Ion Fluxes in Bacteria
Howard Shapiro (hms@shapirolab.com)
Wed, 6 Sep 1995 20:29:54 -0400
Geoff Osborne asks about measuring ion fluxes in bacteria...I and many other
people have measured membrane potential, which reflects sodium and (mostly)
potassium fluxes, variously using cyanine and oxonol dyes and rhodamine 123.
In principle, one ought to be able to use calcium probes such as indo-1 and
pH indicators such as BCECF or the SNARF dyes, although I don't recall
seeing any papers on flow cytometry of bacteria using these dyes. The
lipophilic dyes and AM esters will not readily get into Gram-negative
bacteria because of the impermeability of the outer membrane; this can be
overcome using a buffer containing EDTA, which permeabilizes the membrane
while preserving cell viability at least long enough to detect effects of
stimuli.
--Howard
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