Comparison of the aspartase activity and its stability in Escherichia coli cells immobilized on polyacrylamide gel and carrageenan

The conditions for immobilization of Escherichia coli cells (Soviet strain 85) on the natural polysaccharide carrier carrageenan (Soviet-made) were investigated and kinetic regularities of the aspartase reaction catalysed by immobilized in carrageenan cells of E. coli 85 were established. The conditions for retaining a high aspartase activity and stability of biocatalysts based on the E. coli 85 cells immobilized in PAAG and carrageenan were determined using full-loaded tanks for continuous synthesis of L-aspartic acid. The time-stable aspartase activity of the biocatalyst can be increased by treating the beads of the catalyst with bifunctional reagents (hexamethylenediamine, glutaraldehyde), the most active catalyst for the biotechnological synthesis of L-aspartic acid being obtained when carrageenan is used.     

Climate Change Increases Drought Stress of Juniper Trees in the Mountains of Central Asia

Assessments of climate change impacts on forests and their vitality are essential for semi-arid environments such as Central Asia, where the mountain regions belong to the globally important biodiversity hotspots. Alterations in species distribution or drought-induced tree mortality might not only result in a loss of biodiversity but also in a loss of other ecosystem services. Here, we evaluate spatial trends and patterns of the growth-climate relationship in a tree-ring network comprising 33 juniper sites from the northern Pamir-Alay and Tien Shan mountain ranges in eastern Uzbekistan and across Kyrgyzstan for the common period 1935–2011. Junipers growing at lower elevations are sensitive to summer drought, which has increased in intensity during the studied period. At higher elevations, juniper growth, previously favored by warm summer temperatures, has in the recent few decades become negatively affected by increasing summer aridity. Moreover, response shifts are observed during all seasons. Rising temperatures and alterations in precipitation patterns during the past eight decades can account for the observed increase in drought stress of junipers at all altitudes. The implications of our findings are vital for the application of adequate long-term measures of ecosystem conservation, but also for paleo-climatic approaches and coupled climate-vegetation model simulations for Central Asia.     

Corynebacterium diphtheriae nontoxigenic strain carrying the gene of diphtheria toxin

Among 828 C. diphtheriae nontoxigenic cultures isolated in different region of Russia in 1994-2002, 114 cultures (13.8%) had the gene of diphtheria toxin (gene tox) and were thus called nontoxigenic tox-carrying (NTTC) strains. All NTTC strains were found to belong to biovar mitis and formed neither normal, nor "defective" diphtheria toxin. The most of NTTC strains (94%) belonged to ribotype "Moskva", not occurring among C. diphtheriae toxigenic strains. The incapacity of NNTC strains of forming diphtheria toxin was caused by mutation: the deletion of one nucleotide which led to the shift of the open reading frame and to the formation of the stop codon. The results of these studies are indicative of the fact that a sufficiently homogeneous and isolated group of C. diphtheriae nontoxigenic strains is spread in Russia. These strains carry the nonexpressing gene of diphtheria toxin and are of no epidemic importance in diphtheria infection.     

Fluorometric quantification of RNA and DNA in solutions containing both nucleic acids

A fluorescence-based method for quantitative determination of RNA and DNA in probes containing both nucleic acids has been developed. The total concentration of nucleic acids is determined using SYBR Green II dye under conditions providing independent binding of the fluorophore with DNA and RNA. The concentration of DNA is specifically measured using the Hoechst 33258 dye and the RNA concentration is calculated from these data. The procedure allows for accurate determination of DNA concentration in the range 10-1000 ng/ml in the presence of 200-fold excess of RNA and determination of RNA concentrations in the range 10-1000 ng/ml in the presence of large excess of DNA. An absence of the treatment of mixed samples with RNase-free DNase I provides rapid, reproducible, and accurate RNA quantification.     

