Arcane experiments on sea urchins and mutant yeasts called 鈥渨ee-mus鈥� have earned science鈥檚 top prize for two Britons and an American. Their research showed how living cells grow, divide and multiply, throwing new light on how cancers develop.
Paul Nurse and Tim Hunt of the London-based Imperial Cancer Research Fund became the first Britons since 1988 to win the Nobel prize for Physiology or Medicine. They share the prize with Leland Hartwell, director of the Fred Hutchinson Cancer Research Center in Seattle.
Hunt said: 鈥淚鈥檓 over the moon to win this award, which is a tribute to the work of my whole team at ICRF.鈥� He said he was rung by the academy at 1000, couldn鈥檛 believe it until he saw it in 鈥渆lectronic print鈥� on the Nobel website.
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Aptly, Nurse learned of the award while chairing a meeting to discuss renovation of gene pioneer Gregor Mendel鈥檚 monastery. He had to be told to switch on his mobile phone, which had a garbled recorded message telling him he had won. 鈥淚t鈥檚 all a bit of a shock.鈥�
Check points
Each of the winners discovered key genes and chemicals orchestrating the growth and division of cells, or 鈥渃ell cycle鈥�. This is such a fundamental process in all plants and animals that their work is important in just about every field in biology, especially medicine.
Through experiments on mutant strains of Baker鈥檚 yeast, Saccharomyces cerevisiae, Hartwell discovered a hundred or so 鈥渃ell division cycle鈥� genes. One, called CDC28, triggered the whole process and earned the name 鈥渟tart鈥�. It was also Hartwell who realised that there are 鈥渃heckpoints鈥�, or delays in the cycle while damaged DNA is repaired.
These checkpoints are important because they prevent cells with damaged DNA replicating. If something goes awry with the checkpoints, cells can start to divide out of control and become cancerous.
Wee mutants
By probing mutant strains of Schizzosacharomyces pombe yeast, Nurse later discovered cdc2, a master gene controlling many phases of the cycle. It adds chemical phosphate groupings to other proteins that take the cycle forward. Nurse called the mutant yeasts 鈥渨ee-mus鈥� because they divided while unusually small.
Next, Nurse proved that we humans had our own version of cdc2, that codes for a protein called cyclin dependent kinase 1, or CDK1. 鈥淚t was a real eureka moment,鈥� says Nurse. 鈥淚t meant that the same gene controls everything in organisms from yeast to humans.鈥�
Hunt, working on eggs from Arbachia sea urchins, discovered that CDK1 is activated by chemicals called cyclins. He found that cyclin soars in abundance as cells approach division, then 鈥渧anishes into thin air鈥� once division is complete.
鈥淭he mechanism that makes the cyclin go away is the important one,鈥� says Hunt. 鈥淚 knew I鈥檇 made a very important discovery straight away,鈥� he says.