[Influence of low positive temperatures on osmotic water permeability and activity of plasmalemma aquaporins in a pea root tip]
2009
Zhestkova, I.M. | Ampilogova, Ya.N. | Shevyreva, T.A. | Trofimova, M.S., Russian Academy of Sciences, Moscow (Russian Federation). The K.A. Timiryazev Institute of Plant Physiology
Plasmalemma osmotic water permeability (POWP) was studied. The one was isolated from etiolated 7-day pea (Pisum sativum L., the variety Orlovchanin) seedlings, which were grown at optimal temperature or exposed to a daily cooling by 18 deg C. The roots were homogenized in the medium containing SH-reagents or inhibitors of protein phosphatases for isolating the plasmalemma. Plasmalemma vesicules were received from a microsomal fraction by the method of separation in the 2-staged polymer system. Their speed of compression served as a parameter of POWP. POWP increased at lowering of growing temperature; it was not a result of aquaporin content increase and permeability raise of lipid matrix of membranes. The membranes of the cooled seedlings contained significantly less sulfhydrylic groups and their amount did not increase under reducer of thiol-3-butyl-phosphines in contrast to the ones of untreated seedlings. POWP of control seedling cells rose up if there was dichlorodiphenyltrichloroethane (DDT) and phenilarsin oxide (an inhibitor of thyrosine protein phosphatases) in the medium of homogenization. Different mechanisms of regulation aquaporin POWP are hypotized for optimal and unfavorable conditions. In the 1 case it can be based on a direct action of SH-redox-regulators and in the 2 cases it can be based on indirect proteinphosphatase action.
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