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S A Kuznetsova

Publications and source records attributed to S A Kuznetsova.

33 records · Page 2Linked to original sources
PubMedDate not supplied

Cross-linking of Escherichia coli formamidopyrymidine-DNA glycosylase to DNA duplexes containing photoactivatable phenyl(trifluoromethyl)diazirine groups.

New reactive analogs of substrates for DNA repair enzyme E. coli Fpg protein containing the residues of 8-oxoguanine and photoactivatable phenyl(trifluoromethyl)diazirine groups were synthesized. Their substrate properties were investigated. Using photocross-linking technique, we established the presence of contacts of two nucleosides located near the oxoG with amino acids from the Fpg protein. The cross-linking efficiency achieved 10%.

Base Sequence↗
PubMedDate not supplied

[Possible states of photosystem II reaction center and thermoluminescence of the higher plants. I. Analysis of thermoluminescence models and their applicability to the description of experimental data].

A method for the deconvolution of experimental glow curves into overlapping bands and determination of the activation energies for these bands is proposed. The model includes the S-states of the water-splitting complex, tyrozine Z and P680 on the donor side, pheophytine, primary and secondary quinone acceptors on the acceptor side, and takes into account the connection between different states of the reaction center complex. The rate constants of forward electron transport and the activation energies of backward reactions of electron transfer in photosystem II reaction center, included into the model, are estimated from the known experimental data using the proposed approach.

Luminescence↗
PubMedDate not supplied

[Possible states of the photosystem II reaction centerand thermoluminescence of higher plants. II. Application of the theory to experimental data analysis. Relation of thermoluminescence peaks to initial states of reaction center and excitation conditions].

Initial conditions for the thermoluminescence theory described in the first part of the present work were determined. The initial populations of possible states of the photosystem II reaction center and thermoluminescence of higher plants for different excitation conditions were estimated. The estimation enables one to explain the known experimental conditions favoring the appearance of certain thermoluminescence peaks. The possibility of applying the theory to the deconvolution of experimental curves into components was shown.

Luminescence↗
PubMedDate not supplied

[Comparative experimental and theoretical study of the dependence of parameters of curved induction of fluorescence and millisecond delayed luminescence on dark adaptation time].

The dependences of G = (Fm - Fs)/Fm parameter for slow fluorescence induction and delayed luminescence induction curves on adaptation time t(ad) were obtained both in experiment, for the leaves of Hibiscus rosa chinensis in vivo, and in a theoretical study with the help of the theoretical model developed earlier. In both cases, the G(t(ad)) dependences have the form of curves with saturation, which are well described by G = A(1 - exp(-(t(ad)/T0)). Both in experiment and in theoretical calculations, G values for delayed luminescence were larger than for fluorescence. The ratio of saturation times for G(t(ad)) for fluorescence and delayed luminescence was 1.40 for experiment and 1.46 for theoretical calculations. These results suggest that delayed luminescence induction is more sensitive to changes in the state of plant than the slow fluorescence induction.

Adaptation, Physiological↗
PubMedDate not supplied

[Induction of delayed luminescence of pea photosystem II with genetically changed level of starch in the seeds].

We studied the curves of delayed luminescence induction in leaves of pea plants with mutations affecting the starch branching enzyme (r locus) and ADPG pyrophosphorylase (rb locus). In mutated pants, a 75% reduction of starch content in seeds was observed. The half-decay time of delayed luminescence intensity during induction for double mutants was shown to be longer than for wild type plants.

Luminescence↗
PubMedDate not supplied

[Criteria of primary screening of attenuated strains for live vaccine against Influenza A].

Reassortant strains for live influenza vaccine (LIV) were selected using two additional markers: intensity of cytopathic effect (CPE) at 40 degrees C in MDCK cells and toxicity for mice (induction of acute hemorrhagic pulmonary edema after intranasal challenge with undiluted virus). All wild-type viruses induced a high CPE in MDCK cells, while the reassortants differed by this sign. Only vaccine strains and attenuation donors were characterized by a low CPE. Modern epidemic viruses are highly toxic for mice, causing the death of 60-100% animals from hemorrhagic pulmonary edema on days 3-4 after intranasal infection. Attenuation donors and vaccine strains were not toxic for mice, the level of toxic effect correlating with CPE in MDCK culture. Evaluation of CPE in MDCK culture and toxicity for mice can be used for primary screening of candidates for LIV.

Animals↗
PubMedDate not supplied

[Electron structure of plastoquinone and coupling of electron and proton transport in thylakoids of the higher plants].

