Plasmalemma: The Seat of Dual Mechanisms of Ion Absorption in Chlorella pyrenoidosa.

Dual mechanisms of absorption of rubidium were demonstrated in a nonvacuolate unicellular alga, Chlorella pyrenoidosa, in both the light and the dark. The two mechanisms were sensitive to metabolic inhibitors. At high concentrations rubidium enhanced the respiration of Chlorella cells. The findings support the conclusion that the mechanisms of rubidium absorption in both the low and high concentration ranges are active processes and reside in the plasmalemma.