[The effect of small doses of gamma irradiation on the relative content of H1 and H1(0) histones in the nuclei of the neurons in the rat cerebral cortex]. / Vliianie malykh doz gamma-oblucheniia na otnositel'noe soderzhanie gistonov H1 i H1(0) v iadrakh neironov kory golovnogo mozga krys.

External gamma irradiation of rats under 0.1-2 Gy causes decreasing of histone H1(0) contents on the first two days after irradiation and increasing in fare later in brain cortices neurones. These changes are observed in fraction of chromatin, which has high sensitivity to DNA digestion.

[The characteristics of DNA repair in the neurons of the rat cerebral cortex after gamma irradiation at low doses]. / Kharakteristika reparatsii DNK v neironakh kory golovnogo mozga krys posle gamma-oblucheniia v nizkikh dozakh.

External gamma irradiation of rats under 0.1-5 Gy causes nonreversible decreasing of DNA synthesis in brain cortices neurones in fare later (30 days after irradiation). The relative points number of excision initiation, which were calculated with the method of BrdU photolysis are much more than under normal condition and than just after irradiation also.

[Effect of low doses of irradiation on synthesis of DNA, RNA and proteins in cerebral cortex cells]. / Vliianie nizkikh doz oblucheniia na sintez DNK, RNK i belkov v kletkakh kory golovnogo mozga.

Short-term external gamma-irradiation (0.1-5 Gy) and long-term (30 days) internal irradiation of rats by everyday intake of 137Cs and 85Sr isotopes into their organisms induced, most probably, irreversible changes in the level of synthetic processes in the rat brain cortex neurons. Synthesis of RNA and proteins decreased significantly after 2h-long irradiation. Irradiation which lasted for 30 days has somewhat shortened the level of reparative DNA synthesis and has almost twice increased RNA synthesis. It was accompanied by changes in the relative activity of RNA-polymerases A, B and C. Doses over 1 Gy have induced an exponential delay of dose-dependent changes in the level of synthetic processes.

[Pectin-containing products in the dietary nutrition of subjects exposed to ionizing radiation as a result of the accident at the Chernobyl Atomic Electric Power Station]. / Pektinsoderzhashchie produkty v dieticheskom pitanii lits, podvergshikhsia vozdeistviiu ioniziruiushchego izlucheniia v rezul'tate avarii na Chernobyl'skoi AES.

Effect of natural and enriched with pectin tanned fruits on radiation-induced metabolic disorders was studied in persons subjected to radiation due to Chernobyl accident. It was shown that products in question beneficially influenced blood antioxidant system as well as brought to the norm contents of triglicerides and albumins in patients with IIa and IV types of hyperlipoproteinaemia.

[Superoxide dismutase in the nuclei of cerebral cortex cells of rats: isolation, properties, effect of ionizing radiation]. / Superoksiddismutaza iader kletok kory golovnogo mozga krys: vydelenie, svoistva, vliianie ioniziruiushchei radiatsii.

Superoxide dismutase (SOD) from rat brain cell nuclei has been distinguished. After chromatography on hydroxylapatite Sephacryl S200 and Mono S SOD can be purified 1200 times. It is Mn-depending enzyme, which has molecular weight 10 kDa and firmly associated with transcriptionally active chromatin. SOD is most active at high ion strength (1.2-2 M NaCl). The more sensitive method for SOD activity determination is suggested (modification of adrenaline autoxidation at pH 10.2).

[Isoenzyme spectrum of lactate dehydrogenase, malate dehydrogenase, esterase and acid phosphatase of rat brain cells at different times after external 1 Gy gamma irradiation]. / Izofermentnyi spektr laktatdegidrogenazy, malatdegidrogenazy, ésterazy i kisloi fosfatazy kletok golovnogo mozga krys v raznye sroki posle vneshnego gama-oblucheniia v doze 1 gr.

The influence of external single gamma-irradiation with a dose of 1 Gy on the isoenzyme composition of lactate dehydrogenase, malate dehydrogenase, esterase and acid phosphatase in the cytoplasm of rat brain cells has been investigated. Irradiation was shown to cause differently directed changes in the ratio of the isoenzymes under study at different times after exposure. The isoenzyme spectrum of lactate dehydrogenase and malate dehydrogenase was shown to be normalized on day 30 after irradiation, whereas the isoform composition of esterase and acid phosphatase was not stabilized at that time.

