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  • 1995-1999  (2)
  • Allergens  (1)
  • Impatiens sultani
  • Nicotiana tabacum
  • 1
    ISSN: 1615-6102
    Keywords: Microtubule ; Microtubule organizing centers ; Nicotiana tabacum ; Pericentriolar antigens ; Plasma membrane ; Pollen tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In the pollen and pollen tube of higher plants, the distribution of the microtubular cytoskeleton has been extensively studied. Even though the pattern of microtubules is known, one of the most remarkable deficiencies is the absence of data on the localization of microtubule-nucleation sites in the pollen tubes. In order to get insights about the localization of centrosome-like structures in the pollen tube ofNicotiana tabacum L., we have used the monoclonal antibody 6C6 to search for pericentriolar antigen(s). The antibody was initially raised against a component of animal centrosomes and has been already employed to locate centrosomal structures in other plant cell types. By immunoblotting analysis, a polypeptide of Mr 77,000 was identified specifically in the membrane-associated protein fraction of the pollen tube, and is absent from the soluble protein pool. Immunofluorescence observations have shown the polypeptide to be located in the apical part of the pollen tube (about 40–50 μm from the tip) in association with the cortical area. A purified plasma membrane fraction from the growing pollen tubes has been obtained, using H+-ATPase activity as an organelle marker. The plasma membrane fraction was shown to be enriched in the Mr 77,000 polypeptide, which can be extracted from membranes by treatment with the detergent CHAPS at a concentration of 0.5%. These data open new research perspectives on the localization and analysis of putative cortical microtubule nucleation sites in the pollen tube.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1615-6102
    Keywords: Allergens ; Allergy ; Betula pendula ; Immunolabelling ; Pollen grains ; Tapetum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Although intact pollen grains are assumed to be the primary carrier of pollen allergens, specific immunoreactive components have been found in other aerosol fractions, e.g., starch grains and remains of tapetal cells Cryo-scanning-electron-microscopy results demonstrate the presence of a clear network of strands connecting the tapetum with the microspores. The distribution of protein in tapetal orbicules, pollen wall, and pollen cytoplasm was tested by histochemical stains for light microscopy and transmission electron microscopy. The protein is mainly localized at the apertures and starch grains in the cytoplasm of pollen and in the core and on the surface of tapetal orbicules. Monoclonal antibodies Bv-10, BIP3, and BIP4 have been used to locate the cellular sites of pollen and tapetal allergens inBetula pendula (syn.B. verrucosa). The application of rapid-freeze fixation prevented relocation of allergens from their native sites. The allergens are predominantly found in the starch grains and to lesser extent in the exine. We also tested interactions between mature birch pollen and human fluids: saliva, nostrils fluid, and eyes solution. The aim was to mimic more closely the in vivo situation during allergenic response. In all cases we observed several pollen grains that were burst and had released their cytoplasmic contents. In the nose the allergens are released from the pollen within minutes. In rhinitis, nasal pH is increased from the normal pH 6.0 to 8.0. When we used nasal fluid at pH 8.0, the number of ruptured pollen grains increased. The mechanism that might induce formation of small allergen-bearing particles from living plant cells is discussed.
    Type of Medium: Electronic Resource
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