Influence of Turgor Pressure Manipulation on Plasmalemma Transport of HCO3− and OH− in Chara corallina

Abstract

A modified version of the osmotic shock technique was used to investigate HCO₃⁻ and OH⁻ transport in the alga Chara corallina. Cell turgor was brought close to zero and then restored. When turgor was reduced to near the plasmolytic point using an osmoticum, little effect was observed on H¹⁴CO₃⁻ assimilation and OH⁻ transport. However, when turgor was recovered in these cells, there was a large reduction in HCO₃⁻ and OH⁻ transport activity. In contrast, when cells were air-dried to zero turgor, and rewetted to restore turgor, no significant effect on OH⁻ transport was observed. The effect of plasmolysis was also studied. When Chara cells were plasmolyzed, in most cases, all OH⁻ transport activity was lost and acidification was observed along the cell surface. None of the above treatments had any long term effect on cyclosis. These results are discussed with respect to present concepts of turgorinduced changes in membrane functions.