Changes in cytoplasmic pH are involved in the cell type regulation of Dictyostelium

Abstract

The cytoplasmic pH (pH_i) of populations of developing Dictyostelium discoideum cells was determined by means of two independent pH null-point methods. Both methods reveal in populations containing 75–80% prespore cells a pH_i value of about 0.2 pH units higher than in populations containing 50% prespore cells. During the process of cell type regulation, decreases and increases in the percentage of prespore cells of about 15–20% are accompanied by decreases and increases in pH_i of about 0.2 pH units. Abolition of these changes in pH_i by means of a weak base or acid also prevents the regulation process. It is concluded that changes in pH_i are involved in the prespore cell type regulation in D. discoideum.