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OZONE WHISTLE BLOWERS Rarely does Nobel-prizewinning research galvanize worldwide political action. Yet the findings that have made chemistry laureates of Sherwood Rowland of the University of California at Irvine, Mario Molina of M.I.T. and Paul Crutzen of Germany's Max Planck Institute for Chemistry did just that. Their discovery that man-made chemicals can damage the planet's protective ozone layer was instrumental in triggering the most successful global environmental treaty ever written: the 1987 Montreal Protocol limiting the use of chlorofluorocarbons, or CFCs. Before the treaty, CFCs were widely used in deodorants, spray paints, plastic foam, refrigerators and air conditioners.
Crutzen's work came first, with his demonstration in 1970 that airborne chemicals called nitrogen oxides could damage the ozone gas that floats high in the earth's stratosphere and screens out ultraviolet light, which can cause sunburn and skin cancer. The real breakthrough, though, came in 1974, when Molina and Rowland determined that CFCs are highly efficient ozone destroyers, gobbling up many times their volume in ozone molecules.
Molina's and Rowland's work didn't thrill industrialists, but it did lead to a ban on CFC-based spray cans in the U.S. in 1978. And after an ozone hole over Antarctica was detected in 1985, industry was goaded into taking swift action. CFCs are now being phased out all over the world for all uses, and production will be banned entirely as of 2006.
LORDS OF THE FLIES To most people, fruit flies are those pesky bugs that swarm around overripe bananas. To biologists, however, they are the key to unlocking some of life's deepest mysteries. They are nearly perfect lab animals: not only do the tiny insects grow quickly, but their genetic structure is strikingly similar to that of humans. So it was only natural for the three researchers who shared this year's Nobel Prize for Medicine or Physiology to use fruit flies to help solve the riddle of how genes control embryonic development--in insects and in humans.
Their experiments led to the discovery of so-called pattern-forming genes that control the body's overall organization and direct the development of body segments and specialized features, like the wings and legs of a fruit fly. Scientists now believe that flawed copies of these genes in humans underlie some miscarriages and perhaps 40% of the birth defects that have no apparent cause.
Edward Lewis, of Pasadena's California Institute of Technology, began studying mutant flies in the late 1930s, breeding more than 100,000 insects over 10 years. After a painstaking series of experiments in which fruit flies were exposed to radiation, Lewis identified the complex of master control genes that organize development of the embryo into discrete segments: head, thorax, abdomen. Some bizarre mutations, he found, result from defective control genes ordering normal segments to appear in abnormal places. For example, flies with an extra set of wings have an extra copy of an entire thoracic body segment.