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  • 1
    Electronic Resource
    Electronic Resource
    Calcium and Plant Development (1985)
    Palo Alto, Calif. : Annual Reviews
    Annual Review of Plant Physiology 36 (1985), S. 397-439 
    Details
    ISSN: 0066-4294
    Source: Annual Reviews Electronic Back Volume Collection 1932-2001ff
    Topics: Biology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1146/annurev.pp.36.060185.002145
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  • 2
    Electronic Resource
    Electronic Resource
    Changes in dye coupling of stomatal cells of Allium and Commelina demonstrated by microinjection of Lucifer yellow (1985)
    Springer
    Planta 164 (1985), S. 473-479 
    Details
    ISSN: 1432-2048
    Keywords: Allium (stomatal cells) ; Commelina ; Dye coupling ; Guard cell ; Lucifer yellow ; Plasmodesma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Lucifer yellow has been microinjected into stomatal cells of Allium cepa L. epidermal slices and Commelina communis L. epidermal peels and the symplastic spread of dye to neighboring cells monitored by fluorescence microscopy. Dye does not move out of injected mature guard cells, nor does it spread into the guard cells when adjacent epidermal or subsidiary cells are injected. Dye does spread from injected subsidiary cells to other subsidiary cells. These results are consistent with the reported absence of plasmodesmata in the walls of mature guard cells. Microinjection was also used to ascertain when dye coupling ceases during stomatal differentiation in Allium. Dye rapidly moves into and out of guard mother cells and young guard cells. Hovewer, dye movement ceases midway through development as the guard cells begin to swell but well before a pore first opens. Since plasmodesmata are still present at this stage, the loss of symplastic transport may result from changes in these structures well in advance of their actual disappearance from the guard cell wall.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00395962
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  • 3
    Electronic Resource
    Electronic Resource
    Ultrastructure of freeze-substitutedFrankia strain HFPCcI 3, the actinomycete isolated from root nodules ofCasuarina cunninghamiana (1985)
    Springer
    Protoplasma 127 (1985), S. 64-72 
    Details
    ISSN: 1615-6102
    Keywords: Actinomycete ; Casuarina ; Frankia ; Freeze-substitution ; Quick-freezing ; Ultrastructure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Frankia strain HFPCcI 3 is an actinomycete isolated from root nodules ofCasuarina cunninghamiana. In culture it exhibits typicalFrankia morphology and may produce three distinct morphological forms: branching septate hyphae, terminal or intercalary sporangia, and specialized structures termed vesicles which are the purported site of nitrogenase activity. An examination of the ultrastructure of all three morphological forms using both conventional chemical fixation (CF) and quick-freezing followed by freeze-substitution (FS) reveals some interesting differences between the two fixation methods. Unique to FS material are: 1. smooth membrane profiles; 2. lack of mesosomes; 3. lack of discernible nucleoid regions with condensed chromatin; 4. clarity of cytoplasmic elements such as ribosomes and granular bodies; 5. large cytoplasmic tubules in hyphae and young sporangia; 6. outer wall layer not widely separated from the spherical portion of the vesicle, and 7. bundles of microfilaments in vesicles. The quality of preservation after FS appears to be far superior to that obtained with CF. Accordingly the structures observed after FS are thought to represent more faithfully the structure of the living cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273702
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  • 4
    Electronic Resource
    Electronic Resource
    A method for rapid freeze fixation of plant cells (1986)
    Springer
    Protoplasma 131 (1986), S. 153-165 
    Details
    ISSN: 1615-6102
    Keywords: Freeze substitution ; Hafnium tetrachloride ; Plant cell ultrastructure ; Rapid freeze fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We describe here an apparatus that permits rapid freeze fixation of whole cells, which are then prepared by freeze substitution and resin embedment for examination in the EM. The freezing device utilizes a rotary solenoid that rapidly plunges the specimen holder, a formvar-film-covered thin wire loop, into a well of stirred liquid propane at −180
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01285037
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  • 5
    Electronic Resource
    Electronic Resource
    Immunogold labelling of actin on sections of freeze-substituted plant cells (1989)
    Springer
    Protoplasma 150 (1989), S. 72-74 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Cytoskeleton ; Freeze substitution ; Hyperbaric freezer ; Microfilaments ; Rapid freeze fixation ; Immunogold localization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We have successfully combined the superior ultrastructural preservation capabilities of rapid freeze fixation and freeze substitution (RF-FS) with immunogold antibody localization techniques to label microfilament (MF) bundles with monoclonal antibody to actin in two different plant tissues:Nicotiana pollen tubes andDrosera tentacles. We have thus verified that the extensive MF bundles seen in these cells after RF-FS are composed of actin, a protein that is difficult to preserve by conventional fixation methods for electron microscopy.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01352922
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  • 6
    Electronic Resource
    Electronic Resource
    Caffeine inhibition of cytokinesis: Dynamics of cell plate formation-deformationin vivo (1985)
    Springer
    Protoplasma 129 (1985), S. 28-35 
    Details
    ISSN: 1615-6102
    Keywords: Caffeine ; Cell Plate Formation ; Cytokinesis ; Tradescantia
