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Biomedical subjects

G D Berdyshev

Publications and source records attributed to G D Berdyshev.

At least 19 recordsLinked to original sources
PubMed1979

[Activity of enzymes of nucleic acid metabolism in rat liver nuclei under induction of RNA synthesis by electric stimulation of hypothalamus].

Electrostimulation of hypothalamus results in an increase of RNA synthesis of the AU-type in liver cells of intact and adrenalectomized rats. No such effect is observed in the animals with denervated liver. An increase in RNA synthesis is accompanied by an increase in the activities of RNA-polymerases II and III and histone hydrolase and a decrease in the activities of RNAse and DNAse. The mechanisms of the effect of the nervous system on the activities of the nucleic acid metabolism enzymes are discussed.

Animals↗
PubMed1978

[Tissue-specific decrease and change in the character of DNA methylation in cattle with aging].

The content of 5-methylcytosine (m5C) in DNA of different cow organs is found to decrease in ontogenesis. No other age changes were found in DNA structure and molecular population (GC content, the content of different in the length and the base composition pyrimidine clusters, hyperchromicity value etc.). It is suggested that the age tissue-specific decrease of the m5C content is due to a decrease of the level of DNA methylation, which takes place in heart, kidneys, spleen and brain DNAs and is not observed in lungs. Maximal level of DNA methylation was observed at embryogenesis, when the m5C content in heart DNA decreases (from 1.8 to 1.4 mol. %), then it remains stable up to 1 year old and then sharply decreases with age and reaches 0.94 mol. % at the age of 10 years. The m5C content in liver DNA decreases (from 1.6 to 1.2 mol. %) at the end of embryogenesis and then it does not change. A pronounced decrease of the m5C content was observed in DNAs of cerebral hemispheres, cerebellum, hyppocampus, neurohypophysis and thymus. The decrease of m5C content in thymus DNA is non-random, it concerns only Pu-m5C-Pu, but not long pyrimidine clusters Pu-Pyn-Pu (n greater than or equal to 2). Tissue-specific decrease and the change in pattern of DNA methylation observed are suggested to be a possible mechanism for the age change (distortion) of transcription and cell functioning.

Aging↗
PubMed1976

[Aggregation of histone F2b inthe presence of salt and methanol].

The kinetics of histone F2b aggregation in the presenceof NaCl and methanole was investigated. The size of aggregates increases during 20 hours, and in the following 13 hours the size of formed complexes does not change. It was shown that the stable colloid system was formed by the olygomers of histone F2b.

Histones↗
PubMedDate not supplied

[The nervous system and the genetic apparatus of cells].

Electric stimulation of paraventricular hypothalamic nucleus results in intensification of RNA synthesis in rat brain. Content of acid proteins and RNA in liver and brain chromatin of geese changes in the period of sexual activity controlled by hypothalamus. With long introduction of hydrocortisone content of non-histone proteins of chromatine and RNA as well as total content of RNA in rat liver cells increases. These and other facts confirm the supposition that the central nervous system has an influence on the function of organs and tissues by means of genetical apparatus of cells.

Animals↗
PubMedDate not supplied

[Tertiary structure of histones].

Optical absorption and fluorescence of histones F2a and F2b were studied. An increase in pH and ionic strength induced the structure change in these histones fractions. The hydrofobic sites are formed in protein molecules and this leads to an intensification of histone-histone interactions. The change in the histone tertiary structure is of importance for processes associated with regulation of gene activity in eukaryotic cells.

Histones↗
PubMedDate not supplied

[Effect of intramolecular and intermolecular reactions of the intensity of histone H2A and H4 fluorescence].

Fluorescence of histones H2A and H4 of homo- and hetero-complexes has been studied. It has been found that in the composition of small aggregates consisting of several molecules, the change of histone fluorescence intensity is caused by the change of their tertiary structure. In the composition of large aggregates, including several dozens of molecules, the intramolecular interactions contribute to the change of histone fluorescence. The intermolecular histone interactions are specific and have a cooperative character.

Chemical Phenomena↗
PubMedDate not supplied

[Peculiarities of histones H1, H2b and H4 structure and aggregation in the presence of glycine].

The efficiency of intramolecular and intermolecular interactions of histons H1, H2b and H4 was studied as affected by the glycine concentration in the composition of the glycine-HCl buffer (pH 3.0). It is shown that the concentration of glycine less than 0.01m should be used in experiments with the glycine buffer. Glycine in a higher concentration evokes a considerable aggregation of the histon molecules. Sizes and shape of the aggregates differ in solutions with the lower and high ionic strength. In the presence of glycine the sizes of histone aggregates decrease in the series H1 greater than H2b greater than H4. Changes in the quantum yield of histon fluorescence reflect changes in the tertiary structure of their molecule but not in aggregation.

Animals↗
PubMedDate not supplied

[Study of the structure and aggregation of histones. II. Structure of oligomers forming in mixed solutions of histones H2A and H4].

A change of light-scattering and sedimentation constant of histones H2A and H4 of monomers and oligomers has been studied. It has been shown that in salt-free solution the histone monomers are present. There is a mixture of oligomers (H2A)3, S20,w = 3,8S; (H2A)-(H4)1, S20,w = 3,8S; (H4)60, S20,w = 27S in the solution 0,6 M NaCl depending on fractions correlation. It has been shown that the molecules interactions in the composition of oligomers are cooperative and the cross interactions block the histone H4 self-aggregation.

Chemical Phenomena↗
PubMedDate not supplied

[Structure and aggregation of histones. I. Influence of the ionic composition of the medium on the structure and effectiveness of the intermolecular relationships of histone F2a (H2A+H4)].

The investigation of fluorescence and light-scattering change of histone F2a, ribonuclease, tyrosine, N-acetyltirosinamide, methyl ether tyrosine by the concentration increasing of NaCl, MgCl2, Na2SO4 in the surrounding medium was carried out. In the case of used salts the changes of tertiary structure and histones aggregations depend on the anion type, which is presented in the environment. The tertiary structure of histones formed in the presence of salt is stabilized by weak (hydrophobic and hydrogenic) interactions.

Chemical Phenomena↗