I my personal experience, using co-expression of similar or identical GFP-
or dsRed-fusion proteins and analysis in a standard UV-microscope with
filter sets for blue (485 nm) or green (530 nm) excitation, i found a very
nice signal by the dsRFP using the filter for "red" dyes. The dsRed signal
induced by "blue" light is detectable but significantly weaker, with a
significant higher background (probably due to autofluorescence). The dsRed
gave a higher resolution picture (e.g. for the "spotted" expression of
cytokine receptors on the cell surface) with lower background compared to
the corresponding GFP-constructs.
Up to now i just have been looking on living cells in culture media and
can´t say anything about the signals in fixed cells.
Hope this helped you a bit,
Dr. H. Fehr
Inst. Physiological Chemistry II
University of Wuerzburg
fehr at biozentrum.uni-wuerzburg.de