Template Activity Of Chromatin Research Articles

The effect of vitamin D on absorption of calcium and the template activity of chromatin in intestines of rats and chicks.

The effect of vitamin D on absorption of calcium and the template activity of chromatin in intestines of rats and chicks.

Transcription of rat cortical neurons after homo- and heterotopic transplantation at different stages of postnatal ontogenesis

The template activity of nuclear chromatin of pyramids and stellate neurons of rat sensorimotor cortex during postnatal differentiation is studied in intact brains and after transplantation. In none of the examined periods after homotopic transplantation does the mean level of template activity of the extranucleolar chromatin in different populations of neurons reach the maximum level observed in normal cells. By contrast, at almost at all times after heterotopic transplantation the mean level of transcription is significantly higher than in the control.

Cytophotometric assessment of Feulgen‐DNA and coomassie‐total cell protein in adrenocortical fasciculata cells of noise‐exposed wister rats

The present investigation was undertaken to examine possible noise-induced alterations in adrenal fasciculata cell (AFC) metabolism, and also to determine if the magnitude of these changes differs in male versus female rats. Wistar rats approximately 3 months old were exposed to intense noise for 60 min (100 dB, re 2 x 10(-5) N(m2)-1, 350-20,000 Hz); control rats were housed under identical conditions, at an ambient noise level of 40-60 dB. Adrenal fasciculata cells (AFC) from each animal were examined for noise-induced alterations in Feulgen-DNA reactivity (as an indicator of chromatin template activity) and Coomassie-total cell protein levels using scanning-integrating cytophotometry. The results provide evidence that intense noise elicited a marked AFC metabolic enhancement in both male and female rats; the degree of this enhancement was more pronounced in males. This disparity may be due to pre-existing differences in male versus female AFC enzymatic capability and subsequent responsiveness to noise-induced activation.

Chromatin template activity in purkinje and granule cells of the rat cerebellar cortex during postnatal differentiation

The authors use Moore's autoradiographic method to study template activity of cerebellar cortical cells. Purkinje cells and granule cells from the cerebellar cortex of rats were used. A mixture of Tris-HCl buffer 100, sucrose 150, ammonium sulfate 80, 2-mercaptoethanol 12, /sup 3/H-UTP 0.02, unlabeled triphosphates 0.6 of each, MgCl/sub 2/ 8, and MnCl/sub 2/ 2 was used.

Dosage compensation and template organisation in Drosophila: In situ transcriptional analysis of the chromatin template activity of the X and autosomes of D. melanogaster strains trisomic for the left arm of the second and third chromosomes

The chromatin template activity of the fixed polytene chromosomes of larval salivary glands of Drosophila melanogaster strains trisomic for the entire left arm of chromosome 2 or chromosome 3 was monitored using 3H-UTP and Escherichia coli RNA polymerase holoenzyme. The three doses of active loci in the trisomic strains were found to synthesize 30%–40% more RNA than the normal double dose of the same region in the wild-type male and female. The higher template activity of the genes on 2L or 3L in the trisomic strains, had no marked effect on the chromatin template activity of the X chromosomes of the male or female. These results suggest that (1) the template activity of an autosomal gene must be viewed as a basal level, comparable to the female X-chromosome and (2) hyperploids for any region of chromosome 2L or 3L have very little or no recognisable influence on X chromosomal organisation.

Brain neuronal chromatin responses in acute soman intoxicated rats.

Male Sprague-Dawley rats (200 g) were injected subcutaneously with soman, a potent neuronal acetylcholinesterase (AChE) inhibitor, at doses of 0.5, 0.8 and 1.0 LD50 (1 LD50 = 135 micrograms/kg) before decapitation at 1 and 24 h post-exposure. Correlative data were obtained on the severity of brain AChE inactivation and physicochemical changes in nuclear chromatin of cerebrocortical (layer V) and striatal neurons using Feulgen-DNA (F-DNA) cytophotometry and ocular filar micrometry. Decreased lability of neurons to F-DNA acid hydrolysis (reduced F-DNA yield), nuclear shrinkage and chromatin aggregation (decreased chromophore area) were used as indices of suppression of genomic template activity; conversely, increases in F-DNA yield and chromophore area signify enhanced neuroexcitation. At 1 hr post-soman there was a dose-dependent inactivation of AChE with a moderate increase in chromatin activation, i.e., nuclear hypertrophy and chromatin dispersion. At 24 hr post-soman there was a partial restoration of AChE activity, notably in striatal neurons, with a suppression in chromatin template activity. These data indicate that actions of soman on neuronal functioning are time-dependent. The absence of any dose-related neuronal chromatin changes may signify existence of non-cholinergic mediated events.

