Biomedical subjects

M Erard

Publications and source records attributed to M Erard.

3 recordsLinked to original sources

PubMed1979

Ethidium bromide binding to core particle: comparison with native chromatin.

Ethidium bromide intercalation into DNA of nuclease digested erythrocyte chromatin and core particle, was followed at low ionic strength by fluorescence measurements, equilibrium dialysis using 14C labelled dye, circular dichroism and electron microscopy. High affinity binding sites in the chromatin are no more present in the core particle, i.e. when the linker is removed. In the case of core particle, a cooperative process occurs, accompanied by a partial stripping of the DNA from the core histone. Finally two populations of core particles can be detected by electron microscopy as far as their binding properties are concerned.

Animals↗

PubMed1978

Reconstitution of chromatin: assembly of the nucleosome.

The order of reassociation of the four histones H2a, H2b, H3 and H4 to the DNA during the reconstitution of chromatin was determined. At each step of the reconstitution the DNA and associated histones were separated from the free histones by centrifugation in a glycerol gradient. The unbound and reassociated histones were analysed by gel electrophoresis and the histone-DNA complexes characterized by circular dichroism and electron microscopy. We show that H3 and H4 bind first to the DNA between 1.2 M NaCl and 0.85 M NaCl and impose a nucleosome like structure; in a second step histones H2a and H2b are placed around this kernel to complete the nucleosome.

Animals↗

PubMed1978

Superstructure and CD spectrum as probes of chromatin integrity.

Two types of chromatin were extracted from the same stock of rat liver nuclei by a short exposure to micrococcal nuclease and by shearing respectively. These two materials which are identical in their protein/DNA content and by the presence of the five histones, were compared by means of circular dichroism and electron microscopy. Under the electron microscope and in absence of any divalent cation a superstructure of the unfixed chromatin fiber can be viewed only with native material but is no more present in sheared one. The increase of CD signal at 280 nm (from 2000 to about 4000 cm2 deg.dmole-1) in the case of sheared chromatin is not related to the loss of superstructure but to the structural changes of DNA inside the nucleosomal core which are always produced by shearing. These two correlated observations offer new sensitive probes of the integrity of any native or reconstituted chromatin.

Animals↗