Increasing Cytoplasmic fluorescence

Hector Nolla hector at
Thu Nov 7 13:19:55 EST 1996

Dear Walter,
This may be only a coincidence but what you described is similar to the
"intracellular" fluorescence intensity drift that we sometimes get from
DNA stains like Hoechst and PI. In our case, fluorescence intensity can
either go up or down(most of the time it goes up), skewing the
fluorescence peak and thus increasing CV's, which can be a real "bummer"
if you intent to do cell cycle analysis. This fluorescence intensity drift
can be reduced if we let the sample equilibrate in the sample tubing(by
either running the sample for 30 seconds to 1 min, or by stopping sample
flow thus allowing the sample to remain in the sample tubing).

My best definition for this phenomena is "sample tubing equilibration",
however, this is only "hearsay". Maybe someone out there could shed some
"specific light" as to why this happens? Thanks.

Hector Nolla
Department of Oceanography
University of Hawaii 

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