scholarly journals Tumor promoter 12-O-tetradecanoylphorbol 13-acetate stimulates simian virus 40 induction by DNA-damaging agents and tumor initiators.

1983 ◽  
Vol 3 (5) ◽  
pp. 757-760 ◽  
Author(s):  
S Nomura ◽  
N Shobu ◽  
M Oishi
Keyword(s):  
Molecular Structure ◽  
Uv Irradiation ◽  
Culture Medium ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Tumor Promoter ◽  
Kidney Cells ◽  
Sv40 Virus ◽  
Virus Particles ◽  
Dna Damaging Agents

Simian virus 40 (SV40)-transformed Syrian hamster kidney cells produce infectious SV40 virus particles after treatments which damage DNA, such as UV irradiation or mitomycin C treatment. We have found that the induction of SV40 by DNA-damaging agents is greatly stimulated when a typical tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA), is present in the medium. Phorbol, which has a molecular structure similar to TPA but does not have any tumor-promoting activity, showed no such stimulatory effect on SV40 induction. This apparent synergistic effect of DNA-damaging agents and tumor promoter (TPA) was more pronounced when a tumor initiator, benzo [a]pyrene or 2-acetamido-fluorene, was combined with TPA. The effect of TPA on UV-triggered SV40 induction was greatly influenced by the timing of TPA addition to the culture medium, which was most efficient when addition of TPA was 5 to 20 h before UV irradiation. The effect of TPA, however, was not observed in SV40 rescue from hamster cells by cell fusion with permissive monkey (C7) cells.

Tumor promoter 12-O-tetradecanoylphorbol 13-acetate stimulates simian virus 40 induction by DNA-damaging agents and tumor initiators

1983 ◽  
Vol 3 (5) ◽  
pp. 757-760
Author(s):  
S Nomura ◽  
N Shobu ◽  
M Oishi
Keyword(s):  
Molecular Structure ◽  
Uv Irradiation ◽  
Culture Medium ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Tumor Promoter ◽  
Kidney Cells ◽  
Sv40 Virus ◽  
Virus Particles ◽  
Dna Damaging Agents

Simian virus 40 (SV40)-transformed Syrian hamster kidney cells produce infectious SV40 virus particles after treatments which damage DNA, such as UV irradiation or mitomycin C treatment. We have found that the induction of SV40 by DNA-damaging agents is greatly stimulated when a typical tumor promoter, 12-O-tetradecanoylphorbol 13-acetate (TPA), is present in the medium. Phorbol, which has a molecular structure similar to TPA but does not have any tumor-promoting activity, showed no such stimulatory effect on SV40 induction. This apparent synergistic effect of DNA-damaging agents and tumor promoter (TPA) was more pronounced when a tumor initiator, benzo [a]pyrene or 2-acetamido-fluorene, was combined with TPA. The effect of TPA on UV-triggered SV40 induction was greatly influenced by the timing of TPA addition to the culture medium, which was most efficient when addition of TPA was 5 to 20 h before UV irradiation. The effect of TPA, however, was not observed in SV40 rescue from hamster cells by cell fusion with permissive monkey (C7) cells.

Electron Microscopic Observations on the Rescue of SV40 Virus From Transformed Cells

1972 ◽  
Vol 30 ◽  
pp. 278-279
Author(s):  
Ronald Glaser ◽  
Ross Farrugia
Keyword(s):  
Electron Microscopy ◽  
Cell Fusion ◽  
Sendai Virus ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Transformed Cells ◽  
Density Gradients ◽  
Electron Microscopic ◽  
Sv40 Virus ◽  
Virus Particles

Several laboratories have reported that simian virus 40 (SV40) was rescued from transformed cells when the nonproducing cells were cocultivated or fused in the presence of ultraviolet inactivated Sendai virus (UV-SV), to potentially susceptible cells. Evidence obtained from studies in which nuclei from heterokaryons were isolated and separated on density gradients, indicated that rescued virus was first detected in the transformed nuclei of the heterokaryons formed during cell fusion. The present study was performed to determine how long after fusion SV40 virus particles could be found in the nuclei of the heterokaryons and to investigate the site of rescue by electron microscopy.

