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Biomedical subjects

W R Smith

Publications and source records attributed to W R Smith.

At least 109 records · Page 6Linked to original sources
PubMed1969

Biophysical properties of frog virus and its deoxyribonucleic acid: fate of radioactive virus in the early stage of infection.

Frog virus (FV-3) was banded by isopycnic centrifugation in cesium chloride, sucrose, or potassium tartrate. Two bands of infectivity were regularly found at positions in cesium chloride corresponding to densities of 1.26 and 1.30 g/cm(3), respectively. Deoxyribonucleic acid from either band had the following characteristics: double-stranded; a T(m) of 76.3 C in 0.1 SSC (0.015 m NaCl plus 0.015 m sodium citrate) and a buoyant density of 1.720 g/cm(3) in cesium chloride, corresponding to a guanine plus cytosine content of 56 to 58% and a molecular weight of 130 x 10(6) daltons, determined by velocity sedimentation. These data, together with electron micrographs of sections of cells infected with material from either band suggest that two types of infectious frog virus particles exists, rather than a second virus in the frog virus stocks. The composition of frog virus was determined. It was found that highly purified preparations of frog virus were composed of 55.8% protein, 30.1% deoxyribonucleic acid, and 14.2% lipid. The kinetics of adsorption and uncoating of FV-3 was studied with radioactive virus. Uncoating is comparatively rapid and in contrast to poxvirus is unaffected by inhibitors of protein synthesis.

Adsorption↗
PubMed1968

Deoxyribonucleic acid synthesis in FV-3-infected mammalian cells.

Deoxyribonucleic acid (DNA) synthesis and virus growth in frog virus 3 (FV-3)-infected mammalian cells in suspension were examined. The kinetics of thymidine incorporation into DNA was followed by fractionating infected cells. The cell fractionation procedure separated replicating viral DNA from matured virus. Incorporation of isotope into the nuclear fraction was depressed 2 to 3 hr postinfection; this inhibition did not require protein synthesis. About 3 to 4 hr postinfection, there was an increase in thymidine incorporation into both nuclear and cytoplasmic fractions. The nuclear-associating DNA had a guanine plus cytosine (GC) content of 52%; unlike host DNA it was synthesized in the presence of mitomycin C, it could be removed from nuclei by centrifugation through sucrose, and it was susceptible to nuclease digestion. This nuclear-associating DNA appeared to be a precursor of cytoplasmic DNA of infected cells. The formation of the latter DNA class could be selectively inhibited by conditions (infection at 37 C or inhibition of protein synthesis) that permit continued incorporation of thymidine into nuclear-associating DNA. The cytoplasmic DNA class also had a GC content of 52%, was resistant to nuclease degradation, and its sedimentation profile in sucrose gradients corresponded to that of infective virus. Contrary to previous reports, we found that (i) viral DNA synthesis can continue in the absence of concomitant protein synthesis, and (ii) viral DNA synthesis is not abolished at 37 C. The temperature lesion in FV-3 replication appeared to be in the packaging of DNA into the form that appears in the cytoplasmic fraction of disrupted cells.

Animals↗
PubMed1966

Omphalocele.

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Female↗