[Effect of low doses of external and internal ionizing radiation on proteinases of cells in the rat cerebral cortex of rats]. / Vliianie nizkikh doz vneshnego i vnutrennego ioniziruiushchego izlucheniia na svoistva proteinaz kletok kory golovnogo mozga krys.

Single external gamma-irradiation in a dose of 0.5-2 Gy as well as the long-term (30 days) internal irradiation caused by the everyday influx of Cs-137 and Sr-85 isotopes to the organism have been studied for their effect on the activity and properties of histone-specific proteinase from the nuclei of the rat brain cortex cells. It is found out that external irradiation induces a dose-dependent increase of the activity during the first 24 hours after irradiation followed by its decrease 7-30 days later. Internal irradiation induces a decrease of the enzyme activity at the 30th day as well. Certain specificity of the studied indices depending on the type of irradiation has been also observed.

[Structure and properties of the cell nucleus chromatin in the brain of rats exposed to gamma-radiation]. / Struktura i svoistva khromatina iader kletok golovnogo mozga krys posle gamma-oblucheniia.

Exposure of rats to radiation in a dose of 1 Gy changes sensitivity of chromatin in the cerebral cortex cells to the action of DNAase 1, which promotes an increase of the DNA hydrolysis level and content of dissolved chromatin fractions. A day after irradiation the chromatin structure restores only partially and then (7-30 days after irradiation) it passes into a new, less compact state. The irradiation changes the chromatin ability to aggregation in the presence of Mg2+ and spermidine.

[The effect of low doses of external gamma irradiation on the chromatin structure and activity of the histone-specific proteinases of rat brain cells]. / Vliianie nizkikh doz vneshnego gamma-oblucheniia na strukturu khromatina na aktivnost' gistonspetsificheskikh proteinaz kletok golovnogo mozga krys.

Irradiation of rats with doses of 0.5 to 2 Gy was shown to cause dose-dependent changes in the sensitivity of brain cell chromatin to the effect of DNAase I that were manifested by the increased level of DNA hydrolysis and a high content of the chromatin soluble fractions. The chromatin structure was only partially restored 24 h after irradiation. Changes in the chromatin structure were accompanied by the increase in the histone-specific proteinase activity.

[Isolation of a histone-specific proteinase from brain cell nuclei of rats]. / Vydelenie giston-spetsifichesoi proteinazy iz iader kletok mozga krys.

A method for isolating histone proteinase of rat brain chromatin is described, including ammonium sulphate fractionation gel filtration on sefacryl 5200, ion exchange chromatography on mono S and affinity chromatography with benzamidine sefarose. The enzyme molecular weight equals 25 kDa. It is purified 15621 times in comparison with initial nuclear extract.

[Kinetic characteristics of the pyruvate transport system in the wheat chloroplast envelope]. / Kineticheskie kharakteristiki sistemy transporta piruvata v membranakh obolochek khloroplastov pshenitsy.

Kinetics of pyruvate transport through the envelope chloroplast vesicles has been studied. For wheat cultivar Bezostaya-1 Km is 26 mM, Vmax--33 Mmol/l h per 1 mg of protein, Hill's coefficient--0.56 and the coefficient of temperature inactivation at 40 degrees C is 0.045 min-1. 7 mM Mg or Ca ions for optimal activity of the system are needed. Chloroplast treatment with trypsin increases the pyruvate transport intensity. The simple analytical method is suggested for pyruvate determination at the concentration of 10-150 micrograms/ml.

[Isolation and properties of the Ca2+, phospholipid-dependent protein kinase from the substantia grisea of the rat brain in the early stage of exposure to ionizing radiation]. / Vydelenie i nekotorye svoistva Ca2+, fosfolipid-zavisimoi proteinkinazy serogo veshchestva golovnogo mozga krys na rannem étape vozdeistviia ioniziruiushchei radiatsiei.

