In message Ricky Critchert writes:
> I use an MRC 600 with a Kr\AR laser mainly for FISH. My problem occurs
> when I want to use 2 flourescently labelled probes eg FITC and Texas red
> as I can no longer use propidium iodide as a counter stain to visualize
> the chromosomes and end up with disembodied spots on the moniter. Does
> any one no of a third flourochrome that would give me 2 coloured signals
> and still allow for chromosome counterstaining(ie could I use Cy5)?
> Cheers.
 
FITC and Cy5 should be fine together on a 600.  Get the triple dichroic from
BioRad; if you don't move it when you switch fluorophores things should stay in
good registration.  I haven't run spectra on propidium iodide, but if it's like
ethidium bromide, it may show up slightly using a 505-535 nm FITC emission
filter.  However, it should be fine on the Cy5 filter.
 
Best of luck--
 
Martin Wessendorf