In reference to using an alternative to propidium iodide for DNA staining...you
 might try using PICO green (available from molecular probes) it works ok but h
as a tendancy to bleach faster than PI.  It fluoresces in the same wavelength r
ange as FITC.  You could use texas red, rhodamine or CY3 for your other antibod
y stain.  Hope this helps.  Andrew
 
Andrew Vaillant
University of Ottawa Centre for Confocal Microscopy