[Characteristics of Pseudomonas aurantiaca DNA supramolecular complexes at various developmental stages].

Differences in viscoelasticity (eta) and molecular mass (M) values, as well as in the fatty acid profile of lipids in DNA supramolecular complexes (SC) isolated from Pseudomonas aurantiaca cultures at the exponential and stationary growth phases were established for the first time. Typical characteristics of DNA SC from actively growing cells were the following: eta = 315 +/- 15 dl/g, M(DNA) = 39 x 10(6) Da, C16:0 > C18:0 > C18:1 present as basic fatty acids (FA) in a pool of loosely DNA-bound lipids; the tightly DNA-bound lipid fraction consisted of only two acids C18:0 > C16:0. Significantly higher values of viscoelasticity eta = 779 +/- 8 dl/g and M(DNA) = 198 x 10(6) Da were observed for DNA SC of the stationary phase cells; one more FA, C14:0, was detected in the loosely bound lipid fraction, while lipids tightly bound to DNA contained mainly C16:0 > C18:1 > > C18:0 > C14:0 FA. The content of saturated FA in the DNA-bound lipids in the stationary phase cells was twice as high as in the exponential phase cells. The fraction of tightly bound lipids from the stationary phase cells contained nine times more unsaturated fatty acids than the fraction from proliferating cells. These differences in FA composition of DNA-bound lipids demonstrate the importance of lipids for the structural organization and functioning of genomic DNA during bacterial culture development.

[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-binding lipids: composition and possible functions]. / DNK-sviazannye lipidy: sostav i vozmozhnye funktsii.

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.

[Thiol-induced fragmentation of chromosomal DNA]. / Tiol-indutsirovannaia fragmentatsiia khromosomal'noi DNK.

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.

[DNA-bound lipids from eukaryotic (loach spermatozoa, pigeon erythrocytes) and prokaryotic (E. coli B, phage T2) cells]. / DNK-sviazannye lipidy kletok éukariot (sperma v'iuna, éritrotsity golubia) i prokariot (E. coli B, fag T2).

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.

[Changes in the composition of DNA-bound nonhistone protein in the thymus and liver of gamma-irradiated rats]. / Izmenenie sostava DNK-sviazannogo negistonovogo belka v timuse i pecheni gamma-obluchennykh krys.

A supramolecular DNA complex (SC DNA) and DNA of a phenol nuclear matrix (PNM DNA) were extracted, by the phenol method, from rat thymus and liver 15 min following 10 Gy gamma-irradiation. The method of electrophoresis in polyacrylamide gel was used to study a composition of nonhistone proteins firmly bound to these DNA fractions. Irradiation was shown to induce the occurrence of new proteins and redistribution of proteins between SC DNA and PNN DNA of rat organs.

[DNA-bound lipids of the cells of Zajdela ascites hepatoma and of Ehrlich ascites cancer]. / DNK-sviazannye lipidy kletok astsitnoi gepatomy Zaidela i astsitnogo raka Erlikha.

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.

[Composition of DNA-bound lipids in the regenerating rat liver]. / Sostav DNK-sviazannykh lipidov v regeneriruiushchei pecheni krys.

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.

[The somatic transformation of hens using high-polymeric DNA]. / Somaticheskaia transformatsiia kur s pomoshch'iu vysokopolimernoi DNK.

The transformation studies were performed on genetically pure hen breeds: the donor was Russian white (white colour is a dominant character), the recipient was New Hampshire (pale-yellow-brown). The high-polymeric DNA (2.10(9) dalton) was isolated from erythrocytes and testicles of donor cocks and introduced to a fresh-laid egg of the recipient by replacing the protein. Two sets of experiments on 570 eggs were made. The single injection with 150 micrograms of donor DNA to the recipient egg induced a stable change of feathering colour (particoloured) in 46% of the hatched chicks, which remained for 6 months of observation. Thus, the high-polymeric DNA possesses the property of somatic transformation, that evidences for a high intact character of these preparations.

[Effect of choline on the DNA supramolecular complex in rats and their survival following gamma irradiation]. / Deistvie kholina na nadmolekuliarnyi kompleks DNK krys i ikh vyzhivaemost' pri gamma-obluchenii.

