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  • 1
    Electronic Resource
    Electronic Resource
    The microtubular cytoskeleton during development of the zygote, proemhryo and free-nuclear endosperm in Arabidopsis thaliana (L.) Heynh (1991)
    Springer
    Planta 184 (1991), S. 187-195 
    Details
    ISSN: 1432-2048
    Keywords: Arabidopsis (Cytoskeleton in proembryogenesis) ; Cytoskeleton ; Endosperm (free-nuclear) ; Microtubule ; Preprophase band ; Proembryo ; Zygote
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The microtubular cytoskeleton has been studied during development of the zygote, proembryo and free-nuclear endosperm in A. thaliana using immunofluorescence localization of tubulin in enzymatically isolated material. Abundant micro tubules (MTs) are found throughout proembryogenesis. Microtubules in the coenocytic endosperm are mainly internal. By contrast, there is a re-orientation of MTs to a transverse cortical distribution during zygote development, predominantly in a subapical band which accompanies a phase of apical extension. The presence of these cortical arrays coincides with the elongation of the zygote. Cortical arrays also accompany elongation of the cylindrical suspensor. Extensive networks of MTs ramify throughout the cytoplasm of cells in the proembryo proper. Perinuclear arrays are detected in a number of cell types and MTs contribute to typical mitotic configurations during nuclear divisions. Preprophase bands of MTs are absent throughout megasporogenesis and embryo-sac development and do not occur in endosperm cell divisions. We have observed MTs throughout the first division cycle of the zygote. By placing the observed stages in a most probable sequence, we have identified this cell cycle as the point during embryogenesis at which a preprophase band is reinstated as a regular feature of cell division. Preprophase bands were observed to predict planes of cytokinesis in cell divisions up to the octant stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197947
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  • 2
    Electronic Resource
    Electronic Resource
    The microtubular cytoskeleton during development of the zygote, proembryo and free-nuclear endosperm inArabidopsis thaliana (L.) Heynh (1991)
    Springer
    Planta 184 (1991), S. 187-195 
    Details
    ISSN: 1432-2048
    Keywords: Arabidopsis (Cytoskeleton in proembryogenesis) ; Cytoskeleton ; Endosperm (free-nuclear) ; Microtubule ; Preprophase band ; Proembryo ; Zygote
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The microtubular cytoskeleton has been studied during development of the zygote, proembryo and free-nuclear endosperm inA. thaliana using immunofluorescence localization of tubulin in enzymatically isolated material. Abundant micro tubules (MTs) are found throughout proembryogenesis. Microtubules in the coenocytic endosperm are mainly internal. By contrast, there is a re-orientation of MTs to a transverse cortical distribution during zygote development, predominantly in a subapical band which accompanies a phase of apical extension. The presence of these cortical arrays coincides with the elongation of the zygote. Cortical arrays also accompany elongation of the cylindrical suspensor. Extensive networks of MTs ramify throughout the cytoplasm of cells in the proembryo proper. Perinuclear arrays are detected in a number of cell types and MTs contribute to typical mitotic configurations during nuclear divisions. Preprophase bands of MTs are absent throughout megasporogenesis and embryo-sac development and do not occur in endosperm cell divisions. We have observed MTs throughout the first division cycle of the zygote. By placing the observed stages in a most probable sequence, we have identified this cell cycle as the point during embryogenesis at which a preprophase band is reinstated as a regular feature of cell division. Preprophase bands were observed to predict planes of cytokinesis in cell divisions up to the octant stage.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01102418
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  • 3
    Electronic Resource
    Electronic Resource
    Embryo sac development in Arabidopsis thaliana (1990)
    Springer
    Sexual plant reproduction 3 (1990), S. 244-256 
    Details
    ISSN: 1432-2145
    Keywords: Arabidopsis ; Megasporogenesis ; Microtubular cytoskeleton ; Megaspore tetrad ; Megasporocyte
