%0 Journal Article %A Iijima, Norio %A Maeda, Yasuo %T The influence of pH on the choice between sexual and asexual development in Dictyostelium mucoroides %D 1990 %J Microbiology, %V 136 %N 9 %P 1739-1745 %@ 1465-2080 %R https://doi.org/10.1099/00221287-136-9-1739 %I Microbiology Society, %X The cellular slime mould Dictyostelium mucoroides exhibits clear dimorphism in development which, depending upon environmental conditions, leads to (1) macrocyst formation, a sexual process or (2) sorocarp formation, an asexual process. The present work was undertaken to determine the role of protons in the determination of the developmental mode. Intracellular pH (pHi) was measured at the single-cell level microfluorometrically by use of the pH-sensitive fluorescent dye carboxyfluorescein. The proton-pump inhibitor diethylstilboestrol, the protonophore 2,4-dinitrophenol and a weak acid, propionate, were found to convert the developmental mode from macrocyst to sorocarp formation under conditions otherwise favouring macrocyst formation. All of these drugs lowered pHi. Although no significant difference in pHi was detected between dissociated cells shaken in buffers of pH 50 and pH 70, a marked difference in pHi arose between the two if 5 mm-NH4Cl was included to simulate the expected microenvironment in the cell mass during development. Comparison of the pHi of cells developing toward sorocarps with that of cells developing toward macrocysts revealed a few cells with extremely high pHi (>730) in the latter population. The results obtained suggested that pHi or something related to pHi, influences the developmental choice. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-136-9-1739