The injection of choline-chloride (200 mg/kg) to rats 15 min before 6 Gy irradiation was shown to increase their survival rate over a period of 30 days, to prolong their average life, and to promote the complete restoration of elastoviscosity of DNA supramolecular complexes in thymus, spleen, liver and brain. When administered immediately after irradiation the drug increased the survival rate of rats.

[Radioprotective action of a GGS-10 gaseous hypoxic mixture on the DNA supramolecular complex of normal tissues and sarcoma 45 of rats]. / Radiozashchitnoe deistvie gazovoi gipoksicheskoi smesi GGS-10 na nadmolekuliarnyi kompleks DNK mormal'nykh tkanei i sarkomy 45 krys.

Gas hypoxic mixture (GHM-10) inhaled by rats during gamma-irradiation (2 to 20 Gy) effectively protects the supramolecular complex of DNA (SC DNA) in bone marrow and spleen, but fails to protect this complex in sarcoma 45. GHM-10 itself has been shown to induce rapid and prolonged, but irreversible, decrease in SC DNA elastic viscosity in normal tissues.

[Relation between the supercoiling of DNA from loach sperm and the environmental temperature]. / Zavisimost' superskruchennosti DNK spermy v'iunov ot temperatury okruzhaiushchei sredy.

The effect of environmental temperature changes in the physiological range on DNA supercoiling in the sperm of Misgurnus fossilis L. was studied. Living fishes from the Oka and the Danube and isolated gonads were exposed to temperature changes. In the living fishes, both temperature increase from 4 to 14 degrees C and decrease from 19-21 to 14 degrees resulted in a reversible relaxation of DNA superhelices. Upon decreasing the environmental temperature from 19-21 to 4 degrees C the reversibility of changes in DNA supercoiling was not observed during the next 15 days. In isolated gonads the temperature increase from 4 to 14 degrees C had no effect on the sperm DNA supercoiling. The temperature-dependent changes in the sperm DNA supercoiling were not dependent on the loach population. It is assumed that the effect of changes in environmental temperature on the supercoiling of sperm DNA in vivo plays an important role in the activation of the genome after fertilization.

[Mechanism of the radiation effect at the level of the supramolecular structures of eukaryotic DNA]. / O mehanizme radiatsionnogo éffekta na urovne nadmolekuliarnykh struktur DNA éukariot.

The methods of viscosimetry and light scattering were used to study the radiosensitivity of the supramolecular DNA (SM DNA) structure in vivo. Irreversible lesions were found in SM DNA 2 min after gamma-irradiation of rats with a dose of 10 Gy. They were associated with the damage to the RNA-lipoprotein component (a linker) and with the dissociation of SM DNA to fragments of different molecular weight, that is, 109 +/- 25 X 10(6), 51 +/- 15 X 10(6), and 47 +/- 21 X 10(6) D for liver, spleen, and thymus, respectively, which correlated with the radiosensitivity of these organs.

[Changes in the composition of phospholipids bound to supramolecular DNA of the thymus and liver in gamma-irradiated rats]. / Izmenenie sostava fosfolipidov, sviazannykh s nadmolekuliarnoi DNK timusa i pecheni gamma-obluchennykh krys.

The composition of supramolecular DNA (SM DNA)-bound phospholipids (PL) of thymus and liver of intact rats and those 2 min, 2, 6 and 24 h after gamma-irradiation (9,7 Gy) was studied. In norm, supramolecular DNA of the thymus was shown to contain 6.7 micrograms PL/mg DNA, and that of the liver, 6.1 micrograms PL/mg DNA, the main components of PL being cardiolipin (CL) and phosphatidylethanolamine (PEA). Substantial changes were detected in the PL composition of SM DNA of gamma-irradiated rat organs. During the postirradiation period the concentration of PEA and CL in thymus SM DNA changed symbatically and irreversibly decreased to traces; whereas in SM DNA of the liver, their concentrations changed antibatically and decreased only to a definite level thus maintaining the necessary "lipid volume". It was shown that PL were not restored in SM DNA of the radioresistant liver.