(CNN) -- Three U.S. researchers were awarded the 2009 Nobel Prize in Physiology or Medicine for their work on how chromosomes are protected against degradation, the Nobel Foundation announced Monday.
Elizabeth H. Blackburn, Carol W. Greider and Jack W. Szostak will share the $1.4 million prize for research on structures at the end of chromosomes called telomeres and on an enzyme that forms them, called telomerase.
It is the 100th year the prize will be awarded.
Szostak told CNN he got the news Monday in "that classic early morning phone call from Stockholm."
The Nobels keep their selection process top secret.
Szostak described it as "surprising and exciting" -- perhaps particularly for him, because he has not worked on the subject for the last 20 years. "I've been working on other things," he said. "It started off as a collaboration with me and Liz [Blackburn] -- Carol was a student of hers."
The work began as "a long-standing puzzle that we were interested in solving," he said. He added, "It was only over later years that it emerged, through the work of many people, that this was probably important for aging and cancer."
How it might help fight such diseases is not yet known, Szostak said. "It will take a while yet for that to be figured out."
Blackburn and Greider did not immediately return calls from CNN.
The long, thread-like DNA molecules that carry genes are packed into chromosomes. Telomeres are the caps on the ends of chromosomes. Blackburn and Szostak discovered that a unique DNA sequence in the telomeres protects the chromosomes from degradation, the Nobel announcement said. Greider and Blackburn identified telomerase, the enzyme that makes telomere DNA. These discoveries explained how the ends of the chromosomes are protected by the telomeres and that they are built by telomerase.
If the telomeres are shortened, cells age. Conversely, high telomerase activity leads to telomere length being maintained and the delay of cellular degradation. That is the case with cancer cells, which do not degrade easily. Certain inherited diseases, in contrast, are characterized by a defective telomerase, which results in damaged cells.
According to the Nobel announcement:
Blackburn has U.S. and Australian citizenship. She was born in 1948 in Hobart, Tasmania, Australia. After undergraduate studies at the University of Melbourne, she received her doctorate in 1975 from the University of Cambridge, England, and was a postdoctoral researcher at Yale University in New Haven, Connecticut. She was on the faculty at the University of California, Berkeley, and since 1990 has been professor of biology and physiology at the University of California, San Francisco.
Greider is a U.S. citizen and was born in 1961 in San Diego, California. She studied at the University of California in Santa Barbara and in Berkeley, where she obtained her doctorate in 1987 with Blackburn as her supervisor. After postdoctoral research at Cold Spring Harbor Laboratory, she was appointed professor in the department of molecular biology and genetics at Johns Hopkins University School of Medicine in Baltimore in 1997.
Szostak is a U.S. citizen. He was born in 1952 in London, England, and grew up in Canada. He studied at McGill University in Montreal, Quebec, and at Cornell University in Ithaca, New York, where he received his doctorate in 1977. He has been at Harvard Medical School since 1979 and is currently professor of genetics at Massachusetts General Hospital in Boston, Massachusetts. He also is affiliated with the Howard Hughes Medical Institute.
Szostak, who is married and has two children, told CNN he has "no idea" what he'll do with his portion of the monetary prize -- about $467,000.
CNN asked whether he thinks his children, ages 9 and 12, will suddenly think dad's work is "really cool."
"Well," Szostak said, laughing, "maybe."
