Technical Note

A measure of endosomal pH by flow cytometry in Dictyostelium

Anna Marchetti , Emmanuelle Lelong and Pierre Cosson

Dpt for Cell Physiology and Metabolism University of Geneva, Faculty of Medicine Centre Médical Universitaire, 1. rue Michel Servet, CH1211, Geneva 4, Switzerland

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BMC Research Notes 2009, 2:7doi:10.1186/1756-0500-2-7

Published:	12 January 2009

Abstract

Background

Dictyostelium amoebae are frequently used to study the organization and function of the endocytic pathway, and specific protocols are essential to measure the dynamics of endocytic compartments and their internal pH.

Findings

We have revisited these classical protocols to measure more accurately endosomal pH, making use of a fluorescent probe (Oregon green) more adequate for very acidic pH values. This pH-sensitive probe was combined with a pH-insensitive marker, in order to visualize simultaneously endosome dynamics and pH changes. Finally, a flow cytometer was used to measure endosomal pH in individual cells.

Conclusion

Using these simple protocols the endosomal pH of endocytic compartments can be assessed accurately, revealing the extreme acidity of Dictyostelium lysosomes (pH <3.5).