58 research outputs found

    Взаимодействие авиаперевозчиков и топливозаправочных компанИЙ

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    The article describes the role of aviation fuel in the life of air transport. Fueling industry worldwide solves two main tasks - ensuring the safety and economy of air traffic. In Russia, there is one more task of airlines fuel supply. The article deals with fuel pricing taking into consideration today's realities.В статье описывается роль авиатоплива в жизни воздушного транспорта. Топливозаправочная индустрия во всем мире решает две главные задачи - обеспечение безопасности и экономики воздушных перевозок. Для России же характерна еще одна - снабжение топливом авиакомпаний. В статье рассмотрен вопрос ценообразования авиатоплива с учетом реалий сегодняшнего дня

    Biochemistry

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    www.elsevier.com/locate/yabio SigniWcant enhancement of Xuorescence on hybridization of a molecular beacon to a target DNA in the presence of a site-speciWc DNA nickas

    Properties of the "Orgamax" osteoplastic material made of a demineralized allograft bone

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    We investigated properties of the “Orgamax” osteoplastic material, which was produced from a demineralized bone, in the treatment of extensive caries, in particular chronic pulpitis of the permanent teeth with unformed roots in children. The “Orgamax” osteoplastic material consists of demineralized bone chips, a collagen additive, and antibiotics. The surface morphology of the “Orgamax” osteoplastic materialis macroporous, with the maximum pore size of 250 [mu]m, whereas the surface morphology of the major component of “Orgamax”, demineralized bone chips, is microporous, with a pore size of 10-20 [mu]m. Material “Orgamax” is used in the treatment of complicated caries, particularly chronic pulpitis of permanent teeth with unformed roots in children. “Orgamax” filling a formed cavity exhibits antimicrobial properties, eliminates inflammation in the dental pulp, and, due to its osteoconductive and osteoinductive properties, undergoes gradual resorption, stimulates regeneration, and provides replacement of the defect with newly formed tissue. The dental pulp viability is completely restored, which ensures the complete formation of tooth roots with root apex closure in the long-term period

    Phylogeography and post-glacial dynamics in the clonal-sexual orchid Cypripedium calceolus L.

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    Aim We investigated the phylogeographical history of a clonal-sexual orchid, to test the hypothesis that current patterns of genetic diversity and differentiation retain the traces of climatic fluctuations and of the species reproductive system. Location Europe, Siberia and Russian Far East. Taxon Cypripedium calceolus L. (Orchidaceae). Methods Samples (>900, from 56 locations) were genotyped at 11 nuclear microsatellite loci and plastid sequences were obtained for a subset of them. Analysis of genetic structure and approximate Bayesian computations were performed. Species distribution modelling was used to explore the effects of past climatic fluctuations on the species range. Results Analysis of genetic diversity reveals high heterozygosity and allele diversity, with no geographical trend. Three genetic clusters are identified with extant gene pools derived from ancestral demes in glacial refugia. Siberian populations exhibit different plastid haplotypes, supporting an early divergence for the Asian gene pool. Demographic results based on genetic data are compatible with an admixture event explaining differentiation in Estonia and Romania and they are consistent with past climatic dynamics inferred through species distribution modelling. Current population differentiation does not follow isolation by distance model and is compatible with a model of isolation by colonization. Main conclusions The genetic differentiation observed today in C. calceolus preserves the signature of climatic fluctuations in the historical distribution range of the species. Our findings support the central role of clonal reproduction in the reducing loss of diversity through genetic drift. The dynamics of the clonal-sexual reproduction are responsible for the persistence of ancestral variation and stability during glacial periods and post-glacial expansion.Peer reviewe