Effect of Calcium on the Structure and Template Activity of Pea Chromatin

Effect of Calcium on the Structure and Template Activity of Pea Chromatin

Cytophotometric Analysis of Neuronal Chromatin and RNA Changes in Oxotremorine-Treated Rats

Neuronal nucleic acid responses were examined within the rat striatum and sensorimotor cortex (layer V) following single intraperitoneal injections of the central cholinergic-muscarinic agonist oxotremorine (0.1, 0.7, or 1.0 mg/kg). After stoichiometric Feulgen and azure B staining of brain sections, scanning-integrating microdensitometry was used to quantify Feulgen-deoxyribonucleic acid levels, changes in the susceptibility of chromatin to Feulgen acid hydrolysis (F-DNA yield) and azure B-ribonucleic acid (RNA) content of neurons on an individual basis. Changes in neuronal nuclear and nucleolar volumes were also determined histometrically. Within the striatum and sensorimotor cortex, oxotremorine produced marked dose-dependent elevations in both F-DNA yield and RNA content. These metabolic increases were typically paralleled by elevations in nuclear and nucleolar volumes. The data demonstrate that the oxotremorine-induced central muscarinic activation is associated with dose-related enhancements in neuronal chromatin template activity, RNA content, and protein synthetic capacity.

X chromosomal organisation and dosage compensation. In situ transcription of chromatin template activity of X chromosome hyperploids of Drosophila melanogaster.

The chromatin template activity of the polytene X chromosomal DNA was assayed by in situ transcription on the fixed polytene chromosomes using E. coli RNA polymerase holoenzyme and 3H-UTP as the monitoring substrate in various 1X2A, 2X2A and 3X2A larvae and 1X2A (+ X fragments) segmental aneuploid larvae of Drosophila melanogaster. The segmental aneuploids contained duplications for the segments 15EF-20F, 11A-20F, 8C-20F and 3E-20F of the X chromosome. Results revealed that a double dose of active loci located in the X chromosome regions 15EF-20F, 11A-20F, and 8C-20F in aneuploids synthesized nearly 40%-70% more RNA than the normal single dose of this region in the wild-type males. The activity per gene dose for the two segments in the aneuploids was also significantly higher than in their male counterpart except for the duplication dp (3E-20F), where the duplicated piece extended from the centromeric heterochromatin to include 85% of the euchromatic portion of the X chromosome. In the case of dp (3E-20F), the X chromosome was transcribed at the lower, "female" level. It may also be noted that some regions of the X chromosome when present in extra copy, especially in dp (8C-20F) influenced the template activity of the X-linked genes inside or outside the duplicated segment. Metafemales (3X2A) have 50% higher template activity of the X chromosomes than their diploid sisters. In this study, metafemales behaved as females with duplication.(ABSTRACT TRUNCATED AT 250 WORDS)

Histone acetylation and deacetylation in senescent human diploid fibroblasts

We measured the kinetics of histone H4 hyperacetylation and kinetics of deacetylation for all core histones in young and senescent human diploid fibroblast-like cells. Both cell populations contained a fraction of histone H4 characterized by very rapid acetylation and deacetylation. The kinetics of these reactions were similar in young and senescent cells. The distribution of acetylated species of core histones was also similar in young and senescent human diploid fibroblast-like cells. These results indicated that previously-reported alterations in chromatin template activity in senescent cells were due to a mechanism other than histone acetylation.

