J Integr Plant Biol. ›› 1999, Vol. 41 ›› Issue (2): -.

• Research Articles •    

Influence of Osmotic Stress on the Lipid Physical States of Plasma Membranes from Wheat Roots

QIU Quan-Sheng   

Abstract: The plasma membrane vesicles were purified from wheat ( Triticum sativum L. ) roots by the two phase partitioning method. The results showed that with the increase in sucrose concentrations, light scattering was decreased, diphenyl hexatriene (DPH) polarization and merocyanine 540 (MC540) fluorescence intensity increased, indicating that under osmotic stress the vesicles were getting smaller, the membrane fluidity and surface charge density were decreased. Further experiments showed that the long lifetime and average lifetime of DPH fluorescence decreased under stress, suggesting that plasma membrane hydrophobicity decreased. The long lifetime fluorescence of intrinsic tryptophan was also decreased, indicating that the polarity of the microenvironment surrounding the tryptophan was increased, i.e. protein conformation changed; It was also found that the H + -ATPase activity decreased with the increase in sucrose concentrations, suggesting that the membrane protein function was also affected by the physical state under osmotic stress.

Key words: Wheat roots, Plasma membranes, Physical state, Osmotic stress

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