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  • 1
    Electronic Resource
    Electronic Resource
    Apertural chambers inGeranium: Development and ultrastructure (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 102-106 
    Details
    ISSN: 1432-2145
    Keywords: Apertural protrusion ; Vacuolated microspore ; Starch ; Ectintine ; Pollen germination ; Geranium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pollen grains ofGeranium robertianum andG. pratense are tricolpate. At the time of the vacuolated microspore stage intine protrusions are formed at each aperture. Each aperture becomes separated from the vegetative cytoplasm by a thick ectintine layer. Starch grains are enclosed in the protrusions and do not participate in pollen tube growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02153057
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Apertural chambers in Geranium: development and ultrastructure (1996)
    Springer
    Sexual plant reproduction 9 (1996), S. 102-106 
    Details
    ISSN: 1432-2145
    Keywords: Key words Apertural protrusion ; Vacuolated microspore ; Starch ; Ectintine ; Pollen germination ; Geranium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract  Pollen grains of Geranium robertianum and G. pratense are tricolpate. At the time of the vacuolated microspore stage intine protrusions are formed at each aperture. Each aperture becomes separated from the vegetative cytoplasm by a thick ectintine layer. Starch grains are enclosed in the protrusions and do not participate in pollen tube growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s004970050016
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Gametic differentiation in Chlamydomonas reinhardtii: light dependence and gene expression patterns (1989)
    Springer
    Archives of microbiology 152 (1989), S. 572-577 
    Details
    ISSN: 1432-072X
    Keywords: Chlamydomonas reinhardtii ; Gametic differentiation ; Light requirement ; Light-pulse-studies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Gametes of Chlamydomonas reinhardtii synthesize numerous proteins not observed in vegetative cells and vice versa. Gametogenesis induced changes in gene expression were confirmed by SDS-PAGE of in vitro translation products using total RNA from gametes and vegetative cells. Vegetative cells and gametes thus represent two cell types with distinct patterns of gene expression. The generation of mature gametes from liquid cultures of asynchronously growing vegetative cells was dependent on light. This light requirement could not be substituted for by an organic source of energy and carbon, indicating that light serves as a signal in gametogenesis. The light signal was shown to become effective only after preincubation in nitrogen-free medium. This delayed competence for light indicates that the two external signals — nitrogen-starvation and light —may function in sequence. Execution of the light dependent step in gamete formation required cytoplasmic protein synthesis and RNA synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00425489
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Unusual sperm cells inApiaceae (1988)
    Springer
    Plant systematics and evolution 159 (1988), S. 273-276 
    Details
    ISSN: 1615-6110
    Keywords: Apiaceae ; Cicuta ; Bupleurum ; Apium ; Sperm cells
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The sperm cells in the tricellular pollen grains ofCircuta virosa, Bupleurum subovatum, andApium nodiflorum differ significantly from sperm cells known so far. They are extremely destitute of plasma. Besides the sperm nucleus, no cytoplasmic organelles are observed. The wall of the sperm cell forms long, slender projections on both poles of the spindle-shaped cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00935978
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  • 5
    Electronic Resource
    Electronic Resource
    Metabolism of P-particles (polysaccharide particles) in mature pollen grains ofEryngium campestre L. (Apiaceae) (1988)
    Springer
    Protoplasma 146 (1988), S. 65-71 
    Details
    ISSN: 1615-6102
    Keywords: Apiaceae ; Eryngium campestre ; Metabolism ; Pollen grain ; P-particle ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The metabolism of P-particles (polysaccharide particles) was investigated in mature pollen grains ofEryngium campestre L. Numerous P-particles, originating from dictyosome activity, are found to be accumulated near the apertures, followed by mitochondria. A single layer of ER profiles seems to prevent the fusion of the P-particles with the intine. Instead of this, they fuse with each other forming nonmembrane-bounded polysaccharide-aggregates, which subsequently change their granulated structure to an amorphous. Mitochondria together with small vesicles are involved in the conversion-process. The so formed wall precursors pass through the ER and fuse into the intine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01405914
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  • 6
    Electronic Resource
    Electronic Resource
    Ultrastructural changes in maturing pollen grains ofApium nodiflorum L. (Apiaceae), with special reference to the endoplasmic reticulum (1989)
    Springer
    Protoplasma 152 (1989), S. 69-76 
    Details
    ISSN: 1615-6102
    Keywords: Apiaceae ; Apium nodiflorum ; Endoplasmic reticulum ; Pollen grain ; Polysaccharide particles ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructural events in 3-cellular pollen grains ofApium nodiflorum L. are investigated during pollen maturation. Three distinct developmental stages are distinguished from the formation of sperm cells up to anthesis, whereby the rough endoplasmic reticulum (RER) is mainly involved. The most conspicious form is the highly dilated RER in the vegetative cytoplasm of the youngest pollen grains, which changes to vesicular RER in the following stage. In mature pollen grains the RER has a narrow cisternal configuration and often forms stacks. Pollen activation is preceded by the accumulation of polysaccharide particles.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01323064
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    Formation of sperm cells inGalium mollugo (Rubiaceae),Trichodiadema setuliferum (Aizoaceae), andAvena sativa (Poaceae) (1988)
    Springer
    Plant systematics and evolution 161 (1988), S. 53-64 
    Details
    ISSN: 1615-6110
    Keywords: Rubiaceae:Galium mollugo ; Aizoaceae:Trichodiadema setuliferum ; Poaceae:Avena sativa ; Generative cell ; sperm cell ; sperm cell formation ; tricellular pollen grains
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The formation of sperm cells has been examined ultrastructurally in the tricellular pollen grains ofGalium mollugo L. (Rubiaceae).Trichodiadema setuliferum Schwantes (Aizoaceae), andAvena sativa L. (Poaceae). After detachement from the intine the generative cell of all three species lies free within the vegetative cytoplasm. The two sperm cells are built inTrichodiadema andAvena by a single separating wall, while inGalium mollugo two independent walls are formed. However, both mechanisms separate the two male gametes completely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00936012
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    Paper (German National Licenses)
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