Abstract

We have tested the efficacy of fluorescent probes for the measurement of intracellular pH in Saccharomyces cerevisiae. Of the compounds tested (fluorescein, carboxyseminaphtorrhodafluor-1 (C.SNARF-1) and 2′,7′bis(carboxyethyl)-5(6′)-carboxyfluorescein), C.SNARF-1 was found to be the most useful indicator of internal pH. Fluorescence microscopy showed that in Saccharomyces cerevisiae strain DAUL1, C.SNARF-1 and fluorescein had a heterogeneous distribution, with dye throughout the cytoplasm and concentration of the dye to an area close to the cell.membrane. This region was also labeled by quinacrine, which is known to accumulate in acidic regions of the cell. Saccharomyces cerevisiae BJ4932, which carries a defect in vacuolar acidification, did not show the same degree of dye concentration, suggesting that the site of C.SNARF-1 and fluorescein localisation in DAUL1 is the acidic vacuole. Changes in intracellular pH could be monitored by measuring changes in the fluorescence intensity of C.SNARF-1. The addition of glucose caused an initial, rapid decrease in fluorescence intensity, indicating a rise in cellular pH. This was followed by slow acidification. Fluorescence intensity changes were similar in all strains studied, suggesting that the localisation of dye to acidic regions does not affect the measurement of intracellular pH in DAUL1. The changes in intracellular pH on the addition of glucose correlated well with glucose-induced changes in external pH. Preincubation of cells in the presence of the plasma membrane H+-ATPase inhibitor diethylstilbestrol reduced extracellular acidification and intracellular alkalinisation on the addition of glucose. Both amiloride and 5-(N-ethyl-N-isopropyl)amiloride also inhibited glucose-induced proton fluxes. Phorbol 12-myristate 13-acetate had no effect on the activity of the plasma membrane ATPase.

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.