Jonathan Amos at the BBC:
Today, countless scientists use this knowledge to tag biological systems.
Glowing markers will show, for example, how brain cells develop or how cancer cells spread through tissue.
But their uses really have become legion: they are now even incorporated into bacteria to act as environmental biosensors in the presence of toxic materials.
Jellyfish will glow under blue and ultraviolet light because of a protein in their tissues. Scientists refer to it as green fluorescent protein, or GFP.
Shimomura made the first critical step, isolating GFP from a jellyfish (Aequorea victoria) found off the west coast of North America in 1962. He made the connection also with ultraviolet light.
Meanwhile in the 1990s, Chalfie demonstrated GFP’s value “as a luminous genetic tag”, as the Royal Swedish Academy of Sciences described it in the Nobel citation.