Osamu Shimomura, a scientist emeritus at the Marine Biological Laboratory, was named co-recipient of the 2008 Nobel Prize in Chemistry. The prize recognizes his pioneering work isolating what we now call the Green Flourescent Protein (GFP). After successfully isolating a glowing protein from a mollusc, Shimomura spent a summer cutting the light organs off of jellyfish and gathering what he poetically called "the squeezate" - literally, the liquid that he sqeezed out. After sqeezing thousands of the jellyfish Aequorea victoria, which were abundant around Friday Harbor Laboratory (where the work was done), he and his colleagues were able to purify a tiny amount of the luminescent blue photoprotein aequorin. Check out this animation to see how jellyfish use the two proteins (aequorin and GFP) to produce flashes of light! Many jellies can glow when they are disturbed, possibly as a way of avoiding predators.
Since GFP was cloned, it can and has been applied to all kinds of cells in plants and animals to examine, for example, how our genes are turned on and off, how diseased cells are different from healthy cells, and how animals develop. In the image to the left(source), you can see a worm whose nervous cells are all lit up with GFP. Now a routine tool that researchers employ, GFP has enabled major discoveries in cell physiology, neuroscience and cancer biology. It's also led to some pretty stunning images: check out the most beautiful brain pictures you've ever seen, and have a look at a glowing bunny art project.