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Aspects of megasporogenesis in Arabidopsis thaliana have been investigated using a variety of histochemical techniques to visualize general cell organization, DNA and callose in whole ovules and sections by bright field, fluorescence, differential interference contrast and scanning electron microscopy. The microtubular cytoskeleton has been studied using immunofluorescence localization of tubulin in sections and whole cells. The observations deviate from reports of preceding studies in that the megasporocyte was found to undergo both meiotic divisions followed by simultaneous cytokinesis (i.e. without an intermediate dyad stage) to give a multiplanar tetrad of megaspores. This represents a variation of monosporic development not previously described. Polarized distribution of organelles prior to meiosis ensures that the functional megaspore receives the largest share. Aberrant wall formation is common between degenerating megaspores. Localized callose deposition in the tetrad separates these cells from the active megaspore. Their pattern of degeneration and displacement is extremely flexible within the embryo sac space. The microtubular cytoskeleton is extensive and largely cytoplasmic, as distinct from cortical, throughout megasporogenesis. In the megasporocyte, megaspores and one-nucleate embryo sac, randomly oriented microtubules throughout the cells may serve to maintain cytoplasmic integrity and position organelles. Numerous microtubules (MTs) associate closely with the nucleus and some radiate from it, perhaps functioning in nuclear positioning. During meiosis MTs are restricted to the spindle configurations and later to the phragmoplasts which form between daughter nuclei. The lack of interphase cortical arrays suggests that the role of internal influences on cell shape is small.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00202882
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  • 4
    Electronic Resource
    Electronic Resource
    Embryo sac development in Arabidopsis thaliana II. The cytoskeleton during megagametogenesis (1994)
    Springer
    Sexual plant reproduction 7 (1994), S. 153-163 
    Details
    ISSN: 1432-2145
    Keywords: Arabidopsis thaliana ; Megagametogenesis Cytoskeleton ; Microtubules ; Actin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The microtubular and actin cytoskeletons have been investigated during megagametogenesis in Arabidopsis thaliana using immunofluorescence labelling of isolated coenocytic and mature embryo sacs. We found both actin and microtubules (MTs) to occur in abundance throughout megagametogenesis and in all constituent cells of the mature embryo sac. During many stages, the patterns of distribution of these cytoskeletal elements are congruent and may prove to be co-aligned. Many changes in the arrays of MTs and microfilaments take place and indicate varying roles of the cytoskeleton in the different stages and cell types of megagametogenesis. Two major populations of MTs recur throughout embryo sac formation: (1) Elaborate nuclear-based networks are found during the two-nucleate and four-nucleate developmental stages as well as in the egg cell. These arrays may function in positioning the nuclei. (2) Cytoplasmic MTs in longitudinal orientation in the two-nucleate embryo sac, synergids and part of the egg cell, or in a reticulate pattern in the four-nucleate embryo sac, egg and central cell probably participate in organization of the cytoplasm. Synergid MTs converge at the filiform apparatus. Preprophase bands of MTs are absent throughout megagametogenesis but phragmoplast arrays occur during cellularization of the embryo sac. Well developed arrays of cortical MTs are restricted to the antipodal cells. A large concentration of MTs in the part of the egg cell adjacent to the synergids is well placed for being involved with sperm cell movement within the degenerative synergid. On the basis of the morphology of the cytoskeleton, we concur with views that the shape of megagametophyte is largely determined by the surrounding tissues, including the integumentary tapetum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00228488
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  • 5
    Electronic Resource
    Electronic Resource
    Reorganization of cortical actin microfilaments and microtubules at preprophase and mitosis in wheat root-tip cells: A double label immunofluorescence study (1990)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 15 (1990), S. 76-87 
    Details
    ISSN: 0886-1544
    Keywords: antiactin ; cytochalasin B ; plant cytoskeleton ; tubulin ; oryzalin ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Following our recent description [McCurdy et al.: Protoplasma. 147:204-206, 1988] of arrays of transverse cortical microfilaments (MFs) in preprophase roottip cells of wheat (Triticum aestivum L. cv. Kite), we have performed double label immunofluorescence microscopy to correlate the formation of these arrays with the known rearrangement of cortical microtubules (MTs) that occurs during preprophase. At early preprophase, indicated by a broad (i.e., young) preprophase band (PPB) of MTs, actin MFs are transverse only in the central region of the cell cortex. By late preprophase, however, cells that possess a mature (i.e., narrow) PPB of MTs have arrays of transverse MFs that occupy the entire cortical surface of the cell. Thus, apart from the PPB zone, the transverse MFs in these arrays do not colocalize with transverse cortical MTs. Depolymerization of MTs using the herbicide oryzalin does not effect the arrays of cortical MFs; however, experiments using cytochalasin B in combination with oryzalin indicate that cellular MTs are necessary for the formation of the arrays of transverse cortical MFs. The arrays of cortical MFs disintegrate during prophase into short fragments of random, filamentous actin. This situation persists until the completion of cytokinesis. The absence of MFs during mitosis in densely-cytoplasmic meristematic cells of wheat root tips indicates that filamentous actin may not have a universal function in plant cell division. The possible function of the arrays of cortical MFs in preprophase cells is discussed.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970150204
