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  • 1
    Electronic Resource
    Electronic Resource
    The use of radioautography for investigating wall secretion in plant cells (1967)
    Springer
    Protoplasma 64 (1967), S. 49-66 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01257381
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  • 2
    Electronic Resource
    Electronic Resource
    Xylem wall deposition (1968)
    Springer
    Protoplasma 65 (1968), S. 181-205 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01666378
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  • 3
    Electronic Resource
    Electronic Resource
    Mitosis and autospore formation in the green algaKirchneriella lunaris (1970)
    Springer
    Protoplasma 70 (1970), S. 325-347 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Asexual reproduction inKirchneriella lunaris involves autospore formation. After an initial mitosis, the curved cell cleaves to a variable extent, and then the nuclei divide again; finally the cytoplasm is partitioned into four around each nucleus. Rudimentary centrioles appear prior to the first mitosis; centriole complexes then become associated with a developing sheath of extranuclear microtubules at prophase; fenestrae appear at the poles through which both microtubules and centrioles migrate, preceding intranuclear spindle formation. The nucleus meanwhile is enveloped by a perinuclear layer of endoplasmic reticulum which is also interposed between the golgi body and nuclear envelope. Chromosome separation is accompanied by considerable spindle elongation. Finally the reforming nuclear envelope excludes both centriole complex and interzonal spindle apparatus from daughter nuclei. Cleavage is preceded by i) nuclear movement to the cell center, ii) movement of centriole complexes around daughter nuclei until they are opposite one another, and iii) the concurrent formation of a system of transverse microtubules extending across the cell. Other microtubules encircle the cell predicting the cleavage plane. A septum then appears amongst these cytokinetic microtubules, possibly derived from the plasmalemma; it extends across the cell too, through the cleaving peripheral chloroplast. Secondary mitoses follow (as above) during which this septum may be partially resorbed. Finally this septum is reformed, if necessary, and two other septa appear (as above) to quadripartition the cell. Mitotic and cytokinetic structures in this algae are briefly compared with some others.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275761
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  • 4
    Electronic Resource
    Electronic Resource
    Reproduction by zoospores inOedogonium (1972)
    Springer
    Protoplasma 74 (1972), S. 195-212 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cell division in germlings and young filaments ofOedogonium is described. In one species, division proceeded as expected. The ring was formed at the apical wall weakening, and the basal cell did not divide again; the cap of wall derived from the basal cell was sometimes incorporated into the wall of the new apical cell. The second species showed significant differences. The “ring” laid down in the single-celled germling, and sometimes in the apical cell of a two-celled filament covered the whole apical end wall; the basal cell also usually underwent one more division, utilizing a normal ring. It is suggested that the formation of rings for cell division represents an adaptation of a wound-response mechanism, brought into action by the deliberate creation of the circumferential weakening in the apical cell wall, and a concurrent increase in cell turgor. This proposal helps explain the divergent results above, and is further supported by the following examples, given in the paper: a) the frequent occurrence of accidental breaks in the wall, repaired sequentially by the deposition of amorphous and then layered wall material; b) a similar localized wall reinforcement invoked by the presence of rhizoids of other holdfasts attaching themselves to vegetative cells; c) a continuous layer of ring material being deposited over the entire end wall of a dividing cell, when the adjacent apical cell was empty; and d) the deposition of two rings in cells that had been previously treated with colchicine to prevent cytokinesis, and then been allowed to divide again.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279209
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  • 5
    Electronic Resource
    Electronic Resource
    Reproduction by zoospores inOedogonium (1972)
    Springer
    Protoplasma 74 (1972), S. 169-193 
    Details
    ISSN: 1615-6102
