photographing GFP

[dilip]

Hi:
When GFP came out as a reporter gene we were kind of excited and jumped 
in the band wagon in studying promoters isolated from plants using GFP. 
But to our dismay there were certain factors that you need to know 
before using GFP in your studies.
	1. In plant systems the original GFP will sometimes not work as 
expected due to cryptic splicing. (The original GFP contains higher 
percentage of A & T bases thus mimic an intron in plants - A modified 
GFP is now available in UK that takes care of this problem).
	2. The GFP is excited by blue light, which by the way also excite 
lignin in the vascular system and both show emission at green wave 
length. Therefore if you are studing promoters associated with vascular 
system you may be in for a surprise for green fluorescence you get from 
untransformed controls. (we were studing xylem related genes in plants- 
very unfortunate uh!).
	3. Since GFP is not an enzyme the signal you observe is not amplified 
as in GUS therefore if your expression system is not that good forget 
about the GFP. (Some times GUS carring Agrobacterium can be selected by 
GUS activity in the culture itself but this could not be done with GFP).

Hope these information will help you when you decide on a reporter gene 
since many commercial suppliers donot tell these things.

Dilip Dias
Dept. of Forest Science
Texas A & M University
Dilip at zeus.tamu.edu