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T Hofstaetter

Publications and source records attributed to T Hofstaetter.

24 records · Page 2Linked to original sources
PubMed1978

Asymmetry of chromatin subunits probed with histone H1 in an H1-DNA complex.

Treatment of nucleosomes with a low concentration of sodium dodecyl sulfate removed all proteins except histone H1 from DNA, thus confirming our previous observation on sheared chromatin. No redistribution of H1 occurred during this procedure for isolation of the H1-DNA complex. The H1-DNA complex was isolated from a nucleosome monomer, doubly labeled in its protein and DNA and fractionated according to the length of DNA, and then the distribution of H1 was analyzed quantitatively. The results indicated that the monomer consisted of two subspecies, one containing 160 base pairs of DNA and one molecule of H1, and the other containing 140 base pairs of DNA and no H1. Since no monomer with two molecules of H1 was found, it is concluded that the nucleosome core has a binding site for H1 on only one side, and thus that the nucleosome is not a dyad.

Cell Line↗
PubMed1978

Differences in the binding of methylated albumin to non-replicating, replicating and denatured DNA from Ehrlich ascites cells.

The binding of methylated albumin to DNA, the basis of the chromatography on columns of kieselguhr coated with methylated albumin (MAK chromatography), was investigated. Scatchard plots revealed only one mode of interaction with fully double-stranded DNA. The complexes should be completely dissociated by raising the NaCl concentration of the solution to 0.8 M, indicating a binding by electrostatic attraction between the oppositely charged protein and DNA molecules. In complexes with denatured and partially single-stranded replicating DNA an additional kind of binding was found which made these complexes more stable against salt dissociation. These secondary interactions were stronger at 23 degrees C than at 0 degrees C and could be weakened by the addition of 6 M urea. It was therefore concluded that apolar forces were involved in these interactions.

Animals↗
PubMed1976

Newly synthesized mammalian cell DNA. Separation of Okazaki pieces by thermal chromatography on hydroxyapatite.

The optical melting profile of a fraction of nascent DNA which can be isolated from DNA of logarithmically growing Ehrlich ascites cells by nitrocellullose column chromatography was recorded. In relation to the bulk DNA a slightly lowered Tm and an increased width of the transition was observed. Thermal hydroxyapatite chromatography revealed that melting of the nascent DNA begins at relatively low temperatures in helix regions containing small daughter strand pieces. The pieces were characterized as Okazaki pieces by determining their size and their labeling kinetics during [3H] thymidine pulses. The combination of nitrocellulose chromatography and thermal hydroxyapatite chromatography seems to be suitable for isolating Okazaki pieces.

Animals↗
PubMed1975

[The secondary structure and nitrocellulose affinity of freshly replicated DNA from Ehrlich ascites cells (author's transl)].

Hydroxyapatite chromatography and isopycnic Cs2SO4 centrifugation normally yield no indications of single-stranded DNA when that fraction of replicating DNA from Ehrlich ascites cells which can be separated by nitrocellulose chromatography is analyzed. Single-stranded DNA is detected by both methods if the DNA is fragmented by ultrasound before the nitrocellulose chromatography. The digestion of this DNA fraction by single-strand-specific nucliase leads to a loss of its binding to nitrocellulose and of the indications of single-stranded DNA. The loss for the affinity to nitrocellulose is also observed when the corresponding fraction separated from unfragmented DNA is digested by endonuclease. It is suggested that replicating DNA is bound to nitrocellulose by means of single-stranded gaps on the replication fork. These gaps are apparently too small to be detected within large, otherwise entirely double-stranded molecules by hydroxyapatite chromatography and Cs2SO4 centrifugation. In the case of nitrocellulose-binding ultrasound fragments, this relation seems to be more favorable because of the separation of most of the residual double-stranded part. It is demonstrated that sonication of helical DNA also generates a small amount of fragments with some single-stranded character. The effects observed with replicating DNA could be distinguished from these artifacts.

Animals↗
PubMedDate not supplied

Experimental Klebsiella septicemia in mice: treatment with specific antibodies from the rabbit alone and in combination with gentamicin.

Using a model of an experimental Klebsiella pneumoniae septicemia in mice, we examined the therapeutic effect of passively administered specific antibacterial antibodies from rabbits. Both specific IgM and IgG antibody proved to be therapeutically effective. However, the effect of IgG was markedly superior to that of IgM with regard both to the degree of protection and the time interval allowing efficient therapy after infection. The effect of IgG was due to a marked enhancement of in vivo phagocytosis, as demonstrated by monitoring bacterial numbers in the liver, spleen, lungs and kidneys. In mice immunocompromised with cyclophosphamide, treatment with IgG still exerted protection against low challenge inocula. When higher inocula were used, treatment with IgG ceased to influence the final mortality rates but delayed the course of the disease for several days by transient reduction of bacterial numbers in the parenchymal organs. In both normal and immunocompromised mice, concomitant treatment with gentamicin resulted in a marked synergistic enhancement of survival.

Animals↗