It has been shown that about 50 % of the
whole chromatin DNA exists in a very compact form in calfthymus
chromatin.These compact fragments can be extracted
from the whole chromatin as nuclease resistant fragments
by limited nuclease digestion. These fragments involve four
out of five histones in folding the...
During karyokinesis in the ciliate, Tetrahymena pyriformis, strain GL-I, an extranuclear chromatin body (ECB) is frequently formed as an excluded mass between the two dividing daughter macronuclei. The formation and fate of ECB's were followed by means of Feu lgen, toluidine blue 0, and euchrysine staining and autoradiography (³H-thymidine). The...
Chromatin DNA sequences intimately associated with the "core"
of the basic, repeating chromatin subunit are shown to be relatively
resistant to digestion by micrococcal nuclease. Chromatin DNA
sequences lying between adjacent chromatin subunits, as well as
DNA sequences in regions of chromatin which are free of chromatin
subunits, are subject...
In this work, the four yeast inner histones were prepared by the
use of consecutive slab gel fractionation. The use of this technique
allowed the first complete fractionation and rigorous identification of
the four yeast inner histones, and made possible a study of their
complexing behavior.
Variants and adjuncts of...
This work represents the first study of the conformational changes in histone H1 subfractions as well as the interactions of these subfractions with two nonhistone chromosomal (NHC) proteins. Calf thymus Hi was fractionated by the method of Kincade and Cole (1966a) using a very shallow guanidinium chloride gradient. A possible...
The nucleosome appears to be the basic structural unit of the
eukaryotic chromosome. The usual nucleosome preparation, isolated
from a micrococcal nuclease digest of nuclei, is heterogenous in DNA
length and protein composition with some particles containing spacer
DNA and associated protein. This heterogeneity complicated physical
and reconstitution studies. As...
Several levels of eukaryotic chromatin structure have
been observed: the nucleosome, the 10 nm and 30 nm fibers
and loop domains, apparently attached to the nuclear
matrix. In this research, the structure and function of
chromatin at two of these levels was investigated, with
studies on both nucleosome positioning and...
Five forms of chromatin, which represent the in vivo folded forms
of nucleic acid, were isolated and used as the binding substrate for
model intercalating compound, ethidium bromide. For all forms of
chromatin, the affinity, location and structural effects of binding
were examined. On the level of the nucleosome, the...
The structure and transcriptional activity of intranuclear
and isolated chromatin from logarithmically growing
yeast cells has been compared to chromatin from cells which
have entered the stationary phase and ceased growing. Both
chromatins show a similar nucleosomal repeat pattern and a
160 by repeat size when digested with staphlococcal nuclease....
By using immobilized trypsin, I have been able to
prepare well-defined, stable trypsinized nucleosomes. The
difficulties of lacking of control in the extent of
trypsinization, which were encountered in previous studies
with the use of free trypsin, have been eliminated. The
nucleosomes and oligonucleosomes prepared by immobilized
trypsin are suitable...
Understanding the structure of the 30 nm fiber in chromatin is relevant to understanding eukaryotic replication and transcription. The major controversy among the models of the fiber concerns the disposition of the linker DNA, the DNA between adjacent nucleosomes, and the location of the linker histones. To determine if the...
I examined, in three separate studies, the active chromatin
structure of the yeast, Saccharomyces cerevisiae.
Yeast contains four proteins having amino acid compositions
typical of the high mobility group (HMG) proteins. Three of these
are eluted from chromatin by 0.35 M NaCl; one is not, but is eluted
by 0.25...
Time-resolved fluorescence spectroscopy was used to monitor the effects of
varying ionic strength on nucleosome core particle structure. Two main methods were
used in these studies. First, the fluorescence anisotropy decay of bound ethidium was
measured and was shown to reflect the rotational tumbling of the core particle through
solution,...
In order to better characterize linker histone interactions with DNA, avian erythrocyte-specific linker H5 and the trypsin-resistant globular domain of H5 (GH5) were used in DNA binding studies. To begin, H5 displayed a considerably higher binding
affinity for DNA than the isolated globular domain (GH5), supporting the importance of the...
The aim of this study was to gain more information about the
interactions between DNA and the histone octamer during the
process of transcription. This work used a pUC8 plasmid derivative
that contained the core promoter region of the RNA polymerase I of
Acanthamoeba castellanii, placed upstream of four repeats...