The use of green fluorescent protein (GFP) from the jellyfish Aequorea Victoria to monitor gene expression both in situ and in vivo has grabbed the biotechnology spotlight since this application was reported almost four years ago (M. Chalfie et al., Science 263:802-805, 1994). Biologists could ask for no simpler tool; GFP's bright green fluorescence stems from its inherent chromophore structure and needs no substrate or cofactors, only exposure to UV or blue light. Along with wild-type GFP, several optimized mutants of this protein are on the market. This being the case, researchers in a variety of biological arenas are using this protein to study genes in numerous organisms, from bacteria and yeast to plants and animals. In November 1997, Universal Imaging Corporation released MetaGFP Version 3.0, a unique software package for the collection and analysis of images from GFP and multiprobe fluorescence experiments.
Co-localization of two fluorescent probes