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  • Articles  (3)
  • Cellulose
  • Springer  (2)
  • Wiley-Blackwell  (1)
  • International Union of Crystallography
  • 1
    Electronic Resource
    Electronic Resource
    A model for the pattern of deposition of microfibrils in the cell wall of Glaucocystis (1978)
    Springer
    Planta 141 (1978), S. 51-58 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall ; Cellulose ; Freeze-etching ; Glaucocystis ; Microfibrils (cellulose) ; Morphogenesis ; Plasma membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Freeze-fracturing of Glaucocystis nostochinearum Itzigsohn cells during cell-wall microfibril deposition indicates that unidirectionally polarized microfibril ends are localized in a “zone of synthesis” covering about 30% of the sarface area of the plasma membrane. Within this zone there are about 6 microfibril ends/μm2 cell surface. It is proposed that microfibrils are generated by the passage of their tips over the cell surface and that the pattern of microfibril organization at the poles of the cells, in which microfibrils of alternate layers are interconnected at 3 “rotation centres”, results directly from the pattern of this translation of microfibril tips. In a model of the deposition pattern it is proposed that the zone of synthesis may split into 3 sub-zones as the poles are approached, each sub-zone being responsible for the generation of one rotation centre. It is demonstrated that the microfibrillar component of the entire wall could be generated by the steady translation of the microfibril tips (at which synthesis is presumed to occur) over the cell surface at a rate of 0.25–0.5 μm min-1. Microcinematography indicates that the protoplast rotates during cell-wall deposition, and it is proposed that this rotation may play a role in the generation of the microfibril deposition pattern.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387744
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  • 2
    Electronic Resource
    Electronic Resource
    The formation and development of cellulose-synthesizing linear terminal complexes (TCs) in the plasma membrane of the marine red algaErythrocladia subintegra Rosenv. (1996)
    Springer
    Protoplasma 193 (1996), S. 33-45 
    Details
    ISSN: 1615-6102
    Keywords: Erythrocladia subintegra ; Red alga ; Freeze-fracture ; Cellulose ; Linear terminal complexes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The formation and development of linear terminal complexes (TCs), the putative cellulose synthesizing units of the red algaErythrocladia subintegra Rosenv., were investigated by a freeze etching technique using both rotary and unidirectional shadowing. The ribbon-like cellulose fibrils ofE. subintegra are 27.6 ± 0.8 nm wide and only 1–1.5 nm thick. They are synthesized by TCs which are composed of repeating transverse rows formed of four particles, the TC subunits. About 50.4 ± 1.7 subunits constitute a TC. They are apparently more strongly interconnected in transverse than in longitudinal directions. Some TC subunits can be resolved as doublets by Fourier analysis. Large globular particles (globules) seem to function as precursor units in the assembly and maturation of the TCs. They are composed of a central hole (the core) with small subunits forming a peripheral ridge and seem to represent zymogenic precursors. TC assembly is initiated after two or three gobules come into close contact with each other, swell and unfold to a nucleation unit resembling the first 2–3 transverse rows of a TC. Longitudinal elongation of the TC occurs by the unfolding of globules attached to both ends of the TC nucleation unit until the TC is completed. The typical intramembranous particles observed inErythrocladia (unidirectional shadowing) are 9.15 ± 0.13 nm in diameter, whereas those of a TC have an average diameter of 8.77 ± 0.11 nm. During cell wall synthesis membranes of vesicles originating from the Golgi apparatus and which seem to fuse with the plasma membrane contain large globules, 15–22 nm in diameter, as well as ‘tetrads” with a particle diameter of about 8 nm. The latter are assumed to be involved in the synthesis of the amorphous extracellular matrix cell wall polysaccharides. The following working model for cellulose fibril assembly inE. subintegra is suggested: (1) the ribbon-like cellulose fibril is synthesized by a single linear TC; (2) the number of glucan chains per microfibril correlates with the number of TC subunits; (3) a single subunit synthesizes 3 glucan chains which appear to stack along the 0.6 nm lattice plane; (4) lateral aggregation of the “3-mer” stacks leads to the crystalline microfibril.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01276632
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  • 3
    Electronic Resource
    Electronic Resource
    Practical Aspects of Lattice Imaging of Cellulose (1987)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 6 (1987), S. 349-356 
    Details
    ISSN: 0741-0581
    Keywords: Lattice imaging ; Low dose technique ; Cellulose ; Crystallite size ; Digital image processing ; Formvar micronet ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: The lattice imaging technique for cellulose, a typical electronbeam-sensitive material, was developed by using a conventional 120 kV electron microscope. Routine procedures for specimen preparation and high resolution, low dose electron microscopy are described in detail. A new, simple method was introduced for the preparation of a Formvar micronet to support the thin carbon film. The lattice imaging technique was successfully applied to algal celluloses as well as bacterial cellulose, which is composed of much smaller crystallites than the former. Digital image processing was found to be effective in enhancing the lattice images. The bacterial cellulose ribbon contained crystallites 10-25-nm wide, which is much greater than the basic unit of cellulose fibril extruded from the cell surface. This shows that unit fibrils can fasciate with each other, merging into a single crystallite.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060060405
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