Related Experiment Video
Updated: Aug 23, 2026

Measuring the Osmotic Water Permeability Coefficient (Pf) of Spherical Cells: Isolated Plant Protoplasts as an Example
Published on: October 8, 2014
Novel regulation of aquaporins during osmotic stress
Rosario Vera-Estrella1, Bronwyn J Barkla, Hans J Bohnert
1Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de Mexico, Cuernavaca, Morelos 62250, Mexico. rosario@ibt.unam.mx
Abstract:
Aquaporin protein regulation and redistribution in response to osmotic stress was investigated. Ice plant (Mesembryanthemum crystallinum) McTIP1;2 (McMIPF) mediated water flux when expressed in Xenopus leavis oocytes. Mannitol-induced water imbalance resulted in increased protein amounts in tonoplast fractions and a shift in protein distribution to other membrane fractions, suggesting aquaporin relocalization. Indirect immunofluorescence labeling also supports a change in membrane distribution for McTIP1;2 and the appearance of a unique compartment where McTIP1;2 is expressed. Mannitol-induced redistribution of McTIP1;2 was arrested by pretreatment with brefeldin A, wortmannin, and cytochalasin D, inhibitors of vesicle trafficking-related processes. Evidence suggests a role for glycosylation and involvement of a cAMP-dependent signaling pathway in McTIP1;2 redistribution. McTIP1;2 redistribution to endosomal compartments may be part of a homeostatic process to restore and maintain cellular osmolarity under osmotic-stress conditions.
Related Concept Videos
Aquaporins
Osmoregulation in Fishes
Osmosis
Water, like other substances, moves from a high concentration of free water...
Osmosis
Regulation of Transpiration by Stomata
Factors Influencing Microbial Growth: Osmolarity

