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  • 1
    Electronic Resource
    Electronic Resource
    Distribution of microtubules during the growth of tobacco pollen tubes
    Amsterdam : Elsevier
    Biology of the Cell 79 (1993), S. 125-132 
    Details
    ISSN: 0248-4900
    Keywords: Nicotiana tabacum ; acetylated α-tubulin ; confocal laser scanning microscope ; microtubules ; pollen tube growth ; tyrosinated α-tubulin
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1016/0248-4900(93)90248-D
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  • 2
    Electronic Resource
    Electronic Resource
    Ultrastructural features of Aloe ciliaris pollen (1988)
    Springer
    Sexual plant reproduction 1 (1988), S. 88-96 
    Details
    ISSN: 1432-2145
    Keywords: Pollen activation ; Generative cell ; Vegetative cell ; Cytoskeleton
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Both the internal anatomy and the external morphology of the mature pollen grain of Aloe ciliaris have been studied, together with the cytological changes occurring during pollen activation. In mature pollen, the generative cell (GC) and the vegetative nucleus (VN) are closely associated with each other, and both can be found in the central part of the grain. In the generative cytoplasm, some organelles and microtubular bundles are present. In the vegetative cell, dictyosomes, stacks of rough endoplasmic reticulum, mitochondria, plastids, vacuoles, ribosomes, and masses of fibrillar material have been described. During pollen activation, important changes occur in both the generative and vegetative cells (VC). In the GC, the microtubular bundles become clearly visible, and the GC and VC gradually move towards the germ pore. The RER cisterns become free from the stacks, and organelles, such as dictyosomes, become very active. The fibrillar masses gradually decrease in number, and the individual fibrils become more evident and clearer in resolution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00189267
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  • 3
    Electronic Resource
    Electronic Resource
    In vitro double fertilization in Nicotiana tabacum (L.): polygamy compared with selected single pair somatic protoplast and chloroplast fusions (2000)
    Springer
    Sexual plant reproduction 13 (2000), S. 113-117 
    Details
    ISSN: 1432-2145
    Keywords: Key words Cell fusion ; Gamete interaction ; In vitro polygamy ; Nicotiana tabacum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In vitro polygamy was studied mainly by using isolated sperm and central cells of tobacco in order to elucidate the mechanism that might be involved in preventing in vivo polygamy. In 17.5% 4000 M.W. polyethylene glycol, only when two sperm cells were made close enough to each other and adhered to a female cell simultaneously was polygamy possible. If one sperm cell fused with the egg or central cell, within 30 min another sperm cell could not fuse with the same egg or central cell. Similar phenomena were found in selected single somatic cell fusion. When more than two protoplasts adhered to each other simultaneously, fusion was always successful; after two protoplasts fused, within 30 min the fusion products could not fuse with another protoplast under the same conditions. This comparative study revealed this characteristic to be shared by both sexual and somatic cell fusion. However, after cytoplasm reorganization was complete in the fusion product, it was possible for the fusion product to fuse with the third protoplast. This indicates that the obstruction to additional fusion was present only during a certain period after the preceding fusion under certain condition. The possible reason for the effect is discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970000044
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  • 4
    Electronic Resource
    Electronic Resource
    Responses of tobacco pollen to high humidity and heat stress: viability and germinability in vitro and in vivo (1991)
    Springer
    Sexual plant reproduction 4 (1991), S. 104-109 
    Details
    ISSN: 1432-2145
    Keywords: High humidity and temperature stress ; Nicotiana tabacum ; Tobacco ; Pollen viability ; Vigour ; Semi-vivo technique
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Responses of pollen grains of Nicotiana tabacum to high humidity (95% RH, 4 h) and temperature (38°/45° C, 4 h) stresses were investigated. Pollen grains were subjected to only RH or only temperature, or to both of these stresses. Their viability was assessed on the basis of the fluorochromatic reaction (FCR) test, and vigour was assessed on the basis of the time taken for in vitro germination as well as on the emergence of pollen tubes through the cut end of semi-vivo implanted styles. None of the stress conditions affected pollen viability and high RH or high temperature stress did not individually affect pollen vigour. However, pollen vigour was markedly affected when both the stresses were given together. Pollen grains subjected to high RH at 38° C took a longer time to germinate in vitro and the pollen tubes emerged later from the cut end of the semi-vivo styles; division of the generative cell was also delayed. Pollen grains subjected to high RH at 45° C failed to germinate in vitro, but did germinate on the stigma. Many pollen tubes subjected to this treatment showed abnormalities, and the growth of pollen tubes in the pistil was much slower than that observed in other treatments. Pollen samples subjected to all of the stress conditions were able to induce fruit and seed set. The implications of these results on the relationship between the FCR test and viability, and between viability and vigour, especially in stressed pollen, are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196495
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  • 5
    Electronic Resource
    Electronic Resource
    Effects of high humidity and temperature stress on pollen membrane integrity and pollen vigour in Nicotiana tabacum (1989)
    Springer
    Sexual plant reproduction 2 (1989), S. 137-141 
    Details
    ISSN: 1432-2145