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  • 6
    Electronic Resource
    Electronic Resource
    Effect of cytochalasins on actin in dividing root tip cells of Allium and Triticum: A comparative immunocytochemical study (1991)
    New York, NY : Wiley-Blackwell
    Cell Motility and the Cytoskeleton 18 (1991), S. 107-112 
    Details
    ISSN: 0886-1544
    Keywords: cell division ; cytoskeleton ; root cell ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A collaborative effort was initiated to resolve differences in two recent papers on the effects of cytochalasins in root cells. While both studies reported similar effects on interphase cells (i.e., replacement of microfilaments by many small specks and rods), Palevitz (Cell Motil. Cytoskeleton 9:283-298, 1988) maintained that cytochalasins B and D induce actin aggregation at the poles of dividing Allium root cells at a concentration of 10 μM with rhodamine phalloidin as a reporter probe, whereas McCurdy and Gunning (Cell Motil. Cytoskeleton 15:76-87, 1990) could not find these aggregates following antiactin immunocytochemistry in Triticum roots treated with CB at 50 μM. Employing identical methods and materials in the same laboratory, we found that CD induces polar actin aggregates in dividing cells of both species. However, the aggregates in Triticum are smaller and occur less frequently than those in Allium. A similar pattern is seen with CB.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/cm.970180205
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  • 7
    Electronic Resource
    Electronic Resource
    Immunofluorescent localization of cytoskeletal tubulin and actin during spermatogenesis inPteridium aquilinum (L.) Kuhn (1986)
    Springer
    Protoplasma 134 (1986), S. 163-177 
    Details
    ISSN: 1615-6102
    Keywords: Actin ; Microtubule ; Basal body ; Flagella ; Blepharoplast ; Immunofluorescence ; Microtubule ribbon ; Pteridium spermatogenesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Details concerning the appearance and behaviour of blepharoplasts during spermatogenesis, and the assembly of the cytoskeletal motile apparatus of spermatids were elucidated by immunofluorescence microscopy using antibodies to tubulin and actin, applied to material prepared from antheridia of the fernPteridium aquilinum (L.) Kuhn. Blepharoplast immunofluorescence with antitubulin first appears as spheres at the future spindle poles prior to the last spermatogenous division. Developing spermatids each have one blepharoplast, which gives rise to a triangular layer corresponding to the incipient microtubule ribbon. Compared to the ribbon, immunoreactivity of the multilayered structure is relatively weak. Intensely fluorescing basal bodies appear, increase in number, and become arranged in rows along two edges of the microtubule ribbon as it widens and elongates. Along the dorsal edge is a dense file of basal bodies spaced at about 0.3 μm intervals, parallel to each other and oriented at 145° to the multilayered structure. This spacing and orientation is maintained throughout spermatid development. Basal bodies at the opposite edge are initially oriented at 115° to the multilayered structure but become rearranged into small groups that rotate so that the angle is reduced to 55–70° by the time the assembly of flagella commences on both sets of basal bodies. By this stage the microtubule ribbon has encircled about 2/3 of the nuclear circumference and the nucleus is assuming a crescent shape. In fully developed spermatozoids the groups of basal bodies are oriented at 25° to the multilayered structure, parallel to the long body of the now helical nucleus. Immunofluorescence using antiactin showed that towards the completion of nuclear shaping, actin forms a strip along the helical multilayered structure. Detergent-extraction of mature spermatozoids revealed that actin is associated also with the flagellar band, particularly with basal bodies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01275715
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  • 8
    Electronic Resource
    Electronic Resource
    Field emission scanning electron microscopy of microtubule arrays in higher plant cells (1996)
    Springer
    Protoplasma 195 (1996), S. 168-182 
    Details
    ISSN: 1615-6102
    Keywords: Field emission scanning microscopy ; High resolution scanning electron microscopy ; Microtubules ; Anti-tubulin ; Immunolabelling ; Tobacco ; Onion root tips
