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Plant Physiol. 1999 Mar;119(3):885-96.

Osmotic water permeability of isolated protoplasts. Modifications during development

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  • 1Unite Propre de Recherches de l'Enseignement Superieur Associee Centre National de la Recherche Scientifique 6037, Universite de Rouen, Faculte des Sciences, 76821 Mont-Saint-Aignan cedex, France.


A transference chamber was developed to measure the osmotic water permeability coefficient (Pos) in protoplasts 40 to 120 μm in diameter. The protoplast was held by a micropipette and submitted to a steep osmotic gradient created in the transference chamber. Pos was derived from the changes in protoplast dimensions, as measured using a light microscope. Permeabilities were in the range 1 to 1000 μm s-1 for the various types of protoplasts tested. The precision for Pos was </=40%, and within this limit, no asymmetry in the water fluxes was observed. Measurements on protoplasts isolated from 2- to 5-d-old roots revealed a dramatic increase in Pos during root development. A shift in Pos from 10 to 500 μm s-1 occurred within less than 48 h. This phenomenon was found in maize (Zea mays), wheat (Triticum aestivum), and rape (Brassica napus) roots. These results show that early developmental processes modify water-transport properties of the plasma membrane, and that the transference chamber is adapted to the study of water-transport mechanisms in native membranes.

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