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'Determining the body plan'

Excerpts from the citation naming Edward B. Lewis, Eric F. Wieschaus and Christiane Nusslein-Volhard as winners of the Nobel Prize in medicine:

The 1995 laureates in physiology or medicine are developmental biologists who have discovered important genetic mechanisms which control early embryonic development. They have used the fruit fly, Drosophila melanogaster, as their experimental system. This organism is classical in genetics. The principles found in the fruit fly apply also to higher organisms, including man.

Using Drosophila, 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 into specialized organs. He found that the genes were arranged in the same order on the chromosomes as the body segments they controlled. The first genes in a complex of developmental genes controlled the head region, genes in the middle controlled abdominal segments while the last genes controlled the posterior ("tail") region

Together these three scientists have achieved a breakthrough that will help explain congenital malformations in man.

Most of the genes studied by Nüsslein-Volhard, Wieschaus and Lewis have important functions during the early development of the human embryo. The functions include the formation of the body axis, i.e. the polarity of the embryo, the segmentation of the body, and the specialization of individual segments into different organs

It is likely that mutations in such important genes are responsible for some of the early, spontaneous abortions that occur in man, and for some of the about 40 percent of the congenital malformations that develop due to unknown reasons.