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At least 37 records · Page 2Linked to original sources
PubMed1978

Transfection of Fv-1 permissive and restrictive mouse cells with integrated DNA of murine leukemia viruses.

Whole-cell DNA preparations isolated from SC-1 cells chronically infected with N- or B-tropic murine leukemia viruses (MuLV) were tested for infectious activity in an Fv-1n (NIH-3T3) and two Fv-Ib (C57BL/6 and SV-A31) cell cultures. Efficiency of transfection for all DNAs was better in the NIH-3T3 cells than in C57BL/6 or SV-A31 cells; and an [N-tropic MuLV]SC-1 cell DNA preparation was slightly more infectious than a [B-tropic MuLV]SC-1 cell DNA preparation in all three cell cultures, regardless of their Fv-1 genotypes. Progeny viruses from the transfection showed N- or B-tropism corresponding to that of the parent viruses produced by the infected SC-1 cells that were used for the DNA preparation. DNA dose-response studies in NIH-3T3 cells revealed a one-hit mechanism for both the [B-tropic MuLV]SC-1 cell DNA and the [N-tropic MuLV]SC-1 cell DNA preparation. These results demonstrate that, in contrast to virion infection, transfection of N- and B-tropic MuLV with DNA preparations from chronically infected cells is not affected by the Fv-1 gene.

Cell Line↗
PubMed1979

The influence of host adaptation of Rous sarcoma virus on the transfecting activity of its DNA provirus.

Mammalian cells transformed with either Prague strain Rous sarcoma virus of subgroup C (XC cells) or Schmidt-Ruppin strain Rous sarcoma virus of subgroup D (RSCH cells) yielded virus upon fusion with chick cells. Virus was also rescued by transfection of DNA from these cells on to chick cells. However, virus rescue did not occur upon transfection of duck cells, and fusion with duck cells led to virus rescue only from RSCH and not from XC cells. To investigate this restriction on the duck cells the non-defective Prague strain of Rous sarcoma virus of subgroup C (PR-RSV-C) was adapted for efficient replication in duck embryo cells (daPR-RSV-C) by long-term passage in vitro. However, a second PR-RSV-C isolate, rescued from the rat XC sarcoma line (XC DNA 940 virus), failed to adapt to growth in duck cells. When transformed with daPR-RSV-C, which replicates in duck cells as well as in brown leghorn embryo (BLEF) cells, duck cells yielded DNA which transfects fresh duck cells, in contrast to DNA isolated from chicken or duck cells transformed with parental PR-RSV-C.

Animals↗
PubMed1978

Biological properties of equine herpesvirus type 1 DNA: transfectivity and transforming capacity.

DNA extracted from purified virions of equine herpesvirus type 1 (EHV-1) was examined for its transfectivity and transforming ability. The infectivity of the herpesvirus DNA was demonstrated by addition of calcium phosphate-DNA coprecipitates to monolayers of permissive horse cells, with resultant plaque formation. The efficiency of transfection (50 to 100 plaque-forming units/microgram of DNA) was reduced by treatment of the viral DNA with deoxyribonuclease or sonication but not with Pronase or antivirus neutralizing serum. When nonpermissive mouse 3T3 Cells lacking the enzyme thymidine kinase (TK-) were transfected with intact EHV-1 DNA, clones of cells transformed to the TK+ phenotype were isolated in selective HAT medium (hypoxanthine, aminopterin, thymidine), which prevents growth of the TK- parental phenotype. The efficiency of transformation ranged from one to five transformants per microgram of EHV-1 DNA. The TK activity of the biochemically transformed cells was characterized by biochemical, electrophoretic, and immunological techniques. By these criteria, the TK activity was identical to the EHV-1 TK and different from the host wild-type enzyme. In contrast to the parental TK+ 3T3 cells, the EHV-1-transformed TK+ cells were unable to grow in the presence of arabinosylthymine, a drug selectively phosphorylated by herpesvirus TKs. These results indicate that stable transfer of EHV-1 genes into nonpermissive cells can be achieved with purified viral DNA.

Arabinonucleosides↗
PubMed1979

Search for human tumour viruses by transfection: uptake of melanoma and Epstein-Barr virus DNA by human cells.

In a model system, consistent transfection of chick embryo fibroblasts (CEF) by DNA from the XC cell line occurred, with recovery of infectious Rous sarcoma virus. The techniques were then applied in attempts to recover possible human tumour viruses. Even with various modifications of the XC technique, DNA from three human malignant melanoma cell lines failed to infect adult or foetal human fibroblasts, although melanoma DNA was taken up into nuclei of target cells. XC DNA did not transfect human foetal fibroblasts and melanoma DNA was ineffective in CEF. DNA from the Raji (Epstein-Barr virus non-producer) and QIMR-WIL (producer) lymphoblastoid cell lines did not transfect human cord blood lymphocytes or amnion cells. These broadly applicable techniques therefore failed to recover EB virus, the putative melanoma retrovirus, or other potential tumour virus.

Animals↗
PubMed1975

Transfection of Escherichia coli spheroplasts. V. Activity of recBC nuclease in rec+ and rec minus spheroplasts measured with different forms of bacteriophage DNA.