Cryo-Electron Microscopy and Image Analysis of SV40

1985 ◽  
Vol 43 ◽  
pp. 316-317
Author(s):  
T. S. Baker ◽  
J. Drak ◽  
M. Bina
Keyword(s):  
Electron Microscopy ◽  
Simian Virus 40 ◽  
Carbon Support ◽  
Simian Virus ◽  
Thin Layers ◽  
Sv40 Virus ◽  
Virus Particles ◽  
Frozen Solution ◽  
Cryo Electron Microscopy ◽  
Icosahedral Capsid

The discovery that the T=7 icosahedral capsid of polyoma virus is composed of 72 pentameric capsomers rather than 12 pentamers and 60 hexamers as predicted by constraints of quasi-equivalence has prompted an examination of SV40 virus by electron microscopy to determine whether the capsids of other members of the papovavirus family are similarly constructed.Thin layers of buffered aqueous solutions (∼4 mg/ml) of Simian virus 40 (strain WT776) were prepared for cryo-microscopy using recently developed procedures. Images of virus particles suspended in thin layers of vitreous ice over holes in the carbon support film and maintained at -170°C were recorded using minimal irradiation conditions. Figure 1 shows a typical field in which the frozen solution is similar in thickness to the virus particles (∼49 nm diameter). Particles appear to be excluded or squeezed away from the thinnest regions of solution (e.g., the clear region bordered by particles at the top of Fig. 1).

scholarly journals Human embryonic kidney cells: stable transformation with an origin-defective simian virus 40 DNA and use as hosts for human papovavirus replication.

1984 ◽  
Vol 4 (2) ◽  
pp. 379-382 ◽  
Author(s):  
E O Major ◽  
P Matsumura
Keyword(s):  
Dna Replication ◽  
Sequence Data ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Kidney Cells ◽  
Human Embryonic Kidney ◽  
Human Embryonic Kidney Cells ◽  
Defective Mutant ◽  
Dna Replication Origin ◽  
Human Papovavirus

An origin-defective mutant DNA of simian virus 40 immortalized human embryonic kidney cells, maintaining a T protein which could function for human papovavirus BK DNA replication but not for human papovavirus JC DNA replication. Neither BK virions nor capsid proteins were produced in these cells. This may indicate that the simian virus 40 T protein in human embryonic kidney cells is competent for maintaining transformation and initiating and completing DNA replication for BK but is not competent for switching to late gene functions. Furthermore, it appears that the JC DNA replication origin cannot efficiently use the simian virus 40 T protein for its DNA synthesis, as suggested by its DNA sequence data (R. Frisque, J. Virol. 46:170-176, 1983; T. Miyamura, H. Jikoya, E. Soeda, and K. Yoshiike, J. Virol. 45:73-79, 1983).

scholarly journals Enhancement of DNA-mediated gene transfer by high-Mr carrier DNA in synchronized CV-1 cells

1985 ◽  
Vol 225 (2) ◽  
pp. 529-533 ◽  
Author(s):  
A J Strain ◽  
W A H Wallace ◽  
A H Wyllie
Keyword(s):  
Cell Cycle ◽  
Gene Transfer ◽  
Transfection Efficiency ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
S Phase ◽  
Sv40 Virus ◽  
G2 Phase ◽  
Cycle Dependent ◽  
Sv40 Dna

Synchronized CV-1 cells were transfected with SV40 (simian virus 40) DNA-calcium phosphate co-precipitates. In the presence of carrier DNA, the transfection efficiency of SV40 DNA was decreased 5-fold in S-phase cells and was increased 4-fold in preparations of mitotically enriched cells as compared with asynchronous controls. No difference was observed when carrier DNA was omitted, when cells had progressed through S-phase and into G2-phase, or when the infectivity of cells to intact SV40 virus was tested. These results highlight the importance of cell-cycle-dependent factors on DNA-mediated gene transfer.