The energy dependence on hydrogen position for a system, consisting of plastoquinone (in different redox states) and histidine molecules was studied. The distance between the atoms forming the hydrogen bond, an oxygen of the quinone molecule and a nitrogen of histidine, was supposed to be fixed. It was shown that for neutral quinone the total energy is minimal when the hydrogen is bound to histidine; for reduced quinone, the probability of hydrogen binding to quinone and histidine is approximately equal (so that a hydrogen bond is formed) and on secondary reduction of plastoquinone, the hydrogen binds to it.

Electron Transport↗
PubMedDate not supplied

[Theoretical study of the pulse method for the quenching analysis of photosystem II fluorescence].

The kinetics of photochemical (qQ) and nonphotochemical (qE) fluorescence quenching during induction was studied in terms of the earlier developed theoretical model of photosynthesis. Photochemical and nonphotochemical quenching was calculated from the parameters of fluorescence induction upon simultaneous excitation with continuous light and by high-intensity light pulses by the method used in a PAM fluorometer. It is shown that the fraction of closed reaction centers during the pulse can change in the course of induction. In consequence, even when none of supposed mechanisms of photochemical quenching is taken into account, the value of qE during induction varies and is not equal to zero.

Fluorescence↗
PubMedDate not supplied

[Effect of light of various spectral composition on kinetics of changes in a green leaf resistivity].

The kinetics of changes in the resistance of a green leaf by the action of exciting light was studied. It was shown that the illumination-induced changes in leaf conductance are mainly due to an elevation of temperature caused by the absorption of light energy. Based on the experimental results, the fraction of absorbed light energy converted into heat calculated under assumption that heating of the leaf across the thickness is uniform. It was found that the fraction of absorbed energy converted into heat does not depend on the intensity of radiation in the IR range and increases with decreasing intensity of photosynthetically active radiation. An explanation of the phenomenon is proposed, which is based on that in reality the heating of the leaf across the thickness is nonhomogeneous and this inhomogeneity of heating becomes more pronounced upon photoinduced changes in absorption resulting from a decrease in photosynthetically active radiation. It was shown that nonphotochemical fluorescence quenching does not substantially affect the leaf conductance at intensities of photosynthetically active radiation not higher than 200 Wt/m2.

Electric Conductivity↗
PubMedDate not supplied

[Influence of the sucrose outflow from leaves of higher plants on delayed luminescence induction in photosynthesis].

The effect of the transport of sucrose from leaves of higher plants on the width of the spectra of induction of delayed luminescence was studied. It was shown that the duration of the induction period decreases when the sucrose outflow from the leaves is limited by cooling the leaf petiole for two hours under light. It was concluded that the accumulation of sucrose in the conducting tissues of the leaf stimulates the increase in the CO2 fixation rate on rellumination after dark adaptation.

Luminescence↗
PubMedDate not supplied

[Experimental and theoretical study of temperature dependence of steady-state parameters of delayed luminescence induction in leaves of higher plants].

The temperature dependence of delayed luminescence of Hibiscus rosa sinensis leaves was studied in the temperature range from -25 degrees C to degrees C. Temperature dependence of the steady-state delayed luminescence intensity has two maxima, at -10 and at +35 degrees C. For the theoretical modeling, the mathematical model of plant photosynthesis developed earlier was used. The temperature dependence of the delayed fluorescence induction was obtained by introducing into the model the temperature dependences for 12 rate constants derived from the data on the effect of temperature on different stages of photosynthesis. The theoretical temperature dependence of the steady-state delayed luminescence was shown to have the same shape as the experimental one.

Hibiscus↗
PubMedDate not supplied

[DNA sequencing by hybridization with oligonucleotides immobilized in a gel. Chemical ligation as a method of expanding the prospects for the method].

Chemical ligation was used to obtain a series of modified DNA duplexes containing a substituted pyrophosphate internucleotide bound in a given site of the sugar-phosphate backbone. The efficiency of chemical ligation was shown to depend on the structure of the synthesis center for the modified internucleotide bond, thermosiability of the initial DNA complexes, as well as the nature of the non-nucleotide substituent. Maximal yields (up to 77%) were obtained with DNA complexes of regular structure using for condensation the H-butylamide oligonucleotide derivatives on the terminal phosphate group. Conditions were selected for rapid quantitative cleavage of the substituted pyrophosphate bond in aqueous medium (pH 8.0). It was established that modified oligonucleotides which have a phosphoester bond between the phosphate group and the non-nucleotide substituent are more labile than the corresponding compounds with a phosphoamide bond. The results obtained may be useful for DNA sequencing by hybridization with a set of oligonucleotides. This will allow one to achieve unambiguous recognition of nucleotide sequences containing DNA with repeats and thus extend considerably the sphere of application of the method.

Base Sequence↗