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Biomedical subjects

N B Strazhevskaia

Publications and source records attributed to N B Strazhevskaia.

At least 19 recordsLinked to original sources
PubMed1993

[DNA-binding lipids: composition and possible functions].

The experimental data concerning the composition of DNA-bound lipids of different eukaryotic and prokaryotic cells have been summarized. Using X-ray diffraction patterns, circular dichroism, microcalorimetry, electron microscopy, viscoelastometry and sedimentation methods, it has been proved that the lipids are important integral components of chromosomal DNA. It was shown that the DNA-bound lipids have a specific composition which differs from that of chromatin, nuclear membrane and matrix lipids. The composition of these lipids changes depending on the activity of the genome and the phase of the cell cycle as well as when DNA passes from a supercoiled into a relaxed state. The DNA of cancer cells has a specific composition of the lipid component. The lipids take part in the regulation of transcription. The DNA-bound lipids are hypersensitive target sites for ionizing radiation and anticancer agents. The role of this lipid class in structure-functional organization of chromosomal DNA is discussed.

Animals↗
PubMed1992

[Thiol-induced fragmentation of chromosomal DNA].

Supramolecular complexes of DNA (SC DNA) were isolated from loach sperm, loach erythrocytes and hen erythrocytes by the phenol method. By the use of UV-sedimentation on neutral 5-20% sucrose gradient, we studied the effect of 2-mercaptoethanol (ME), dithiothreitol (DTT) and NaBH4 on SC DNA at different pH and long-time incubation (5 and 10 days). It appeared that ME treatment at pH 4.4 fragmented SC DNA of three objects into subunits of size 5 x 10(5)D. Incubation with DTT at pH 8 in the presence of EDTA resulted in subunits of size 1-2 x 10(7)D. However, NaBH4 at pH 8 failed to induce fragmentation of SC DNA. It is shown that ME-induced at pH 4.4 fragmentation is accompanied by a decrease in hyperchromatic effect of subunits, indicating the presence of "sticky" ends. Thus, ME-induced fragmentation of SC DNA results from a "clayting" double-strand break, involving, on an average, 180 bp.

Animals↗
PubMed1990

[DNA-bound lipids from eukaryotic (loach spermatozoa, pigeon erythrocytes) and prokaryotic (E. coli B, phage T2) cells].

Using thin-layer chromatography, some specific DNA-bound neutral lipids and phospholipids of loach spermatozoa, pigeon erythrocytes, E. coli B and phage T2 cells were studied. These lipids are represented by loosely and firmly bound components. The content of neutral lipids in the above DNAs (per mg of DNA) is 10.6, 4.8, 7.81 and 1.43 micrograms, respectively; that of phospholipids is 4.31, 1.28, 1.14 and 0.54 micrograms, respectively. The eucaryotic DNA-bound lipids are highly deficient of free cholesterol, phosphatidylcholine, phosphatidylinositol and phosphatidylserine but are rich in cardiolipin, phosphatidylethanolamine, cholesterol esters, diglycerides and free fatty acids. The quantitative and qualitative composition of DNA-bound lipids of loach spermatozoa changes during the transition from the superhelical to the relaxed conformation of DNA. Procaryotic DNA-bound neutral lipids are also represented by the free cholesterol, diglyceride and free fatty acid fractions, whereas the DNA-bound phospholipids of procaryotes consist of only two fractions, i.e., cardiolipin and phosphatidylethanolamine. The role of DNA-bound lipids in the structural and functional organization of eucaryotic and procaryotic genomes is discussed.

Animals↗
PubMed1989

[DNA-bound lipids of the cells of Zajdela ascites hepatoma and of Ehrlich ascites cancer].

DNA-bound neutral lipids (NL) and phospholipids (PL) were isolated and characterized from the Zajdel ascites hepatoma (ZAH) and Ehrlich ascites carcinoma (EAC) cells. The lipids are represented by light- and tightly bound components. It was shown, that the tumour DNA contained minor amount of NL (25, 17 micrograms and 16.87 micrograms per mg DNA, respectively) and of PL (4.54 micrograms and 5.36 micrograms per mg DNA, respectively, for ZAH and EAC). The composition of the tumour DNA-bound lipids was shown to differ from that of DNA-bound lipids of liver and thymus of intact rats by the next parameters: NL/PL ratio is much more than one; increased content of FC; equal values of the three basic ratios--CE/FC, NL/PL, cholesterol/PL, presence of mono- and triglycerides.