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Specimen preparation protocols that allow field emission scanning electron microscope imaging of microtubules in plant cells were developed, involving simultaneous permeabilization with saponin and stabilization of microtubules with taxol. All categories of microtubule array were observed in onion root tip cells and in tobacco BY-2 cells grown in suspension culture and synchronized to provide high frequencies of mitotic stages. Cortical arrays consist of overlapping microtubules with free ends; individual microtubules directly overlie individual microfibrils in the cell wall. Preprophase bands and spindle microtubule bundles were also imaged. Phragmoplasts revealed early stages of wall deposition in the included cell plates and features interpreted as relating to high rates of microtubule turnover at the growing margins. It was possible to combine high resolution three-dimensional imaging with immunogold labelling of microtubules. Individual gold particles were readily distinguished decorating microtubules in the preparations; the method should be vaulable for studying many features of plant cell microtubules and their associated macromolecules.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01279195
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  • 9
    Electronic Resource
    Electronic Resource
    Confocal fluorescence microscopy of plant cells (1998)
    Springer
    Protoplasma 201 (1998), S. 121-157 
    Details
    ISSN: 1615-6102
    Keywords: Confocal laser scanning microscopy ; Cytoskeleton ; Fluorescence microscopy ; Fluorescent dyes ; Optical sectioning ; Plant cell structure ; Z-axis resolution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The confocal laser scanning microscope (CLSM) has become a vital instrument for the examination of subcellular structure, especially in fluorescently stained cells. Because of its ability to markedly reduce out-of-focus flare, when compared to the conventional wide-field fluorescence microscope, the CLSM provides a substantial improvement in resolution along the “z” axis and permits optical sectioning of cells. These developments have been particularly helpful for the investigation of plant cells and tissues, which because of their shape, size, and optical properties have been difficult to analyze at high resolution by conventional means. We review the contribution that the CLSM has made to the study of plant cells. We first consider the principle of operation of the CLSM, including a discussion of image processing, and of lasers and appropriate fluorescent dyes. We then summarize several studies of both fixed and live plant cells in which the instrument has provided new or much clearer information about cellular substructure than has been possible heretofore. Attention is given to the visualization of different components, including especially the cytoskeleton, endomembranes, nuclear components, and relevant ions, and their changes in relationship to physiological and developmental processes. We conclude with an effort to anticipate advances in technology that will improve and extend the performance of the CLSM. In addition to the usual bibliography, we provide internet addresses for information about the CLSM.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01287411
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  • 10
    Electronic Resource
    Electronic Resource
    Actin in living and fixed characean internodal cells: identification of a cortical array of fine actin strands and chloroplast actin rings (1996)
    Springer
    Protoplasma 190 (1996), S. 25-38 
    Details
    ISSN: 1615-6102
    Keywords: Chara ; F-actin ; Immunofluorescence ; Microtubule ; Nitella ; Phalloidin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary We report on the novel features of the actin cytoskeleton and its development in characean internodal cells. Images obtained by confocal laser scanning microscopy after microinjection of living cells with fluorescent derivatives of F-actin-specific phallotoxins, and by modified immunofluorescence methods using fixed cells, were mutually confirmatory at all stages of internodal cell growth. The microinjection method allowed capture of 3-dimensional images of high quality even though photobleaching and apparent loss of the probes through degradation and uptake into the vacuole made it difficult to record phallotoxin-labelled actin over long periods of time. When injected at appropriate concentrations, phallotoxins affected neither the rate of cytoplasmic streaming nor the long-term viability of cells. Recently formed internodal cells have relatively disorganized actin bundles that become oriented in the subcortical cytoplasm approximately parallel to the newly established long axis and traverse the cell through transvacuolar strands. In older cells with central vacuoles not traversed by cytoplasmic strands, subcortical bundles are organized in parallel groups that associate closely with stationary chloroplasts, now in files. The parallel arrangement and continuity of actin bundles is maintained where they pass round nodal regions of the cell, even in the absence of chloroplast files. This study reports on two novel structural features of the characean internodal actin cytoskeleton: a distinct array of actin strands near the plasma membrane that is oriented transversely during cell growth and rings of actin around the chloroplasts bordering the neutral line, the zone that separates opposing flows of endoplasm.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01281192
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