Changes in the template activity of chromatin and the transcriptive specificity of RNA polymerase II of wheat leaves during the early stages of rust infection

The template potential of chromatin from healthy wheat leaves ( Triticum vulgare L. cv. W2691) and from those at 3 days after inoculation with wheat rust fungus ( Puccinia graminis f. sp. tritici, race 126-ANZ-6,7) was assessed by (i) actinomycin D binding and (ii) in vitro transcription with RNA polymerise from different sources. There was no quantitative difference in the actinomycin D binding to chromatin from either healthy or inoculated leaves. Commercial preparations of Escherichia coli RNA polymerase holoenzyme and wheat germ RNA polymerase II synthesized only low molecular weight RNA with chromatin as template and no difference was observed in the template activity of chromatin from healthy or inoculated leaves. By contrast, RNA polymerase II isolated from wheat leaves synthesized high, intermediate and low molecular weight RNA. A comparison of different size classes of RNA radiolabelled in vitro by wheat leaf RNA polymerase II in homologous and heterologous enzyme-chromatin combinations, revealed significant changes in the template activity of chromatin and in the transcriptive specificity of RNA polymerase II of wheat leaves during the early stages of rust infection.

RNA polymerase activity and template activity of chromatin after butyrate induced hyperacetylation of histones in Physarum.

We have studied the effect of sodium-n-butyrate on endogenous RNA polymerase in Physarum polycephalum. 1 mM butyrate strongly reduces RNA polymerase activity measured in isolated nuclei or chromatin; both RNA polymerase A as well as the alpha-amanitin sensitive RNA polymerase B are equally affected. Despite a concomitant hyperacetylation of histone H4 the template activity of chromatin, as analyzed by in vitro transcription of the chromatin with exogenous RNA polymerase from E. coli or RNA polymerase II from wheat germ, remains unaltered as compared to untreated control chromatin, indicating that there is no positive correlation between histone acetylation and template activity of chromatin for transcription in this organism. The results further indicate, that butyrate acts primarily as a quick but reversible inhibitor of protein synthesis in Physarum; the fast decrease of endogenous RNA polymerase activity after butyrate treatment is due to inhibition of enzyme synthesis rather than inactivation of other factors necessary for transcription.

Enhancement of template activity of chromatin in pea by gibberellic acid

Chromatin was prepared from 8-day old pea seedlings ( Pisum sativum, var Alaska) which had been treated with gibberellic acid (GA 3) for 48 h or 0 h, and its template actiivity was measured using a purified cauliflower RNA polymerase II (nucleosidetriphosphate: RNA nucleotidyltransferase, EC 2.7.7.6) added in a challenge experiment. The template activity was enhanced approx. 1.5 times by GA 3-treatment compared with control. The quantity of enzyme binding to chromatin was also increased 1.4-fold by GA 3-treatment. No significant increase in the chain elongation rate was observed and the increase in activity is ascribable to an increase of available initiation sites for transcription. An increase of reaction rate for formation of the rapid-starting complex shows that GA 3 also affects the chromatin in a way which results in binding of enzyme to chromatin more easily. These results suggest that GA 3 acts on chromatin to mediate changes in genetic transcriptional activity.

Stimulation of intestinal chromatin template activity by dietary carbohydrates in adult rats.

Oral administration of a 70% solution of sucrose to starved adult rats resulted 1 h after feeding in a 3.5-fold stimulation of intestinal chromatin template activity assayed in vitro using E. coli RNA polymerase. A similar stimulatory effect was observed with fructose, whereas glucose exhibited a weaker effect, indicating that the nature of the ingested carbohydrate may have a direct effect on the extent of intestinal chromatin template activation.

Characterization and transcription of bovine thyroid chromatin

1. 1. Thyroidal chromatin, isolated from bovine thyroid nuclei, has been characterized and the endogenous RNA polymerase activity was studied. 2. 2. The template activity of chromatin was investigated for exogenous homologous RNA polymerase I and II. 3. 3. The influence of chromosomal proteins on the transcription process was described.