Animals↗
PubMed1988

[Composition of DNA-bound lipids in the regenerating rat liver].

Using thin-layer chromatography, the qualitative and quantitative composition of specific DNA-bound neutral lipids (NL) and phospholipids (PL) of regenerating rat liver 22 hours (S-phase) and 28 hours (G2-phase) after hepatectomy was studied. These lipids are represented by light and tightly bound components. The intact liver DNA contains minor amounts of NL and PL (15.02 micrograms and 5.82 micrograms per mg of DNA, respectively). The composition of DNA-bound lipids in rat liver differs markedly from that of nuclear membrane and chromatin total lipids. The former are strongly deficient in free cholesterol (FC), but are rich in cholesterol esters (CE), very rich in cardiolipin (CL) and deficient in phosphatidylcholine. The basic parameters of DNA-bound lipids of rat liver (NL/PL, CE/FC and cholesterol/PL) are more than unity and depend on the cell cycle. It was shown that in the S-phase the content of DNA-bound NL and PL increases 1.5-fold, in the G2-phase the NL content shows a still greater increase--2.3-fold, while that of DNA-bound PL decreases to normal values. The basic changes of the DNA-bound lipids in regenerating rat liver are due to FC, CE and CL, which determine the tissue specificity of these lipids.

Animals↗
PubMedDate not supplied

[Change in the elastoviscosity of supramolecular DNA of sturgeon spawn after conservation with 4.5-5% NaCl].

Elastoviscosity of supermolecular DNA of beluga, sevruga and sturgeon pawn 6 months after conservation with 4.5-5% NaCl was studied. It is shown that a positive relation exists between elastoviscosity of SM DNA and its gustatory qualities. Therefore the value of elastoviscosity of SM DNA may be used for testing the changes of sturgeon pawn properties during conservation.

DNA↗
PubMedDate not supplied

[Effect of alkylhydroxybenzenes, microbial anabiosis inducers, on the structural organization of Pseudomonas aurantiaca DNA and on phenotypic dissociation induction].

We revealed a relationship between alkylhydroxybenzene (AHB)-induced changes in the structural organization of supramolecular complexes (SC) of the DNA of Pseudomonas auraniaca and the phenotypic dissociation of this bacterium. The addition of 0.1-0.3 mM hexylresorcinol (C6-AHB), a chemical analogue of microbial anabiosis autoinducers, caused the formation of cystlike refractile cells (CRC) in these gram-negative, nonsporulating bacteria. Inoculating pseudomonad CRC on solid nutrient media resulted in phenotypic dissociation of the microbial population that yielded several variants with different colony structure and morphology. This manifested itself in the conversion of the original S-colony-forming phenotype into the R form and in the formation of less pigmented colonies. These transitions were possibly linked to AHB-induced structural changes in the DNA. In vitro studies revealed that AHB could interact with DNA SC, resulting in their structural modification that manifested itself in changes in their elastoviscosity. DNA supramolecular complexes isolated from proliferating, stationary-phase, and anabiotic P. aurantiaca cells differed in their elastoviscosity and capacity to interact with AHB homologues with different hydrophobicity, such as hexylresorcinol and methylresorcinol (C1-AHB). The DNA SC from actively proliferating cells were characterized by smaller elastoviscosity compared with those from stationary-phase and anabiotic cells, due to the difference in the DNA superspiralization degree and the physiological age of the bacteria involved. C6-AHB produced a pronounced relaxing effect on the DNA SC from exponential-phase P. aurantiaca cells. The less hydrophobic C1-AHB produced a similar effect on the DNA SC from stationary-phase cells. The curve of the dose-effect dependence of C6-AHB had a breaking point within the submillimolar (10(-4) M) concentration range. These concentrations induce the formation of cystlike anabiotic pseudomonad cells that are characterized by an unstable genotype and dissociate into distinct variants upon inoculation on solid media.

DNA, Bacterial↗