Comparison of Yields and Repair Kinetics of Interphase Chromosome Breaks Visualized by Sendai-virus or PEG-mediated Cell Fusion in Irradiated CHO Cells

The dose response of Sendai virus-induced cell fusion was studied in 10 mammalian cell lines, comprising 5 continuous and 5 diploid cell lines originating from 5 species. The extent of fusion was calculated using a parameter directly proportional to the number of fusion events (t-parameter). At lower levels of fusion the dose response was found to be based on the same simple kinetic rules in all cell lines and was defined by the formula: t = FS. FAU/(I + FS. FAU), where FS (fusion sensitivity) is a cell-specific constant of the fusion rate and FAU (fusion activity units) is the virus dose. The FS potential of a cell line was determined as the linear regression coefficient of the fusion index (t/(I - t)) on the virus dose. At higher levels of fusion, when the fusion extent reached cell-line-specific maximal levels, the dose response was not as uniform. In general, and particularly in the cases of the diploid cell lines, these maximal levels were directly proportional to the FS potentials. Thus, it was concluded that the FS potential is the basic quantitative feature, which expresses the cellular fusion efficiency. The fact that FS varied extensively between cell lines, but at the same time apparently followed certain patterns (being higher in continuous compared to diploid cell lines and being related to the species of origin of the cells), emphasizes it biological significance as well as its possible usefulness in studies of the efficiency of various molecular interactions in the cell membrane/cytoskeleton system.

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

Journal of Cell Science ◽

10.1242/jcs.43.1.103 ◽

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.

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Kinetics of the HIV-CD4 interactions and virus-cell fusion

AIDS ◽

10.1097/00002030-199203000-00010 ◽

1992 ◽

Vol 6 (3) ◽

pp. 325???328 ◽

Cited By ~ 1

Author(s):

P. J. Klasse ◽

John P. Moore

Keyword(s):

Cell Fusion ◽

Kinetics Of

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

Journal of Cell Science ◽

10.1242/jcs.36.1.85 ◽

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.

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The role of cell swelling and haemolysis in Sendai virus-induced cell fusion and in the diffusion of incorporated viral antigens

Journal of Cell Science ◽

10.1242/jcs.42.1.153 ◽

1980 ◽

Vol 42 (1) ◽

pp. 153-167

Author(s):

S. Knutton ◽

T. Bachi

Keyword(s):

Cell Fusion ◽

Erythrocyte Membrane ◽

Sendai Virus ◽

Viral Envelope ◽

Cell Swelling ◽

Haemolytic Activity ◽

Erythrocyte Ghosts ◽

Viral Antigens ◽

Cell Cell

The role of the haemolytic activity of Sendai virus in cell-cell fusion has been examined in monolayers of human erythrocytes and erythrocyte ghosts fused with either haemolytic or non-haemolytic virus. Morphological observations indicate that cell swelling and haemolysis is a distinct event in cell-cell fusion irrespective of whether it is virally induced or, in the case of non-haemolytic virus, experimentally induced. Osmotic swelling appears to be the driving force by which cells which have established sites of membrane fusion expand such sites to form poly-erythrocytes. Immunofluorescent labelling of viral antigens incorporated into the erythrocyte membrane as a result of viral envelope-cell fusion indicates that diffusion of antigens in the plane of the membrane is restricted in intact erythrocytes and resealed erythrocyte ghosts but not in haemolysed erythrocytes or unsealed ghosts. A perturbation of the erythrocyte membrane resulting from osmotic lysis appears to form a prerequisite for the lateral diffusion of viral elements.

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