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The effect of caffeine on cell plate formation inTradescantia stamen hair cells has been studiedin vivo using Nomarski differential interference contrast microscopy. It is well known that caffeine is a potent inhibitor of cell plate formation. Direct examination of drug-treated cells reveals that the cell plate always arises and grows centrifugally until almost complete. Up to this point drug-treated cells are indistinguishable from controls. However in the presence of caffeine the plate never reaches completion but rather appears to melt away until no refractile structure remains. Even after cells have been cultured for 24 hours in caffeine a cell plate always arises only to subsequently break down. Studies on the time of caffeine action show that within minutes before the onset of cell plate formation, the drug efficiently reaches the target site. This effect is partially reversible by washing out the caffeine with HEPES/KCl buffer, however the time required for the cell plate to reach completion is prolonged and in some instances the plate appears to be fragmented. Adenosine is also partially effective in reversing the caffeine inhibition of cell plate formation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282302
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  • 7
    Electronic Resource
    Electronic Resource
    Bud formation inFunaria: Organelle redistribution following cytokinin treatment (1986)
    Springer
    Protoplasma 131 (1986), S. 211-223 
    Details
    ISSN: 1615-6102
    Keywords: Bud formation ; Cytokinin ; Funaria ; Morphometry ; Polarity ; Tip growth
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cytokinin stimulates caulonemata ofFunaria to undergo an asymmetric division leading to the gametophore. The earliest detectable event is a small protuberance at the distal portion of the cell accompanied by the reorganization of the underlying organelles into a polarized distribution reminiscent of a tip growing cell. Dictyosomes and associated vesicles accumulate in the protuberance directly beneath the plasma membrane with mitochondria subjacent to the vesicular layer. Endoplasmic reticulum lies beneath the mitochondrial zone directly above the large central vacuole, while chloroplasts are outside the bud. As development continues the bud elongates causing the outer cell wall to exfoliate. During the above events the nucleus migrates toward the bud site concomitant with an increase in the number of microtubules between the nucleus and the base of the outgrowth. Nucleoli, extruded from the nucleus during a previous division, persist as diffuse fragments within the protuberance. Upon reaching the bud site, division occurs with the developing phragmoplast being initiated distal to the caulonema tip cell. The former polarized distribution of the cytoplasm is altered as mitochondria, chloroplasts and small vacuoles become evenly dispersed throughout the cytoplasm; dicytosomes and endoplasmic reticulum occupy a cortical position. These events indicate a change from 2-D tip growth to 3-D diffuse growth. To quantify the ultrastructural changes associated with bud formation we performed a morphometric analysis of cells in various stages of budding. The relative volumes of dictyosomes and vesicles adjacent to the bud apex decrease during bud development coincident with an increase in these organelles in lower portions of the cytoplasm. Mitochondria and chloroplasts follow this same pattern although their highest relative volumes initially are 4 μm from the bud apex and outside the bud site, respectively. These data, as well as density profile topographic maps for vesicle fractions, support the contention that cytokinin induces a change in morphological symmetry and polarity in the fine structure ofFunaria.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01282984
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  • 8
    Electronic Resource
    Electronic Resource
    Ultrastructure of the cytoskeleton in freeze-substituted pollen tubes ofNicotiana alata (1987)
    Springer
    Protoplasma 140 (1987), S. 141-150 
    Details
    ISSN: 1615-6102
    Keywords: Cytoskeleton ; Freeze substitution ; Nicotiana ; Pollen tubes ; Rapid freeze fixation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The ultrastructure of the cytoskeleton inNicotiana alata pollen tubes grownin vitro has been examined after rapid freeze fixation and freeze substitution (RF-FS). Whereas cytoplasmic microtubules (MTs) and especially microfilaments (MFs) are infrequently observed after conventional chemical fixation, they occur in all samples prepared by RF-FS. Cortical MTs are oriented parallel to the long axis of the pollen tube and usually appear evenly spaced around the circumference of the cell. They are always observed with other components in a structural complex that includes the following: 1. a system of MFs, in which individual elements are aligned along the sides of the MTs and crossbridged to them; 2. a system of cooriented tubular endoplasmic reticulum (ER) lying beneath the MTs, and 3. the plasma membrane (PM) to which the MTs appear to be extensively linked. The cortical cytoskeleton is thus structurally complex, and contains elements such as MFs and ER that must be considered together with the MTs in any attempt to elucidate cytoskeletal function. MTs are also observed within the vegetative cytoplasm either singly or in small groups. Observations reveal that some of these may be closely associated with the envelope of the vegetative nucleus. MTs of the generative cell, in contrast to those of the vegetative cytoplasm, occur tightly clustered in bundles and show extensive cross-bridging. These bundles, especially in the distal tail of the generative cell, are markedly undulated. MFs are observed commonly in the cytoplasm of the vegetative cell. They occur in bundles oriented predominantly parallel to the pollen tube axis. Although proof is not provided, we suggest that they are composed of actin and are responsible for generating the vigorous cytoplasmic streaming characteristic of living pollen tubes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01273723
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