[Cytokines as mediators of neuroimmune interactions].

Cytokines regulate numerous physiological and pathological processes in the central nervous system (CNS), i.e. they function both as immune regulators and neuromodulators. Acting upon the CNS via different ways, cytokines, mainly proinflammatory ones IL-1beta and TNF-alpha, can disturb physiological functions of the CNS, cause neurotoxic and neurodegenerative damage and stimulate IL-1beta synthesis in hypothalamus nuclei and posterior pituitary. They can produce stress-like effects upon the CNS and affect the activity of the axis hypothalamus--pituitary--adrenal glands, levels of neuropeptides in hypothalamic regions of brain, synthesis and utilization of central monoamines. These influences can implement the effects of sensitization, which enhances neuroendocrine responses to later stresses. Microglia and astrocytes, secondary messengers and interaction between hypothalamus and anterior pituitary play an important role in range of these processes as well as in the maintenance of Th1/Th2 cytokine balance.

[Immunomodulating peptides, regulation of interleukin-2 expression and its possible mechanism]. / Immunomoduliruiushchie peptidy, reguliatsiia obrazovaniia interleikina-2 i vozmozhnyi ee mekhanizm.

The influence of some immunomodulation peptides SKD, R and L on the interleukin-2 (IL-2) synthesis in T-lymphocytes and possibility of their specific interaction with nucleotide sequences of IL-2 gene were studied. It was firstly shown that peptides R and L specifically interacted with regulatory nucleotide sequences of IL-2 gene and, possibly, play a key role in the immunomodulation actions on the IL-2 production.

[Probing of the linear distribution of nucleosomes in chromatin]. / Zondirovanie lineinogo raspredeleniia nukleosom v khromatine.

The binding of the antibiotic dyes to chromatin fragmented by various ways and to preparations of "complete" (MH3, 206 DNA base pairs) and "minor" MH1, 155 DNA base pairs) nucleosomes was studied. The latter were obtained from the total hydrolysate of nuclear chromatin hydrolysis by Ca-Mg-dependent endonuclease, using preparative electrophoresis in polyacrylamide gel. In liver chromatin of different vertebrate species the actinomycin D binding is decreased by 70% as compared to DNA binding, while that of ethidium bromide is reduced only by 40%. The splitting of part of internucleosomal DNA by Ca-Mg-dependent endonuclease further decreases the number of binding sites for ethidium bromide, but not for actinomycin D. MH3 bid 24 molecules of actinomycin D per 10(3) of nucleotides; their DNA contain 43.4% of GC-pairs. The GC content in MH1 is 47.7%; they bind 28 dye molecules per 10(3) of nucleotides. The data obtained are discussed in terms of possible predominant localization of nucleosomal cores in GC-pair-rich DNA sites.

[Study of heterogeneity of the chromatin endonuclease fragment by free flow electrophoresis]. / Issledovanie geterogennosti endonukleaznykh fragmentov khromatina elektroforezom v svobodnom potoke.

The oligomer chromatin fragments relatively uniform in size (8--11 nucleosomes) were prepared by a short-term endonycleolysis. The heterogeneity of these fragments with respect to their electrophoretic mobility was revealed using free flow electrophoresis. The individual fragmentated chromatin subfractions were obtained. These subfractions differed in their protein and RNA content per DNA weight unit, in quantitative ratios of different zones of high molecular weight non-histone proteins and in thermal and alkaline denaturation kinetics. It was also found that the parameters investigated are correlated with electronegativeity of the fragmentated chromatin subfractions.

[Analysis of brain chromatin subunit composition using different endonucleases]. / Analiz syb'edinichnoi organizatsii khromatina mozga s pomoshch'iu razlichnykh endonykleaz.

A comparison of the processes of chromatin digestion in brain and liver nuclei by Ca, Mg-dependent and staphylococcal endonucleases demonstrates a similarity of the subunit composition of chromatin from both tissues and reveals the same type of linked DNA regions. However, a formation of low molecular weight DNP fragments during hydrolysis and the DNA spectra of soluble and insoluble DNP fragments suggest that brain chromatin contains these fragments alongside with the regions, which are specific for this particular tissue, predominate in it and are resistant to staphylococcal and, particularly, to Ca, Mg-dependent endonucleases. This is paralleled with a non-histone protein enrichment of different brain chromatin fractions and an expansion of the electrophoretic monomer band towards the fragment with a greater molecular weight. It may be assumed that brain nucleosomes are characterized by a higher size heterogeneity of linked DNA, part of which are mostly covered by non-histone proteins, and/or are characterized by a greater set variety.

