STOCKHOLM: Australian researcher Elizabeth Blackburn and U.S. colleagues Carol Greider and Jack Szostak have won the Nobel Prize for Physiology or Medicine for identifying a key molecular switch in cellular ageing.

The trio were honoured for the discovery of how chromosomes are protected by telomeres and the role of an enzyme called telomerase in maintaining or stripping away this vital shield.

"The award of the Nobel Prize recognises the discovery of a fundamental mechanism in the cell, a discovery that has stimulated the development of new therapeutic strategies," the Nobel jury said.

The three scientists told Swedish Radio they were overjoyed by the news. Greider said she was "just thrilled, I just think that the recognition for curiosity-driven basic science is very, very nice," adding that she was up doing laundry in the U.S. when the early morning call came from Sweden.

First Australian woman

Blackburn, 60, a Hobart-born graduate of Melbourne University, becomes the first Australian woman to win a Nobel Prize. She said she knew when they made their discovery that they were on to something big. "I felt very excited ... and I thought this is very interesting, this is a very important result, and you don't often feel that about a result," she said.

Blackburn, who has worked in the U.S. for many years, was one of the favourites for the Nobel for physiology or medicine.

Szostak said meanwhile he expected "to have a big party at some point" to celebrate the prestigious award.
Telomeres are a minute yet vital factor in ageing. They are like a nubby, protective cap, fitting on the ends of the strands of DNA - the chemical recipe for life - that are packed into chromosomes.

Blackburn and Szostak discovered in 1982 that a unique DNA sequence in the telomeres protects the chromosomes from degradation when the cells divide. With Greider, Blackburn also identified telomerase, the enzyme that makes the telomere DNA.

If telomeres become worn, cells age. But if telomerase levels are high, the telomere length is maintained, and cellular ageing is braked.

A small number of rare but very destructive diseases, including a form of severe anaemia, are linked to defective telomerase, resulting in damaged cells.

Insights into cancer

Yet there is also a darker and more complex side to this picture. Many experts initially speculated that ageing could be pinned to telomere shortening, but the process has emerged as something that encompasses different factors, as well as telomeres.

In addition, high telomerase also helps cancer, enabling its cells to replicate endlessly and achieve what scientists call 'cellular immortality'. Finding ways of blocking this machinery through 'telomerase inhibitors' is one of the most eagerly explored areas of cancer research.

The trio's work has "added a new dimension to our understanding of the cell, shed light on disease mechanisms, and stimulated the development of potential new therapies," the Nobel citation said.

Elizabeth Blackburn, Carol Greider and Jack Szostak won the 2009 Nobel prize for medicine or physiology on Monday for their work on chromosomes.

Here are some details about the winners:

* ELIZABETH H. BLACKBURN:

– Elizabeth Helen Blackburn is a molecular biologist and biochemist who conducted ground-breaking research on DNA (deoxyribonucleic acid) and cell division that has provided a new line of inquiry into the chemical bases of life.

– Her discovery of a key enzyme, telomerase, which is necessary for chromosomes to make copies of themselves before cell division, has been applied to the study of chromosome behavior and of certain diseases, such as fungal infections and cancer.

– Blackburn, who has U.S. and Australian citizenship, was born in Hobart, Australia in November 1948. Blackburn’s interest in medicine and biology was influenced early on by her parents, both of whom were physicians.

– Blackburn graduated from the University of Melbourne in 1970 and with a MS degree in 1971.

– She went to Cambridge University, where she obtained a Ph.D. in molecular biology in 1975. She then went to the United States, drawn by professional and personal reasons. While attending Cambridge, Blackburn met and married John Sedat, an American postdoctoral researcher in biology. — Blackburn then began her work with telomeres, which help chromosomes to remain stable and whole, thereby ensuring completion of the DNA replication cycle. In 1978 she became assistant professor at the University of California, Berkeley, where she was to make her ground-breaking discoveries concerning chromosomes and DNA.

– In 1990 she went to the University of California at San Francisco. She is currently the Morris Herzstein Professor of Biology and Physiology at UCSF.

– She was fired in 2004 from then-President George W. Bush’s Council on Bioethics for her criticism of his restrictive policy on embryonic stem cell research. Earlier this year she said “The previous administration had this strange impression that science was the enemy of morality.”

* CAROL W. GREIDER:

– Greider began with her adviser, Elizabeth Blackburn, to investigate how a certain single-celled pond organism maintained the tens of thousands of caps on the ends of its mini-chromosomes – specialized structures known as telomeres that protect against DNA damage.

– Greider is a U.S. citizen and was born in 1961 in San Diego, near the University of California, Davis campus, where her father was a physics professor.

– Greider received her Ph.D. from University of California, Berkeley, in 1987 in molecular and cell biology. 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.

– Greider was credited with helping co-discover telomerase, an enzyme that maintains the length and integrity of telomeres. She has continued her work on telomeres and documented a mouse model for dyskeratosis congenital, a rare, inherited disorder related to stem cell failure.

– Greider shared the 2006 Albert Lasker Award for Basic Medical Research with Blackburn and Szostak.

JACK W. SZOSTAK:

– Szostak was born in November 1952 in London and grew up in Canada.

– He studied at McGill University in Montreal and at Cornell University in Ithaca, New York, where he received his PhD in 1977.

– He has been at Harvard Medical School since 1979 and is currently professor of genetics at Massachusetts General Hospital in Boston. He is also affiliated with the Howard Hughes Medical Institute.

– Szostak has made pioneering contributions to the field of genetics. He has studied the origin and early evolution of life through efforts to design and synthesize a self-replicating protocell capable of Darwinian evolution.