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Biomedical subjects

M G Rush

Publications and source records attributed to M G Rush.

At least 55 records · Page 3Linked to original sources
PubMed1981

DNA mediated gene transfer using simian virus 40 or polyoma virus morphological transformation as selective markers.

The stable uptake of a bacterial plasmid by mouse or rat cells has been detected following the respective co-transfection of these cells with plasmid in the presence of either Simian virus 40 (SV40) or Polyoma virus DNAs. About 60-70 percent of the resulting SV40-transformed mouse cell clones and about 40 percent of the Polyoma transformed rat cell clones contained plasmid DNA sequences.

Animals↗
PubMed1979

Integration of herpes simplex virus type 1 DNA into the DNA of growth-arrested BHK-21 cells.

The ability of HSV-1 DNA to become associated with host cell DNA in an alkaline-stable form has been demonstrated following infection of a ts baby hamster kidney growth mutant (ts BTN-1), at the non-permissive temperature (39.5 depgrees C). After 8 h pre-incubation at 39.5 degrees C, ts BTN-1 cells infected at this temperature using m.o.i. ranging from 0.5 to 200 p.f.u./cell fail to replicate virus DNA even though transport of input virus genomes to the nucleus is the same at both permissive and non-permissive temperatures. Virions containing 3H-labelled DNA were used to infect ts BTN-1 cells at 39.5 degrees C, and the total cellular DNA isolated from these cells was resolved into host and virus material by repeated CsCl equilibrium gradient centrifugation. A significant amount of the input radioactivity was found as a distinct band in the host region in both neutral and alkaline CsCl gradients, strongly suggesting a covalent association between host and virus DNAs. Evidence for this association was strengthened by demonstrating that radioactive material (virus DNA) banding in the host region of CsCl gradients could be driven towards the density expected for virus DNA following degradation of the putative hybrid molecules by shearing.

Animals↗
PubMed1978

Change in quantity and size distribution of small circular DNAs during development of chicken bursa.

Small circular DNAs ranging in contour length from 0.06 to 3.5 micrometers have been isolated from bursas of 19-day chicken embryos and 4- to 5-week-old chickens. Small circular DNA is present in bursas of 19-day embryos at approximately 0.2 molecules per cell and is very heterogeneous, lacking distinct size classes; most molecules have contour lengths of less than 0.04 micrometers. In contrast, small circular DNA is present in bursas of 4- to 5-week old chickens at about 4 molecules per cell, and although this DNA is still heterogeneous, it contains a major distinct class of molecules 0.8 micrometers in size. These small circular DNAs may be products of developmental gene rearrangements occurring in the chromosomal DNA of lymphocytes in the bursa.

Animals↗
PubMed1978

Inhibition of herpes simplex virus type 1 replication in temperature-sensitive cell cycle mutants.

Herpes simplex virus type 1 DNA synthesis and infections progeny production were studied in five different conditional hamster (BHK-21) cell cycle mutants. At the nonpermissive temperature (39.5 degrees C), both events were strongly inhibited in four of these cell lines. The degree of inhibition was a reproducible characteristic of each cell mutant and in two cases was dependent upon the multiplicity of infection. Experiments involving shifts to the nonpermissive temperature at least 3 h postinfection at 33.5 degrees C suggested that the defects in viral replication were not due to faulty adsorption, penetration, or uncoating, whereas experiments involving shifts of infected cells from the nonpermissive temperature to 33.5 degrees C revealed the reversible nature of the inhibition.

Animals↗
PubMed1977

Analysis of the structure of human papilloma virus DNA.

Human papilloma virus DNA has been examined for heterogeneity by electron microscopy, reassociation kinetics, and restriction endonuclease digestion. No heterogeneity in contour length was detected. The reassociation rate of papilloma DNA isolated from pooled warts was consistent with that expected for a homogeneous, unique DNA of molecular weight 5 X 10(6). Restriction endonuclease digestions of five papilloma DNA preparations isolated from pooled warts yielded predominantly fragments of the expected sizes, but significant quantities of fragments atypical in size were also commonly produced.

Base Sequence↗
PubMed1976

Preparation of radioiodinated simian virus 40 DNA for use in DNA - DNA reassociation kinetics experiments.

A method is described for the preparation of 125I-labelled SV40 DNA. Using this method, SV40 DNA can be routinely labelled to 15 - 10(6) dpm per mug; much higher specific activities are easily obtained by minor modifications of the method. Once incorporated, the radioactive label dissociates from DNA exceedingly slowly at 4 degrees C or at 68 degrees C. Iodinated SV40 DNA is shown to be useful in the quantitation of viral nucleic acid sequences in SV40-transformed 3T3 cells by DNA - DNA reassociation kinetics.

Base Sequence↗
PubMed1969

Penicillinase plasmid DNA from Staphylococcus aureus.

A penicillinase plasmid from Staphylococcus aureus and three of its derivatives, all previously identified as extrachromosomal genetic elements, have been isolated in high yield as circular duplex DNA molecules. The wild-type plasmid was found by contour-length measurements of electron micrographs to have a molecular weight of 18.6 x 10(6) daltons. Two plasmids with deletions encompassing six and eight of the eleven known plasmid cistrons had molecular weights of 16.4 x 10(6) and 15.3 x 10(6) daltons, respectively. This information was used to establish approximate physical distances for the genetic map. A high-frequency transducing element also derived from the plasmid had a molecular weight of approximately 24 x 10(6) daltons. Although each plasmid preparation appeared homogeneous by ultracentrifugal analysis, electron micrographs always revealed the presence of a low percentage of complex oligomeric forms, particularly circular and catenated dimers.

DNA, Bacterial↗
PubMed1969

Circular deoxyribonucleic acid from Shigella dysenteriae Y6R.

Circular deoxyribonucleic acid was isolated from Shigella dysenteriae Y6R and was found to consist of six species having molecular weights of 10(6), 1.3 x 10(6), 2.6 x 10(6), 3.8 x 10(6), 20 x 10(6), and 24 x 10(6) daltons. These size classes were partially resolved by sucrose density gradient centrifugation. The minicircles (10(6) and 1.3 x 10(6)) were found to have a buoyant density in CsCl of 1.710 g/ml. The 3.8 x 10(6) dalton class had a density of 1.707 g/ml. The two largest species had a density of 1.702 g/ml. Two other strains, S. sonnei II and S. dysenteriae 60, also contained circular deoxyribonucleic acid.

Centrifugation, Density Gradient↗