Two Americans and a Japanese researcher won the 2008 Nobel Prize in Chemistry for the discovery of a glowing jellyfish protein that makes cells, tissues and even organs light up -- a tool used by thousands of researchers around the world.

The 10 million Swedish crown ($1.4 million) prize recognises Japanese-born Osamu Shimomura, now of the Woods Hole Marine Biological Laboratory in Massachusetts, Martin Chalfie of Columbia University in New York and Roger Tsien of the University of California, San Diego, for their discoveries with green fluorescent protein.

"The remarkable brightly glowing green fluorescent protein, GFP, was first observed in the beautiful jellyfish, Aequorea victoria in 1962," the Nobel Committee for Chemistry at the Royal Swedish Academy of Sciences said in a statement.

"Since then, this protein has become one of the most important tools used in contemporary bioscience."

Shimomura first isolated GFP from jellyfish drifting off the western coast of North America and discovered that it glowed bright green under ultraviolet light. For 20 years from 1967, he made a summer pilgrimage to Friday Harbor in Washington state to gather more than 3,000 jellyfish per day.

Chalfie and colleagues got bacteria such as E. coli and tiny worms called C. elegans to produce the protein by splicing in the right gene. The green color of the jellyfish protein appears under blue and ultraviolet light, allowing researchers to illuminate tumor cells, trace toxins and to monitor genes as they turn on and off.

"We can simply look inside an animal and say where has this gene been turned on, when is it turned on and when the protein is made, where does it go?" Chalfie said in a telephone interview. "They have their own flashlight telling you where they are."

Tsien, a Howard Hughes Medical Institute investigator, used coral proteins too, and extended the palette beyond green to yellow, blue and other colours, allowing scientists to follow several different biological processes at the same time.

He said asthma kept him indoors as a child, so he spent hours playing with colours as part of chemistry experiments in his basement.

Tsien said he was grateful for the prize and acknowledged that others in the field could also have been included. "I know only three people could get it and I'm sure the committee had a difficult decision," he said.

Chalfie said he missed the first call from the Nobel committee: "I looked on the computer, my laptop, and I found that I had won the prize. I slept through the phone call."

GFP has been used for art as well as for science. A green-glowing bunny named Alba was made in 2000 at the request of Chicago artist Eduardo Kac and green-glowing pigs have been gene engineered and bred to make green-glowing piglets.

As Nobel chemistry laureates, the three researchers join the ranks of some of the greatest names in science, such as Marie Curie, who also won a physics Nobel, and Linus Pauling, the scientist and renowned peace activist who won the prize in 1954.

The prizes were established in the will of 19th century dynamite tycoon Alfred Nobel and have been awarded since 1901.

The laureate for literature will be unveiled on Thursday, followed by the Nobel Peace Prize on Friday and the economics award on Monday. -Reuters