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  • 1
    ISSN: 1365-2958
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Actinobacillus actinomycetemcomitans (Aa) is one of the pathogenic bacteria involved in periodontal diseases. We have previously identified six major outer membrane proteins (Omps) of Aa Y4. Among them is an Omp with high molecular mass, designated Omp100, which has homology to a variety of virulence factors. Electron microscopic observation indicated that Omp100 is randomly localized on the cell surface of Aa. Aa Y4 has been shown to adhere and invade KB or normal human gingival keratinocytes. Anti-Omp100 antibody inhibited 50% of adhesion and 70% of invasion of Aa Y4 to KB cells. An Omp100 knock-out mutant had a decreased adhesion and invasion efficiency of 60%, compared with that of the wild type. Escherichia coli HB101 expressing Omp100 adhered twofold and invaded 10-fold more than the wild-type E. coli HB101. HB101 expressing Omp100 showed resistance to serum by trapping factor H, an inhibitor for C3b, with Omp100. Omp100 induced inflammatory cytokine responses of interleukin (IL)-8, IL-6 and tumour necrosis factor (TNF)α in epithelial cells, and induced IL-1β and TNFα production in mouse macrophages. These results indicate that Omp100 is a versatile virulence factor that may demonstrate potential significance in the onset of periodontal diseases related to Aa.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1399-3054
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: 3-Deoxy-D-arabino-heptulosonate 7-phosphate (DAHP) synthase (EC 4.1.2.15) is the first enzyme in the shikimate pathway, which leads to the biosynthesis of the aromatic amino acids. These amino acids are utilized as precursors for the synthesis of some secondary metabolites. The relationship between the accumulation of anthocyanin and the activity of DAHP synthase in suspension cultures of Vitis hybrid (Bailey Alicante A) was investigated. The activity of the plastidic isozyme, designated DS-Mn, was very low throughout the culture of cells. However, the activity of the cytosolic isozyme, designated DS-Co, increased transiently and then decreased after transfer of cells to fresh medium, reaching minimum levels during the logarithmic phase. Thereafter, the activity of DS-Co increased rapidly prior to the accumulation of anthocyanin. When phosphate was removed from the culture medium, growth of cells was limited and rapid accumulation of anthocyanin occurred, coincident with the termination of cell division. The activity of phenylalanine ammonia-lyase continued to increase from day 1 and the activity of DS-Co in phosphate-free culture also was 1.6-fold greater than that in the control culture on day 1, while the activity of DS-Mn was unaffected by this treatment. These results suggest a close correlation between the activity of DS-Co and the biosynthesis of anthocyanin.
    Type of Medium: Electronic Resource
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