Hi Brian... We too have seen this phenomenon with phenotype-specific 7-AAD cell cycle analysis, even with PE surface labeling - the presence of 7-AAD appears to diminish the intensity of the PE signal. Quenching due to energy transfer never seemed like a viable explanation to me for the reduced surface labeling, although it might play into your intracellular labeling problem. The only way we were able to partially correct the problem was to reduce the 7-AAD to as low a concentration as possible that still gave good DNA histograms. We were able to use 7-AAD at 5 - 10 ug/ml and still get reasonable DNA CVs. Take care, Bill Telford NCI-NIH At 03:02 PM 1/28/2002 -0600, Newsom, Brian S. wrote: >Question to all of you DNA experts. We have someone who is tring to run an >experiment staining a nuclear localized protien with PE and then staining >with 7-AAD. The 7-AAD staining works well with a good CV. The antibody >staining looks decent (although low percentage and fairly dim) when by >itself, but when the 7-AAD is added the antibody staining totally goes away. >Is there an energy transfer or steric hinderance issue that may be going on? >Any help appreciated. > >Brian
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