Open AccessDecreased endo‐lysosomal acidification capacity in methylene diphosphonate‐resistant mutants of Dictyostelium discoideum
Author(s) -
Brénot Françoise,
Satre Michel
Publication year - 1993
Publication title -
fems microbiology letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.899
H-Index - 151
eISSN - 1574-6968
pISSN - 0378-1097
DOI - 10.1111/j.1574-6968.1993.tb06135.x
Subject(s) - acridine orange , dictyostelium discoideum , nigericin , chemistry , mutant , biochemistry , bafilomycin , biophysics , fluorescence , microbiology and biotechnology , biology , membrane , apoptosis , physics , quantum mechanics , gene , autophagy
The in vivo capacity for endo‐lysosomal acidification has been monitored in Dictyostelium discoideum amoebae with acridine orange, a fluorescent weak base dye commonly used to probe transmembrane pH gradients. In the presence of aerobic amoebae, the initial rate of fluorescence quenching was found to be proportional to cell density between 5 × 10 5 and 2.5 × 10 6 cells ml −1 and independent of acridine orange concentration in the 1.5 to 7.5 μM range. The dye response was sensitive to agents that perturb endo‐lysosomal acidification such as NaN 3 , nigericin or imidazole. Several mutant cell lines whose growth was resistant to methylene diphosphonate were found to be partially deficient in the acridine orange quenching test, suggesting that endo‐lysosomal acidification was altered in these mutants.