title: Measuring the osmotic water permeability coefficient (Pf) of spherical cells: isolated plant protoplasts as an example.
abstract: Studying AQP regulation mechanisms is crucial for the understanding of water relations at both the cellular and the whole plant levels. Presented here is a simple and very efficient method for the determination of the osmotic water permeability coefficient (P(f)) in plant protoplasts, applicable in principle also to other spherical cells such as frog oocytes. The first step of the assay is the isolation of protoplasts from the plant tissue of interest by enzymatic digestion into a chamber with an appropriate isotonic solution. The second step consists of an osmotic challenge assay: protoplasts immobilized on the bottom of the chamber are submitted to a constant perfusion starting with an isotonic solution and followed by a hypotonic solution. The cell swelling is video recorded. In the third step, the images are processed offline to yield volume changes, and the time course of the volume changes is correlated with the time course of the change in osmolarity of the chamber perfusion medium, using a curve fitting procedure written in Matlab (the 'PfFit'), to yield P(f).
authors.affiliation: The RH Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem.
authors.forename: Arava
authors.initials: A
authors.lastname: Shatil-Cohen
authors.affiliation: The RH Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem.
authors.forename: Hadas
authors.initials: H
authors.lastname: Sibony
authors.affiliation: Earth and Life Institute, Université catholique de Louvain.
authors.forename: Xavier
authors.initials: X
authors.lastname: Draye
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain.
authors.forename: François
authors.initials: F
authors.lastname: Chaumont
authors.affiliation: The RH Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem; nava.moran@mail.huji.ac.il.
authors.forename: Nava
authors.initials: N
authors.lastname: Moran
authors.affiliation: The RH Smith Institute of Plant Sciences and Genetics in Agriculture, The Hebrew University of Jerusalem.
authors.forename: Menachem
authors.initials: M
authors.lastname: Moshelion
mesh_terms: D020346:Aquaporins / Q000378:metabolism; D017360:Arabidopsis / Q000378:metabolism*; D009997:Osmotic Pressure; D010539:Permeability; D010940:Plant Proteins / Q000378:metabolism; D011523:Protoplasts / Q000378:metabolism*; D014867:Water / Q000378:metabolism*
chemical_list: D020346:Aquaporins; D010940:Plant Proteins; D014867:Water