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Differentiation of immobile zoospores into future basal cells of vegetative filaments ofOedogonium is described. Once flagella are shed, the constriction disappears from around the dome which soon starts pushing out rhizoid(s); these may become long and/or numerous if cells cannot attach themselves to a substrate. The flagellar apparatus, including the basal bodies, slowly disintegrates within the dome without involving lysosomal structures. A wall is secreted around the elongating cell; several distinguishable types of vesicular components are discharged into it at the dome. Some are derived from hypertrophied golgi bodies, and others from the numerous basal particles (characteristic of zoospores) which had undergone changes in appearance and cytochemical reactivity. The growing rhizoids flatten and extend, finger-like, across the surface of flat substrates, or wrap around vegetative filaments of other alga. The thick holdfats wall is secreted around them, usually forming a structure like a flattened cone; meanwhile the holdfast's interior containing much endoplasmic reticulum becomes increasingly subdivided into a labyrinth by ingrowing folds of wall. Microtubules and extensive arrays of smooth reticulate membranes are present near these walls. The hypertrophied golgi bodies in the holdfast soon revert to their usual smaller size. Eyespots degenerate, and the apical wall develops the circumferential discontinuity which will be the site of the future ring. In unattached germlings, the large accumulation of rough endoplasmic reticulum in the holdfast often shows evidence of breakdown, being replaced by masses of smooth membranes or else homogeneous “souplike” cytoplasm devoid of membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279208
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  • 6
    Electronic Resource
    Electronic Resource
    Microtubule-like structures in the growing plastids or chloroplasts of two algae (1968)
    Springer
    Planta 81 (1968), S. 193-200 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00417448
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  • 7
    Electronic Resource
    Electronic Resource
    Incorporation of radioactivity into wheat xylem walls (1966)
    Springer
    Planta 71 (1966), S. 1-14 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00384638
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  • 8
    Electronic Resource
    Electronic Resource
    Some ultrastructural features of Volvox, with particular reference to the phenomenon of inversion (1970)
    Springer
    Planta 90 (1970), S. 174-190 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Some features of the ultrastructure of Volvox are described. Golgi bodies were often associated with the endoplasmic reticulum (ER), and the two basal bodies appeared to be accompanied by two probasal bodies. A few vegetative cells were binucleate. All cells examined had a peripheral cytoskeleton of microtubules which was particularly well developed in the cells of sperm packets. During inversion of a colony, the cells elongated considerably, possibly due to the increased length of these peripheral microtubules; the cell profile also became some-what narrowed at the inner edge of the flexing colony. Cytoplasmic connections were large and numerous in young coenobia, but were generally absent in older vegetative colonies; by inversion, they had become confined to the chloroplast end of the cells where they seemed to act as hinges. Elements of the ER ran through these interconnections, possibly providing an intercellular communication network needed for the coordinated activity of inversion. A new structural feature was discovered in the form of circular (or possibly spiral) striations on the plasmalemma around these cytoplasmic connections. They were detectable just before inversion, and were most pronounced immediately after.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388045
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  • 9
    Electronic Resource
    Electronic Resource
    “Bristly” cristae in algal mitochondria (1971)
    Springer
    Planta 100 (1971), S. 357-359 
    Details
    ISSN: 1432-2048
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In forming zoospores of Oedogonium, mitochondria were found to contain numerous, evenly-spaced bristle-like structures projecting from the surface of cristae.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385200
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  • 10
    Electronic Resource
    Electronic Resource
    Ultrastructural localization of polysaccharides in the motile diatomNavicula cuspidata (1982)
    Springer
    Protoplasma 113 (1982), S. 10-22 
    Details
    ISSN: 1615-6102
    Keywords: Diatom ; Motility ; Mucopolysaccharide ; Secretion ; Staining ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Generation of movement in benthic diatoms is thought to be intimately associated with secretion at the raphe, a slit in the silica cell wall. The presence and distribution of extracellular substances and their source was investigated cytochemically by transmission electron microscopy. Extracellular material, possibly-acid mucopolysaccharide, was observed consistently within the entire length of the raphe of both valves and also as a sheath enveloping the silica frustule. Such quantities of extracellular material are absent in conventionally fixed motile diatoms. Numerous cytoplasmic vesicles, with fibrillar contents, distributed peripherally but concentrated along the raphe and at the cell poles, react strongly with a polysaccharide specific stain; their distribution in the cell and polysaccharide content suggest these may be the source of raphe and sheath material. Results support the most recent theories on the mechanism of locomotion in outline only; the details cannot be clarified. Localization procedures using alcian blue and silver staining of peroxidised sections are discussed briefly.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01283035
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