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  • 1
    Electronic Resource
    Electronic Resource
    Microtubular organization during asymmetrical division of the generative cell inGagea lutea (1995)
    Springer
    Journal of plant research 108 (1995), S. 269-276 
    Details
    ISSN: 1618-0860
    Keywords: Gagea lutea ; Generative cell ; Microtubule organization ; Mitosis ; Sperm cell dimorphism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Video microscopy and conventional or Confocal Laser Scanning Microscopy after DAPI staining and anti-α-tubulin labelling were used to study the asymmetrical division of the generative cell (GC) inGagea lutea. Pollen was cultured for up to 8 hr in a medium containing 10% poly (ethylene glycol), 3.0% to 3.8% sucrose, 0.03% casein acid hydrolysate, 15 mM 2-(N-morpholinoethane)-sulphonic acid-KOH buffer (pH 5.9) and salts. In the pollen grain, the GC had a spherical or ovoid shape and contained a fine network of intermingled microtubules. As the GC entered into the pollen tube, it assumed a cylindrical shape with a length often exceeding 250 μm. A cage of microtubules then developed around the nucleus. The presence of dense and thick microtubular bundles in front of the generative nucleus within the GC coincided with the translocation of the nucleus to the leading end of the GC. No pre-prophase band was ever detected, but a distinct prophase spindle of microtubules was formed. In some GCs a tubulin-rich dot became visible at each pole of the spindle. After nuclear envelope breakdown, the bundles of microtubules spread between the chromosomes and became oriented into parallel arrays. The spindle became shorter at metaphase, and there was no tubulin labelling at the site of the metaphase plate. At anaphase, the microtubular apparatus lost its spindle-shape and a bridge of prominent bundles of microtubules connected the two daughter nuclei. At telophase, the site of the cell plate remained unstained by the anti-α-tubulin antibody, but a distinct phragmoplast of microtubules was formed more closely to the leading nucleus, resulting in the formation of unequal sperm cells (SCs). The leading SC was up to 2.5 times smaller than the following SC and it contained a smaller or equal number of nucleoli.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02344352
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  • 2
    Electronic Resource
    Electronic Resource
    Changes in volume, surface area, and frequency of nuclear pores on the vegetative nucleus of tobacco pollen in fresh, hydrated, and activated conditions (1990)
    Springer
    Planta 181 (1990), S. 304-309 
    Details
    ISSN: 1432-2048
    Keywords: Germination (pollen) ; Nicotiana (pollen germination) ; Nucleus (generative, vegetative) ; Pollen(germination, ultrastructure)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The vegetative nucleus (VN) of Nicotiana tabacum L. has been qualitatively and quantitatively studied in fresh, hydrated, and activated pollen. Techniques included the use of optical sectioning by confocal scanning laser microscopy to obtain volume and surface area measurements, and stereoscopic pairs; and freeze-etch electron microscopy to estimate the frequency of nuclear pores per μm2 in the vegetative nucleus. Several morphological changes were observed to occur in pollen grain nuclei during the early processes of tube growth. In freshly dehisced pollen grain, the vegetative and generative nuclei were side by side, but following hydration and activation of the grain, the elongated generative nucleus became partially surrounded by the vegetative nucleus. It was found that during hydration, the surface area of the vegetative nucleus increased and there was a decrease in the frequency of nuclear pores. The calculated total number of pores remained similar. After activation and pollen-tube growth, the vegetative nucleus retained the same surface area as in the hydrated state but the frequency of nuclear pores decreased; therefore, the calculated total number of pores was significantly lowered. When considered alongside complementary biochemical data, these morphological results indicate that RNA production in the vegetative nucleus decreases following germination.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00195880
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  • 3
    Electronic Resource
    Electronic Resource
    Dynein-related polypeptides in pollen and pollen tubes (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 312-317 
    Details
    ISSN: 1432-2145
    Keywords: Key words Pollen tube ; Nicotiana tabacum ; Ginkgo biloba ; Dynein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Microtubules in pollen tubes are evident within the vegetative and generative cell cytoplasm. This observation led to the formulation of several hypotheses regarding the role of microtubules in cytoplasmic movement and the migration of the vegetative nucleus/generative cell along the pollen tube. The study of microtubular motor proteins in pollen tubes followed the discovery and characterization of an immunoreactive homolog of mammalian kinesin in tobacco pollen tubes. Recent identification of dynein-related polypeptides in pollen tubes of Nicotiana tabacum and pollen of Ginkgo biloba is a significant step in the definition of the role of microtubule function within pollen and pollen tubes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050048
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  • 4
    Electronic Resource
    Electronic Resource
    Dynein-related polypeptides in pollen and pollen tubes (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 312-317 
    Details
    ISSN: 1432-2145
    Keywords: Pollen tube ; Nicotiana tabacum ; Ginkgo biloba ; Dynein
