In response to the question of Jaume Comas: Dyes of the YOYO, TOTO and SYTO
series (and perhaps others as well) are pretty lipophilic. As a result,
they may stain proteins and lipids in bacterial envelopes in addition to
staining of DNA and RNA. In the May 1996 issue of Applied and Environmental
Microbiology (vol. 62, pp. 1649-1455) an interesting paper on the these dyes
has been published.
In mammalian cells we found an appreciable amount of fluorescence in fixed
cells tretated exhaustively with DNase and RNaseA and then stained with
YOYO-1. We have not done such experiments with microorganisms. I feel that
it would be interesting to follow up on this observation.
People of Molecular Probes will be available at the upcoming ASM meeting to
discuss this matter with anybody interested.
Martin Poot