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  • Articles: DFG German National Licenses  (5)
  • cellulose  (3)
  • Cellulose  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biology of the Cell 73 (1991), S. 173-178 
    ISSN: 0248-4900
    Keywords: cellulose ; liquid-crystal ; quince ; self-assembly ; xylans
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biology of the Cell 67 (1989), S. 209-220 
    ISSN: 0248-4900
    Keywords: cell walls ; cellulose ; fiber composite ; helicoids
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biology of the Cell 71 (1991), S. 43-55 
    ISSN: 0248-4900
    Keywords: cell wall ; cellulose ; enzyme-gold complex ; helicoidal pattern ; monoclonal antibodies ; polygalacturonans
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1615-6102
    Keywords: Cell wall ; Helicoidal texture ; Modelling ; Flexibility ; Cellulose
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The concept of the cell wall organized in a helicoidal pattern was outlined. When studied in transmission electron microscopy, the observed textures appear as a deceptive figure,i.e., as a “trompe l'oeil”. Difficulties—both technological and visual in the reconstitution of the actual geometry (exposure of the microfibrillar framework, 3-dimensional and 4-dimensional restoration), and the interest of simple modelling to understand the changes in cellulose orientation according to space and time are emphasized. The morphogenesis of helicoidal walls presents two main characteristics: it is both very defined and flexible, thus adaptable to varied programs of differentiation and to different environmental conditions. The observations of various cell examples and of responses to experimental treatments, lead to the following considerations: a) the shift of cellulose occurs continuously with time through a constant mutual angle. The wall seems to be built up as an indefinite continuum and forms a monotonous oscillatory system (unvarying motion); b) the shift of cellulose occurs through a mutual angle variable with time (varying motion, change from monotonous helicoid to bimodal helicoid, or sporadic bursts with arrested motion). The helicoidal wall appears as a fibrous composite with multifunctional possibilities ranging from fluidity to stiffness. The helicoidal assembly is remarkably adaptable to different physiological conditions of growth and specialization.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1615-6102
    Keywords: Cell wall ; Cellulose ; Xylan ; Disclinations ; Liquid crystal ; Cholesteric mesophases
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The study was devoted to the microstructure of the thick walled cells of the endocarp of prune (Prunus domestica L.), cherry (Prunus cerasus L.), walnut (Juglons regia L.). The tissue is formed of closely associated cells showing a homogeneous development characterized by an intense constructive activity of ordered walls with a typically twisted pattern (cholesteric-like). The arced layers are produced in tens, each corresponding to a 180° full rotation of the molecules (axis of rotation oriented radially) and their succession gives rise to a basic regular and monotonous periodicity. On the other hand, observation of the tissue revealed the large capacity of the helicoidal morphogenesis to adjust itself under the influence of two topological contingent constraints: (1) the spherical shape (and derivated shapes) of the cell and (2) the numerous pit canals which maintain the symplastic transport and produce a recess during the construction of the wall. Spherical shape (closed surfaces) and recess both introduce additional internal strains which are relieved by deviations of the molecular array in the basic pattern (moiré and knotty aspects). Special attention was given to the defects integrated in the spherical twist. The defects emerging in the angled stacks of microfibrils (disclinations, distortions) were a diagnostic feature of an actual liquid crystal behaviour under mechanical constraints. The abundance of such defects, of cusps and spiral motions strengthened the hypothesis that a transient fluid phase, later on consolidated and stiffened, operates during the cellulose ordering. The saddle-like figures developed in the complex polylobed situation of walnut were particularly demonstrative. The fractionation of the secondary wall yielded the glucidic matrix in the same ratio as cellulose. The bulk of this embedding matrix was composed of acidic xylans more or less tightly bound to the microfibrils. The coat of negatively charged polysaccharides visualized by the binding of cationic gold to wall strips might be expected to act as a surfactant generating an electrostatic repulsion between microfibrils. This could be a cooperative mechanism for the self-positioning (aligment in sheets and progressive rotation) of the composite.
    Type of Medium: Electronic Resource
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