Flourescent fading GFP

[claude selitrennikoff]

Has anyone ever observed GFP bleaching in certain organisms?
I am expressing GFP in a fungus and I have noticed that the GFP is
fading under extended UV exposure.  This occurs very quickly when I put
on a microscope slide, which I presume is due to lack of oxygen.
However, it occurs more slowly when I leave the microscope slide off.
As far as I can tell, the bleaching is irreversible.

My guess is that the chromophore formation is slightly altered in this
fungus, and the result is a lower stability.
Any suggestions?
Dr. S. Canada