Methodological aspects of assessing chitin utilization by soil microorganisms

A computational method for estimating specific activity of chitin decomposition by microorganisms is proposed. Spectrophotometric and gas chromatographic methods have been used to determine the rates of chitinase production, biomass accumulation, and carbon dioxide emission by pure cultures of microorganisms grown on a chitin-containing medium. Among dominants of the chitinolytic community of chernozem (Trichoderma viride, Stretomyces albolongus, Alcaligenes, and Arthrobacter), the highest chitinolytic activity is characteristic of prokaryotes. In brown desert-steppe soil, the main destructor prokaryotes are actinomycetes (S. roseolilacinus). The biomass of the fungus T. viride growth on the chitin-containing medium markedly exceeds that of prokaryotes, but the specific activity of respiration and chitinase production in actinomycetes S. roseolilacinus and S. albolongus is an order of magnitude higher than in T. viride.     

Absorption of electromagnetic surface waves by electrons in a transition layer between the plasma and dielectric

The effect of the Debye layer on the absorption of an electromagnetic surface wave propagating along the plasma-dielectric interface is considered. The electric field distribution in the Debye layer and the energy absorbed by the plasma electrons in this layer are determined. It is shown that the ratio of the rate at which surface waves are damped due to Cherenkov absorption by the electrons reflected from the electric field potential in the transition layer to their frequency is on the order of the ratio of the electron thermal velocity to the wave phase velocity.     

Winter wheat cells subjected to freezing temperature undergo death process with features of programmed cell death

Programmed cell death is a process defined as genetically regulated self-destruction or cell suicide. It can be activated by different internal and external factors, but few studies have investigated whether this process occurs under cold and freezing temperatures. In this study, a freezing treatment (?8 °C for 6 h) induced cell death with features of programmed cell death in suspension cultures of winter wheat (Triticum aestivum L.). This process occurred for 10 days after cold exposure. The death of cells in culture was slow and prolonged, and was accompanied by protoplast shrinkage, DNA fragmentation, and an increase in the level of reactive oxygen species. Other changes observed after the freezing treatment included an increase in the respiration rate, changes in mitochondrial transmembrane potential (?Ψ _m ), and the release of cytochrome c from mitochondria into the cytosol. These findings indicated that mitochondria are involved in the cell death process that occurs after a freezing treatment in cells of winter wheat.     

Genetic diversity of chloroquine-resistant Plasmodium vivax parasites from the western Brazilian Amazon

The molecular basis of Plasmodium vivax chloroquine (CQ) resistance is still unknown. Elucidating the molecular background of parasites that are sensitive or resistant to CQ will help to identify and monitor the spread of resistance. By genotyping a panel of molecular markers, we demonstrate a similar genetic variability between in vitro CQ-resistant and sensitive phenotypes of P. vivax parasites. However, our studies identified two loci (MS8 and MSP1-B10) that could be used to discriminate between both CQ-susceptible phenotypes among P. vivax isolates in vitro. These preliminary data suggest that microsatellites may be used to identify and to monitor the spread of P. vivax-resistance around the world.     

Effect of chemical chaperones on properties of lysozyme and the reaction center protein from Rhodobacter sphaeroides

The influence of three chemical chaperones: glycerol, 4-hexylresorcinol, and 5-methylresorcinol on the structure, equilibrium fluctuations, and the functional activity of the hydrophilic enzyme lysozyme and the transmembrane reaction center (RC) protein from Rb. sphaeroides in a broad range of concentrations has been studied. Selected chemical chaperones are strongly different by the structure and action on hydrophilic and membrane proteins. The influence of the chemical chaperones (except methylresorcinol) on the structure, dynamics, and functional properties of lysozyme and RC protein are well described within the frames of extended models of preferential hydration and preferential interaction of protein with a chemical chaperone. A molecule of hexylresorcinol consists of a hydrophobic (alkyl radical) and a hydrophilic (aromatic nuclus) moieties. This fact provides additional regulation of functional activity of lysozyme and RC by hexylresorcinol. The influence of methylresorcinol on proteins differs from that of glycerol and hexylresorcinol. Methylresorcinol interacts with the surface of lysozyme directly, not via water hydrogen bonds. This leads to a decrease in denaturation temperature T(d), and an increase in the amplitude of equilibrium fluctuation, which allows him to be a powerful activator. Methylresorcinol interacts with the membrane RC protein only by the condensation of hydration water, which is negligible in the case of methylresorcinol. Therefore, methylresorcinol does not effect the functional properties of the RC protein. It was concluded that various chaperones at one and the same concentration and chaperones at different concentrations form diverse 3D structures of proteins, which differ by dynamic and functional characteristics.     

Paramagnetic form of ribonucleotide reductase in human tissues

The paramagnetic form of ribonucleotide reductase was detected by ESR method in human cervix tissues, especially in tumor ones. The magnetic relaxation rate was proved to be slower for this form than for that in normal animal tissues having a high level of proliferative activity or in Ehrlich tumor cells studied before.     

Analysis of eight polymorphic Alu elements in the Teleuts population

Allele frequencies and genetic diversity in the population of Teleuts were assessed by the Alu repeat polymorphism at eight autosomal loci (ACE, APOA1, PLAT, F13, PV92, A25, CD4, D1). For comparison, the study included previously obtained data on the Alu polymorphism in 19 indigenous populations of Siberia. On the dendrogram of genetic distances, the Teleut population is located in the cluster of Siberian ethnic groups, which are similar in origin, geography, and cultural traditions.     

Population study of frequency of methylenetetrahydrofolate reductase C677T gene polymorphism in Yakutia

The enzyme methylenetetrahydrofolate reductase (MTHFR) catalyzes synthesis of 5'-methylenehydrofolate, which is the methyl donor for the conversion of homocysteine to methionine. According to the numerous literature data, polymorphic variant of the MTHFR-encoding gene, C677T, is associated with hyperhomocysteinemia, vascular pathologies, neural tube defects, dementia, perinatal mortality, mental disorders, long-term neurodegenerative disorders, lens displacement, arachnodactyly, and venous thromboses. The present study was focused on the analysis of the C677T polymorphism (missence mutation leading to the replacement of cytosine by thymine at position 677) of the MTHFR gene in three indigenous populations of the Republic of Sakha (Yakutia), living in the settlements of Cheriktei, Byadi, and Dyupsya. Comparison of the genotype and allele frequencies revealed no substantial differences between the three Yakut populations, as well as between Yakuts and other Mongoloid ethnic groups.