[Analysis of brain chromatin subunit organization]. / Analiz subdedinichnoí organizatsiikhromatina mozga.

Autodigestion of chromosomal DNA does not take place during the brain nuclei incubation in the presence of Ca2+ and Mg2+. The kinetic of chromatin digestion in brain and liver nuclei by staphylococcal nuclease and the formation of DNP-fragments suggest that subnucleosomes are generated in both cases by digesting of monomer specific sites. This monomer contains 185--200 DNA base pairs and the most starting DNA going throughout it. However the quantity of nuclease-resistant DNA in brain chromatin is more and the rate of subnucleosome formation is less than in liver chromatin. Redigestion of isolated monomers of brain chromatin results in the appearance of subnucleosomes similar to those which are formed under limited digestion of nuclear chromatin. The incubation of brain nuclei in the presence of Ca, Mg-dependent endonuclease prepared from liver nuclei results in the appearance of fragment. DNA-spectra of these fragments are similar to those prepared under digestion of liver chromatin in situ. These data suggest definite resemblance of subunit organization in brain and liver chromatin.

[Comparative characteristics of chromatin endonuclease fragments]. / Sravnitel'naia kharakteristika endonukleaznykh fragmentov khromatina.

Soluble fragments of chromatin obtained by Ca, Mg-dependent endonuclease digest of rat liver nuclei, have been separated by gel chromatography on Sepharose 4B into three zones, containing oligomers, tetramers--dimers and monomers, respectively. The content of nonhistone proteins and particularly lysine-rich histones is decreased with a transition from theoligomers to monomers. The average protein/DNA ratio of the monomers is equal to 1.36 and that of histone/DNA ratio--to 0.82. The dependence of the degree of chromatin digest by endonuclease on its protein content and conditions of isolation and incubation of nuclei is discussed. The chromatin monomer formed appears to be made up of a nucleosome and short portions of spacer DNA bound to some part of histone HI and nonhistone proteins.

[Effect of the conditions of isolation and incubation of the nuclei on digestion of DNA chromatin by calcium- and magnesium-dependent endonuclease. Change in the spectrum of chromosomal proteins and possible role of DNA-protein interactions]. / Vliianie uslovii vydeleniia i inkubatsii iader na droblenie DNK khromatina Ca, Mg-zavisimoi endonukleazoi. Izmenenie spektra khromosomal'nykh belkov i vozmozhnaia rol' DNK-belkovykh vzaimodeistvii.

Digesting of chromosomal DNA of interphase rat liver nuclei by Ca, Mg-dependent endonuclease in situ in the presence of chelating agents results in the appearance of the soluble DNP--up to 30% of the total DNA. In addition, 50% of the chromatin is solubilised after mild ultrasonication. In the absence of the chelating agents the degree of fragmentation is considerably increased. The process is accompanied by a loss of some histone and nonhistone chromosomal proteins; the nonhistone proteins are lost selectively. The preliminary removal of the nuclear membrane and significant part of the proteins by tritone X-100 promotes the chromatin degradation and the appearance of low molecular weight fragments. The DNA-fragments of solubilised chromatin are similar to the DNA-fragments of residual chromatin, but in the presence of the chelating agents the latter does not contain monomeric fragments.

[Effect of growth hormone on protein phosphorylation in rat liver chromatin]. / Vliianie gormona rosta na fosforilirovanie belkov khromatina lecheni krys

The regular injection of hormone results in a decrease of phosphate groups content in total and non-histone proteins of rat liver chromatin. The quanitity of organic phosphate in total liver histone was increased by 17 per cent. This result is due to the increase of the alkaline-labile phosphate content in lysine-rich histones (approximately by 25 per cent) and unsignificant decrease in arginine-rich histones (approximately by 5 per cent). The intensity of the 32P incorporation was increased under the effect of somatotropin in all fraction of basic proteins; this increase being especially for lisine-rich histone subfractions. The quantity of histone f1 subfractions was also increased. A possible importance of changes in the degree of chromatin protein phsophorylation for realization of growth hormone function on the transcription level is considered.