DNA polymorphism in the beta-Esterase gene cluster of Drosophila melanogaster

We have analyzed nucleotide polymorphism within a 5.3-kb region encompassing the functional Est-6 gene and the psiEst-6 putative pseudogene in 28 strains of Drosophila melanogaster and one of D. simulans. Two divergent sequence types were detected, which are not perfectly associated with Est-6 allozyme variation. The level of variation (pi) is very close in the 5'-flanking region (0.0059) and Est-6 gene (0.0057), but significantly higher in the intergenic region (0.0141) and putative pseudogene (0.0122). The variation in the 3'-flanking region is intermediate (0.0083). These observations may reflect different levels of purifying selection in the different regions. Strong linkage disequilibrium occurs within the region studied, with the largest values revealed in the putative pseudogene and 3'-flanking region. Moreover, recombination is restricted within psiEst-6. Gene conversion is detected both within and (to a lesser extent) between Est-6 and psiEst-6. The data indicate that psiEst-6 exhibits some characteristics that are typical of nonfunctional genes, while other characteristics are typically attributed to functional genes; the same situation has been observed in other pseudogenes (including Drosophila). The results of structural entropy analysis demonstrate higher structural ordering in Est-6 than in psiEst-6, in accordance with expectations if psiEst-6 is indeed a pseudogene. Taking into account that the function of psiEst-6 is not known (but could exist) and following the terminology of J. Brosius and S. J. Gould, we suggest that the term "potogene" may be appropriate for psiEst-6, indicating that it is a potential gene that may have acquired some distinctive but unknown function.     

Progression of pulmonary tuberculosis and efficiency of bacillus Calmette-Guérin vaccination are genetically controlled via a common sst1-mediated mechanism of innate immunity

Using a mouse model for genetic analysis of host resistance to virulent Mycobacterium tuberculosis, we have identified a genetic locus sst1 on mouse chromosome 1, which controls progression of pulmonary tuberculosis. In vitro, this locus had an effect on macrophage-mediated control of two intracellular bacterial pathogens, M. tuberculosis and Listeria monocytogenes. In this report, we investigated a specific function of the sst1 locus in antituberculosis immunity in vivo, especially its role in control of pulmonary tuberculosis. We found that the sst1 locus affected neither activation of Th1 cytokine-producing T lymphocytes, nor their migration to the lungs, but rather controlled an inducible NO synthase-independent mechanism of innate immunity. Although the sst1(S) macrophages responded to stimulation with IFN-gamma in vitro, their responsiveness to activation by T cells was impaired. Boosting T cell-mediated immunity by live attenuated vaccine Mycobacterium bovis bacillus Calmette-Guérin or the adoptive transfer of mycobacteria-activated CD4(+) T lymphocytes had positive systemic effect, but failed to improve control of tuberculosis infection specifically in the lungs of the sst1(S) animals. Thus, in the mouse model of tuberculosis, a common genetic mechanism of innate immunity mediated control of tuberculosis progression in the lungs and the efficiency of antituberculosis vaccine. Our data suggest that in immunocompetent humans the development of pulmonary tuberculosis and the failure of the existing vaccine to protect against it, in some cases, may be explained by a similar defect in a conserved inducible NO synthase-independent mechanism of innate immunity, either inherited or acquired.     

Taxonomic revision of the cestodes of the family Progynotaeniidae (Cyclophyllidea) parasitising stone curlews (Charadriiformes: Burhinidae)

The type series of Progynotaenia evaginata Fuhrmann, 1909 from Burhinus senegalensis in Sudan, P. foetida Meggitt, 1928 from B. oedicnemus in Egypt and Angularia australis Maplestone, 1921 from B. grallarius in Australia are redescribed. As a comparative material, specimens of P. evaginata from B. oedicnemus in Kazakhstan were studied. The type-series of P. evaginata and P. foetida were found to be heterogeneous due to the presence of scoleces and fragments of cestodes of the genus Stenovaria Spasskii & Borgarenko, 1973 (Dilepididae). For P. foetida, a lectotype is designated. P. foetida is recognised as a synonym of P. evaginata (new synonymy). Angularia australis, previously considered a member of the Dilepididae, is transferred to the Progynotaeniidae as a synonym of P. evaginata (new synonymy). The synonymy of P. indica Johri, 1963 with P. evaginata, proposed by Ryzhikov & Tolkacheva (1981), is supported. The host range and the geographical distribution of P. evaginata are restricted to birds of the genus Burhinus from the Eastern Hemisphere.