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Biomedical subjects

B Otto

Publications and source records attributed to B Otto.

At least 73 records · Page 4Linked to original sources
PubMed1978

DNA polymerase alpha is associated with replicating SV40 nucleoprotein complexes.

Simian virus 40 (SV40) nucleoprotein complexes were extracted from nuclei of infected monkey cells and fractionated on neutral sucrose density gradients. Complexes which contained replicating SV40 DNA (95S) separated well from those containing closed circular supercoiled viral DNA (75S). DNA polymerase activity was associated with the replicating nucleoprotein complexes but not with the slower sedimenting complexes. This DNA polymerase activity coprecipitated with the nucleoprotein complexes in the presence of MgCl2 and remained associated with the 95S complexes. This DNA polymerase activity has been identified as primarily DNA polymerase alpha on the basis of its sedimentation behavior, optimum salt concentration, and sensitivity to N-ethylmaleimide. DNA polymerase gamma activity was also detected in the complexes, but DNA polymerase beta was not associated with the complexes.

Cell Line↗
PubMed1978

Binding of phosphorylated histone H1 to DNA.

A chromatin associated protein kinase was used to add 3 moles of phosphate to seryl side chains of 1 mole of histone H1. The DNA binding properties of this in vitro phosphorylated H1 were compared with those of unmodified H1. Considerably more radioactive superhelical DNA was retained on nitrocellulose filters at 20mM-40mM NaCl by phosphorylated H1 than by unmodified H1. However, zone velocity sedimentation analysis of histone-DNA complexes indicated that similar amounts of phosphorylated and unmodified H1 are bound to DNA. It is therefore concluded that phosphorylated H1 binds distributively to many or all DNA molecules available (depending on the histone/DNA ratio) while unmodified H1 binds cooperatively to a fraction of the DNA molecules in the reaction mixture.

Animals↗
PubMed1977

A single-strand-specific DNA-binding protein from mouse cells that stimulates DNA polymerase.

A protein of 30000-35000 molecular weight was isolated from mouse ascites cells. This protein binds preferentially to single-stranded DNA. Evidence is presented that this protein maintains single-stranded DNA in an extended configuration. In the presence of single-stranded template the protein stimulates mammalian DNA polymerase alpha but not the mammalian DNA polymerase beta and not some microbial DNA polymerases. The protein is phosphorylated in vitro by a chromatin-associated protein kinase. The modified DNA-binding protein does not stimulate the DNA polymerase alpha.

Animals↗
PubMed1977

[Studies on tooth migration in animal experiments].

The migration of the germ of the 2nd lower molars after the extraction of all adjacent teeth in comparison to the health side was investigated in Vietnamese hanging belly pigs. The animals were killed in seven age groups so that the results could be evaluated in dependence upon the time. The biometric results reveal migratory phenomena similar to those described for humans after tooth extraction.

Age Factors↗
PubMed1977

[Modification by drugs of cellular and humoral resistance mechanisms in animal experiments. I. In-vitro studies of peritoneal leukocytes and serums in rats].

44 rats were fed p.o. with 3.1 ml/kg of Esberitox over a period of 5 days once daily, for increasing their non-specific resistance against injections. It could be shown that peritoneal leucocytes exhibited an increased phagocytosis of staphylococcus aureus. Besides the direct influence on the ingestion of this pathogenic microorganism, the leucocytes of the Esberitox group showed a stimulated uptake of oxygen when tested in vitro. The humoral defence seems also to be improved due to the elevated bactericidal activity of sera from Esberitox treated rats.

Animals↗
PubMed1976

An endonuclease from mouse cells specific for single-stranded DNA.

An endonuclease with a molecular weight of about 70000 (5-6S) was extensively purified from mouse ascites cells. The enzyme specifically attacks single-stranded DNA which is degraded mainly to oligonucleotides, with 5-10 residues. Supercoiled covalently closed circular phage DNA is converted to the linear relaxed form. The enzyme activity is highly sensitive to salt and can be stimulated by reagents lowering the dielectric constant of the buffer such as dimethylsulfoxide and glycerol.

Animals↗
PubMed1975

Replication of polyoma DNA in isolated nuclei. V. Complementation of in vitro DNA replication.

Nuclei from polyoma-infected 3T6 fibroblasts elongate in vitro the progeny strands of the replicative intermediates of polyoma DNA. When high concentrations of such nuclei were incubated, short DNA fragments were formed and subsequently added onto growing progeny strands. When nuclei were repeatedly washed with buffer containing detergent and then incubated at low concentrations. DNA synthesis was decreased. In particular, the joining process was reduced, resulting in an accumulation of short DNA fragments. All aspects of the synthetic capacity of the nuclei were restored by addition of cytoplasmic extract. Additions of purified enzymes (polynucleotide ligase from calf thymus or Escherichia coli together with E. coli DNA polymerase I) increased the joining function of the nuclei. The system can be used for the identification of the enzymatic steps concerned with polyoma DNA replication.

Animals↗