Ca2+, phospholipid-dependent proteinkinase was isolated from intact and exposed (1 h following whole body X-irradiation with a dose of 0.21 C/kg) gray substance of rat brain, and the dependence of this enzyme on pH and temperature, and substrate specificity were studied. Changes were shown to occur in some Ca2+, phospholipid-dependent proteinkinase properties under the effect of X-radiation while the substrate specificity remained unchanged.

[Interaction of histone H1 molecules in a solution]. / Vzaimodeistvie molekul gistonov H1 v rastvore.

Molecules of histones H1 isolated from the calf thymus, carp testicles and spermatozoa as well as trypsin-stable fragments of these proteins have been studied from the standpoint of their structure and interaction using methods of differential spectrophotometry, gel filtration and turbidimetry. The globular structure of histone H1 of the calf thymus is formed with an increase in the ionic strength of the medium and it is eluted as dimer with gel chromatography. With a considerable local increase of ionic strength (by addition of NaCl crystals) molecules of histones H1 form high-molecular aggregates from all the studied tissues. This aggregation is a result of interaction of globular trypsin-stable sites. Molecules of histone H1 from carp testicles and spermatozoa as well as their trypsin-stable fragments revealed no differences in the ability to form dimers and aggregates.

[Two structural forms of histone octamer]. / Dve strukturnye formy oktamera gistonov.

It has been found that histone octamer of calf thymus (H2A--H2B--H3--H4)2 can exist in two structural states--"loose" (2M NaCl) and "compact" one (4M NaCl). The compact state of the octamer is characterized by screening of part of tyrosyls for quenching effect of ions I-, longer relaxation time of tyrosyls, greater stability of histone H3 towards trypsinolysis, complete absence of interactions between histone H3 SH-groups and parachlormercuribenzoate.

[Spatial organization of the (H3-H4-H2A-H2B)2 histone octamer]. / Prostranstvennaia organizatsiia oktamera gistonov (H3-H4-H2A-H2B)2.

Structure of the (H2A-H2B-H3-H4)2 histone octamer isolated from calf thymus chromatin at ionic strength 0.1 to 4.0 M NaCl, pH 7.6, was studied spectrofluorometrically. Sensitivity of lambda max tyrosine fluorescence position to structural changes of histone oligomers and to the processes of their association was shown. It were detect two ranges of cooperative changes in histone optical parameters at 0.6-1.4 M NaCl (transition I) and at 2.4-3.4 M NaCl (transition II): Transition I corresponds to the formation of equilibrium system (hexamer) + (dimer) in equilibrium octamer. Transition II corresponds to the structural changes of the histone octamer. Thus, fluorescence anisotropy increases, lambda max for fluorescence spectrum is shifted to the longer wavelengths, contributions of two components to fluorescence decay change, a fraction of fluorescence accessible to the quenching by I- decreases. Histone octamer formation is characterized by making specific contacts between the (H2A-H2B) dimer and (H3-H4)2 tetramer. These contacts are realized at gradual changing of ionic strengths (by dialysis). In the case of abrupt local changes of the environment the process is irreversibly shifted to formation of unspecific high molecular aggregates. The important function role for energetically degenerated states of histone oligomers, energy barriers between which can be overcome by changing total conditions of histone microenvironment in chromatin is discussed.

[Accessibility of histone oligomers to the action of trypsin in a solution or in chromatin with different degrees of compactness]. / Dostupnost' oligomerov gistonov deistviiu tripsina v rastvore i v sostave khromatina s razlichnoi stepen'iu kompaktnosti.

The accessibility to trypsin of "core" histones within the dimer (H2A-H2B), tetramer (H3-H4)2, octamer (H2A-H2B-H3-H4)2 and in chromatin was studied. It was shown that the hydrolysis of histones H2A and H2B within the dimer and octamer occurs in essentially the same way. The tetramer (H2-H4)2 becomes more compact with an increase in the ionic strength. Some of the tetramer (H3-H4)2 sites within the octamer are protected against trypsin. It was demonstrated that in terms of the histone accessibility to trypsin chromatin can exist in three states, i.e., tightly packed (in the presence of histone H1 and bivalent cations), intermediate (in the absence of histone H1 or bivalent cations) and folded (in the absence of histone H1 and bivalent cations). The folding of histones in neither of these chromatin states coincides with that within the octamer in 2M NaCl.

