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Biomedical subjects

A Burny

Publications and source records attributed to A Burny.

At least 307 records · Page 17Linked to original sources
PubMed1976

Bovine leukemia virus: an exogenous RNA oncogenic virus.

Short-term cultures of bovine leukemic lymphocytes release virus particles with biochemical properties of RNA oncogenic viruses. These particles, tentatively called bovine leukemia virus (BLV), have a high molecular weight RNA-reverse transcriptase complex and a density of 1.155 g/ml in sucrose solutions. Molecular hybridizations between BLV/[3H]cDNA and several viral RNAs show that BLV is not related to Mason-Pfizer monkey virus, simian sarcoma associated virus, feline leukemia virus, or avian myeloblastosis virus. These results were confirmed by hybridization between BLV 70S RNA and [3H]cDNA synthesized in the various viruses tested. The high preference of BLV reverse transciptase for Mg++ as the divalent cation suggests that BLV might be an atypical mammalian leukemogenic "type C" virus. DNA-DNA hybridization studies using BLV [3H]cDNA as a probe strongly suggest that the DNA of bovine leukemic cells contains viral sequences that cannot be detected in normal bovine DNA.

Animals↗
PubMed1976

Thermosensitive mutations affecting ribonucleic acid polymerases in Saccharomyces cerevisiae.

Among 150 temperature-sensitive Saccharomyces cerevisiae mutants which we have isolated, 15 are specifically affected in ribonucleic acid (RNA) synthesis. Four of these mutants exhibit particularly drastic changes and were chosen for a more detailed study. In these four mutants, RNA synthesis is immediately blocked after a shift at the nonpermissive temperature (37 C), protein synthesis decays at a rate compatible with messenger RNA half-life, and deoxyribonucleic acid synthesis increases by about 40%. All the mutations display a recessive phenotype. The segregation of the four allelic pairs ts-/ts+ in diploids is mendelian, and the four mutants belong to three complementation groups. The elution patterns (diethylaminoethyl-Sephadex) of the three RNA polymerases of the mutants grown at 37 C for 3.5 h show very low residual activities. The in vitro thermodenaturation confirms the in vivo results; the half-lives of the mutant activities at 45 C are 10 times smaller than those of the wild-type enzymes. Polyacrylamide gel electrophoresis shows that the synthesis of all species of RNA is thermosensitive. The existence of three distinct genes, which are each indispensable for the activity of the three RNA polymerases in vivo as well as in vitro, strongly favors the hypothesis of three common subunits in the three RNA polymerases.

DNA↗
PubMed1975

Absence of polyadenylate segment in globin messenger RNA accelerates its degradation in Xenopus oocytes.

Rabbit globin poly(A)-free and native mRNA preparations were microinjected into Xenopus oocytes. The amount of globin message remaining after incubation of injected oocytes was determined by molecular hybridization with a radioactive complementary DNA probe, synthesized by copying globin mRNA with purified RNA-dependent DNA polymerase (reverse transcriptase) from avian myeloblastosis virus. The results show that 56 hr after injection about 85% of the poly(A)-free mRNA molecules are degraded, while native poly(A)-containing mRNA chains are almost completely preserved during the same period of time.

Animals↗
PubMed1975

Biochemical approach to bovine leukemia.

Many bovine leukemic lymphocytes produce virus particles when kept in survival cultures in Eagle's Minimum Essential Medium supplemented with 20 percent of inactivated fetal calf serum. Virus particles equilibrate at a density of 1.16 g/ml in sucrose gradients and at a density of 1.12 g/ml in metrizamide gradients. Simultaneous detection tests show that a high molecular weight RNA-reverse transcriptase complex exists in these viruses. Hybridizations between total RNA from bovine leukemic lymphocytes and C-DNA prepared in various known RNA oncogenic viruses show that the virus associated with bovine leukosis is unrelated to RLV, SSV-1, MSV-Ki, FSV-Ga and FLV-Ri.

Animals↗