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Biomedical subjects

N B Khristoliubova

Publications and source records attributed to N B Khristoliubova.

At least 19 recordsLinked to original sources
PubMed1988

[Heterogeneous packing of the Escherichia coli chromosome and its decompaction in in vitro experiments].

The chromatin organization of E. coli cells, taken on various growth stages of the culture (active, stationary, grown with heightened density), displays different characters when examined by the Miller method. In the active phase of growth, the cell chromatin is released as threads and loops of DNA, threads of nucleosome-like particles and granules 25-38 nm in size. The chromatin from cells in the stationary phase of growth, grown in heightened density conditions, contains not only granules of average size 30 and 100 nm, but also larger conglomerates consisting of several 100 nm particles. The chromatin decompaction of cells grown under heightened density, in conditions of weak alkali medium and low salt buffer, was in general of two types: creation of diffusion cloud with no clear-cut outlines, and spherical structure of 1.5-2 microns in diameter with electron dense centre. In one chromosome both the types of chromatin decompaction can be found at the same time with regions of compact chromatin, which undoubtedly shows different functional activity of some regions of the chromosome.

Cell Division↗
PubMed1987

[Characteristics of the ultrastructural organization of the nuclei of somatic cell hybrids].

A study was made of the ultrastructure of cell nuclei of two types of hybrid clones obtained from the fusion of Chinese hamster with human skin fibroblasts, and from that of mouse hepatoma cells with mink fibroblasts. In cell nuclei of the eight hybrid clones deep invaginations of the inner membrane, not characteristic of the parent cells, were revealed. Analysis of serial sections, and application of electron microscopic radioautography and histochemistry have suggested that these structures are associated with the nuclear envelope which is necessary for regulating the superfluous chromosome localization in the hybrid nucleus.

Animals↗
PubMed1986

[Electron microscopic research on the extrachromosomal genetic elements of Escherichia coli].

The structural organization of extrachromosomal genetic elements were studied in a subfraction obtained after centrifugation of the lysate of E. coli spheroplasts. With this method of isolation, the tertiary structure of the extrachromosomal genetic elements was preserved. The majority of DNA macromolecules were released in the form of single and connected rosettes. Typical rosettes composed of radial loops of DNA clustered around the central dense core (the diameter is about 60 nm). The mean length of the rosette loops was 1.06 +/- 0.4 micron. Both relaxed folded and supercoiled folded forms of DNA were observed on the preparation. Sometimes the rosettes were connected with large aggregates of DNA (possibly the material of bacterial chromosomes) and had the appearance of thick fibers with numerous lateral loops. Linear, cyclic and various replicative forms of DNA have also been observed. It is assumed that rosettes of the extrachromosomal elements of E. coli reflect one of the levels of organization of prokaryotic genetic material.

DNA, Bacterial↗
PubMed1985

[Quantitative analysis of the ultrastructure of gastric mucocytes in the rat after prostaglandin treatment].

Effect of prostaglandin E2 (PGE2) on mucus secretion by mucocytes of the fundal part of the rat stomach has been studied electron microscopically, morphometrically and biochemically. PGE2 is found to stimulate synthesis of glycoproteins and their secretion by the mucocytes that results in increasing the relative volume of Golgi complex and in decreasing that of secretory granules. Actinomycin does not affect and cycloheximide blocks the stimulating activity of prostaglandin. This demonstrates that prostaglandin produces its action at the posttranscriptional (translational) level controlling mucus secretion of mucocytes. Owing to the results of the investigation and of those previously obtained on incorporation of 3H-pentagastrin and 3H-histamine into the cells of the mucous tunic, at least two mechanisms are supposed to control the gastric mucus secretion.

Animals↗
PubMed1985

[New method of encapsulating isolated nuclei into a lipid membrane].

A new method of the coating of isolated cell nuclei with additional phosphatidylcholine membranes is described. The additional membrane was visualized under the electron microscope using ferritin as a label. The coating diminished leakage of the content of the nuclei and restricted permeability of the nuclei for exterior macromolecules.

Animals↗
PubMed1985

[Use of cell enucleation in studying the stability of cytoplasmic organelles and cytoplasm organization].

A study was made of the viability and ultrastructure of cytoplasts produced by enucleation of cytochalasin-induced A9 cells in suspension. These cytoplasts are in general as viable as cells enucleated in the monolayer. The organization of the cytoplasm, i.e. a specific distribution of cytoplasmic organelles, is conserved for at least 24 hours in the absence of the nucleus. This fact may reflect a high degree of autonomy of the cytoskeleton.

Animals↗
PubMed1984

[Electron microscopy study of deoxyribonuclease penetration into chick embryo fibroblasts and the effect of the enzyme on the cells].

Peroxidase labeled DNase (0.25 g/ml) penetrated into the chick fibroblast culture cells by means of pinocytosis to be localized in pinocytotic vacuoles. Within a 24 hour-incubation of the cell culture with DNase a relative volume of vacuoles in cells increased from 4.6 to 19.5 per cent, the majority of pinocytic vacuoles being filled with labeled DNase. The incubation of cells with non-labeled DNase (24 hours) did not damage DNA-containing cell structures. The data obtained permit to explain the selective effect of the enzyme on the viral DNA and the inhibition of reproduction of DNA-containing viruses by the interaction of the viral DNA and DNase inside pinocytic vacuoles which protect the cells from the enzyme damaging effect.

Animals↗
PubMed1977

[Comparative study of the ultrastructure of cells of the zona fasciculata of the adrenal cortex of rats of different lines].

By means of morphometric analysis, some tissue and cellular parameters of the zona fasciculata of the adrenal cortex of three rat inbred strains (Wistar, Sprague-Dawley, August) and of the wild grey rats were calculated. Significant genotypic differences were found in the absolute volume in the number of cells per mm3 of tissue, and in relative volumes of basis cellular compartments (smooth endoplasmic reticulum, liposomes) which take part in corticosteroid biosynthesis. A hypothesis is put forward that these differences determine different potential possibilities of rat adrenals, which are realized when their functional activity is enhanced under extreme conditions.

Adrenal Cortex↗
PubMed1975

[An electron microscopic and morphometric study of the gastric parietal cells of rats following administration of gastrin, histamine and cyclic 3',5'-adenosine monophosphate].

The ultrastructure of the gastric parietal cells was studied in rats affected by a genetic inductor of the hydrochloric acid secretion and its mediators in this process - histamine and cyclic 3', 5'-adenozinemonophosphate playing the role of the enzyme activators. All these stimulators caused similar changes in the cell structure. The square surface of the intracellular secretory tubules was shown to become 2,5 times larger, and that of the canaliculi - vesiculoid elements which seemed to be the cell membrane depot became 2,5 times less. It may be supposed that the gastric mucosa parietal cells are not the target-cells for pentagastrine (gastrine).

Animals↗