Re: Must the GFP gene be induced or does the gene remain in an organism ?

Dear Traci, 

From the question, it seems that you have not understood transgenic mice 
at all. Basicly, if the gene is introduced into the germ line, the whole 
mouse glows (i.e. all cells), depending on the promoter. The question is 
thus : is the promoter active in all cell lines ? Something like SV40 or 
CMV would be active in almost all cell types. Now, provided it is stably 
introduced, there should be no loss as individual cells reproduce, and 
the promoter should stay active over time.
Theoretically, once a mouse glows, it should glow all its life, and it 
should have FLK (normally FLK = funny looking kids, but this time 
Fluorescent Kids)
If you have not made a stable line, but injected GFP after provoked a 
muscle injury, then I would be surprised that ALL the mouse glows, and 
even if yes, you might probably have loss of fluorescence over time...

Hope that helps

Regards,