Biomedical subjects

B Drescher

Publications and source records attributed to B Drescher.

41 records · Page 3Linked to original sources

PubMed1979

Purification and characterization of bovine leukemia virus DNA polymerase.

An RNA-directed DNA polymerase was purified from bovine leukemia virus (BLV) by successive glycerol gradient centrifugation, column chromatography on phosphocellulose and gel filtration on Sephadex G-200. The purified DNA polymerase transcribes heteropolymeric regions of 30--40 S RNA isolated from avian myeloblastosis virus. The enzyme differs from other known DNA polymerases of mammalian type-C RNA tumor viruses by the following properties: 1. Its apparent molecular weight as estimated by velocity sedimentation data is 58,000 at 0.12 M KCl and 43,000 in the presence of 0.50 M KCl. 2. It has a Mg2+ optimum of 10 mM, and a Mn2+ optimum of 0.25 mM with (rA)n-(dT)10 as template. 3. At 50 mM KCl it is inhibited more than 70%, but it is not inhibited by phosphate ions at 2 mM. These properties confirm the peculiar position of BLV within the family Retraviridae.

Animals↗

PubMed1979

RNA-primed DNA synthesis by an enzyme preparation of calf thymus containing highly enriched RNA polymerase B and DNA polymerase.

RNA polymerase B and DNA polymerase alpha were highly enriched simultaneously from calf thymus. It was shown that the preparation exhibits RNA-synthesizing activity, which is able to stimulate in vitro DNA synthesis by DNA polymerase alpha by its preceding RNA synthesis. A part of the DNA was found to be covalently attached to RNA in Cs2SO4 equilibrium gradients after denaturation by formamide.

Animals↗

PubMed1979

[Separation of cellular and viral DNA polymerase from oncornavirus infected chicken cells].

RNA-directed DNA polymerase was isolated from the liver, spleen, and myeloblasts of chickens that had been infected with virus of avian myeloblastosis. The enzyme was chromatographically purified from the myeloblasts and brought to about 1,000-fold concentration. The method consisted in cell fractionation, lysis of the microsomal fraction, chromatography on Sephadex G-200 and phosphocellulose, as well as ultracentrifugation in the glycerol gradient. The cellular DNA polymerases alpha and beta were clearly separated from the DNA polymerase of avian myeloblastosis virus and could be distinguished from one another by template-specific reactions. The viral DNA polymerase activities in the microsomal fractions of liver, spleen, and myeloblasts were compared with one another. The amount of avian myeloblastosis virus and related DNA polymerase recorded from the myeloblasts was about six times that in the liver and four times higher than that in the spleen. The procedure described, together with the use of cell fractionation and gel filtration, is an appropriate method for biochemical detection of avian oncorna viruses in cells.

Animals↗

PubMed1978

Purification of RNA-directed DNA polymerase from mouse spleen infected with Rauscher leukemia virus.

RNA-directed DNA polymerase was purified from spleens of Balb/c and NMRI mice infected with Rauscher murine leukemia virus. The method includes cell fractionation and lysis of microsomal fraction, chromtography on Sephadex G-200 and phosphocellulose. Estimation of molecular weight from the sedimentation rate of the purified enzyme in a glycerol gradient was consistent with a structure containing one polypeptide with a molecular weight of 70,000. Purified RLV DNA polymerase from spleen could transcribe purified DNA polymerase from purified virions. This simple preparation method offers a procedure for large scale preparation of the RNA-directed DNA polymerase which can be used for synthesis of DNA complementary to mRNA.

Animals↗

PubMed1977

[Studies on the virus demonstration in enzootic bovine leukosis using the revertase test].

This exogenic test for the detection of enzyme activities (revertase) is helpful in differentiating between leucocytes of leukaemic cattle, on the one hand, and those of intact animals, on the other. The mechanism of such identification is based on differences in enzyme activity in the presence of poly rA/oligo dT and poly dA/oligo dT. The best results were obtained from short-time cultured leucocytes which gave ten times higher margins of incorporation by comparison between intact and preleucotic cattle. The morphological findings obtained by electron microscopy confirmed the results by other authors and enlarged them by determination, for the first time, of RNA filaments and protein rings.

Animals↗