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  • 1985-1989  (6)
  • Generative cell  (3)
  • Brassica napus  (2)
  • Biologia del polline  (1)
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Sexual plant reproduction 1 (1988), S. 88-96 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Aerobiologia 1 (1985), S. 31-38 
    ISSN: 1573-3025
    Keywords: Pollen biology ; Aerobiology ; Allergology ; Biologia del polline ; Aerobiologia ; Allergologia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Riassunto Nel presente lavoro vengono riportati alcuni brevi cenni sulla biologia del polline. Viene descritto il processo di formazione del granulo pollinico e la sua dispersione con particolare riguardo alle piante anemofile. Vengono brevemente riportati anche alcuni dati sulla composizione chimica del polline.
    Notes: Summary In the present paper some data on the pollen biology are reported. The current knowledge on the pollen development, pollen dispersion in the wind pollination are shortly described. The chemical composition of some pollen grains are also reported.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 150 (1989), S. 54-71 
    ISSN: 1615-6102
    Keywords: Generative cell ; Microtubules ; Mitosis ; Cytokinesis ; Pollen ; Sperm ; Tradescantia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytoskeletal organization and chromosome behavior were studied inTradescantia generative cells prior to and during sperm formation using in vitro grown pollen tubes and fluorescence staining methods. Before pollen germination, the crescent-shaped generative cell contains a reticulate microtubule (Mt) system. The cell elongates dramatically after germination, and its Mts assume a helical to longitudinal arrangement. Chromosome condensation is evident approximately 3hr after germination. Kinetochores appear as dark interruptions in the Mt array, and thus seem to attach directly to interphase fibers. No metaphase plate typical of other cells is observed with either DAPI or anti-tubulin staining. Instead, the chromosomes adopt a twisted or braided arrangement, with kinetochores distributed along the length of the cell and kinetochore fibers linked to each other and to surrounding fibers. Anaphase is characterized by a staggered, overlapping separation of chromosomes and by elongation of Mt branches connecting opposing kinetochore fibers. Cytokinesis appears to utilize a furrowing process; a phragmoplast or cell plate was never seen. As a result of these events, the sperm directly inherit their cytoskeleton from generative cell Mts involved in division. No actin fibers are observed at any stage using rhodamine-phalloidin staining. The results are discussed in terms of other reports on sperm formation, possible mitotic and cytokinetic mechanisms, and past distinctions between Mt arrays in higher plant somatic cells.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 146 (1988), S. 28-34 
    ISSN: 1615-6102
    Keywords: Generative cell ; Microtubule ; Sperm ; Pollen ; Tradescantia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Microtubules were visualized in the sperm ofTradescantia virginiana pollen tubes grownin vitro and processed for antitubulin immunocytochemistry. The sperm contain thick microtubule bundles from which emerge numerous branches of various dimensions disposed longitudinally and helically along the cell axis. Sperm are usually spindle or cigar-shaped, but cells of various sizes and shapes can be found. All contain microtubule arrays. No F-actin was detected in sperm using rhodamine-phalloidin staining. Sperm microtubules are discussed in terms of their potential roles in cell shaping and motility and their origin during generative cell division.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1615-6102
    Keywords: Brassica napus ; Cell division ; Male germ unit ; Pollen ; Sperm cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The association of the two sperm cells inBrassica napus pollen following the generative cell division was investigated. The generative cell during division is located in the center of the pollen grain, within the vegetative cell. The space present between the two cells is slightly irregular as seen following standard glutaraldehyde fixation. After completion of mitosis vesicles appear in the equatorial plane, coalescing centripetally to form a cell plate which fuses with the membrane of the generative cell, dividing it in two sperm cells. They are isolated from the vegetative cell by the space between the two cell membranes and are separated from each other by a similar space resulting from the cell plate formed during cytokinesis.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1615-6102
    Keywords: Brassica napus ; Vegetative cell ; Microbodies ; Pollen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the vegetative cell ofBrassica napus tricellular pollen grains, just before anthesis with standard chemical fixation, is reported. The vegetative cell may be regarded as a highly differentiated and metabolically active fat-storage cell. It contains many mitochondria with a well developed internal membrane system, starchless plastids, microbodies, lipid bodies, dictyosomes and numerous vesicles thought to originate from the dictysomes. Rough endoplasmic reticulum organized in stacks of cisternae is also spatially associated with certain organelles, mainly lipid bodies, microbodies and plastids. There are also randomly distributed polyribosome areas. The microbodies are mainly polymorphic in shape and are often observed in contact with lipid bodies. The above spatial relationship implies that the microbodies may have a glyoxysomal function. In the late period of vegetative cell maturation, the microbodies are probably involved in the process of glyconeogenesis in which the conversion of lipid reserves to sugar takes place.
    Type of Medium: Electronic Resource
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