HealthCare

Blackburn, 60, who holds U.S. and Australian citizenship, is a professor of biology and physiology at the University of California, San Francisco. It's the first time two women have shared in a single Nobel science prize. Elizabeth H. Blackburn revealed the workings of chromosome features called telomeres, which play an important role in the aging of cells. Their work, done in the 1970s and 1980s, showed how features at the tips of chromosomes — telomeres can keep them from getting progressively shorter as cells divide. It's been compared to the way plastic tips on the ends of shoelaces keep the laces from fraying.

Blackburn discovered an enzyme, telomerase that maintains the lengths of the telomeres. Later research has shown that telomerase is switched on in almost all cancers. Telomerase is active before birth, when cells are dividing rapidly. By age 4 or 5 it's basically shut off in almost all cells. That means the telomeres degrade over time, leading those cells to age and eventually stop dividing. But scientists have shown that adding telomerase to human cells can extend their lifespan indefinitely.

Telomeres are caps at the end of chromosomes, protecting the precious strands of genetic code that contain the chemical recipe for life. Australian-American cell biologist Elizabeth Blackburn likens them to "tips of shoelaces" - when you lose the little plastic end, the lace starts to fray. The length of your telomeres, a repetitive sequence of the chemical code TTAGGG, and the repair job played by the enzyme telomerase, are unseen yet vital players in the ageing business.

Such research spurred speculation that telomerase might turn out to be a fountain of youth. But experts say that aging is more complicated than just changes in telomeres. Scientists are still studying what impact telomeres might have; perhaps they will reveal ways to ward off some aspects of aging, researchers say.