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G Vidali

Publications and source records attributed to G Vidali.

At least 55 records · Page 3Linked to original sources
PubMed1988

Histone hyperacetylation is induced in chick erythrocyte nuclei during reactivation in heterokaryons.

Transcriptionally inactive avian red blood cell nuclei were reactivated by Sendai virus-induced fusion of chicken erythrocytes with HeLa cells. We have used antibodies which specifically recognize the tetraacetylated form of H4 histone to show that histone hyperacetylation is an event required for chromatin reorganization leading to a transcriptionally competent chromatin structure.

Acetylation↗
PubMed1987

Nucleosomal repeat length in active and inactive genes.

Nucleosomal repeat lengths of total chromatin, H4 histone and beta-DR genes have been measured in logarithmically growing HeLa cells. We have detected significant differences in nucleosomal spacing between inactive chromatin and chromatin regions actively engaged in transcription. These differences are also maintained in metaphase chromosomes at times when transcription ceases although a shortening in nucleosomal repeat length is observed in active and inactive chromatin. These observations support a model where DNA-core histone interactions are temporarily altered to allow selective remodelling of chromatin organization.

Chromatin↗
PubMed1987

Nucleosomal structure as probed by H3 histone thiol reactivity. Conformation of H3 histone variants is differently affected by thiol group reagents.

Two H3 histone variants are found in equal amount in HeLa cells, and they have been characterized by two-dimensional gel electrophoresis followed by reaction with specific antibodies. These molecules are the only cysteine-containing histones, and they have been used as the target for thiol-specific reagents, in intact nuclei, isolated nucleosomes, histone complexes, and purified histones. Cysteine residues are available to N-ethylmaleimide only when histones are disassembled from the core particles. Upon reaction with these reagents, one of the H3 variants undergoes profound conformational changes, as revealed by an altered electrophoretic mobility.

Acetylation↗
PubMed1986

Availability of hyperacetylated H4 histone in intact nucleosomes to specific antibodies.

Specific antibodies against the tetra-acetylated form of H4 histone have been elicited in the rabbit. They do not cross-react with the non-, mono-, and di-acetylated forms of the histone molecule but a slight cross-reactivity with the tri-acetylated form of H4 histone is observed. Our studies also show that hyperacetylated H4 histones are recognized by the antibodies in intact nucleosomes.

Acetylation↗
PubMed1986

Terminal erythroid differentiation in the K-562 cell line by 1-beta-D-arabinofuranosylcytosine: accompaniment by c-myc messenger RNA decrease.

Two erythroid markers, acetylcholinesterase and hemoglobin, can be reversibly induced in the K-562 cell line after sodium butyrate treatment. In the present paper we show that 1-beta-D-arabinofuranosylcytosine (ara-C), induces the coordinate, irreversible expression of these two erythroid markers. This induction occurs at an ara-C concentration (0.05 mM) that results in K-562 cytostasis and is accompanied by deep morphological changes of cells. The differentiated phenotype is independent of the K-562 cell clone used [K-562, K-562 (S), K-562 (S)P] and is associated with the loss of cell renewal capacity. Continuous presence of the inducer is not necessary to achieve terminal differentiation. In contrast to what is seen for other inducers (sodium butyrate and hemin), one of the early effects of ara-C treatment is the marked decrease of c-myc mRNA expression after the first 4 hours of induction, whereas N-ras and histone 4 expression remain constant during the first 48 h. Our results suggest that ara-C treatment can irreversibly activate the erythroid differentiative program of K-562 cells.

Acetylcholinesterase↗
PubMed1985

Effects of retinol on chromatin structure.

The effect of retinol is studied in 3T3 cultured cells. The vitamin induces a decreased rate of cell proliferation and an augmented sensitivity of chromatin to DNase I digestion. Biochemical analyses of chromosomal components establish that the rates of radioactive acetate uptake and turnover on histones are increased leaving unaltered the steady-state level of histone acetylation. The presence of retinol in the culture medium also causes the disappearance of a protein of Mr 20 000, which is co-extracted with the high-mobility-group proteins. The observed changes in chromatin structure and composition are reversible when retinol is removed from the culture medium.

Acetylation↗
PubMed1984

Effects of vitamin E on liver DNA.

Vitamin E, both in the form of dl-alpha-tocopherol and dl-alpha-tocopheryl acetate, was capable of inducing an increased alkaline elution rate of liver DNA from rats treated i.p. with the vitamin. This activity was clearly both dose- and time-dependent. A statistically significant effect was observed at dosages (1.25-5.00 mg/kg) that are in the range of biological activity of the vitamin in the rat (reabsorption-gestation bioassay). Moreover, the effect was observed at dosages that are clearly not toxic. An increased alkaline elution rate of DNA is usually interpreted as suggestive of DNA damage, however recent observations seem to indicate that functional modifications of chromatin packaging can also affect the elution rate of DNA.

Animals↗
PubMed1983

[Clinical study of a prepared reducing diet: adequacy of the vitamin-mineral contribution in comparison to the nutritional and immunity status].

