Three scientists who pioneered research into the genetics of embryo development in fruit flies - thereby shedding light on spontaneous abortions and congenital defects in humans - were awarded the Nobel Prize in Physiology or Medicine. Edward Lewis, 77, from the California Institute of Technology; Christiane Nuess- lein-Volhard, 52, from the Max Planck Institute for Developmental Biology in Tuebingen, Germany, and Eric F Wie-schaus, 48, of Princeton University in the United States, share the pounds 1m prize.
The Nobel Assembly at the Karolinska Institute in Stockholm said the three had discovered ''important genetic mechanisms'' controlling embryo development in the fruit fly's body segments that also apply to higher organisms, including man.
''Using Drosophila [the fruit fly] Nusslein-Volhard and Wieschaus were able to identify and classify a small number of genes that are of key importance in determining the body plan and the formation of body segments. Lewis investigated how genes could control the further development of individual body segments in specialised organs. He found that the genes were arranged in the same order on the chromosomes as the body segments they controlled.''
How an embryo with millions of cells and an array of specialised tissues and organs develops from a single fertilised egg is one of the greatest mysteries in biology. ''Together these three scientists have achieved a breakthrough that will help explain congenital malformations in man,'' the Nobel Assembly said.
Nusslein-Volhard and Wie-schaus did their pioneering work while young researchers at the European Molecular Biology Laboratory in Heidelberg.
They developed a system- atic method of seeing how different mutations caused corresponding abnormalities in embryo development. ''It was a brave decision by two young scientists at the beginning of their scientific careers. Nobody had done anything similar and the chances of success were very uncertain.''
Eventually they identified 15 different genes which if mutated would cause defects in the development of the embryo. They established that genes controlling development could be systematically identified.
Lewis discovered that the order of genes along a chromosome corresponds to the developmental sequence along the segmented body of the fruit fly - a crucial finding that has since been shown to be mirrored in humans.
News analysis, page 17