Change in the actin cytoskeleton during seismonastic movement of Mimosa pudica.
The seismonastic movement of Mimosa pudica is triggered by a sudden loss of turgor pressure. In the present study, we compared the cell cytoskeleton by immunofluorescence analysis before and after movement, and the effects of actin- and microtubule-targeted drugs were examined by injecting them into the cut pulvinus. We found that fragmentation of actin filaments and microtubules occurs during bending, although the actin cytoskeleton, but not the microtubules, was involved in regulation of the movement. Transmission electron microscopy revealed that actin cables became loose after the bending. We injected phosphatase inhibitors into the severed pulvinus to examine the effects of such inhibitors on the actin cytoskeleton. We found that changes in actin isoforms, fragmentation of actin filaments and the bending movement were all inhibited after injection of a tyrosine phosphatase inhibitor. We thus propose that the phosphorylation status of actin at tyrosine residues affects the dynamic reorganization of actin filaments and causes seismonastic movement.
Department of Chemistry, Faculty of Science and Technology, Sophia University, Tokyo, 102-8554 Japan. n-kanza@sophia.ac.jp
Nobuyuki
N
Kanzawa
Yoshinori
Y
Hoshino
Makiko
M
Chiba
Daisuke
D
Hoshino
Hidetaka
H
Kobayashi
Naomi
N
Kamasawa
Yoshiro
Y
Kishi
Masako
M
Osumi
Masazumi
M
Sameshima
Takahide
T
Tsuchiya
D000199:Actins / Q000032:analysis* / Q000187:drug effects / Q000502:physiology; D001549:Benzamides / Q000494:pharmacology; D003078:Colchicine / Q000494:pharmacology; D003080:Cold Temperature; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D046529:Microscopy, Electron, Transmission; D008870:Microtubules / Q000187:drug effects / Q000502:physiology / Q000648:ultrastructure; D031298:Mimosa / Q000502:physiology*; D009068:Movement; D017239:Paclitaxel / Q000494:pharmacology; D010590:Phalloidine / Q000494:pharmacology; D010766:Phosphorylation; D010812:Physical Stimulation; D018515:Plant Leaves / Q000502:physiology* / Q000648:ultrastructure; D017027:Protein Tyrosine Phosphatases / Q000378:metabolism; D018516:Pulvinus / Q000187:drug effects / Q000502:physiology
D000199:Actins; D001549:Benzamides; D004791:Enzyme Inhibitors; D010590:Phalloidine; D015638:Cytochalasin D; C001059:pronamide; D017027:Protein Tyrosine Phosphatases; D017239:Paclitaxel; D003078:Colchicine