Intrinsic fluorescence, difference spectrophotometry and theoretical studies on tertiary structure of calf thymus histone H1.

Tyr-72 is included in the hydrophobic cleft which is formed in the histone H1 globular head. Tyr-72 is screened against polar aqueous environment and its intramolecular mobility is sharply retarded. This microenvironment causes a red shift (lambda max = 279 nm) and a sharpening of the longer wavelength shoulder of absorption spectra, a high fluoresence anisotropy value (A = 0,11), high quantum yield of fluoresence (approximately 0.2) and a decrease of the Stern-Volmer Constant during quenching of histone H1 fluorescence by acrylamide. It has been found that the change in the intensity of histone fluorescence at lambda excit = 265 nm, but not at lambda excit = 280 nm, is due to the changes in the quantum yield of fluorescence. The increase of fluorescence intensity at lambda excit = 280 nm depends on the changes in the quantum yield and molar extinction coefficient of histone H1 tyrosyl chromophore. The change in the ratio of fluorescence intensity exited at 280 nm (F280) to the fluorescence intensity excited at 265 nm (F265) corresponds to the change of delta epsilon 286 in difference absorption spectra. The introduction of the parameter Cf = F280/F265 allows one to go over to studying excitation spectrum shifts instead of histone absorption spectrum shifts, which is much more convenient methodologically since in this case it is possible to carry out research using lower protein concentrations and turbid solutions. The results make it possible to designate Tyr-72 of histone H1 as a special class of fluorescent tyrosyls whose properties differ from those of tyrosyls of other tryptophane-free proteins: RNAase, insulin, core histones--H2A, H2B, H3, H4 and some others.

[Stages of assembly and structural forms of histone oligomers-- (H2A-H2B) dimer, (H3-H4)2 tetramer and (H3-H4-H2A-H2B)2 octamer]. / Etapy sborki i strukturnye formy oligomerov gistonov--dimera (H2A-H2B), tetramera (H3-H4)2 i oktamera (H3-H4-H2A-H2B)2.

The process of dimer (H2A-H2B), tetramer (H3-H4)2 and octamer (H3-H4-H2A-H2B)2 formation was analyzed by the methods of gel-filtration and differential spectrophotometry. Histone octamer with the parameters most close to the native ones is established to be reconstructed only from denaturated monomers at neutral pH. The necessary condition for formation of histone octamer is the stage of tetramer (H3-H4)2 and (H2A-H2B) formation. Histone H3 with intramolecular disulphide bond (formula: see text) does not form tetramer (H3-H4)2 and is not a part of octamer. When passing through the dimer (H3-H4) stage it produces nonspecific high-molecular aggregates. Structural changes preceding the formation of histone octamer may play a significant role for transition of chromatin and nucleosomes into the transcription-active, repressed and other states.

[Characteristics of the tertiary structure of histone H1 from the calf thymus]. / Osobennosti tretichnoi struktury molekuly gistona H1 iz timusa telenka.

By optical methods it has been previously shown that the globular "head" of histone H1 forms a hydrophobic cavity containing Tyr72. The latter is screened from the polar water surrounding and its intramolecular mobility is drastically hindered. As a consequence of the alteration in the micromilieu are a long wave shift (lambda max = 279,5 nm) and a more pronounced longwave absorption spectra, higher anisotropy (A = 0,11), augmented quantum yield of fluorescence (approximately 0,2) and a decrease of the Stern-Volmer constant for Hl at fluorescence quenching by acrylamide. It was found that changes in fluorescence intensity of histones are connected with alterations in the quantum yield of fluorescence at lambda exc = = 265 nm, but not at lambda exc = 280 nm. The changes in fluorescence intensity at light excitation 280 nm (F280) and 265 nm (F265) are in good accordance with shift delta E286 in differential absorption spectra. Introduction of parameter Cf = F280/F265 allows to study shifts of excitation spectra instead of shifts in absorption spectra of histones. This method has certain advantages, since it permits investigations with lower protein concentrations and in turbid solutions. The data obtained allow to draw out Tyr72 of histone Hl into a special class of fluorescent-tyrosyls, that differ in properties from those of other tryptophandevoided proteins: RNAse, insulin and core-histones H2A, H2B, H3 and H4.