title: Behavior of plant plasma membranes under hydrostatic pressure as monitored by fluorescent environment-sensitive probes.
abstract: We monitored the behavior of plasma membrane (PM) isolated from tobacco cells (BY-2) under hydrostatic pressures up to 3.5kbar at 30 degrees C, by steady-state fluorescence spectroscopy using the newly introduced environment-sensitive probe F2N12S and also Laurdan and di-4-ANEPPDHQ. The consequences of sterol depletion by methyl-beta-cyclodextrin were also studied. We found that application of hydrostatic pressure led to a marked decrease of hydration as probed by F2N12S and to an increase of the generalized polarization excitation (GPex) of Laurdan. We observed that the hydration effect of sterol depletion was maximal between 1 and 1.5 kbar but was much less important at higher pressures (above 2 kbar) where both parameters reached a plateau value. The presence of a highly dehydrated gel state, insensitive to the sterol content, was thus proposed above 2.5 kbar. However, the F2N12S polarity parameter and the di-4-ANEPPDHQ intensity ratio showed strong effect on sterol depletion, even at very high pressures (2.5-3.5 kbar), and supported the ability of sterols to modify the electrostatic properties of membrane, notably its dipole potential, in a highly dehydrated gel phase. We thus suggested that BY-2 PM undergoes a complex phase behavior in response to the hydrostatic pressure and we also emphasized the role of phytosterols to regulate the effects of high hydrostatic pressure on plant PM.
authors.affiliation: Laboratoire Plantes-Microbe-Environnement, UMR INRA 1088/CNRS 5184/Université de Bourgogne, Dijon, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Roche
authors.forename: Andrey S
authors.initials: AS
authors.lastname: Klymchenko
authors.forename: Patricia
authors.initials: P
authors.lastname: Gerbeau-Pissot
authors.forename: Patrick
authors.initials: P
authors.lastname: Gervais
authors.forename: Yves
authors.initials: Y
authors.lastname: Mély
authors.forename: Françoise
authors.initials: F
authors.lastname: Simon-Plas
authors.forename: Jean-Marie
authors.initials: JM
authors.lastname: Perrier-Cornet
mesh_terms: D015081:2-Naphthylamine / Q000031:analogs & derivatives; D002460:Cell Line; D002462:Cell Membrane / Q000737:chemistry* / Q000187:drug effects / Q000378:metabolism*; D005454:Fluorescence Polarization; D005456:Fluorescent Dyes; D006874:Hydrostatic Pressure; D007848:Laurates; D044367:Phase Transition; D010840:Phytosterols / Q000378:metabolism; D011726:Pyridinium Compounds; D013050:Spectrometry, Fluorescence; D055672:Static Electricity; D014026:Nicotiana / Q000737:chemistry* / Q000166:cytology / Q000378:metabolism*; D047392:beta-Cyclodextrins / Q000494:pharmacology
chemical_list: D005456:Fluorescent Dyes; D007848:Laurates; D010840:Phytosterols; D011726:Pyridinium Compounds; D047392:beta-Cyclodextrins; C541550:di-4-ANEPPDHQ; C108732:methyl-beta-cyclodextrin; D015081:2-Naphthylamine; C065580:laurdan