2',3'-Dideoxy-3'-aminonucleoside 5'-triphosphates inhibit the repair of DNA in rat liver chromatin

2',3'-Dideoxy-3'-aminonucleoside 5'-triphosphates are shown to be strong inhibitors of repair DNA synthesis in gamma-irradiated rat liver chromatin. The activity of these compounds is comparable with that of the most effective inhibitor of the DNA polymerase beta-catalyzed repair DNA synthesis.     

Combined Effect of Neutron and Proton Radiations on the Growth of Solid Ehrlich Ascites Carcinoma and Remote Effects in Mice

Doklady Biochemistry and Biophysics - The combined effect of the irradiation with a proton pencil scanning beam (PBS) at a total dose of 80 Gy and neutron radiation at a dose of 5 Gy on the growth...     

IR and Raman spectroscopy in the study of carotenoids of <Emphasis Type="Italic">Cladophora rivularis</Emphasis> algae

Using Raman and infrared spectroscopy it has been found that during the normal life of algae (pH changes from 8.0 to 9.0) the content of carotenoids increases and the molecules change their conformation: the contribution of–C=C–bonds of the polyene chain of a carotenoid molecule (Raman spectroscopy) is reduced and the contribution of methyl groups (～2940 cm^–1) and aromatic C–H-plane deformation vibrations (band at 1050 cm^–1) of carotenoid molecules (infrared spectroscopy) decreases as well. It is the opinion of the authors that a change in the extracellular pH within the normal range has no influence on the content of chlorophyll a and b, but tends to increase the content and alter the conformation or structure of carotenoid molecules.     

Genetic system for maintaining the mitochondrial human genome in yeast <Emphasis Type="Italic">Yarrowia lipolytica</Emphasis>

For the first time, the possibility of maintaining an intact human mitochondrial genome in a heterologous system in the mitochondria of yeast Yarrowia lipolytica is shown. A method for introducing directional changes into the structure of the mitochondrial human genome replicating in Y. lipolytica by an artificially induced ability of yeast mitochondria for homologous recombination is proposed. A method of introducing and using phenotypic selection markers for the presence or absence of defects in genes tRNA-Lys and tRNA-Leu of the mitochondrial genome is developed. The proposed system can be used to correct harmful mutations of the human mitochondrial genome associated with mitochondrial diseases and for preparative amplification of intact mitochondrial DNA with an adjusted sequence in yeast cells. The applicability of the new system for the correction of mutations in the genes of Lys- and Leu-specific tRNAs of the human mitochondrial genome associated with serious and widespread human mitochondrial diseases such as myoclonic epilepsy with lactic acidosis (MELAS) and myoclonic epilepsy with ragged-red fibers (MERRF) is shown.     

Establishing a Cultivable Cell Line of the Tick Dermacentor marginatus

Russian Journal of Genetics - Owing to the changes in the general ecological situation in Russia, livestock losses from ovine anaplasmosis have rapidly increased in recent years. The development of...     

A new inhibitor of the CoQ-dependent redox reactions in mitochondria and chromatophores

The effects of 3,4-dimethoxyphenyl-1-amylketone (DPK) on the CoQ-dependent stages of the electron transport systems in mitochondria and Rhodobacter sphaeroides chromatophores were studied. The two systems contain the complete Q-cycle. The sensitivities of the Q-cycles of two electron transport systems to antimycin, myxothiazole, and other inhibitors are virtually indistinguishable from one another, but these systems have different CoQ reduction processes. The dependence of the inhibition extent of the mitochondrial succinate oxidase on the DPK concentration was studied. The effective concentration of DPK is 0.5-2.5 mM. The presence of the point of inflection in the titration curve indicates that there are two mechanisms of inhibition. The effects of DPK on the extent of reduction of cytochromes b and c1 + c in mitochondria as well as on the electrogenic stages of the Q-cycle in chromatophores were examined. The experiments showed that DPK prevents three CoQ-dependent reactions related to the Q-cycle: electron transport between succinate dehydrogenase and the Q-cycle in mitochondria and functioning of the Z (o) and C (i) sites of the Q-cycle in chromatophores. DPK does not affect the electrogenic reaction associated with protonation of the secondary quinone acceptor QB in the reaction center of chromatophores. The mitochondrial NADH-dehydrogenase is inhibited by DPK at lower but comparable concentrations (C50 = 0.2 mM).     

Degradation of proteinaceous substrates by xylotrophic basidiomycetes

The ability of various xylotrophs to produce extracellular proteolytic enzymes has been studied, with emphasis on medium-related factors regulating their secretion. Direct measurement of proteolytic activity in the culture liquid and postelectrophoresis determination of protease activity in polyacrylamide gel copolymerized with gelatin demonstrated that the secreted enzymes are quantitatively and qualitatively diverse. Activity levels of extracellular proteolytic enzymes strongly depend on pH and contents of protein and carbohydrate in the medium. All secreted proteases notably differed in molecular weight (of 51 kDa or higher and in excess of 95 kDa) and belonged mostly to two classes of proteolytic enzymes (serine proteases and metalloproteinases).     

Description of “<Emphasis Type="Italic">Desulfotomaculum nigrificans</Emphasis> subsp. <Emphasis Type="Italic">salinus</Emphasis>” as a New Species, <Emphasis Type="Italic">Desulfotomaculum salinum</Emphasis> sp. nov.

This study focused on the physiological, chemotaxonomic, and genotypic characteristics of two thermophilic spore-forming sulfate-reducing bacterial strains, 435^T and 781, of which the former has previously been assigned to the subspecies “Desulfotomaculum nigrificans subsp. salinus”. Both strains reduced sulfate with the resulting production of H₂S on media supplemented with H₂ + CO₂, formate, lactate, pyruvate, malate, fumarate, succinate, methanol, ethanol, propanol, butanol, butyrate, valerate, or palmitate. Lactate oxidation resulted in acetate accumulation; butyrate was oxidized completely, with acetate as an intermediate product. Growth on acetate was slow and weak. Sulfate, sulfite, thiosulfate, and elemental sulfur, but not nitrate, served as electron acceptors for growth with lactate. The bacteria performed dismutation of thiosulfate to sulfate and hydrogen sulfide. In the absence of sulfate, pyruvate but not lactate was fermented. Cytochromes of b and c types were present. The temperature and pH optima for both strains were 60–6°C and pH 7.0. Bacteria grew at 0 to 4.5–6.0% NaCl in the medium, with the optimum being at 0.5–1.0%. Phylogenetic analysis based on a comparison of incomplete 16S rRNA sequences revealed that both strains belonged to the C cluster of the genus Desulfotomaculum, exhibiting 95.5–98.3% homology with the previously described species. The level of DNA–DNA hybridization of strains 435^T and 781 with each other was 97%, while that with closely related species D. kuznetsovii 17^T was 51–52%. Based on the phenotypic and genotypic properties of strains 435^T and 781, it is suggested that they be assigned to a new species: Desulfotomaculum salinum sp. nov., comb. nov. (type strain 435^T = VKM B 1492^T).