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  • 1
    Electronic Resource
    Electronic Resource
    Some events of mitosis and cytokinesis in the generative cell of Ornithogalum virens L. (1996)
    Springer
    Planta 199 (1996), S. 202-208 
    Details
    ISSN: 1432-2048
    Keywords: Cytokinesis ; Generative cell ; Mitosis ; Ornithogalum ; Phragmoplast ; Pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The organization of the microtubule (Mt) cytoskeleton during mitosis and cytokinesis of the generative cell (GC) in Ornithogalum virens L. (bicellular pollen type, chromosome number, n = 3) from prophase to telophase/sperm formation was investigated by localization of α-tubulin immunofluorescence using a conventional fluorescence microscope and a confocal laser scanning microscope. Chromosomes were visualized with DNA-binding fluorochrome dyes (ethidium bromide and 4′6-diamino-2-phenyl-indole). The GC of O. virens is characterized by G2/M transition within the pollen grain and not in the pollen tube as occurs in the majority of species with bicellular pollen. It was found that prophase in the GC starts before anthesis and prometaphase takes place after 10 min of pollen germination. The prophase Mts are organized into three prominent bundles, located near the generative nucleus. The number of these Mt bundles is the same as the number of GC chromosomes, a relation which has not previously been considered in other species. The most evident feature in the prophase/ prometaphase transition of O. virens GC is a direct rapid rearrangement of Mt bundles into a network which appears to interact with kinetochores and form a typical prometaphase Mt organization. The metaphase chromosomes are arranged into a conventional equatorial plate, and not in tandem as is thought to be characteristic of GC metaphase. The metaphase spindle consists of kinetochore fibres and a few interzonal fibres which form dispersed poles. Anaphase is characterized by a significant elongation of the mitotic spindle concomitant with the extension of the distance between the opposite poles. At anaphase the diffuse poles converge. Cytokinesis is realized by cell plate formation in the equatorial plane of the GC. The phragmoplast Mts between two future sperm nuclei appear after Mts of the mitotic spindle have disappeared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196560
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  • 2
    Electronic Resource
    Electronic Resource
    Immunoelectron microscopy of myosin associated with the generative cells in pollen tubes of Nicotiana tabacum L. (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 233-237 
    Details
    ISSN: 1432-2145
    Keywords: Key words Generative cell ; Nicotiana tabacum ; Immunogold ; Myosin ; Pollen tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  In this study, polyclonal anti-myosin antibodies were used for immunogold labeling of ultrathin sections of pollen tubes of Nicotiana tabacum L. to unravel the ultrastructural localization of myosin associated with the generative cells. Clusters of immunogold particles were consistently found in association with the area of the outer surface of the vegetative cell plasma membrane present around the generative cell. Compared to the generative cell cytoplasm, the nucleoplasm showed higher numbers of gold particles. This is the first direct evidence demonstrating the presence of myosin in the nuclei of the generative cell of flowering plants. The possible implications of these findings are discussed in relation to movement of the generative cell in the pollen tube cytoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050037
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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: 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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  • 4
    Electronic Resource
    Electronic Resource
    Dynein heavy chain-related polypeptides are associated with organelles in pollen tubes of Nicotiana tabacum (1998)
    Springer
    Sexual plant reproduction 11 (1998), S. 31-40 
    Details
    ISSN: 1432-2145
    Keywords: Key words Pollen tube ; Nicotiana tabacum ; Dynein heavy chain related polypeptides ; Immunolocalization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  It is known that pollen tubes contain two high molecular weight polypeptides which share some biochemical and immunological properties with dynein heavy chains. This paper reports data on the subcellular localization of the two dynein heavy chain-related polypeptides during pollen tube growth. Immunofluoresence studies using a purified antibody (Dy-1) raised against a synthetic peptide reproducting the P-loop conserved sequence of dynein heavy chains showed spot-like structures, with a characteristic distribution pattern that depended on the tube length. Biochemical evidence confirmed the presence of dynein heavy chain-related bands in the pollen tube membrane fraction. The association of proteins carrying dynein heavy chain-related polypeptides to cell membranes was affected by detergent (Triton×100), whereas other stripping agents, like NaCl and Na2CO3, did not significantly influence the interaction of dynein heavy chain-related doublet with their cytoplasmic targets. These data suggest that dynein heavy chain-related polypeptides associate with membranous organelles within the vegetative cell of Nicotiana tabacum pollen tubes, implying their involvement in the cytoplasmic distribution of these organelles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050118
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  • 5
    Electronic Resource
    Electronic Resource
    Immunoelectron microscopy of myosin associated with the generative cells in pollen tubes ofNicotiana tabacum L. (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 233-237 
    Details
    ISSN: 1432-2145
    Keywords: Generative cell ; Nicotiana tabacum ; Immunogold ; Myosin ; Pollen tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In this study, polyclonal anti-myosin antibodies were used for immunogold labeling of ultrathin sections of pollen tubes ofNicotiana tabacum L. to unravel the ultrastructural localization of myosin associated with the generative cells. Clusters of immunogold particles were consistently found in association with the area of the outer surface of the vegetative cell plasma membrane present around the generative cell. Compared to the generative cell cytoplasm, the nucleoplasm showed higher numbers of gold particles. This is the first direct evidence demonstrating the presence of myosin in the nuclei of the generative cell of flowering plants. The possible implications of these findings are discussed in relation to movement of the generative cell in the pollen tube cytoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02173104
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    Paper (German National Licenses)
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  • 6
    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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    Paper (German National Licenses)
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  • 7
    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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  • 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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  • 9
    Electronic Resource
    Electronic Resource
    Immunogold localization of arabinogalactan proteins, unesterified and esterified pectins in pollen grains and pollen tubes ofNicotiana tabacum L. (1995)
    Springer
    Protoplasma 189 (1995), S. 26-36 
    Details
    ISSN: 1615-6102
    Keywords: Nicotiana tabacum ; Pollen ; Pollen tube ; Cell wall ; Immunogold localization ; Pectins ; Arabinogalactan proteins
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The monoclonal antibodies JIM 5 (against unesterified pectin), JIM 7 (against methyl esterified pectin), MAC 207 (against arabinogalactan proteins, AGPs), and JIM 8 (against a subset of AGPs) were utilized singly or in combinations for immunogold labelling of germinated pollen grains and pollen tubes ofNicotiana tabacum. Pectins were localized in the inline of pollen grain, unesterified pectin being more abundant than the esterified one. AGPs were co-localized with pectin in the inline, but were present preferably close to the plasma membrane. In pollen tubes, AGPs, unesterified and esterified pectins were co-localized in the outer and middle layers of the cell wall. The density of the epitopes was not uniform along the length of the pollen tube, but showed alterations. In the pollen tube tip wall esterified pectin was abundantly present, but not AGPs. In the cytoplasm esterified pectin and AGPs were detected in Golgi derived vesicles, indicating their role in the pathway of the cell wall precursors. In the “cell wall” of generative cell only AGPs, but no pectins were localized. The co-localization of pectins and AGPs in the cell wall of pollen grain and pollen tube might play an important role, not only in maintenance of the cell shape, but also in cell-cell interaction during pollen tube growth and development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01280289
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