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  • 1
    Electronic Resource
    Electronic Resource
    Calmodulin and wound healing in the coenocytic green alga Ernodesmis verticillata (Kützing) Børgesen (1991)
    Springer
    Planta 183 (1991), S. 281-293 
    Details
    ISSN: 1432-2048
    Keywords: Actin ; Calmodulin ; Ernodesmis ; Microfilament ; Microtubule ; Tubulin ; Wound healing (alga)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The involvement of calmodulin (CaM) in wound-induced cytoplasmic contractions in E. verticillata was investigated. Indirect immunofluorescence of CaM in intact cells showed a faint, reticulate pattern of fluorescence in the cortical cytoplasm. Diffuse fluorescence was evident deeper within the cytoplasm. In contracted cells, CaM co-localizes with actin in the cortical cytoplasm in extensive, longitudinal bundles of microfilaments (MFs), and in an actin-containing reticulum. No association of CaM with tubulin was ever observed in the cortical cytoplasm at any stage of wound-healing. When contraction rates in wounded cells are measured, a lag period of 2 min is followed by a rapid, steady rate of movement over the subsequent 10 min. The delay in the initiation of longitudinal contraction corresponds to the time necessary for the assembly of the longitudinal MF bundles. Cytoplasmic motility was inhibited in a dose-dependent manner by CaM antagonists. In these inhibited cells, MF bundles did not assemble, or were poorly formed. In the latter case, CaM was always found associated with MFs. These results indicate a direct spatial and temporal correlation between CaM and actin, and a potential role for CaM in regulating the formation of functional MF bundles during wound-induced cytoplasmic contraction in Ernodesmis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00197800
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  • 2
    Electronic Resource
    Electronic Resource
    Calmodulin and wound healing in the coenocytic green alga Ernodesmis verticillata (Kützing) Børgesen: Ultrastructure of the cortical cytoskeleton and immunogold labeling (1991)
    Springer
    Planta 186 (1991), S. 17-26 
    Details
    ISSN: 1432-2048
    Keywords: Actin ; Calmodulin ; Ernodesmis ; Membrane skeleton ; Microfilaments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Ultrastructural changes in the cortical cytoskeleton during wound-induced cytoplasmic contraction were examined in the coenocytic green alga Ernodesmis verticillata. Both calmodulin (CaM) and actin were localized in intact and contracting cells by immunogold labeling. Within 5 min after wounding, compact microfilament (MF) bundles were observed which increase in diameter as cytoplasmic contraction proceeds. Calmodulin labeling is associated with amorphous material studding the MF bundles, whereas actin labeling occurs along the individual MFs. No MF bundles were ever observed during contraction that were not also labeled with anti-CaM antibodies. In cells treated with the CaM antagonist W-7 (N-[6-aminohexyl]-5-chloro-1-naphtha-lenesulfonamide), MF bundles do not form, and the formation of loosely arranged MFs (similar to nascent bundles in untreated cells) is greatly retarded. We propose that CaM binds indirectly to actin by activating an actin-binding regulatory protein which functions in early stages of the transduction sequence leading to functional MF bundles. Additionally, ultrastructural evidence is presented for a plasma-membrane skeleton or undercoating in this alga.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00201493
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  • 3
    Electronic Resource
    Electronic Resource
    Novel changes in the plasma membrane and cortical cytoplasm during wound-induced contraction in a giant-celled green alga (1993)
    Springer
    Protoplasma 176 (1993), S. 75-83 
    Details
    ISSN: 1615-6102
    Keywords: Alga ; Actin ; Calmodulin ; Ernodesmis ; Membrane recycling ; Microfilaments
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Changes in the plasma membrane surface and in the cortical cytoplasm during wound healing in giant green algal cells ofErnodesmis verticillata (Kützing) Bφrgesen were followed using scanning and transmission electron microscopy. Microvillus-like structures that contain cytoplasmic and cytoskeletal constituents were observed emanating from the surface of the plasma membrane at the retracting/cut end of wounded cells. These delicate structures seem to be remnants of cell wall-plasmalemma connections that draw out the plasma membrane and cortical components from the contracting cytoplasm as it pulls away from the cell wall. Most of these connections break during wound healing and, when contraction stops, the microvillus-like protrusions become progressively shorter. In cells treated with a calmodulin antagonist (W-7), a number of distinctive bodies accumulate that are of unknown composition, are oblong in shape, and have a diameter slightly smaller than the protoplasmic protrusions. Ultrastructural and other data indicate that these bodies result from retrieved constituents of the plasma-membrane protrusions, as they do not accumulate in unwounded drugtreated cells or in cells treated in W-5. These findings suggest that the protoplasmic protrusions accumulate membrane and cytoplasmic components that are retrieved and recycled during wound healing inErnodesmis by a novel mechanism. The combined plasma membrane surfaces of the microvillus-like protrusions may help to account for the drastic decrease in surface area that occurs during wound healing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01378941
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