Colonies of E. coli expressing wild type dsFP483 (wt) or its mutant N68S/I112S (mut) as viewed by fluorescence microscopy. (A) - using FITC filter set. (B) - using TRITC filter set. Colony expressing the wild type protein possesses only green fluorescence. In contrast, colony expressing the mutant protein is clearly visible in both filter set due to dual color (green and red) fluorescence of dsFP483-N68 S/I112S.