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  • 1
    Electronic Resource
    Electronic Resource
    Effects of two chitin synthesis inhibitors on Thalassiosira fluviatilis and Cyclotella cryptica (1986)
    Oxford, UK : Blackwell Publishing Ltd
    FEMS microbiology letters 37 (1986), S. 0 
    Details
    ISSN: 1574-6968
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Abstract The effects of two commercial chitin synthesis inhibitors, dimilin and polyoxin D, on chitin fiber formation and cell sedimentation for the diatoms Thalassiosira fluviatilis and Cyclotella cryptica (Bacillariophyceae) were investigated. Dimilin treatments for both diatom species were indistinguishable from controls in terms of chitin fiber productions, cell density and sedimentation. Polyoxin D-treated cells of both diatom species completely lacked the characteristic chitin fibers. Polyoxin D cultures were also characterized by a significant decrease in population density, increased sedimentation rates and a strong tendency to clump in comparison with control and dimilin treatments. It was concluded that (1) dimilin does not directly inhibit chitin synthesis in diatoms; (2) polyoxin-D inhibits β-chitin fibril formation, and (3) chitin fibers play an important role in cell separation and cell buoyancy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1574-6968.1986.tb01806.x
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  • 2
    Electronic Resource
    Electronic Resource
    The plasma membrane of the Funaria caulonema tip cell: morphology and distribution of particle rosettes, and the kinetics of cellulose synthesis (1984)
    Springer
    Planta 160 (1984), S. 428-435 
    Details
    ISSN: 1432-2048
    Keywords: Caulonema ; Funaria (caulonema) ; Cellulose synthesis ; Polar growth ; Plasma membrane rosettes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Freeze-fracturing of Funaria hygrometrica caulonema cells leads to a cleavage within the plasma membrane. The extraplasmatic and the plasmatic fracture faces differ in their particle density. The plasmatic fracture face in caulonema tip cells or in tip cells of side branches, but never in other caulonema cells, is further characterized by the occurrence of particle rosettes. The highest density of rosettes is found at the cell apex but decreases steeply toward the cell base. The shape of the rosettes varies remarkably; 20% of them are found in an incomplete, presumably disintegrating or aggregating state. The complete rosette has a diameter of about 25 nm and consists of five to six particles. The size of the single particles varies between 4 nm to 10 nm. The rosettes are thought to posses cellulose-synthase activity. It is assumed that one rosette produces one elementary fibril; rough calculations, considering the number of rosettes and the estimated amount of cellulose produced in the tip region, indicate that an elementary fibrillar length of 900 nm is formed in 1 min by one rosette. The consequence of the kinetics on the life-time of the rosettes and the cellulose-synthase activity are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00429759
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  • 3
    Electronic Resource
    Electronic Resource
    Disoriented growth of pollen tubes of Lilium longiflorum Thunb. induced by prolonged treatment with the calcium-chelating antibiotic, chlorotetracycline (1982)
    Springer
    Planta 156 (1982), S. 218-225 
    Details
    ISSN: 1432-2048
    Keywords: Calcium, dynamics ; Chlorotetracycline ; Disorientation of growth ; Lilium ; Organelle distribution ; Pollen tube growth ; Tip growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Pollen of Lilium longiflorum Thunb. was germinated for 12 h in growth medium containing 1·10-4 M chlorotetracycline (CTC), or growing tubes were treated with 1·10-4 M CTC for up to 2 h. These treatments have drastic effects: In the CTC-containing medium, out-growing tubes form only short tubes. Irregular wall thickenings are visible. Thirty minutes CTC-treatment cause growing tubes to bend and grow back toward the grain. Electron micrographs of CTC-treated tubes show that CTC affects the organelle distribution: The polar zonation of organelles is disturbed. Vesicle-and endoplasmic reticulum-accumulations are found in the wrong places, together with extensive wall thickenings and a very irregular plasma membrane. The structural details of most cell organelles look normal after CTC treatment, but the mitochondria possess unusual cristae, and microtubules are absent. The disoriented growth is interpreted as an effect of the ability of CTC to chelate intracellular calcium ions, to bind them to membranes, and thus to disturb the dynamics of the delicate Ca2+-equilibria thought to regulate oriented exocytosis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393728
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  • 4
    Electronic Resource
