The Nobel science prizes

This year's Nobel science prizes have been awarded for cosmology and two sorts of genetics



WELL, the waiting is over for another year. The great and good of Sweden's Royal Academy of Science and of the country's principal medical school, the Karolinska Institute, have deliberated. The laurels have been assigned, if not yet awarded (that happens in December). And the disappointed will no longer have to cling to their telephones like politicians hoping for a ministerial posting. With much fanfare, the Nobel science prizes have been announced.

This year, the prize committees have done well. They have managed to pick winners who, if not exactly household names, have at least done work that has had some resonance in the wider world. The physics prize is for a piece of research that has enabled cosmologists to map the universe as it was before the first star formed. The physiology prize (or “prize for physiology or medicine”, as it is known in the citation) is for the discovery of a phenomenon called RNA interference, which helps cells fight off viral infections and is widely touted as a possible basis for a new class of drugs. The chemistry prize is for a piece of X-ray crystallography, a favourite subject of the academy's prize committees over the decades, and a way of awarding an extra physiology prize (since X-ray crystallography is used mainly to examine large biological molecules) without confessing that much of the intellectual oomph has gone out of chemistry in the century since Alfred Nobel, himself a chemist, drew up his will.

And the winners are

The physics prize went to John Mather of America's National Aeronautics and Space Administration (NASA) and George Smoot of the University of California, Berkeley. Together, they were responsible for discovering irregularities in the microwave radiation formed soon after the beginning of the universe, and which bathes the universe to this day.

The cosmic microwave background, as this radiation is known, began its journey about 300,000 years after the Big Bang in which everything started. When discovered, it appeared to be perfectly uniform. Some researchers, however, reasoned that it ought to carry imprints of the slight concentrations of matter that must have existed in the early universe if structures such as galaxies—and eventually stars and planets—were going to form. These concentrations would have acted as gravitational nuclei, drawing in gas from their surroundings and thus forming galaxies.

To test this idea, NASA built and launched a satellite called the Cosmic Background Explorer. Dr Mather ran the instrument on this satellite that looked for telltale variations in the microwave background, and Dr Smoot analysed the results, which were published in 1992. Their work, and subsequent refinements of it using a second satellite called the Wilkinson Microwave Anisotropy Probe, not only showed the ultimate roots of galaxies, it also provided evidence that the early universe underwent a sudden, massive expansion known as inflation.

Andrew Fire, of Stanford University, and Craig Mello, of the University of Massachusetts, were not the first people to notice the phenomenon now known as RNA interference, but they were the first to have an inkling about what was happening. The observation they built on, first made in plants, and then extended to animals, was that the activity of individual genes can be silenced by versions of a molecule called RNA. This substance is similar to DNA (the chemical difference is in the group of atoms employed to stand as one of the four chemical “letters” of the genetic alphabet). The main physical difference is that RNA's molecules usually come in single strands, unlike those of DNA, the material of the genes, which are usually double-stranded (the famous double helix).

One of RNA's jobs in the cell is to act as a messenger: RNA copies of DNA genes are translated into protein molecules in cellular structures called ribosomes. In a nutshell, what Dr Fire and Dr Mello found, in 1998, was that what silences genes is adding double-stranded versions of their RNA messengers to the mix. This stimulates the formation of what are known as RISC complexes, which carry part of the double-stranded RNA around as a reference, and destroy any RNA that matches it.

The reason, from the cell's point of view, for doing this, is that healthy animal and plant cells never make double-stranded RNA. On the other hand, many viruses do. Recognising and destroying double-stranded RNA is thus a safe way of attacking infection. Whether that insight can be turned into drugs remains to be seen. But many are trying, and billions of dollars rest on their success.

Roger Kornberg, the winner of the chemistry prize, and another member of the faculty of Stanford University, studied the process by which genes are copied into RNA in the first place. This is done by an enzyme called RNA polymerase, which binds to the DNA and runs along one of the strands of the double helix. Each time it comes to a new chemical letter on the strand it is reading, it reconfigures itself to add a complementary letter to the RNA molecule it is creating.

Dr Kornberg worked out the details by crystallising the complex of DNA, RNA and polymerase at various stages of the process. He then photographed each version of the complex with X-rays.

That process of X-ray crystallography, which calls for a lot of complex mathematics rather than the mere creation of a photographic image, was invented by two Britons, Sir William Bragg and his son Lawrence. They jointly won the Nobel prize for physics in 1915. Coincidentally, Dr Kornberg's father, Arthur, is also a Nobel laureate. He won the physiology prize in 1959 for working out the details of how DNA is synthesised. Whether such familial talent is a matter of nature or nurture will, no doubt, be the subject of a future prize.

Source : Economist