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Microtubules in pollen tubes are evident within the vegetative and generative cell cytoplasm. This observation led to the formulation of several hypotheses regarding the role of microtubules in cytoplasmic movement and the migration of the vegetative nucleus/generative cell along the pollen tube. The study of microtubular motor proteins in pollen tubes followed the discovery and characterization of an immunoreactive homolog of mammalian kinesin in tobacco pollen tubes. Recent identification of dynein-related polypeptides in pollen tubes ofNicotiana tabacum and pollen ofGinkgo biloba is a significant step in the definition of the role of microtubule function within pollen and pollen tubes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441948
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  • 5
    Electronic Resource
    Electronic Resource
    An immunoreactive homolog of mammalian kinesin in Nicotiana tabacum pollen tubes (1992)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 21 (1992), S. 132-137 
    Details
    ISSN: 0886-1544
    Keywords: microtubules ; vesicles ; cytoplasmic movement ; monoclonal antibody ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A cytoskeletal apparatus is involved in the movement of vesicles, organelles, and gametes in the pollen tube. The function of microfilaments has been defined quite precisely, but the role of microtubules needs to be further clarified. On the basis of immunological and biochemical investigations, we have identified a polypep-tide showing common properties with kinesin, a microtubule-based motor mainly described in nonplant tissues, in the pollen tube of Nicotiana tabacum. Like mammalian kinesin, the kinesin-immunoreactive homolog from Nicotiana tabacum pollen tubes binds to mammalian microtubules in an AMP-PNP dependent manner. The kinesin-like component is likely to be involved in the movement of vesicular material in the growing pollen tube.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970210206
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  • 6
    Electronic Resource
    Electronic Resource
    Kinesin-related polypeptide is associated with vesicles from Corylus avellana pollen (1994)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 29 (1994), S. 155-166 
    Details
    ISSN: 0886-1544
    Keywords: Golgi vesicles ; pollen ; pollen tube ; microtubules ; kinesin-related protein ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A 100-kDa polypeptide with microtubule-interacting properties was identified in a Golgi vesicle-enriched fraction from Corylus avellana pollen. The k71s23 antibody (directed to the kinesin heavy chain from bovine brain) [Tiezzi et al., 1992: Cell Motil. Cytoskeleton 21:132-137] localized the polypeptide on the external surface of membrane-bounded organelles. Some 100-kDa-containing vesicles co-pelleted with microtubules (polymerized from purified bovine brain tubulin) either in presence or absence of 5 mM AMPPNP, but they could be released by 10 mM ATP or 0.5 M KCl. The pollen microtubule-interacting protein, salt-extracted from membranes and partially purified by gel filtration, exhibited an ATPase activity (16.2 nmolPi/mg/min) which could be stimulated about 2-fold (32.5 nmolPi/mg/min) by addition of bovine brain microtubules. We suppose that the 100-kDa polypeptide is part of a molecular complex showing properties of the kinesin class. © 1994 Wiley-Liss, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970290207
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  • 7
    Electronic Resource
    Electronic Resource
    Characterization of the intermediate filament apparatus in skin fibroblasts from patients with giant axonal neuropathy: Effect of trypsin (1987)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 8 (1987), S. 55-60 
    Details
    ISSN: 0886-1544
    Keywords: vimentin ; hereditary disease ; proteolysis ; serum ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Skin fibroblasts from two siblings with giant axonal neuropathy (GAN) were examined by both biochemical and immunocytochemical studies. The presence of intermediate filaments (IF) characteristic of these cells was affected by the growth conditions. Immediately after plating and during the following 24 hours the majority of the cells contained an IF “bundle”; however, after 4-6 days in culture only a minority of the cells retained this structure. We present evidence that trypsinization but not serum concentration is likely to influence the formation of the “bundle.” The results indicate that the formation of the “bundle” may result from a defective association or relationship between the cytoskeleton and the plasma membrane.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970080108
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructure of the stylar canal cells ofCitrus limon (Rutaceae) (1981)
    Springer
    Plant systematics and evolution 138 (1981), S. 263-274 
    Details
    ISSN: 1615-6110
    Keywords: Angiosperms ; Rutaceae ; Citrus limon ; Style ; canal cells ; canal filling substance ; ultrastructure ; anatomy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The ultrastructure of the canal cells and the canal filling substance ofCitrus limon have been studied. At maturity the canal cells are very rich in cytoplasm. Their inner tangential walls lining the canal are much thickened and formed by two layers: the outer corresponds to the original wall, the inner is formed by subsequent deposition of abundant materials of different origin. This thickening occurs at the same time as the filling of the stylar canal. Both events are paralleled by considerable dictyosomic activity, the formation of a large amount of rough endoplasmic reticulum, and the incorporation of small cytoplasmic masses into the cell wall, due to plasmalemma evaginations. — The material in the stylar canal has a heterogeneous ultrastructure aspect and consists of polysaccharides, proteins and lipids; it presumably provides nutrients for the growing pollen tubes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00985190
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