    Electronic Resource
    Arrays of plasma-membrane “rosettes” involved in cellulose microfibril formation of Spirogyra (1983)
    Springer
    Planta 159 (1983), S. 347-356 
    Details
    ISSN: 1432-2048
    Keywords: Cellulose microfibril formation ; Plasma membrane rosettes ; Spirogyra (freeze fracture)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The cell-wall structure and plasma-membrane particle arrangement during cell wall formation of the filamentous chlorophycean alga Spirogyra sp. was investigated with the freeze-fracture technique. The cell wall consists of a thick outer slime layer and a multilayered inner wall with ribbon-like microfibrils. This inner wall shows three differing orientations of microfibrils: random orientation on its outside, followed by axial bundles of parallel microfibrils, and several internal layers of bands of mostly five to six parallel associated microfibrils with transverse to oblique orientation. The extraplasmatic fracture face of the plasma membrane shows microfibril imprints, relatively few particles, and “terminal complexes” arranged in a hexagonal package at the end of the imprint of a microfibril band. The plasmatic fracture face of the plasma membrane is rich in particles. In places, it reveals hexagonal arrays of “rosettes”. These rosettes are best demonstrable with the double-replica technique. These findings on rosette arrays of the zygnematacean alga Spirogyra are compared in detail with the published data on the desmidiacean algae Micrasterias and Closterium.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00393174
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  • 5
    Electronic Resource
    Electronic Resource
    Calcium gradients in tip growing plant cells visualized by chlorotetracycline fluorescence (1979)
    Springer
    Planta 146 (1979), S. 615-621 
    Details
    ISSN: 1432-2048
    Keywords: Ca2+ gradient ; Cells (tip growth) ; Chlorotetracycline-fluorescence ; Growth (tip) ; Tip growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract With chlorotetracycline (CTC)-fluorescence a tip-to-base Ca2+ gradient is visualized in all tested, tip-growing plant cells: pollen tubes of Lilium longiflorum, root hairs of Lepidium sativum, moss caulonema of Funaria hygrometrica, fungal hyphae of Achlya and in the alga Acetabularia mediterranea. The fluorescence gradients in the different species vary in intensity and extension. Sometimes a punctate mobile CTC-fluorescence, in the size range of mitochondria, is observed. Bursting cells lose their fluorescence rapidly, indicating a cytoplasmic localization of the gradient. Only in Acetabularia is the wall also fluorescent with CTC. The results are interpreted as evidence for a general role of a calcium gradient in tip growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00388841
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  • 6
    Electronic Resource
    Electronic Resource
    Development of membrane- and calcium-gradients during pollen germination of Lilium longiflorum (1985)
    Springer
    Planta 163 (1985), S. 84-90 
    Details
    ISSN: 1432-2048
    Keywords: Calcium ; Lilium ; Membrane distribution ; Pollen germination ; Proton microprobe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Chlorotetracyclin (10-4M) has been used to observe the distribution of membrane-associated calcium during pollen germination of Lilium longiflorum. For comparison, the general membrane distribution has been determined with 4·10-5 M fluorescamine. The pollen grains show a calcium gradient with either weak or strong chlorotetracycline-fluorescence intensity, but always increasing toward the germination colpus. This gradient intensifies during germination, reaching a maximum before the pollen tube emerges. The typical tip-to-base calcium gradient of the tube does not change during growth. Independent of the developmental stage, the pollen grains show a flat fluorescamine-fluorescence gradient with the highest intensity in one half of the grain. Pollen tubes reveal a tip-to-base membrane gradient, independent of their length. As an additional marker for membrane distribution, the distribution of phosphorus, measured by proton-induced X-ray emission in chemically fixed tubes, has been used. A tip-to-base phosphorus gradient, distinct from the calcium gradient measured with the same method, was detected.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00395901
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  • 7
    Electronic Resource
    Electronic Resource
    Chemical inhibition of cell wall formation and cytokinesis, but not of nuclear division, in protoplasts of Nicotiana tabacum L. cultivated in vitro (1978)
    Springer
    Planta 142 (1978), S. 253-262 
    Details
    ISSN: 1432-2048
    Keywords: Cell wall formation ; Cytokinesis ; Inhibitors ; Mitosis ; Nicotiana
