The process of acidification of the external medium after addition of glucose and subsequently of KCl to a suspension of yeast cells varies substantially from species to species. After glucose it is most pronounced in Saccharomyces cerevisiae and Schizosaccharomyces pombe but is very much lower in Lodderomyces elongisporus, Dipodascus magnusii and Rhodotorula gracilis. Both the buffering capacity and the varied effects of vanadate, suloctidil and erythrosin B indicate that the acidification is by about one-half due to the activity of plasma membrane H(+)-ATPase and by about one-half to the extrusion of acidic metabolites from cells. This is supported by the finding that a respiratory quotient greater than one (in various strains of S. cerevisiae and in S. pombe) is indicative of a greater buffering capacity and overall acidification of the medium. Taking into account the virtually negligible buffering capacity of the medium in the pH range where the effect of K+ is observed, the effect of K+ is generally of a similar magnitude as that of adding glucose. It is clearly dependent on (anaerobic) production of metabolic energy, quite distinct from the dependence of the H(+)-ATPase-caused acidification.

• MeSH
• Biological Transport MeSH
• Potassium pharmacology   MeSH
• Erythrosine pharmacology   MeSH
• Glucose pharmacology   MeSH
• Cations, Monovalent pharmacology   MeSH
• Acids metabolism   MeSH
• Proton-Translocating ATPases metabolism   MeSH
• Saccharomycetales drug effects   metabolism   MeSH
• Oxygen Consumption MeSH
• Suloctidil pharmacology   MeSH
• Vanadates pharmacology   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• Potassium MeSH
• Erythrosine MeSH
• Glucose MeSH
• Cations, Monovalent MeSH
• Acids MeSH
• Proton-Translocating ATPases MeSH
• Suloctidil MeSH
• Vanadates MeSH

The widely used fluorescent probe 2',7'-bis-(2-carboxyethyl)-5(6)-carboxyfluorescein (BCECF) serves as a pH-sensitive indicator in classical microscopy. Characteristics of BCECF were studied and a way of employing the probe in a confocal laser scanning microscope equipped with an argon laser at 488 nm was developed, based on the fact that the emission fluorescence spectra are pH-dependent with spectral maximum shift from 518 to 529 nm. Optical filters for the dual-emission ratio method were set to 506 and 529 nm. pH values measured inside a single cell of Saccharomyces cerevisiae were similar to those obtained with other pH estimation methods.

• MeSH
• Argon MeSH
• Fluoresceins * MeSH
• Fluorescent Dyes * MeSH
• Spectrometry, Fluorescence MeSH
• Intracellular Fluid metabolism   MeSH
• Hydrogen-Ion Concentration MeSH
• Microscopy, Confocal methods   MeSH
• Lasers MeSH
• Flow Cytometry methods   MeSH
• Saccharomyces cerevisiae metabolism   MeSH
• Publication type
• Journal Article MeSH
• Research Support, Non-U.S. Gov't MeSH
• Comparative Study MeSH
• Names of Substances
• 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein MeSH Browser
• Argon MeSH
• Fluoresceins * MeSH
• Fluorescent Dyes * MeSH