Green Fluorescent Protein (GFP) as a Reporter

Demonstration that Green Fluorescent Protein -- a bioluminescence-signaling protein from the jellyfish Aequorea victoria, with no natural function related to any human use -- can be expressed in a heterologous organism (E. coli, C. elegans) as a genetically encoded, non-invasive fluorescent reporter of gene expression, needing no substrate or cofactor unlike other bioluminescent systems. Chalfie, Tu, Euskirchen, Ward & Prasher, "Green Fluorescent Protein as a Marker for Gene Expression" (Science 263, 802-805, 1994-02-11, OpenAlex W2032579724, 6,785 citations). Built on Shimomura's original 1962 isolation of GFP and Prasher's 1992 cloning of the gene (a co-author on this paper). Chalfie, Shimomura and Tsien (who later engineered the color-variant palette) shared the 2008 Nobel Prize in Chemistry. Became a near-universal fluorescent reporter/imaging tag across modern molecular and cell biology and drug-discovery research -- a foundational R&D tool rather than a single product line.