ISSN:
1615-6102
Keywords:
F-actin
;
Plasma membrane
;
Cell wall
;
Calcium
;
Hydrogen
;
Peptide RGD
;
Tip growth
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Summary Membrane-wall adhesions in zygotes of the brown algaPelvetia were visualized following plasmolysis. Strands of cytoplasm remained firmly attached to the cell wall at discrete adhesion sites during plasmolysis. Adhesion sites were uniformly distributed in ungerminated zygotes, but were concentrated in the apical 5 μm of the elongating rhizoid in germinated zygotes. Few adhesions were detected along the flanks of the rhizoid or in the thallus region of germinated zygotes. The structure, physiology and function of apical adhesions in the rhizoid were characterized. F-actin was found at adhesion sites in plasmolyzed zygotes labeled with rhodamine phalloidin, and disruption of cortical F-actin reduced the number of adhesions. Manipulation of cytosolic H+ and Ca2+ activities also disrupted adhesions. On the extracellular surface, the number of adhesions was reduced by inhibition of cellulose synthesis, protease cleavage of wall proteins, and changes in extracellular H+ and Ca2+ activities. Chronic treatment with the synthetic peptide RGDS, which prevents cell adhesion in fibroblasts, also reduced adhesion number. The number of adhesions per cell did not correlate with growth rate, but was inversely correlated with the ability to establish new rhizoid growth sites. The results indicate that membrane wall adhesions containing F-actin on the cytoplasmic face are localized in the growing rhizoid apex. The adhesions may be structurally related to focal adhesions in animal cells.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01281193
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