FLUORESCENT MEASUREMENT OF THE INTRACELLULAR PH DURING SPORULATION OFSACCHAROMYCES-CEREVISIAE

This work reports the intracellular pH (pH(i)) dynamics of Saccharomyc es cerevisiae cells in sporulation medium. Cells loaded with the pH-se nsitive dye carboxy-seminaphthorhodafluor-1 (C.SNARF-1) exhibited an a lkalization of the pH(i) following the extracellular pH during sporula tion in the absence of buffer and almost no change in pH(i) or Delta p H when sporulation was carried out in buffered medium. The results ind icate that the pH gradient does not appear to be directly involved in the regulation of acetate uptake during sporulation. However, the alka lization of pH(i) by eliciting a decrease in metabolic fluxes could ac count for a lower demand for acetate.