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effect of cytochalasin B, colchicine, coumarin and 2,6-dichlorobenzonitrile on cell wall formation and cellular division was studied by light and electron microscopy with tobacco mesophyll protoplasts cultivated in vitro. 2,6-dichlorobenzonitrile was found to be the most effective and reversible inhibitor of cell wall formation. The other inhibitors caused irreversible damage and/or inhibited mitosis. In protoplasts cultivated in the presence of 2,6-dichlorobenzonitrile the total inhibition of cell wall formation had no effect on nuclear division, but cytokinesis was totally inhibited so that multinucleate protoplasts were obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385074
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  • 8
    Electronic Resource
    Electronic Resource
    Cytology of budding and cleavage in tobacco mesophyll protoplasts cultivated in saline medium (1978)
    Springer
    Planta 142 (1978), S. 11-21 
    Details
    ISSN: 1432-2048
    Keywords: Budding ; Cleavage ; Mesophyll ; Protoplasts ; Tobacco
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Tobacco (Nicotiana tabacum L., cv. Maryland) mesophyll protoplasts cultivated in saline medium divide by bud formation, migration of one nucleus into the bud, and subsequent furrowing. This process was investigated light and electron microscopically. The cytoplasm of the growing bud is richer in dictyosomes, rough endoplasmic reticulum profiles, mitochondria, and small vacuoles than is the cytoplasm of the mother cell, but in early stages lacks plastids. Only patches of wall material are found; most of the cell surface appears naked. Oriented sections of the cleavage furrow do not reveal a contractile ring of microfilaments under the fixation conditions used. The furrow is flanked by numerous microtubules, and is rich in coated vesicles. Nuclear division appears normal, but the phragmoplast vesicles appear empty, and the phragmoplast seems to disintegrate again later. The nucleus migrating into the bud does not show any signs of associated contractile structures. The results demonstrate that, in principle, higher plant cells are capable of a mode of division usually said to be “yeast-like”. The events of karyokinesis and cell plate formation are not therefore obligatorily linked processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385114
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  • 9
    Electronic Resource
    Electronic Resource
    Calcium ionophore A 23187 affects localized wall secretion in the tip region of pollen tubes of Lilium longiflorum (1979)
    Springer
    Planta 145 (1979), S. 225-232 
    Details
    ISSN: 1432-2048
    Keywords: Ca2+ gradient ; Disorientation of exocytosis ; Ionophore A23187 ; Lilium ; Pollen tubes ; Tip growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of the calcium inonophore A 23187 on growing pollen tubes of Lilium longiflorum Thunb. cv. Ace were investigated with the light and electron microscope. Tip growth is slowed down and stopped within 20 min after application of 5x10-5 M ionophore A 23187. The main effects are the disappearance of the clear zone at the pollen tube tip and a thickening of the cell wall at the tip and at the pollen tube flanks. This effect on cell wall formation is confirmed under the electron microscope: The vesicular zone in treated pollen tubes is reduced, numerous vesicular contents are irregularly integrated in the pollen tube wall not only in the tip, but over a long distance of the pollen tube wall. In addition, effects on mitochondria and dictyosomes are observed. These results are interpreted as a disorientation of the Ca2+-based orientation mechanism of exocytosis after equilibration of the Ca2+-gradient
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00454445
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  • 10
    Electronic Resource
    Electronic Resource
    Broad-range effects of ionophore X-537A on pollen tubes of Lilium longiflorum (1980)
    Springer
    Planta 147 (1980), S. 295-301 
    Details
    ISSN: 1432-2048
    Keywords: Cationophore X-537A ; Cell growth (tip) ; Ionophore X-537A ; Lilium ; Pollen tubes ; Tip growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The effects of the broad-range cationophore X-537A on pollen tubes of Lilium longiflorum were investigated, using both light and electron microscopy. Pollen tube growth is completely inhibited within 30 min after the application of 5·10-5 M ionophore X-537A; cytoplasmic streaming is stopped only after 60 min of ionophore treatment. Ultrastructurally, X-537A effects are a vacuolation of Golgi cisternae and a general vacuolation. The wall is thickened at the very tip. Coated vesicles and coated regions are enriched close to and at the plasma membrane. The results indicate that pollen tube tip growth needs a specific ion distribution.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379836
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