The Authors studied the effectiveness and safety of a commercial hypocaloric diet on 11 obese postmenopausal women. During the experimental period 1 meal/day has been replaced with a chemically defined low calories product. Different parameters have been evaluated to assess the nutritional status 1), anthropometric: weight, skinfold thickness, arm muscle circumference; 2) biochemical total plasma proteins, transferrin, vitamins A, E, C, B12, folic acid; plasma iron, hemoglobin, MCV, RBC; 3) immune status (T lymphocytes and immunoglobulins). Moreover blood sugar, cholesterol and triglyceride levels, as well as blood pressure have been taken into account. All the possible side effects and the diet acceptance for all the patients have been scored. After 1 month all the abnormal conditions (weight, cholesterol, blood pressure) improved, while the nutritional status and immune response remained at an optimal level.

Aged↗
PubMed1983

Effect of retinol on macromolecular synthesis in cultured cell lines.

The effects of retinol on SK Mel 28 and HeLa cell lines were studied with regard to DNA and protein synthesis. It was found that vitamin A added to the culture media at a 50 microM concentration causes a 60% inhibition of DNA synthesis, that the inhibition is reversible and that this treatment does not select retinol-resistant clones. The synthesis of cytoplasmic, acid-soluble nuclear proteins and that of non-histone chromosomal proteins is inhibited as soon as the vitamin reaches the cell.

DNA Replication↗
PubMed1981

Studies of acetylation and deacetylation in high mobility group proteins. Identification of the sites of acetylation in high mobility group proteins 14 and 17.

Duck erythrocytes were incubated with [3H]acetate both in the presence and absence of sodium butyrate. Subsequent perchloric acid extraction of the nuclei, followed by selective acetone precipitation, CM-Sephadex ion exchange chromatography, and gel filtration yielded radioactively labeled high mobility group (HMG) proteins HMG-14 and HMG-17 in pure form. Extensive enzymatic degradation of the proteins followed by amino acid analysis of the digests yielded a significant amount of material eluting in the position of epsilon-N-acetyllysine. Furthermore, automated Edman degradation of intact 3H-labeled HMG-14 and HMG-17 identified the specific sites of acetylation of these proteins. In both erythrocyte HMGs isolated from cells not exposed to butyrate, the lysine residue at position 2 was the only one found to be labeled. However, one additional site in HMG-14 and two additional sites in HMG-17 were found in the proteins from cells incubated in butyrate. Finally, studies of the enzymatic deacetylation of HMG-14 and HMG-17 confirmed that both nuclear proteins serve as deacetylase substrates and that butyrate inhibits their deacetylation, just as in the case of other HMG proteins and nucleosomal core histones.

Acetates↗
PubMed1981

High mobility group proteins 1 and 2 are present in simian virus 40 provirions, but not in virions.

Viral particles at the late stages of SV40 morphogenesis were examined for the presence of HMG proteins 1 and 2, by an immunochemical method involving the transfer of proteins from polyacrylamide gels to nitrocellulose membranes. It was found that these proteins are present in SV40 provirions, in which histone H1 is still associated with viral chromatin, but absent in mature SV40 virions.

Chromosomal Proteins, Non-Histone↗
PubMed1980

Solid phase radioimmunoassay for chromosomal components.

This manuscript describes the use of a solid phase radioimmunoassay for serological analysis of chromosomal components. The applicability of this assay for various studies on nonhistone chromosomal proteins, histones, and chromatin subunits is illustrated. By this technique it is possible to detect and quantify nuclear antigens in the nanogram range. The assay has all the inherent sensitivity and precision of radioimmunoassays and, as such, introduces a new, convenient method for serological analyses of chromosomal components. The results presented reconfirm the serological similarity among the HMG (high mobility group) proteins derived from various sources. The amount of HMG proteins present in mononucleosomes purified from calf thymus is similar to that present in mononucleosomes purified from HeLa cells, suggesting that various tissues contain similar amounts of these proteins. Per nucleosome, dinucleosomes and trinucleosomes contain as much HMG-1 protein as mononucleosomes, suggesting that the protein is not exclusively associated with those regions of DNA which have been solubilized by micrococcal nuclease. Part of the antigenic determinants present in HMG-1 forming a complex in the nucleosomal conformation do not interact with antibodies.

Animals↗
PubMed1980

Intracellular forms of simian virus 40 nucleoprotein complexes. III. Study of histone modifications.

The modification patterns of histones present in various forms of intracellular simian virus 40 nucleoprotein complexes were analyzed by acetic acid-urea-polyacrylamide gel electrophoresis. The results showed that different viral nucleoprotein complexes contain different histone patterns. Simian virus 40 chromatin, which contains the activities for the synthesis of viral RNA and DNA, exhibits a histone modification pattern similar to that of the host chromatin. However, virion assembly intermediates and mature virions contain highly modified histones. Pulse-chase experiments with [3H]lysine showed that the newly incorporated histones in the virion assembly intermediates were already highly modified. The majority of in vivo acetylation activity of histones occurred on the 70S simian virus 40 chromatin as analyzed by pulse-labeling with [3H]acetate. These results and our previous analysis of the virion assembly pathway suggest that three stages are involved in the packaging of simian virus 40 chromatin into the mature virion: (i) modification of histones, (ii) accumulation of capsid protein around the chromatin with highly modified histones, and (iii) organization of capsid proteins into salt-resistant shells. The role of histone modification in virion assembly is discussed.

Acetylation↗