Reconstitution of Endogenous DNA Synthesis in Isolated Nuclei and Template Activity of Chromatin with Respect to Mode of Inhibition by Aphidicolin1

We succeeded in reconstituting the endogenous nuclear DNA synthesis of the sea urchin. Endogenous DNA synthesis of isolated nuclei was reconstituted by mixing the salt-treated nuclei (chromatin exhibiting essentially no endogenous DNA synthesis) and the salt extract containing DNA polymerase-alpha. DNA synthesis in this reconstitution system showed a level of activity and a mode of inhibition by aphidicolin similar to those of the original isolated nuclei (noncompetitive with respect to dCTP). On the other hand, the inhibitory mode was competitive with respect to dCTP in DNA synthesis in the reconstituted system obtained from the chromatin and purified DNA polymerase-alpha, indicating that some other factor(s) in addition to DNA polymerase-alpha is necessary for the reconstitution with reference to the inhibitory mode of aphidicolin. We also studied the template activity of the chromatin. When chromatin was used as a template, inhibition by aphidicolin of DNA polymerase-alpha was noncompetitive and uncompetitive with respect to the template at high and low concentrations, respectively. Treatment of chromatin with 5 M urea gave urea-treated chromatin (nonhistone protein-deprived chromatin) and the extract (mainly nonhistone protein fraction). Inhibition by aphidicolin of DNA polymerase-alpha was uncompetitive with respect to the urea-treated chromatin. However, when chromatin reconstituted from the urea-treated chromatin and the extract was used as a template, the inhibitory mode by aphidicolin was similar to that with original chromatin, indicating that the nonhistone protein fraction contained factor(s) which modified the inhibitory mode of aphidicolin. Thus, the inhibitory mode of aphidicolin is a useful parameter for monitoring the resolution and reconstitution of endogenous DNA synthesis of isolated nuclei.

Studies on Ehrlich ascites tumour cells: DNA synthesis, and template activity of chromatin for DNA polymerase

Chromatin obtained from Ehrlich ascites cells on different days after cell inoculation has been assayed for its template activity with added DNA polymerase I. We have found that the template activity is 2 times higher in 7-8 day cell chromatin than in 4-day chromatin. Studies with added polylysine indicate that this increase reflects an increase in initiation sites rather than in accessibility to the enzyme. We have measured the growth fraction, mitotic index and rate of DNA chain growth in the intact cells. The results show that there is a large decrease in growth fraction with age of tumour, the number of cells dropping out of cycle approximately doubling over the period studied. The overall rate of chain growth decreases in the later stages of growth but in a small proportion of cells there is an increase in rate with fewer replicons involved in DNA synthesis. We suggest that in the ascites cells there is a decrease in level of repair and replicative enzymes with age of tumour; this would account both for the increase in initiation sites in the chromatin DNA, for the decrease in number of cells in cycle and for the overall decreased rate of chain growth.

Differences in salt solubility, DNase II sensitivity and template activity of chromatin from antibody synthesizing spleen cells and myeloma cells RPC 5 and ABPC 22.

Chromatin from myeloma cells RPC5 and ABPC22, and from spleen and liver cells of immunized rats and mice, and mice bearing tumours, was fractionated into three part: 0.35 M NaCl-soluble, 2 M NaCl-soluble and residual. The residual fraction from myeloma cells differed from that of immunized spleen cells, described previously as containing unique sequences (5), in that it has higher protein and DNA levels, lower DNase II sensitivity and lower template activity.

Chromatin changes related to dedifferentiation and differentiation in tobacco tissue culture (Nicotiana tabacum L.)

Non-histone chromosomal proteins (NHP) were isolated from different stages of Nicotiana tabacum L. pith dedifferentiation to callus and callus redifferentiation. The NHP were separated by sodium dodecylsulfate-polyacrylamide gel electrophoresis on slab gels and analyzed by densitometry. Simultaneous histological changes are reported. In both processes, some high molecular weight protein (HMWP) bands increase drastically in an induction period, previous to cell proliferation, and decrease when cell division declines. Some low molecular weight protein bands, intense in pith tissue, decrease early when callus is forming and increase when cells differentiate. chromatin template activity is high when cells proliferate, coinciding with maximum HMWP-bands intensity.

非ヒストン蛋白質およびH1ヒストン除去のクロマチンの鋳型活性とヌクレアーゼ消化性への影響

非ヒストン蛋白質およびH1ヒストン除去のクロマチンの鋳型活性とヌクレアーゼ消化性への影響