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  • 1
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: O-antigens are highly polymorphic. The genes specifically involved in O-antigen synthesis are generally grouped together on the chromosome as a gene cluster. In Escherichia coli, the O-antigen gene clusters are characteristically located between the housekeeping genes galF and gnd. In this study, the O-antigen gene clusters of E. coli O59 and E. coli O155 were sequenced. The former was found to contain genes for GDP-mannose synthesis, glycosyltransferase genes and the O-antigen polymerase gene (wzy), while the latter contained only glycosyltransferase genes and wzy. O unit flippase genes (wzx) were found immediately downstream of the gnd gene, in the region between the gnd and hisI genes in these two strains. This atypical location of wzx has not been reported before, and furthermore these two genes complemented in trans despite the fact that different O-antigen structures are present in E. coli O59 and O155. A putative acetyltransferase gene was found downstream of wzx in both strains. Comparison of the region between gnd and hisI revealed that the wzx and acetyltransferase genes are closely related between E. coli O59 and O155, indicating that the two gene clusters arose recently from a common ancestor. This work provides further evidence for the O-antigen gene cluster having formed gradually, and selection pressure will eventually bring O-antigen genes into a single cluster. Genes specific for E. coli O59 and O155, respectively, were also identified.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 234 (2004), S. 0 
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Shigella strains are human pathogens and their identification is usually based on their O-antigens. The O-antigen gene cluster of Shigella boydii O11 was sequenced. All the expected genes for the synthesis of the O-antigen were identified on the basis of homology and genes for the biosynthesis of dTDP-l-Rhamnose, genes encoding sugar transferases, as well as genes encoding O unit flippase (wzx) and O-antigen polymerase (wzy). The identity of the putative wzy gene was confirmed by showing that a wzy deficient mutant strain of S. boydii O11 produced a semi-rough LPS phenotype. The predicted wzx gene has an opposite transcription direction to that of all of the other genes in the S. boydii O11 O-antigen gene cluster. This unusual feature for the wzx gene has only previously been reported in S. boydii O6. Further comparison revealed an evolutionary relationship between O6 and O11 O-antigen gene clusters. Adjacent-gene PCR showed that Escherichia coli O105 and S. boydii O11, which share the identical O-antigen, also have the same genes and organization for their respective O-antigen gene clusters. Three genes specific for the S. boydii O11 and E. coli O105 gene clusters were identified.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Aerobic methanotrophic bacteria consume methane as it diffuses away from methanogenic zones of soil and sediment. They act as a biofilter to reduce methane emissions to the atmosphere, and they are therefore targets in strategies to combat global climate change. No cultured methanotroph grows ...
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    World journal of surgery 14 (1990), S. 796-803 
    ISSN: 1432-2323
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Résumé Deux aspects de la réponse inflammatoire à l'infection, la modification du débit sanguin et la mobilisation des leucocytes, sont étudiés chez le chien. La réalisation de lambeaux appariés musculocutanés, basée ou pas sur en pédicule nourricier, permet la comparaison de la cicatrisation avec des différences significatives dans le débit sanguin (plus faible dans les lambeaux quelconques) et par la résistance à l'infection (plus importante dans les lambeaux musculocutanés). Les changements du débit sanguin, déterminés par le lavage au xénon radioactif, sont comparés dans la peau normale et dans la peau des lambeaux distaux après réalisation et innoculation bactérienne. L'utilisation simultanée des leucocytes marqués à l'Indium 111 permet de déterminer la mobilisation des leucocytes et leur localisation subséquente en réponse à l'infection du lambeau. Le débit sanguin s'est amélioré de faÇon significative dans les lambeaux musculocutanés, en réponse à l'infection. Bien que la mobilisation totale des leucocytes soit plus importante dans les lambeaux quelconques, les leucocytes dans les lambeaux musculocutanés sont localisés autour du site de l'innoculation bactérienne à l'intérieur du derme. Les différences dans le débit sanguin et la mobilisation des leucocytes peuvent en partie expliquer l'importante sécurité des lambeaux musculocutanés lors de leur transposition en présence d'une infection.
    Abstract: Resumen Dos aspectos principales de la reacción inflamatoria a la infectión, la alteratión en el flujo sanguíneo y la movilización leucocitaria, fueron investigados en un modelo experimental canino. La construcción simultánea de colgajos musculocutáneos y de colgajos al azar permite la comparación de los colgajos en proceso de cicatrización con diferencias significativas en cuanto al flujo sanguíneo (inferior en los colgajos de patrón al azar) y a la resistencia a la infección (mayor en los colgajos musculocutáneos). Se hizo la comparación de los cambios en flujo sanguíneo mediante la determinación de la excresión de xenón radioactivo entre la piel normal y la piel en la región distal del colgajo después de su elevación y después de inoculación bacteriana. La utilización simultánea de leucocitos radiomarcados con In-111 permite la determinación de la movilización leucocitaria y la subsiguiente localización en respuesta a la infección del colgajo. El flujo sanguíneo mejora en forma significativa en el colgajo musculocutáneo como respuesta a la infección. Aunque la movilización leucocitaria total fue mayor en los colgajos de patrón al azar, los leucocitos en el colgajo musculocutáneo se localizaron en el lugar de la inoculación bacteriana en la dermis. Las diferencias en el flujo dinámico y en la movilización leucocitaria puede explicar, en parte, la mayor confiabilidad de los colgajos musculocutáneos cuando se hace su transferencia en presencia de infección.
    Notes: Abstract Two aspects of the inflammatory response to infection—blood flow alteration and leukocyte mobilization—are investigated in the canine model. The elevation of paired musculocutaneous (MC) and random pattern (RP) flaps allowed comparison of healing flaps with significant differences in blood flow (lower in random pattern flaps) and resistance to infection (greater in musculocutaneous flaps). Blood flow changes as determined by radioactive xenon washout were compared in normal skin and distal flap skin both after elevation and following bacterial inoculation. Simultaneous use of In-111 labeled leukocytes allowed determination of leukocyte mobilization and subsequent localization in response to flap infection. Blood flow significantly improved in the musculocutaneous flap in response to infection. Although total leukocyte mobilization in the random pattern flap was greater, the leukocytes in the musculocutaneous flap were localized around the site of bacterial inoculation within the dermis. Differences in the dynamic blood flow and leukocyte mobilization may, in part, explain the greater reliability of musculocutaneous flaps when transposed in the presence of infection.
    Type of Medium: Electronic Resource
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