Molecular analysis of enhanced replication of UV-damaged simian virus 40 DNA in UV-treated mammalian cells

1988 ◽  
Vol 8 (6) ◽  
pp. 2428-2434
Author(s):  
J M Treger ◽  
J Hauser ◽  
K Dixon
Keyword(s):  
Uv Radiation ◽  
Uv Irradiation ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Viral Dna ◽  
Repair Capacity ◽  
Pyrimidine Dimers ◽  
Infected Cells ◽  
Replicative Intermediates ◽  
Kinetics Of

Irradiation of simian virus 40 (SV40)-infected cells with low fluences of UV light (20 to 60 J/m2, inducing one to three pyrimidine dimers per SV40 genome) causes a dramatic inhibition of viral DNA replication. However, treatment of cells with UV radiation (20 J/m2) before infection with SV40 virus enhances the replication of UV-damaged viral DNA. To investigate the mechanism of this enhancement of replication, we analyzed the kinetics of synthesis and interconversion of viral replicative intermediates synthesized after UV irradiation of SV40-infected cells that had been pretreated with UV radiation. This enhancement did not appear to be due to an expansion of the size of the pool of replicative intermediates after irradiation of pretreated infected cells; the kinetics of incorporation of labeled thymidine into replicative intermediates were very similar after irradiation of infected control and pretreated cells. The major products of replication of SV40 DNA after UV irradiation at the low UV fluences used here were form II molecules with single-stranded gaps (relaxed circular intermediates). There did not appear to be a change in the proportion of these molecules synthesized when cells were pretreated with UV radiation. Thus, it is unlikely that a substantial amount of DNA synthesis occurs past pyrimidine dimers without leaving gaps. This conclusion is supported by the observation that the proportion of newly synthesized SV40 form I molecules that contain pyrimidine dimers was not increased in pretreated cells. Pulse-chase experiments suggested that there is a more efficient conversion of replicative intermediates into form I molecules in pretreated cells. This could be due to more efficient gap filling in relaxed circular intermediate molecules or to the release of blocked replication forks. Alternatively, the enhanced replication observed here may be due to an increase in the excision repair capacity of the pretreated cells.

scholarly journals Enhanced transformation by a simian virus 40 recombinant virus containing a Harvey murine sarcoma virus long terminal repeat.

1983 ◽  
Vol 3 (3) ◽  
pp. 325-339 ◽  
Author(s):  
M Kriegler ◽  
M Botchan
Keyword(s):  
Long Terminal Repeat ◽  
Recombinant Virus ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Viral Dna ◽  
Sv40 Virus ◽  
Transformed Cell ◽  
Murine Sarcoma Virus ◽  
Sarcoma Virus ◽  
Murine Sarcoma

We have constructed a recombinant simian virus 40 (SV40) DNA containing a copy of the Harvey murine sarcoma virus long terminal repeat (LTR). This recombinant viral DNA was converted into an infectious SV40 virus particle and subsequently infected into NIH 3T3 cells (either uninfected or previously infected with Moloney leukemia virus). We found that this hybrid virus, SVLTR1, transforms cells with 10 to 20 times the efficiency of SV40 wild type. Southern blot analysis of these transformed cell genomic DNAs revealed that simple integration of the viral DNA within the retrovirus LTR cannot account for the enhanced transformation of the recombinant virus. A restriction fragment derived from the SVLTR-1 virus which contains an intact LTR was readily identified in a majority of the transformed cell DNAs. These results suggest that the LTR fragment which contains the attachment sites and flanking sequences for the proviral DNA duplex may be insufficient by itself to facilitate correct retrovirus integration and that some other functional element of the LTR is responsible for the increased transformation potential of this virus. We have found that a complete copy of the Harvey murine sarcoma virus LTR linked to well-defined structural genes lacking their own promoters (SV40 early region, thymidine kinase, and G418 resistance) can be effectively used to promote marker gene expression. To determine which element of the LTR served to enhance the biological activity of the recombinant virus described above, we deleted DNA sequences essential for promoter activity within the LTR. SV40 virus stocks reconstructed with this mutated copy of the Harvey murine sarcoma virus LTR still transform mouse cells at an enhanced frequency. We speculate that when the LTR is placed more than 1.5 kilobases from the SV40 early promoter, the cis-acting enhancer element within the LTR can increase the ability of the SV40 promoter to effectively operate when integrated in a murine chromosome. These data are discussed in terms of the apparent cell specificity of viral enhancer elements.

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