussed. The technique of cell hybridization has been applied to two types of cellular responses to glucocorticoids. The induction of specific proteins has been investigated in hybrids of inducible cells with uninducible cells. Most studies dealt with the liver-specific enzyme tyrosine aminotransferase, whose inducibility was extinguished in the majority of the hybrids between hepatoma and nonliver cells. However, upon chromosome segregation, inducibility reappeared in some of these hybrid cells. The current ideas about cellular control of inducibility are discussed. The other major glucocorticoid-responsive system investigated in cell hybridization studies consists of lymphoid cells which are killed when exposed to the steroid. Such sensitive cells were hybridized with several types of glucocorticoid-resistant lymphoid lines, and sensitivity was found to be dominant over resistence. Hybrids between sensitive and resistant lymphoid cells, however, showed an increase in the frequency at which resistance occurred as compared to the rate observed with the wild-type parental cells. No complementation to steroid sensitivity was found in hybrids between different types of resistant cells with defects in the glucocorticoid-specific receptor system.

Animals↗
PubMed1976

Expression of differentiative traits in the absence of cell fusion during myogenesis in culture.

Fusion of myoblasts is inhibited in cultures at low Ca++ concentration (0.44 mM); yet creatine phosphokinase and myokinase activities as well as myosin synthesis and the appearance of post-mitotic myoblasts do not significantly differ from those of control cultures (grown at 1.04 mM Ca++) which undergo cell fusion. When Ca++ concentration is increased to the control value after the second day of culture, fusion occurs very rapidly and it is not inhibited by actinomycin D or cycloheximide. Treatment with 0.06 mM bromodeoxyuridine strongly inhibits creatine phosphokinase activity and myotubes formation. The study of the kinetics of reversal of cell fusion and of creatine phosphokinase activity after removal of the analog, shows that this process is slower than the decrease of the relative content of bromodeoxyuridine incorporated into DNA. The result obtained support the following conclusions: a) the expression of the differentiative characters examined does not require cell fusion; b) the process of myotube formation seems to imply two subsequent stages consisting first of a slow maturative process, which is followed by the actual fusion of cell membranes; the former is Ca++ independent, the latter is Ca++ dependent and does not require RNA or protein synthesis.

Adenylate Kinase↗
PubMed1975

Kinetics of cell fusion induced by a syncytia-producing mutant of herpes simplex virus type I.

We have isolated a number of plaque-morphology mutants from a strain of herpes simplex virus type I which, unlike the wild type, cause extensive cell fusion during a productive viral infection. After the onset of fusion, there is an exponential decrease in the number of single cells as a function of time after infection. At a multiplicity of infection (MOI) of 3.8 plaque-forming units per cell, fusion begins 5.3 h after infection with the number of single cells decreasing to 10% of the original number 10.2 h after infection. As the MOI is gradually increased from 0.4 to 8, the onset of fusion occurs earlier during infection. However, when the MOI is increased from 8 to 86, the onset of fusion does not occur any earlier. The rate of fusion is independent of the MOI for an MOI greater than 1. The rate of fusion varies linearly with initial cell density up to 3.5 X 10(4) cells/cm2 and is independent of initial cell density at higher cell concentrations. To assay cell fusion we have developed a smiple quantitative assay using a Coulter counter to measure the number of single cells as a function of time after infection. Data obtained using a Coulter counter are similar to those obtained with a microscope assay.

Cell Count↗
PubMed1979

[Cell fusion in higher organisms under polyethylene glycol exposure].

An electron microscope study of higher plant protoplasts and human cell fusion was made using polyethylene glycol. The successive stages of proteoplast cell fusion, and the formation of intraspecific, interfamiliar, or interkingdom "hybrid" cells, and some details of their submicroscopic changes at the early stages of culturing are shown.

Cell Fusion↗
PubMed1978

Use of latex particles for analysis of heterokaryon formation and cell fusion.

A simple method for the quick and accurate detection of cell fusion utilizing latex particles as cytoplasmic markers was developed and is reported here. The method is particularly useful for demonstrating human skin fibroblast heterokaryons. Ingestion of latex particles did not affect the growth of primary human and established BHK(21)/C(13) hamster fibroblasts. In addition, somatic cell hybridization between hypoxanthine phosphoribosyltransferase-deficient (HPRT-) and thymidine kinase-deficient (TK-) mutants of BHK(21)/C(13) was also unaffected by lates particle ingestion.

Cell Fusion↗