Increase of seizure threshold and resistance to stress in rats after immunization against fragment of diazepam-binding inhibitor]

White rats were immunized against fragment of diazepam-binding inhibitor octadecaneuropeptide (ODN) with conjugate ODN bovine serum albumin. This rats have reduced reactions of fear and anxiety in stress model of "open field" and in conflict Vogel test; their pain sensitivity ("tail flick" test) was lowered. The number and intensity of generalized seizure reactions after injection of pentylenetetrazole were decreased. The results show that active immunization to endogenous ODN has stress--protective and anti-seizure effects.     

Changes in direct current input resistance in horizontal cells of fish retina during excitation

The input resistance of pike retinal horizontal cells was measured by means of coaxial electrodes under various conditions of illumination. With moderate intensities of illumination, the resistance (determined from a potential drop caused by the current passed through the microelectrode) increases, whereas at high saturating intensities it decreases, as compared with its value in darkness. Such changes in resistance of the horizontal cells explain the effects of input signals interaction in these cells, such as enhancement and complete saturation, observed earlier. Some properties of the horizontal cell response permit us to assume that the "active" cell response to polarization makes a substantial contribution to the measured resistance of these cells. Possible mechanisms of such changes in input resistance of horizontal cells are discussed.Institute of Problems in Information Transmission, Academy of Sciences of the USSR, Moscow. Translated from Neirofiziologiya, Vol. 3, No. 2, pp. 210–216, March–April, 1971.     

Association between 242C>T polymorphism of NADPH oxidase p22phox gene (CYBA) and longevity in Russian population

Life span depends on many factors, including the level of reactive oxygen species, like superoxide radical. Superoxide radical is produced from oxygen in the course of the oxidation of NADPH to NADP⁺. The process is catalyzed by NADPH oxidase. In this study, genotype and allele distributions of the C242T (rs4673) polymorphism in the CYBA gene, which encodes the α subunit of NADPH oxidase (p22phox), were examined in the sample of long livers and in the population sample of the city of Tomsk. Statistically significantly higher frequency of T allele among female long livers (34.625%), compared to the females from Russian population (26.32%) was demonstrated (χ² = 5.226; p = 0.022; OR = 1.48). Thus, the T allele is associated with a high life expectancy in females from the Russian population. No such association was observed for males from the same population.     

Low-voltage underwater electric discharges: Physical properties and application possibilities

Electrical discharges that burn inside an electrolyte bulk and have challenging practical applications are presented. The data on electrophysical and spectral properties of an underwater end-face discharge allowed suggesting the scenario of the discharge origination and development. It includes three stages: bubble growth, a quiet discharge, and an active discharge stage.     

Non-photochemical fluorescence quenching in photosystem II antenna complexes by the reaction center cation radical

In direct experiments, rate constants of photochemical (k_P) and non-photochemical (k_P⁺) fluorescence quenching were determined in membrane fragments of photosystem II (PSII), in oxygen-evolving PSII core particles, as well as in core particles deprived of the oxygen-evolving complex. For this purpose, a new approach to the pulse fluorometry method was implemented. In the “dark” reaction center (RC) state, antenna fluorescence decay kinetics were measured under lowintensity excitation (532 nm, pulse repetition rate 1 Hz), and the emission was registered by a streak camera. To create a “closed” [P680⁺Q_A^–] RC state, a high-intensity pre-excitation pulse (pump pulse, 532 nm) of the sample was used. The time advance of the pump pulse against the measuring pulse was 8 ns. In this experimental configuration, under the pump pulse, the [P680⁺Q_A^–] state was formed in RC, whereupon antenna fluorescence kinetics was measured using a weak testing picosecond pulsed excitation light applied to the sample 8 ns after the pump pulse. The data were fitted by a two-exponential approximation. Efficiency of antenna fluorescence quenching by the photoactive RC pigment in its oxidized (P680⁺) state was found to be ～1.5 times higher than that of the neutral (P680) RC state. To verify the data obtained with a streak camera, control measurements of PSII complex fluorescence decay kinetics by the single-photon counting technique were carried out. The results support the conclusions drawn from the measurements registered with the streak camera. In this case, the fitting of fluorescence kinetics was performed in three-exponential approximation, using the value of τ₁ obtained by analyzing data registered by the streak camera. An additional third component obtained by modeling the data of single photon counting describes the P680⁺Pheo^– charge recombination. Thus, for the first time the ratio of k_P⁺/k_P = 1.5 was determined in a direct experiment. The mechanisms of higher efficiency for non-photochemical antenna fluorescence quenching by RC cation radical in comparison to that of photochemical quenching are discussed.     