The in vivo activity of the recBC nuclease was assayed by transfection of isogenic rec+ and rec minus spheroplasts with bacteriophage DNA of various origin and structure. The results indicate that the recBC nuclease can limit transfection at several stages during the production of an infective center; such limitations depend primarily on whether the DNA is in, or assumes, a nuclease-sensitive structure. The first stage of limitation can occur when a nuclease-sensitive transfecting molecule enters the spheroplast. Other potential limitation points occur during replication and maturation of the bacteriophage DNA. The initial stage can be bypassed by using recBC nuclease-resistant molecules such as circular forms. Through analysis of results with other DNA structures, we found that in vivo the effects of the double-strand exonucleolytic activity of the recBC nuclease predominated. The effects of the single-strand nuclease activities seem to be modified from those observed for the purified enzyme in vitro (Karu et al., 1974). Inside the cell, the single-strand exonuclease activity is very weak and the single-strand endonuclease activity is abolished almost completely.

Adenosine Triphosphatases↗
PubMedDate not supplied

Sensitivity of Escherichia coli to viral nucleic acid, X. Ba2+-induced competence for transfecting DNA.

Effect of alkaline earth metal ions on induction of the competence for DNA transfection was investigated. Unlike spheroplasts, the bulk of the bacteria treated with these ions retains colony-forming ability. The order of effectiveness for transfection of phiA replicative-form DNA has been found to be Ba2+ greater than Ca2+ greater than Sr2+ greater than Mg2+. The competence of Ba2+-treated cells is 3 to 5 times higher that that of Ca2+-treated bacteria and about 40 times higher than that of lysozyme-EDTA spheroplasts. The Ba2+-dependent transfection is cryophilic and formation of the infective complex occurs very rapidly at 0 degrees C, But not at 37 degrees C.

Barium↗
PubMed1976

[The influence of bacterial genes recB, recA, exr and polA on T4 phage DNA transfection of lysozyme spheroplasts of Escherichia coli].

The transfection efficiency of T4 phage DNA of Escherichia coli spheroplasts, carrying mutations in four genes, involved in recombination and reparation (recB, recA, exr, polA), is studied. RecB- and recA- mutations increased the phage yield during transfection, and exr- and polA- mutations decreased it. RecA- mutation is suggested to influence on spheroplasts membrane state, resulting in more efficient replication of transfecting phage DNA.

Coliphages↗
PubMed1975

Effect of sera on transfection Bacillus subtilis.

The effect of normal human, rabbit and cow sera, SP50 phage antiserum and the albumin and globulin fractions of normal rabbit serum on transfection of Bacillus subtilis 168 ind was studied. All the sera reduced to varying degrees the efficiency of the process within 60 min. from infection of the culture. None of the sera, except for the antiphage serum, influenced the further course of the process. The albumin fraction of normal rabbit serum otherwise than the globulin fraction, was found to stimulate transfection. The effect of the sera on transfection was influenced by the composition of the media.

Antibodies, Viral↗
PubMed1977

[Transfectable strains of Salmonella].

It the Ca2+-dependent system of an intact bacterial recipient the efficacy of DNA transfection of P22 H5 bacteriophage was determined in 48 strains of bacteria belonging to the Salmonella genus and in 5 Escherichia coli strains with known genetic characteristics and phenotypical properties. The sensitivity of the salmonella strains under study to R- and RS-specific bacteriophages, and also their capacity to ferment galactose were determined. Transfectable mutants of bacteria belongin to the Salmonella genus were referred to the Ra-type. The salmonella P22 H5 bacteriophage of the heterologous E. coli recipient isolated DNA transfection was demonstrated.

Bacteriophages↗
PubMed1979

Transformation and transfection of Pseudomonas aeruginosa: effects of metal ions.

The ability of different metal ions to promote transformation of Pseudomonas aeruginosa by deoxyribonucleic acid of the plasmid RP1 was examined. CaCl2, MgCl2, and MnCl2 were found to promote such transformation, although at different frequencies and with the optimum response at different concentrations. Only MgCl2 promoted transfection of P. aeruginosa by the linear deoxyribonucleic acid of phage F116. CaCl2 was demonstrated to allow adsorption and entry into the cell of F116 deoxyribonucleic acid such that it became resistant to exogenous deoxyribonuclease, but phage production occurred only when MgCl2 was provided. Inactivation of linear phage deoxyribonucleic acid taken up in the absence of MgCl2 was observed. The transfection frequencies at various concentrations of MgCl2 were compared, and the optimum response occurred at the concentration which promoted the highest frequency of transformation by RP1 deoxyribonucleic acid.

Bacteriophages↗
PubMed1978

Mechanism of transfection of chicken embryo fibroblasts by Rous sarcoma virus DNA.

