Surface mucopolysaccharides of polyoma virus transformed cells

1963 ◽  
Vol 62 (1) ◽  
pp. 23-31 ◽  
Author(s):  
V. Defendi ◽  
G. Gasic
Keyword(s):  
Polyoma Virus ◽  
Transformed Cells

scholarly journals Role of the Three Polyoma Virus Early Proteins in Tumorigenesis

1983 ◽  
Vol 3 (8) ◽  
pp. 1451-1459 ◽  
Author(s):  
Claude Asselin ◽  
Celine Gelinas ◽  
Marcel Bastin
Keyword(s):  
Cultured Cells ◽  
Virus Genome ◽  
T Antigen ◽  
Polyoma Virus ◽  
Transformed Cells ◽  
Newborn Rats ◽  
Wild Type ◽  
Complementary Function ◽  
Small T Antigen ◽  
Middle T Antigen

A modified polyoma virus genome which can encode the middle T protein but not the large or small T proteins transforms rat cells in culture with an efficiency about 20% that of the wild-type genome. Although middle T-transformed cells grow as tumors when transplanted into nude mice or syngeneic rats, the middle T gene alone is totally inactive when used in a more stringent and rigorous assay for tumorigenicity such as the injection of DNA into newborn rats. Thus, functions other than those expressed by middle T antigen are required for the elaboration of all the properties associated with tumorigenesis. To assess whether a complementary function could be exerted by the large or the small T antigen, we constructed plasmids containing two modified early regions which independently encoded middle T and one of the two other proteins. Both recombinants were tumorigenic in newborn rats. Cell lines derived by transfer of these plasmids under no special selective conditions did not acquire the property of growth in low-serum medium but exhibited the same tumorigenic properties as wild-type polyoma DNA-transformed cells. Furthermore, a recombinant which encoded the middle and small T antigens, but not the large T antigen, was tumorigenic in newborn rats. Although the small T antigen provides a complementary function for tumorigenicity, it cannot complement the middle T antigen for an efficient induction of transformation of cultured cells. This suggests that the complementary function exerted by the small T antigen is different from that of the N-terminal fragment of the large T protein.

Properties of Polyoma virus-transformed cells II. Characteristics of the virus-specific RNA

1972 ◽  
Vol 18 (2) ◽  
pp. 247-254
Author(s):  
James B. Hudson
Keyword(s):  
Dna Hybridization ◽  
Infectious Virus ◽  
Specific Radioactivity ◽  
Polyoma Virus ◽  
Transformed Cells ◽  
Viral Genomes ◽  
High Specific Radioactivity ◽  
Mouse Cells ◽  
Covalently Linked ◽  
Competition Hybridization

The Polyoma virus-specific RNA (PyRNA) synthesized in a line of Polyoma-transformed hamster cells, was analyzed and compared with the viral-specific RNA synthesized "late" in productively infected mouse cells. The PyRNA from the transformed cells sedimented heterogeneously on sucrose gradients, including appreciable amounts of PyRNA in the > 40-S region. The overall sedimentation profile resembled that of "late" PyRNA synthesized in mouse cells. Competition hybridization experiments, however, revealed that the bulk of the PyRNA sequences in the transformed cells were different from "late" PyRNA sequences. The use of DNA–DNA hybridization experiments (with Polyoma DNA of high specific radioactivity) enabled an estimate to be made of the average number of viral genomes per transformed cell. No more than two, and possibly less than one, complete genomes were found. These studies support the hypothesis that this line of Polyoma transformed cells contains an incomplete genome, possibly only comprising "early" genes (hence the inability to rescue infectious virus), and that the viral RNA transcribed is covalently linked to host cell RNA moieties.

scholarly journals Structure of Normal and Polyoma Virus-Transformed Hamster Cell Cultures

1966 ◽  
Vol 1 (2) ◽  
pp. 169-173
Author(s):  
W. HOUSE ◽  
M. G. P. STOKER
Keyword(s):  
Cell Division ◽  
Cell Cultures ◽  
Polyoma Virus ◽  
Transformed Cells ◽  
Vertical Sections

Vertical sections of colonies and confluent sheets of normal and polyoma virus-transformed BHK21 cells, and of a spontaneous malignant variant of BHK21 cells, and also of freshly isolated hamster fibroblasts, were examined to determine the structural interrelationship of the cells in relation to their varying transplantability. All cells except the freshly isolated fibroblasts formed multilayers, but the virus-transformed cells were arranged in the form of a loose network, in which cell division took place. The untransformed BHK21 cells were very tightly packed and mitosis was rare. A spontaneous malignant variant which superficially resembled the normal BHK21 cells was shown by section to have features in common with virus-transformed cells.

scholarly journals Requirements for Excision and Amplification of Integrated Viral DNA Molecules in Polyoma Virus-Transformed Cells

1982 ◽  
Vol 43 (2) ◽  
pp. 617-628 ◽  
Author(s):  
Vittorio Colantuoni ◽  
Lisa Dailey ◽  
Giuliano Della Valle ◽  
Claudio Basilico
Keyword(s):  
Polyoma Virus ◽  
Transformed Cells ◽  
Dna Molecules ◽  
Viral Dna

Contact behaviour and pattern formation of BHK and polyoma virus-transformed BHK fibroblasts in culture

1978 ◽  
Vol 33 (1) ◽  
pp. 53-84
Author(s):  
C.A. Erickson
Keyword(s):  
Cellular Transformation ◽  
Time Lapse ◽  
Polyoma Virus ◽  
The Other ◽  
Transformed Cells ◽  
Cell Contact ◽  
Bhk Cells ◽  
Contact Behaviour ◽  
Parallel Arrays ◽  
Scanning Electron

Certain behavioural and morphological aspects of cellular transformation have been studied, using baby hamster kidney cells (BHK21/13) and polyoma virus-transformed BHK cells. BHK cellsgrow to monolayer arranged in parallel arrays, whereas the transformed cells show a much greater incidence of crisscrossing and multilayering. Time-lapse cinemicrography and scanning electron microscopy were used to examine the behaviour producing these striking differences in cellular pattern. It was found, contrary to previous thought, that in both cell lines, when contact is made ruffle to ruffle, ruffling is inhibited. When BHK cell contact each other ruffle to side, strong adhesions always occur, as evidence by a large deformation of the contacted cell margin, with accompanying paralysis of ruffling. Then, the contacting cell either changes direction, usually spreading along the side of the contacted cell, or occasionally continues to protrude and underlap the other cell, although the original adhesions are seen to remain. Transformed cells never form strong ruffle-to-side adhesions, and usually underlap each other totally. When the cells were filmed, fixed and the same cells relocated in the scanning electron microscope, neither cell type was seen to move over the surface of another (overlap). Rather, all cells crisscross by underlapping (moving under the other cell). SEM also reveals PyBHK cells to have many fewer side-to-substratum adhesions than BHK cells. The smaller number of these attachments could explain the ease with which PyBHK cells underlap.

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