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Glowing Coral Proteins Aid Medical Research
John Roach
for National Geographic News
January 12, 2005
Tiny proteins that give coral reefs a mysterious glow may be key to keeping coral species
alive, according to scientists. Those same proteins, they say, may also help blaze trails to
new health cures.
Known as fluorescent protein, the molecules absorb light of one color and emit light of a different color.
Scientists are uncertain as to why the proteins do this. But researchers believe the proteins may either
help in the production of food or serve as a sunscreen.
Scientists say gaining a better understanding of the proteins' role may help prevent further reef
destruction.
"Corals are some of the most endangered organisms on the Earth. There are thousands of different kinds
of coral, and many are headed for near extinction," said Vincent Pieribone, an associate professor of
cellular and molecular physiology and neurobiology at Yale University School of Medicine in New Haven,
Connecticut.
Away from the oceans, the medical community is using fluorescent protein in the lab to monitor and study
biological processes associated with AIDS, Alzheimer's disease, cancer, and a host of other diseases.
Researchers can attach the fluorescent molecules to a protein inside a dividing cancer cell or a spreading
virus. Then, by shining a light of the appropriate color, scientists can watch as a cell divides or a virus
spreads—processes they wouldn't be able to see without the special proteins.
Scientists say the proteins may one day illuminate intricacies of the human nervous system. "Our big goal
is to put these [glowing proteins] in the brains of organisms and actually look at what the brain is doing,"
Pieribone said.
By watching how the brain works—observing what nerves are fired to command a certain action, such as
lifting a foot—researchers may find a way to bypass spinal cord injuries, Pieribone said.
Many people with severed spinal cords can create muscle commands in their brains. But damage to
nerve tissue prevents brain messages from reaching muscles.
The task for medical researchers is to devise a means to read these brain commands and transfer them
to appropriate body tissues, perhaps through robotics.
"We're laying the groundwork to do that sort of thing," Pieribone said. "It could happen 30 or 40 years
from now."
First, however, Pieribone and his colleagues are searching global coral reefs for new fluorescent proteins,
ones that better shine through bones and muscle tissue.
Fluorescent Jellyfish
Fluorescent proteins were first discovered about 40 years ago in an
Aequorea jellyfish that thrives in the coastal waters of the Pacific
Northwest. The protein, named green fluorescent protein, or GFP,
was shown to play a secondary role in the bioluminescence
periodically emitted by the jellyfish.
In the 1990s researchers cloned the fluorescent molecules. Scientists learned how to attach the
molecules to cells and proteins inside the bodies of other living animals, including humans. The
breakthrough allowed widespread use of fluorescent proteins in biomedical research.
"Once GFP was cloned and became an important biological tool, people felt the need to find more colors
of fluorescent proteins," said David Gruber, a graduate student in biological oceanography at Rutgers
University in New Brunswick, New Jersey. Gruber collaborates with Pieribone, the Yale cell scientist and
neurobiologist, on fluorescent protein research.
Researchers were able to manipulate the DNA of jellyfish GFP to obtain yellow and cyan, or dark blue,
colors. However, scientists were unable to engineer red florescent proteins. The color is desirable
because it penetrates deeper into living tissue.
In 1999 a team of Russian scientists found a GFP-like protein in a common sea anemone (Anemonia
majano) sitting in a Moscow fish tank. The team has since discovered and cloned a handful of other
fluorescent proteins from coral-reef species, and the race is on to find more.
"If the Russians found both green and red fluorescent protein from a few fish-tank corals, what
discoveries would the most diverse coral ecosystem hold?" Gruber said. "We quickly set off for Australia's
Great Barrier Reef to look for new fluorescing proteins."
Coral Conservation
Fluorescent proteins are now known to be common to coral reefs around the world. The largest number
to date have been discovered on Australia's Great Barrier
Reef.
What the proteins accomplish in coral reefs, however,
remains uncertain and is a major focus of biological studies.
Some researchers believe the fluorescent protein may act
as a sunscreen for the corals reefs. Another theory is that
the proteins provide algae—the main food of many coral
species—with light to grow in deeper, darker waters. Algae
requires light to live.
"Coral reefs are extremely complex systems, and there is a tremendous amount of information still to be
learned," Gruber said.
Regardless of the fluorescent proteins' exact ecological function, research shows that corals shed their
covering of algae when water temperatures rise, a process widely known as coral bleaching. When corals
bleach, they also alter their fluorescence levels.
"That leads us to believe that fluorescence is important when algae is there," Pieribone said.
Pieribone and other conservationists express alarm at the rapid disappearance of coral species around
the world. By some estimates, thousands of coral species may go extinct by the end of the century,
primarily owing to rising global temperatures.
EBQ Questions:
1. What was the purpose of this article?
2. What is biofluorescence?
3. What causes the coral to glow?
4. Why are medical scientists studying the fluorescent protein?
5. How does the fluorescent protein do for the Coral?
6. How does this article relate to Topic 2: Chemistry of life?
7. Why do you think it is important to study the chemical composition of organisms
(support your answer)
8. Why is it important to preserve the diversity of life on this planet (support your
answer)?