The mechanism of transfection by Rous sarcoma virus DNA was investigated by assaying DNA-mediated transformation under conditions which restricted secondary virus infection. Chicken embryo fibroblasts which were genetically resistant to virus infection as a result of the absence of receptors for virus penetration were also resistant to transformation by integrated or unintegrated Rous sarcoma virus DNA. In addition, DNA of replication-defective Bryan hightiter Rous sarcoma virus was noninfectious, and transformation by DNA of a temperature-sensitive DNA polymerase mutant was temperature sensitive. These results indicated that secondary virus infection was necessary for transformation by Rous sarcoma virus DNA. Since transformation was assayed by colony formation in soft agar, as well as by focus formation, the requirement for secondary virus infection was not an artifact of potential difficulty in detection of foci formed by division of single transformed cells. Therefore, it appeared that donor DNA did not stably transform recipient cells by direct integration. Instead, the results were consistent with the hypothesis that transfection of chicken embryo fibroblasts by Rous sarcoma virus DNA proceeded by transcription of donor DNA, formation of extracellular progeny virus, and secondary virus infection of sensitive cells.

Animals↗
PubMed1979

[Transfer of a bacterial gene using phage lambda transfecting DNA].

A new amber mutation of phage with the gene coding synthesis of beta-galactosidase was received by recombination. With the help of transfection DNA isolated from this phage the transfer of the gene coding the beta-galactosidase synthesis to the recipient phage-resistant E. coli cell was realized. The suggested model can be used for the gene transfer to the recipient phage-resistant cells or other species of bacteria with transfection DNA.

Coliphages↗
PubMed1978

Enhanced efficiency of transfection of HSV DNA in HSV-1 DNA-transformed hamster cells.

The efficiency of transfection, i.e., the number of plaques per microgram of DNA, was compared for herpes simplex virus (HSV) type 1 and type 2, and herpesvirus eidolon (antigenically unrelated to HSV) DNAs in HSV DNA-transformed cells (EH/A44) and control hamster cells (EHT). The efficiency of transfection of HSV-1 and HSV-2 DNAs was significantly higher in EH/A44 cells than in EHT cells, showing that an early step in HSV infection was involved in the partial resistance of HSV DNA-transformed cells to superinfection by various intact herpesviruses.

Animals↗
PubMed1979

Passage of phenotypes of chemically transformed cells via transfection of DNA and chromatin.

DNA was prepared from 15 different mouse and rat cell lines transformed by chemical carcinogens in vitro and in vivo. These DNAs were applied to NIH3T3 mouse fibroblast cultures by using the calcium phosphate transfection technique. DNAs of five donor lines were able to induce foci on the recipient monolayers. Ten other donor DNAs yielded few or no foci. DNAs from control, nontransformed parental cell lines induced few or no foci. Chromosomes were transfected from one donor whose naked DNA was unable to induce foci, and morphologic transformation of recipients was observed. These experiments prove that in five of these cell lines the chemically induced phenotype is encoded in DNA, and the sequences specifying the transformed phenotype behave as a dominant allele in the NIH3T3 recipient cells. The sequences encoding the transformation are likely found on a single fragment of DNA.

Alleles↗
PubMed1975

Infectivity of Rous sarcoma cell DNA: comparison of two techniques of transfection assay.

A DNA extracted from a clone of chicken cells transformed by the Schmidt-Ruppin strain of Rous sarcoma virus, subgroup D(SR-RSV-D), was assayed for infectivity by means of DEAE-dextran and calcium techniques. The calcium technique like the previously described DEAE-dextran procedure gave rise to viruses in transfection assays with both native and denatured (S1 nuclease susceptible) DNAs. The efficiency of these transfection techniques with native DNA was compared and found to be about the same provided that with the calcium technique carrier DNA was used to complement DNA concentrations lower than 2.5 mug/ml.

Animals↗
PubMed1977

[Conditions for S. typhimurium transfection by isolated DNA from bacteriophage P22 H5].

Transfection of spontaneous S. typhimurium LT2 WTR mutant, sensitive to bacteriophages FO, Ffm, 6SR, and resistant to bacteriophages P22 H5, C-21 and P1 vir, by DNA of P22 H5 bacteriophage in the presence of Ca2+ ions was demonstrated. The following were conditions of infection providing maximal and reproducible results: concentration of the recipient cells of 6--7x 109 cells/ml, DNA concentration of 30 microng/ml, CaC12 concentration of 0,25 M. The efficacy of transfection was 5 x 10-8.

Calcium Chloride↗
PubMedDate not supplied

[Infectivity of different forms of lambda bacteriophage DNA in transfection of calcinated Escherichia coli].

Infectivity of linear lambdaDNA molecules is proved to be about a hundred times higher in calcinated E. coli K12 (lambai434) than in E. coli K12(lambda-): the levels of transfection were 1-3-10(7) and 1-2-10(5) infective centers per 1 mug DNA, respectively. In E. coli JC 5743 rec B21 defective for exonucleases I and V the level of transfection was 1-3-10(6). High infectivity of linear lambdaDNA in lysogenic cells cannot be explained by a helping effect of phage particles spontaneously liberated by these cells. It can be caused by recombinations of inserted lambdaDNA molecules with prophage or by the low activity of some nucleases in the lysogenic cells. Covalently closed and "Hershey" ring forms of lambdaDNA penetrate the calcinated cells as readily as linear molecules do but the infectivity of the former ones is proved to be very low.

Coliphages↗