This is in reply to the questions about GFP in yeast....I'm not sure
how to post a followup and so I'm posting a new message.
I work with GFP in S. pombe and have found that the best way to
look at them is to make a polylysine slide and overlay the cells with
fluorenscence mounting media containing antifade. The fluorescence is
well defined, bright and fade resistant (and *green*).
One of the nice things about GFP is that you don't necessarily need to
fix the cells. Sounds like the formaldehyde is definitely quenching
I hope this helps...