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  • Bacteroides  (1)
  • Hyperpolarizing wave  (1)
  • Tumble generator  (1)
  • 1
    ISSN: 1572-9699
    Keywords: Bacteroides ; Peptostreptococcus ; Fusobacterium ; periodontitis ; protein degradation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study was undertaken to identify ecological factors that favour opportunistic pathogenic species in the subgingival microflora. In a first approach, human serum as a substitute for gingival exudate, was used for batch-wise enrichment of subgingival plaque. The microflora resulting after 5–6 enrichment steps consisted of black-pigmented and non-black-pigmented Bacteroides species, Peptostreptococcus micros and Fusobacterium nucleatum as the main organisms. It is noted that the same group of species was found to be enriched independent upon the origin of the subgingival plaque sample. It was suggested that these organisms are favoured by the increased flow of gingival exudate during inflammation. The consortium of organisms was capable of selective degradation of serum (glyco-)proteins. Four different types of degradation occurred. After a prolonged period of growth complete degradation of immunoglobulins, haptoglobin, transferrin and complement C3c was observed. Partial degradation of immunoglobulins, haptoglobin, transferrin, albumin, alpha1-antitrypsin and complement C3c and C4 was generally observed after 48 h of growth. Besides, immunoglobulin protease activity yielding Fc and Fab fragments was found. The consortium was also capable of consuming carbohydrate side-chains as indicated by an altered electrophoretic mobility of the serum glycoproteins.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 111 (1976), S. 7-11 
    ISSN: 1432-072X
    Keywords: Bacillus subtilis ; Motility ; Chemotaxis ; Chemoreceptor ; Tumble generator ; Proton-motive force
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Changes in the proton-motive force cause a transient change in the motile behavior of Bacillus subtilis cells. Both an increase and a decrease in the proton-motive force cause transient tumbling. Simultaneous decrease of proton-motive force and increase of attractant concentration lessens the response toward the attractant. A simultaneous increase of proton-motive force and increase of attractant concentration prolonges the response toward attractant. A hypothesis explaining the various effects is given.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Archives of microbiology 116 (1978), S. 1-8 
    ISSN: 1432-072X
    Keywords: Chemotaxis ; Bacillus subtilis ; Motility ; Valinomycin ; Nigericin ; Lipophilic cations ; Methylation ; Hyperpolarizing wave ; Ion gate ; Proton-motive force
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of nigericin, valinomycin and some lipophilic cations on the motile behavior of non-starved and methionine-starved Bacillus subtilis cells were studied. For valinomycin and nigericin a quantitative relationship between the flux in the proton-motive force and the duration of the twiddle response was found. Lipophilic cations bind to the ion gate controlling the twiddle frequency and thereby cause the cells to swim smoothly. To explain the transmission of the chemotactic signal a model is given in which receptors, a hyperpolarizing wave, an ion gate and two methylation sites, viz. methyl-accepting chemotaxis proteins and a further methylation site (MT), play a role. For the transmission of the signal caused by an attractant both the hyperpolarizing wave and an interaction between receptor and methylation site (MT) are needed. The methyl-accepting chemotaxis proteins are involved in the adaptation/deadaptation to altered levels of attractant. Artificial changes in the proton-motive force act directly on the ion gate, which finally controlls the twiddle frequency of the cells.
    Type of Medium: Electronic Resource
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