    Keywords: Humidity ; Temperature stress ; Nicotiana tabacum ; Pollen germination ; Pollen membrane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The prolonged exposure of pollen Nicotiana tabacum to high humidity at both room temperature and 38° C did not affect membrane integrity as revealed by the fluorochromatic reaction (FCR) test, but did affect pollen vigour. At room temperature germination was not affected, although tube growth was reduced; at 38° C, there was both a reduction in tube growth and delayed germination. When the pollen was subjected to 1 h hydration followed by 1 h desiccation (up to a maximum of four cycles) at room temperature, a reduction in the FCR, germination and tube length after each desiccation treatment was observed. Subsequent hydration fully restored the FCR, but only partially restored germination and tube growth. At 38° C, however, FCR, germination, and tube growth were drastically reduced. The implications of these results on the relationship between FCR and germinability, the responses of pollen exposed to humidity and temperature stress in the field, and on pollen storage are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00192759
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  • 6
    Electronic Resource
    Electronic Resource
    Striped projections of the outer membrane of the generative cell in Convallaria majalis pollen (1995)
    Springer
    Sexual plant reproduction 8 (1995), S. 223-227 
    Details
    ISSN: 1432-2145
    Keywords: Pollen ; Generative cell ; Cytoskeleton ; Motility ; Myosin immunogold labelling
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In pollen grains of Convallaria majalis the outer membrane of the generative cell (GC) is the inner membrane of the vegetative cell (VC). Striped projections (SP) at the cytoplasmic face of the outer membrane of the GC were revealed by chemical fixation and also by a rapid freeze-fixation and freeze-substitution. The projections, located in groups on the protruding lobes of the GC, were arranged parallel to each other and were equally spaced (40 nm apart). The length of the SP, estimated from grazing sections of GC, was 400 nm. Each projection was composed of T-shaped elements, about 35 nm high, spaced at an average distance of 25 nm. SP were observed in mature, hydrated, activated and germinated pollen grains and seemed to be associated with microtubules and microfilaments of the VC. No evidence exists yet of SP on the sperm cell membrane. Immunogold labelling with anti-myosin antibodies showed many gold particles attached preferentially to the surface of the protruding lobes of the GC in the area of the projections. These results may suggest that the SP of Convallaria GC contain myosin-like protein and play an important role in the motility of the GC during pollen tube growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228941
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  • 7
    Electronic Resource
    Electronic Resource
    Ultrastructure of the cytoskeleton in freeze-substituted pollen tubes ofNicotiana alata (1987)
    Springer
    Protoplasma 140 (1987), S. 141-150 
    Details
    ISSN: 1615-6102
    Keywords: Cytoskeleton ; Freeze substitution ; Nicotiana ; Pollen tubes ; Rapid freeze fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the cytoskeleton inNicotiana alata pollen tubes grownin vitro has been examined after rapid freeze fixation and freeze substitution (RF-FS). Whereas cytoplasmic microtubules (MTs) and especially microfilaments (MFs) are infrequently observed after conventional chemical fixation, they occur in all samples prepared by RF-FS. Cortical MTs are oriented parallel to the long axis of the pollen tube and usually appear evenly spaced around the circumference of the cell. They are always observed with other components in a structural complex that includes the following: 1. a system of MFs, in which individual elements are aligned along the sides of the MTs and crossbridged to them; 2. a system of cooriented tubular endoplasmic reticulum (ER) lying beneath the MTs, and 3. the plasma membrane (PM) to which the MTs appear to be extensively linked. The cortical cytoskeleton is thus structurally complex, and contains elements such as MFs and ER that must be considered together with the MTs in any attempt to elucidate cytoskeletal function. MTs are also observed within the vegetative cytoplasm either singly or in small groups. Observations reveal that some of these may be closely associated with the envelope of the vegetative nucleus. MTs of the generative cell, in contrast to those of the vegetative cytoplasm, occur tightly clustered in bundles and show extensive cross-bridging. These bundles, especially in the distal tail of the generative cell, are markedly undulated. MFs are observed commonly in the cytoplasm of the vegetative cell. They occur in bundles oriented predominantly parallel to the pollen tube axis. Although proof is not provided, we suggest that they are composed of actin and are responsible for generating the vigorous cytoplasmic streaming characteristic of living pollen tubes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273723
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  • 8
    Electronic Resource
    Electronic Resource
    Microtubule organization in sperm cells in the pollen tubes ofBrassica oleracea L. (1990)
    Springer
    Protoplasma 154 (1990), S. 151-156 
    Details
    ISSN: 1615-6102
    Keywords: Cytoskeleton ; Male gamete ; Motility
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Microtubules tightly cross-linked into bundles are described in the sperm cells ofBrassica oleracea pollen tubes. The sperm cells are lobed and “tailed” and the microtubule bundles are often located in these parts of the cells. In the present paper we suggest that the cross-linked microtubule organization could determine an intertubular sliding, probably generating a motility system that propels the sperm cells through the tube.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01539842
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  • 9
    Electronic Resource
    Electronic Resource
    The anti-centrosome monoclonal antibody 6C6 reacts with a plasma membrane-associated polypeptide of 77 kDa fromNicotiana tabacum pollen tubes (1996)
    Springer
    Protoplasma 190 (1996), S. 68-78 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01281195
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