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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Phytochemistry 27 (1988), S. 2027-2031 
    ISSN: 0031-9422
    Keywords: Nicotiana sylvestris ; Solanaceae ; acetate incorporation ; lipid composition ; phosphate incorporation. ; pollen germination
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1076
    Keywords: GH, LH, and FSH in plasma of children, repeated circadian patterns, intra-individual reproducibility, influence of 9-alpha-F ; Pubertal changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Description / Table of Contents: Zusammenfassung Wachstumshormon (GH) und Gonadotropine (LH, FSH) wurden im Plasma von 5 Kindern verschiedener Pubertätsentwicklung und mit leichtem orthostatischem Syndrom radioimmunologisch (RIA) gemessen. Als Parameter dienten Argininbelastung und die Spiegel über 24 h gemessen stündlich von 8 bis 20 Uhr und halbstündlich von 20 bis 8 Ubr vor und nach sechswöchentlicher Behandlung mit 9-alpha-Fluorhydrocortison (9-alpha-F, Astonin-H®, Fa. Merck, Darmstadt, 0,1–0,2 mg/Tag). Die Werte für GH blieben unverändert, dagegen waren die circadianen Werte für LH nach Therapie leicht erhöht bei allen Kindern. Abhängig vom Pubertätsstadium nahmen Häufigkeit und Höhe der circadianen GH-Spitzen bei den drei Jungen zu, bei den zwei Mädchen gegen Ende der Pubertät eher ab. Schwankungen des LH und FSH waren im Schlaf deutlicher und nahmen bei den Jungen mit der Pubertät zu. Zwischen den beiden circadianen Kurven der einzelnen Kinder bestand eine deutliche Ähnlichkeit bei GH und LH, nicht aber bei FSH. Ein zeitlicher Zusammenhang der Spitzen von GH und LH fällt auf. Eine endogene, erbliche Langzeitregulation wird diskutiert.
    Notes: Abstract Growth hormone (GH), luteinizing hormone (LH), and follicle-stimulating hormone (FSH) in plasma of 5 children at different pubertal stages and suffering from moderate orthostatic complaints, were measured by radioimmunoassay (RIA). Parameters for secretory capacity were arginine loading and circadian hormonal patterns in hourly intervals from 8 a.m. to 8 p.m. and in half-hourly intervals from 8 p.m. to 8 a.m. before and after 6 weeks treatment with 9-alpha-fluorohydrocortisone (9-alpha-F, Astonin-H, Fa. Merck, Darmstadt, 0.1–0.2 mg/day). Plasma GH during arginine tests and in circadian levels remained unchanged, but circadian LH showed a consistent slight rise in all children. With pubertal development, magnitude and timing of GH peaks increased in boys, and rather decreased in the two girls toward late puberty. Episodic fluctuation of LH and FSH were more marked during sleep, and increased in the three boys as puberty advanced. Similar intraindividual patterns for GH and LH, but not for FSH were noted in 4 children. Timing of GH and LH peaks appeared to be correlated. An intrinsic hereditary long-term regulatory principle is discussed.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Planta 173 (1988), S. 35-41 
    ISSN: 1432-2048
    Keywords: Membrane extension ; Nicotiana (plasmatubules) ; Nutrient uptake (pollen tube) ; Plasma membrane ; Plasmatubule ; Pollen tube
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ultrastructural studies of the pollen tubes of Nicotiana sylvestris grown in the pistil revealed an extensive development of plasmatubules formed by evaginations of the plasma membrane. The plasmatubules occurred as twisted tubular structures in the periplasmic space along the tube wall and, in cross section, exhibited circular profiles with an outer diameter of 28±4 nm. They were also seen in deep, pocket-like invaginations of the plasma membrane and in this case the profiles had an outer diameter of 34±8 nm. In the pocket-like invaginations they were partially branched and often closely packed to form groups with obvious patterns. The enlargement of the plasma-membrane area resulting from plasmatubules formed along the tube wall was about six-to tenfold. Pollen tubes grown in vitro exhibited poorly developed plasmatubules. It is suggested that the large extension of the plasma membrane could enhance the uptake of nutrients, and thus might be responsible for the comparatively fast growth of pollen tubes in the pistil. Moreover, it is also assumed that the turnover rate of the Golgi apparatus must be higher in pollen tubes growing in vivo than in vitro, in order to provide a sufficient amount of membrane for the formation of the plasma membrane with its tubular modifications.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1615-6102
    Keywords: Pollen tube ; Endoplasmic reticulum ; Golgi apparatus ; Membrane biogenesis ; Plasma membrane (Tobacco)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tobacco (Nicotiana tabacum L.) pollen, germinated 4 hours in suspension culture, was labeled with radioactive leucine and fractionated into constituent membranes by the technique of preparative free-flow electrophoresis. Tubes were ruptured by sonication directly into the electrophoresis buffer. Unfortunately, the Golgi apparatus of the rapidly elongating pollen tubes did not survive the sonication step. However, it was possible to obtain useful fractions of endoplasmic reticulum and mitochondria. To obtain Golgi apparatus, glutaraldehyde was added to the homogenization buffer during sonication. Plasma membrane, which accounted for only about 3% of the total membrane of the homogenates as determined by staining with phosphotungstate at low pH, was obtained in insufficient quantity and fraction purity to permit analysis. Results show rapid incorporation of [3H]leucine into endoplasmic reticulum followed by rapid chase out. The half-time for loss of radioactivity from the pollen tube endoplasmic reticulum was about 10 minutes. Concomitant with the loss of radioactivity from endoplasmic reticulum, the Golgi apparatus fraction was labeled reaching a maximum 20 minutes post chase. The findings suggest flow of membranes from endoplasmic reticulum to the Golgi apparatus during pollen tube growth.
    Type of Medium: Electronic Resource
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