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  • 1965-1969  (4)
Material
Years
Year
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Planta 71 (1966), S. 1-14 
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Studies on the fine structural changes accompanying xylem differentiation in wheat coleoptile have indicated that the microtubules are concerned with the inception of a regular wall thickening pattern, and later with wall deposition at the thickening site. The endoplasmic reticulum is situated characteristically in continuous profiles between the thickenings. Radioautographic studies at the electron microscope level using labelled glucoses have shown that the endoplasmic reticulum, golgi bodies and the cytoplasm near the microtubules were often labelled during deposition into nearby thickenings of radioactive materials derived from the tritiated glucoses. Incorporation into the wall occurred mainly at the top of the thickenings. The plastids of the xylem cells were also often labelled, but only during the earlier stages of differentiation; when massive wall deposition was evident, such an incorporation was never observed. The fine structural and radioautographic results are briefly discussed in terms of the possible functions of the organelles in the plant cell.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Planta 81 (1968), S. 193-200 
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary During oogenesis in Chara fibrosa, and in the enlarging, young daughter coenobia of Volvox spec., microtubule-like structures were found in growing plastids. These were appreciably bigger than the usual 240 Å cytoplasmic microtubules, measuring about 320 Å in diameter; a helical or banded organisation in the wall of these tubules was also evident. The tubules were generally present in greatest numbers when the plastids were elongating or enlarging.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 64 (1967), S. 49-66 
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The paper summarises results of simple radioautographic experiments using tritiated glucoses to investigate wall secretion in plant cells. In outer root cap cells, labelled material was first concentrated in the Golgi bodies; it later appeared in vesicles, and was incorporated into the wall immediately under the plasmalemma. It finally collected mainly in the slime layer surrounding the root tip. Biochemical analyses have indicated that this material was pectic in nature. In inner root cap and epidermal cells, labelled material incorporated into the walls and also the cell plates of dividing cells was also apparently mainly derived from Golgi bodies. In meristematic (less differentiated) cells, however, the endoplasmic reticulum was more frequently labelled than the Golgi bodies near walls that had incorporated derivatives of labelled glucose. Considerable incorporation of labelled derivatives into the wall thickenings in coleoptile xylem cells was often detected; nearby elements of the endoplasmic reticulum were again frequently labelled in these cells and less often, Golgi bodies and the cytoplasm in the region occupied by microtubules contained radioactivity. Labelling of starch grains in the plastids was generally observed, but not in cells secreting large amounts of wall materials (outer root cap and older xylem cells); however, addition of larger amounts of exogenous glucose to outer root cap cells, following their incubation in tritiated glucose, promoted such incorporation. The paper finally sets forth some considerations on experimental techniques for radioautography that might be of more general application.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 65 (1968), S. 181-205 
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Tritiated leucine, tyrosine, phenylalanine, methyllabelled methionine, and cinnamic acid were used to study xylem wall deposition and lignin formation with radioautography. Leucine did not specifically label xylem thickenings; tyrosine, phenylalanine and methionine were quite good precursors in this regard. Cinnamic acid was also readily taken up by the tissues and was very markedly concentrated in the xylem thickenings; the labelling of thickenings also occurred in empty tracheids. In developing xylem cells, labelling of the cytoplasm indicated that both the endoplasmic reticulum and Golgi bodies were associated with the wall incorporation. Vesicles probably derived from the Golgi bodies, were generally observed to aggregate in the cytoplasm near the bands of wall microtubules (even if secondary wall thickening had not commenced). Simple biochemical analyses showed that incorporation of cinnamic acid into amino acids and proteins was negligible, but some lignin oxidation products were heavily labelled. The results are related to the biochemistry of lignin synthesis, and confirm that cinnamic acid is a highly specific marker for some forms of wall synthesis.
    Type of Medium: Electronic Resource
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