They also were marked with a unique design that could only be viewed under ultraviolet light. (si.com)
He used compounds that change under ultraviolet light, such as the light from the sun. (sciencenewsforstudents.org)
The target fragment binds to a gene switch in the DNA, which triggers the production of a colourful substance such as the protein that gives jellyfish a green glow under ultraviolet light, or proteins from bacteria that produce colour changes visible to the naked eye. (newscientist.com)