Proton transfer in the photosynthetic reaction center of Blastochloris viridis

Photosynthetic reaction centers of Blastochloris viridis require two quanta of light to catalyse a two-step reduction of their secondary ubiquinone Q(B) to ubiquinol. We employed capacitive potentiometry to follow the voltage changes that were caused by the accompanying transmembrane proton displacements. At pH 7.5 and 20 degrees C, the Q(B)-related voltage generation after the first flash was contributed by a fast, temperature-independent component with a time constant of approximately 30 micros and a slower component of approximately 200 micros with activation energy (E(a)) of 50 kJ/mol. The kinetics after the second flash featured temperature-independent components of 5 micros and 200 micros followed by a component of 600 micros with E(a) approximately 60 kJ/mol.     

Changes in physicochemical properties of proteins, caused by modification with alkylhydroxybenzenes

Kinetic characteristics of model enzymes and physicochemical properties of globular proteins modified by chemical analogues of low-molecular-weight microbial autoregulators (alkylhydroxybenzenes, AHBs) have been studied. C₇ and C₁₂ AHB homologues were used, differing in the length of the alkyl radical and the capacity for weak physicochemical interactions. Both homologues affected the degree of protein swelling, viscosity, and the degree of hydrophobicity. The effects depended on the structure of AHBs, their concentration, and pH of the solution, which likely reflects changes in the charge of the protein globule and its solvate cover. Variations of hydrophobicity indices of AHB-modified enzymes (trypsin and lysozyme) were coupled to changes in the catalytic activity. The values of K _M, measured for the enzymes within both AHB complexes, did not change, whereas V _max increased (in the case of C₇ complexes) or decreased (C₁₂ complexes). Possible molecular mechanisms of changes in the physicochemical and catalytic parameters of enzymatically active proteins, induced by modification with structurally distinct AHBs, are described, with emphasis on targeted regulation of functional activity.     

Synthesis of Anabiosis Autoinducers by Non-Spore-Forming Bacteria as a Mechanism Regulating Their Activity in Soil and Subsoil Sedimentary Rocks

Non-spore-forming bacteria of the genera Arthrobacterand Micrococcus, isolated from permafrost subsoil, were found to produce greater amounts of the d ₁extracellular factor than closely related collection strains isolated from soil. The effect of this factor, responsible for cell transition to anabiosis, was not species-specific. Thus, the d ₁preparation isolated from the culture liquid of the permafrost isolate Arthrobacter globiformis245 produced an effect on the collection strain Arthrobacter globiformisB-1112 and also on Micrococcus luteusand Bacillus cereus.The d ₁preparation from the permafrost isolate of Arthrobacterdiffered from the chemical analogue of this factor, 4-n-hexylresorcinol, in the level of the induced cell response, which may have resulted from different cell sensitivity to various homologs of alkylhydroxybenzenes contained in the d ₁preparation. Thus, additional evidence was obtained indicating that autoregulation of bacterial growth and development is implemented at the level of intercellular interactions in microbial communities. Abundant production of the d ₁anabiosis-inducing factors by bacteria isolated from permafrost subsoil is probably a result of special antistress mechanisms responsible for the survival of these bacteria under extreme conditions of natural long-term cooling.     

Production and specificity of polyclonal antibodies against soluble proteins from the arbuscular mycorrhizal fungus Glomus intraradices

Rabbit polyclonal antibodies were produced against a soluble protein fraction from a vesicle and spore mixture of the arbuscular mycorrhizal fungus (AMF) Glomus intraradices. The protocol for isolation of vesicles and spores from plant roots was optimized to minimize debris contamination. Protein extract purification and preparation for immunization was adapted to increase protein content and immunogenicity. Active antisera were produced starting from the second boost immunization. Antibodies obtained were specific for surface antigens of AMF and revealed different patterns of soluble protein antigens in G. intraradices, G. constrictum and an unidentified Glomus species. Accepted: 6 December 2000     

L1 (LINE-1) retrotransposable elements provide a "fossil" record of the phylogenetic history of murid rodents

The single most difficult problem in phylogenetic analysis is deciding whether a shared taxonomic character is due to common ancestry or one that appeared independently due to convergence, parallelism, or reversion to an ancestral state. Mammalian L1 retrotransposons undergo periodic amplifications in which multiple copies of the elements are interspersed in the genome. Because these elements apparently are transmitted only by inheritance and are retained in the genome, a shared L1 amplification event can only be an inherited ancestral character. We propose that L1 amplification events can be an excellent tool for analyzing mammalian evolution and demonstrate here how we addressed several refractory problems in rodent systematics using L1 DNA as a taxonomic character.      

Results of experimental radiobiological studies made within the 10-kilometer zone of the Chernobyl AES accident]

A study was made of the effect of high radioactive contamination on the animal organism (C57BL/6 mice) and HeLa cell culture within the ten-kilometer zone of the Chernobyl A.P.S. accident. The total radiation dose, as calculated by a gamma-component, was 0.09 to 2 Gy. A long-term exposure of mice within the zone (cumulative dose of 1.8 to 2 Gy) caused a significant decrease in bone marrow stem potencies and changes in the brain vascular system; subsequent acute exposure of animals increased interferon titres in the serum to a much greater extent than a single acute exposure did. As to HeLa cells, irradiation there of with doses of 0.09 to 0.4 Gy during 15-20 postirradiation generations caused a decrease in the proliferative activity, an emergence of cells with micronuclei and of giant cells, and remote cell death.     

Analysis of EEG Structural Synchrony in Adolescents with Schizophrenic Disorders

A total of 39 healthy adolescents and 45 adolescents with schizophrenic disorders (mean age 12.3 years) were examined to study the EEG structural synchrony as reflecting temporal synchronization of the operational activity of neuronal networks. A significant decrease in the EEG structural synchrony was observed in the adolescents with schizophrenic disorders as compared to the healthy adolescents. The decrease was detected predominantly in the interhemispheric pairs of EEG derivations, as well as in the pairs related to the frontal, temporal (predominantly on the left), and right parietocentral regions. The findings provide evidence in favor of Friston’s hypothesis of disintegration of cortical electrical activity in schizophrenia and extend the hypothesis in that it is the operational synchrony of cortical activity that might suffer first in schizophrenia.__________Translated from Fiziologiya Cheloveka, Vol. 31, No. 3, 2005, pp. 16–23.Original Russian Text Copyright © 2005 by Borisov, Kaplan, Gorbachevskaya, Kozlova.     

Pyruvate and glucose transport through the erythrocyte membranes and the role of spectrin in these processes

Effect of antibody to peripheral protein spectrin and antibody to integral protein of band 3 on kinetic parameters of pyruvate and glucose transport in the pink erythrocyte ghosts has been studied. It is shown that spectrin structure reorganization induced by the antibody to this protein has different effect on pyruvate and glucose transport parameters. Band 3 protein modification with the help of the antibody to this protein changes pyruvate transport parameters, while glucose transport is not changed. The data obtained show that facilitated diffusion of glucose and anions in the erythrocyte membrane is carried out by different carriers, the action of these carriers essentially depending on the structure state of spectrin.