Detection of nanodiamonds in biological samples by EPR spectrometry

In model experiments in vitro, the applicability of the EPR spectrometry method for the detection of modified nanodiamonds (MNDs) in blood and homogenates of mouse organs has been established. A characteristic signal (g = 2.003, ΔH ≈ 10 G) is observed in the samples of biomaterials containing MNDs, the intensity of which increases linearly with the concentration of nanoparticles in the range of 1.6–200 μg MNDs per 1 mL of the sample. The EPR method in biomaterials reveals the presence of intrinsic paramagnetic centers, signals from which are superimposed on the signal from the MNDs. However, the intensity of these signals is small, which makes it possible to register the MNDs using EPR spectrometry with the necessary accuracy. The data obtained open up the prospects of using the EPR method for studies of the interorgan distribution, accumulation, and elimination of MNDs during their intravenous injection into experimental animals.     

Biophysical modeling of in vitro and in vivo processes underlying regulated photoprotective mechanism in cyanobacteria

Non-photochemical quenching (NPQ) is a mechanism responsible for high light tolerance in photosynthetic organisms. In cyanobacteria, NPQ is realized by the interplay between light-harvesting complexes, phycobilisomes (PBs), a light sensor and effector of NPQ, the photoactive orange carotenoid protein (OCP), and the fluorescence recovery protein (FRP). Here, we introduced a biophysical model, which takes into account the whole spectrum of interactions between PBs, OCP, and FRP and describes the experimental PBs fluorescence kinetics, unraveling interaction rate constants between the components involved and their relative concentrations in the cell. We took benefit from the possibility to reconstruct the photoprotection mechanism and its parts in vitro, where most of the parameters could be varied, to develop the model and then applied it to describe the NPQ kinetics in the Synechocystis sp. PCC 6803 mutant lacking photosystems. Our analyses revealed  that while an excess of the OCP over PBs is required to obtain substantial PBs fluorescence quenching in vitro, in vivo the OCP/PBs ratio is less than unity, due to higher local concentration of PBs, which was estimated as ~10^?5 M, compared to in vitro experiments. The analysis of PBs fluorescence recovery on the basis of the generalized model of enzymatic catalysis resulted in determination of the FRP concentration in vivo close to 10% of the OCP concentration. Finally, the possible role of the FRP oligomeric state alteration in the kinetics of PBs fluorescence was shown. This paper provides the most comprehensive model of the OCP-induced PBs fluorescence quenching to date and the results are important for better understanding of the regulatory molecular mechanisms underlying NPQ in cyanobacteria.

     

Linkage disequilibrium and haplotypes of the rs1042522, rs1625895, and rs1787862 markers of TP53 in patients with diffuse large B-cell lymphoma

The association of the rs1042522, rs17878362, and rs1625895 polymorphisms of TP53 with risk of non-Hodgkin’s lymphoma (NHL) has not been studied in full detail. NHL has many variants, and each individual polymorphism exerts only a minor effect, requiring the polymorphisms to be studied for particular histological subtypes of lymophomas and as components of haplotype groups. The objective of this work was to analyze the frequencies and linkage disequilibrium for rs1042522, rs1625895, and rs17878362 and their combined haplotype in patients with diffuse large B-cell lymphoma (DLBCL) and control subjects. Differences in linkage disequilibrium structure were observed for rs17878362, rs1042522, and rs1625895 in the Siberian population. The haplotype proved to be more informative than the individual TP53 polymorphisms in a case-control association analysis in DLBCL. Haplotype wArgG was associated with predisposition to DLBCL, while haplotypes wProG and dupProG were found to exert a protective effect. The effect of the haplotype at three TP53 polymorphisms was observed to vary depending on their homozygous or heterozygous state.     

3-Dimensional microscopy as a method for volume measurement in cells undergoing apoptosis

Different patterns of cell volume perturbations are commonly used for modes of cell death: necrosis (cell swelling) and apoptosis (cell shrinkage). In this study we employed recently developed three dimensional microscopy for the measurement of the volume of attached vascular smooth muscle cells transfected with E1A-adenoviral protein. These cells undergo rapid apoptosis in the absence of growth factors or in the presence of staurosporine. In 30–60 min of serum deprivation the volume of these cells is increased by ～40% that corresponds to the time point of maximal activation of caspase 3 and chromatin cleavage. In 10–15 min swollen cells exhibit morphological collapse indicated by formation of apoptotic bodies. In contrast to serum-deprived cells, staurosporine leads to attenuation of cell volume by 30%. In this case, apoptotic bodies are detected in ～2.5 h after maximal shrinkage. Thus, our results show that cell shrinkage can not be considered as universal hallmark of apoptosis. The role of stimulus-specific cell volume perturbation in the triggering of the cell death machinery should be examined further.