3 Americans share Nobel for DNA work

WASHINGTON — Three U.S. scientists were awarded a Nobel Prize on Monday for discovering how cells protect their genetic material as they divide repeatedly throughout an organism's life, a crucial discovery with fundamental implications for research on aging, cancer and other issues.

Elizabeth Blackburn of the University of California at San Francisco, Carol Greider of Johns Hopkins in Baltimore and Jack Szostak of Harvard Medical School in Boston shared the 2009 Nobel Prize in Physiology or Medicine. It was the first time two women shared the prize.

The three scientists won the prize for experiments that showed that the long, threadlike molecules that carry genes inside every cell known as chromosomes have protective caps on their ends — like the protective tips on shoelaces — called telomeres, which are replenished with an enzyme known as telomerase.

"If the telomeres are shortened, cells age. Conversely, if telomerase activity is high, telomere length is maintained, and cellular senescence is delayed. This is the case in cancer cells, which can be considered to have eternal life. Certain inherited diseases, in contrast, are characterized by a defective telomerase, resulting in damaged cells," the Nobel Assembly at Karolinska Institute in Stockholm said in its announcement.

Greider, 48, said she received the call notifying her that she had won just before 5 a.m. EDT.

"I was actually doing the laundry when the call came in," said Greider, who will split the $1.4 million payment that accompanies the prize with Blackburn, 60, and Szostak, 56.

Greider, who was born in San Diego, obtained her doctorate in 1987 from the University of California at Berkeley with Blackburn as her supervisor. After conducting postdoctoral research at Cold Spring Harbor Laboratory in New York, she was appointed in 1997 as a professor in the department of molecular biology and genetics at Johns Hopkins University School of Medicine in Baltimore.

Blackburn, a native of Tasmania, Australia, studied at the University of Melbourne before receiving a doctorate in 1975 from the University of Cambridge in England. She then did postdoctoral research at Yale University and joined the faculty at Berkeley. Since 1990, she has been a professor of biology and physiology at UC San Francisco. She has dual U.S. and Australian citizenship.

Szostak was born in London and grew up in Canada. He studied at McGill University in Montreal and at Cornell University in New York, where he received his doctorate in 1977. He has been at Harvard Medical School since 1979. Szostak now is a professor of genetics at Massachusetts General Hospital in Boston and is also affiliated with the Howard Hughes Medical Institute headquartered in Chevy Chase, Md.