title: Early membrane events induced by salicylic acid in motor cells of the Mimosa pudica pulvinus.
abstract: Salicylic acid (o-hydroxy benzoic acid) (SA) induced a rapid dose-dependent membrane hyperpolarization (within seconds) and a modification of the proton secretion (within minutes) of Mimosa pudica pulvinar cells at concentrations higher than 0.1mM. Observations on plasma membrane vesicles isolated from pulvinar tissues showed that SA acted directly at the membrane level through a protonophore action as suggested by the inhibition of the proton gradient and the lack of effect on H(+)-ATPase catalytic activity. Comparative data obtained with protonophores (carbonylcyanide-m-chlorophenylhydrazone and 2,4-dinitrophenol) and inhibitors of ATPases (vanadate, N,N'-dicyclohexylcarbodiimide, and diethylstilbestrol) corroborated this conclusion. Consequently, the collapse of the proton motive force led to an impairment in membrane functioning. This impairment is illustrated by the inhibition of the ion-driven turgor-mediated seismonastic reaction of the pulvinus following SA treatment. SA acted in a specific manner as its biosynthetic precursor benzoic acid induced much milder effects and the m- and p-OH benzoic acid derivatives did not trigger similar characteristic effects. Therefore, SA may be considered both a membrane signal molecule and a metabolic effector following its uptake in the cells.
authors.affiliation: Laboratoire Physiologie Moléculaire du Transport des Sucres, Université de Poitiers, EBI UMR CNRS 7267, 3 rue Jacques Fort, F-86022 Poitiers cedex, France.
authors.forename: Saed
authors.initials: S
authors.lastname: Saeedi
authors.forename: Françoise
authors.initials: F
authors.lastname: Rocher
authors.forename: Janine
authors.initials: J
authors.lastname: Bonmort
authors.forename: Pierrette
authors.initials: P
authors.lastname: Fleurat-Lessard
authors.forename: Gabriel
authors.initials: G
authors.lastname: Roblin
mesh_terms: D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism*; D031298:Mimosa / Q000187:drug effects* / Q000378:metabolism*; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism; D018516:Pulvinus / Q000187:drug effects* / Q000378:metabolism*; D020156:Salicylic Acid / Q000494:pharmacology*
chemical_list: D006180:Proton-Translocating ATPases; D020156:Salicylic Acid