Journal Article

Rhizoid Differentiation in <i>Spirogyra</i>: Position Sensing by Terminal Cells

Naoko Inoue, Shin-ya Yamada, Yoko Nagata and Teruo Shimmen

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 43, issue 5, pages 479-483
Published in print May 2002 | ISSN: 0032-0781
Published online May 2002 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcf056
Rhizoid Differentiation in Spirogyra: Position Sensing by Terminal Cells

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Some species of Spirogyra anchor themselves to the substrate by differentiating rhizoids. A rhizoid is differentiated only from the terminal cell, suggesting that this cell can recognize its terminal position in a filament. In the present study, we have analyzed the mechanism for position sensing by the terminal cell. When a filament is cut, a new cell occupies the terminal position, and three phenomena are induced: (1) the cell wall of the cut cell detaches from the new terminal cell; (2) adhesive material is secreted by the terminal cell; and (3) the terminal cell begins to differentiate a rhizoid via tip growth. All of these phenomena were inhibited by adding sorbitol to the external medium, suggesting that turgor pressure is involved in position sensing by the terminal cell. The inhibition by sorbitol was reversible. Upon cutting a filament, the distal end of a new terminal cell became convex. However, when a filament was cut in the presence of sorbitol, the distal end of a new terminal cell became less convex. Either treatment with Gd3+ or decrease in extracellular Ca2+ resulted in inhibition of all these phenomena, suggesting possible involvement of stretch-activated ion channel in position sensing by terminal cells.

Keywords: Key words: Calcium — Rhizoid — Spirogyra — Stretch-activated channel.; Abbreviations: APW, artificial pond water; [Ca2+], Ca2+ concentration in the external medium; EGTA, ethylene glycol bis(β-aminoethyl ether)-N,N′-tetraacetic acid; FL-BSL, fluorescein-Bandeiraea (Griffonia) simplicifolia lectin; LBM, lectin-binding material; SA channel, stretch-activated channel.

Journal Article.  3129 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

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