Transient Increase in Intracellular pH during Dictyostelium Differentiation

The intracellular pH (pHi) of Dictyostelium discoideum amebae has been determined using the pH-dependent fluorescence of intracellularly trapped fluorescein. The pHi of cells measured 45-60 min after initiation of differentiation was between 6.2 and 6.3. At ∼2 h into differentiation cells underwent...

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Bibliographic Details
Published in:The Journal of cell biology 1984-11, Vol.99 (5), p.1883-1887
Main Authors: Jamieson, Gordon A., Frazier, William A., Schlesinger, Paul H.
Format: Article
Language:English
Subjects:
Amiloride - pharmacology
Biological and medical sciences
Cell cycle
Cell differentiation, maturation, development, hematopoiesis
Cell growth
Cell physiology
Cells
Cellular differentiation
Chemical suspensions
Dictyostelium - cytology
Dictyostelium - physiology
Fluoresceins
Fluorescence
Fundamental and applied biological sciences. Psychology
Gene expression regulation
Hepatocytes
Hydrogen-Ion Concentration
Intracellular Fluid
Molecular and cellular biology
Neurons
Protons
Rapid Communications
Sodium - metabolism
Spectrometry, Fluorescence
Swiss 3T3 cells
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Summary:The intracellular pH (pHi) of Dictyostelium discoideum amebae has been determined using the pH-dependent fluorescence of intracellularly trapped fluorescein. The pHi of cells measured 45-60 min after initiation of differentiation was between 6.2 and 6.3. At ∼2 h into differentiation cells underwent a transient intracellular alkalinization during which the pHi rose to 7.13 (± 0.3, n = 4), after which the pHi returned to approximately the original value (6.2-6.4). Cells that were removed from growth medium but were incubated in differentiation medium containing 3% dextrose did not exhibit this transient increase in pHi. The alkalinization event can also be prevented from occurring by differentiation in Na+-free solutions or by the addition of amiloride to sodium-containing buffer solutions, suggesting that the alkalinization is sodium dependent. When the alkalinization was prevented by amiloride treatment, cells did not progress normally into differentiation. This increase in pHi was initiated by the cells 2 h after removal from nutrient medium and it could be inhibited by several treatments that had been observed to delay the differentiation program, suggesting that it plays a major role in the initiation of the developmental program of this organism.
ISSN:0021-9525
1540-8140
DOI:10.1083/jcb.99.5.1883