Mice, Magnetism, and Reactions on Solids: Nobels Awarded in Genetics, Materials Science, and Surface Chemistry

Article excerpt

The 2007 Nobel prizes in the sciences were announced early this week.

Physiology or Medicine

The discovery of techniques to identify the roles of genes has earned three scientists the 2007 Nobel Prize in Physiology or Medicine.

The award is shared by Mario R. Capecchi of the Howard Hughes Medical Institute and the University of Utah in Salt Lake City, Martin J. Evans of Cardiff University in Wales, and Oliver Smithies of the University of North Carolina at Chapel Hill.

Nearly 3 decades ago, Capecchi and Smithies separately investigated the process that cells use to fix damaged genes. Both researchers managed to harness this process, called recombination. By injecting normal DNA into a cell, they were able to modify targeted genes.

But to test the actual roles of individual genes, the scientists needed to make the DNA changes in live organisms, not just in cells in a lab dish.

Across the Atlantic, Evans had discovered embryonic stem cells in mice. By adding cells from one mouse embryo to an embryo from a different kind of mouse, he was able to modify the genes passed along to the second animal's offspring. Moreover, by using embryonic stem cells infected with a virus--and its DNA--Evans showed that it was possible to add genetic material to an embryo. The work suggested a way to alter an animal so that its eggs and sperm pass on those changes.

Scientists seized upon these breakthroughs as a means to determine what individual genes do by replacing genes with inactive versions in mice and then noting the consequences. In 1989, several laboratories published accounts of mice that were genetically engineered to lack particular genes and produced offspring with the same change.

The work had inaugurated a technique that would ultimately elucidate the roles of hundreds of genes.

"The best way to understand the function of a gene is to remove it," says geneticist David W. Melton of the University of Edinburgh. "This technology, for the first time, generated an experimental system in mice that enabled us to study relationships between genetic changes and the symptoms of specific diseases."

Few diseases are attributable to a single faulty gene. In recent years, Capecchi notes, scientists have gained the ability to assess several genes at once. "We want to see ... how these genes interact with each other," he says.

Capecchi was born in Italy in 1937. When his mother was imprisoned in Germany during World War II, he lived on the streets for 4 years before being reunited with her in 1945. They moved to the United States, where his studies put him on the ground floor of the burgeoning science of genetics.

Capecchi's life has now come full circle in a story of rags to research to riches. He and the other two scientists will split the $1.54 million prize. --N. SEPPA


In less than 10 years, a physical effect discovered in the lab made its way into computer technology, ultimately yielding dramatic improvements in data-storage capacity. The discoverers of that effect, Albert Fert of the Universite Paris-Sud in Orsay, France, and Peter Grunberg of the Research Center Julich in Germany, will share this year's Nobel Prize in Physics.

The phenomenon, which each of the physicists' teams observed independently in 1988, is called giant magnetoresistance. It has enabled engineers to increase the sensitivity of hard disk reading heads and pack more data into less space.

Certain metals, notably iron, are magnetic because their atoms, which act individually like small bar magnets, all tend to line up in the same direction. And when electrons flow through such a metal, constituting an electric current, their spins also tend to line up with the metal's magnetization. …