    Transcription regulation of the type II restriction-modification system AhdI

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    The Restriction-modification system AhdI contains two convergent transcription units, one with genes encoding methyltransferase subunits M and S and another with genes encoding the controller (C) protein and the restriction endonuclease (R). We show that AhdI transcription is controlled by two independent regulatory loops that are well-optimized to ensure successful establishment in a naïve bacterial host. Transcription from the strong MS promoter is attenuated by methylation of an AhdI site overlapping the -10 element of the promoter. Transcription from the weak CR promoter is regulated by the C protein interaction with two DNA-binding sites. The interaction with the promoter-distal high-affinity site activates transcription, while interaction with the weaker promoter-proximal site represses it. Because of high levels of cooperativity, both C protein-binding sites are always occupied in the absence of RNA polymerase, raising a question how activated transcription is achieved. We develop a mathematical model that is in quantitative agreement with the experiment and indicates that RNA polymerase outcompetes C protein from the promoter-proximal-binding site. Such an unusual mechanism leads to a very inefficient activation of the R gene transcription, which presumably helps control the level of the endonuclease in the cell

    Transcription regulation of the type II restriction-modification system AhdI

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    The Restriction-modification system AhdI contains two convergent transcription units, one with genes encoding methyltransferase subunits M and S and another with genes encoding the controller (C) protein and the restriction endonuclease (R). We show that AhdI transcription is controlled by two independent regulatory loops that are well-optimized to ensure successful establishment in a naïve bacterial host. Transcription from the strong MS promoter is attenuated by methylation of an AhdI site overlapping the -10 element of the promoter. Transcription from the weak CR promoter is regulated by the C protein interaction with two DNA-binding sites. The interaction with the promoter-distal high-affinity site activates transcription, while interaction with the weaker promoter-proximal site represses it. Because of high levels of cooperativity, both C protein-binding sites are always occupied in the absence of RNA polymerase, raising a question how activated transcription is achieved. We develop a mathematical model that is in quantitative agreement with the experiment and indicates that RNA polymerase outcompetes C protein from the promoter-proximal-binding site. Such an unusual mechanism leads to a very inefficient activation of the R gene transcription, which presumably helps control the level of the endonuclease in the cell

    Highlights of the DNA cutters:a short history of the restriction enzymes

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    In the early 1950’s, ‘host-controlled variation in bacterial viruses’ was reported as a non-hereditary phenomenon: one cycle of viral growth on certain bacterial hosts affected the ability of progeny virus to grow on other hosts by either restricting or enlarging their host range. Unlike mutation, this change was reversible, and one cycle of growth in the previous host returned the virus to its original form. These simple observations heralded the discovery of the endonuclease and methyltransferase activities of what are now termed Type I, II, III and IV DNA restriction-modification systems. The Type II restriction enzymes (e.g. EcoRI) gave rise to recombinant DNA technology that has transformed molecular biology and medicine. This review traces the discovery of restriction enzymes and their continuing impact on molecular biology and medicine

    Results of a study of Cypripedium in several regions of Siberia (Russia)

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    This study of populations of Cypripedium calceolus L., Cypripedium macranthon Sw. and their hybrid Cypripedium ventricosum Sw. in several regions of Siberia was carried out in 2009–2014. Isolated and mixed populations of the two species and their hybrid were surveyed. In sympatric populations, C. macranthon is most common in the central part and those of C. calceolus prevail in the western part of the range. Mature vegetative and/or reproductive shoots were present but vegetative reproduction was clearly most important in most of the populations investigated. Five colour variations were recorded for C. ventricosum. All species benefit from the increase in the intensity of light reaching ground level in forests after ground fires in spring destroy young trees and undergrowth. Vegetative reproduction and the size of the plants increases in burnt areas. Important factors determining the size and the ontogenetic structure of Cypripedium populations are: the duration of the growing season, the ecological conditions, the activities of pollinators and the relationships among the three species in sympatric populations

    INTERACTION OF AIR TRANSPORTATION AND FUEL-SUPPLY COMPANIES

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    The article describes the role of aviation fuel in the life of air transport. Fueling industry worldwide solves two main tasks - ensuring the safety and economy of air traffic. In Russia, there is one more task of airlines fuel supply. The article deals with fuel pricing taking into consideration today's realities
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