ALUMINUM AND TEMPERATURE ALTERATION OF CELL-MEMBRANE PERMEABILITY OF QUERCUS-RUBRA

This report extends research on Al-induced changes in membrane behavior of intact root cortex cells of Northern red oak (Quercus rubra). Membrane permeability was determined by the plasmometric method for individual intact cells at temperatures from 2 or 4 to 35-degrees-C. Al (0.37 millimolar) significantly increased membrane permeability to urea and monoethyl urea and decreased permeability to water. Al significantly altered the activation energy required to transport water (+32%), urea (+9%), and monoethyl urea (-7%) across cell membranes. Above 9-degrees-C, Al increased the lipid partiality of the cell membranes; below 7-degrees-C, Al decreased it. Al narrowed by 6-degrees-C the temperature range over which plasmolysis occurred without membrane damage. These changes in membrane behavior are explainable if Al reduces membrane lipid fluidity and kink frequency and increases packing density and the occurrence of straight lipid chains.