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Beadle, George Wells

genetics genes eye biochemical

(1903–89) US geneticist: pioneer of biochemical genetics.

Born on a farm at Wahoo, NE, Beadle first planned to return there after graduation, but became an enthusiast for genetics and was persuaded to work for a doctorate at Cornell on maize genetics. In 1935 he worked with B Ephrussi in Paris on the genetics of eye-colour in the fruit fly Drosophila ; as a result of this work, ingeniously transplanting eye buds in the larvae, they suspected that genes in some way controlled the production of the eye pigment. When he returned to the USA, to a job at Stanford, he met the microbiologist E L Tatum (1909–75), and in 1940 they decided to use the pink bread fungus Neurospora crassa for a study of biochemical genetics. It grew easily, reproduced quickly and has an adult stage which is haploid (only one set of chromosomes) so that all mutant genes show their phenotypic expression. ( Drosophila , like other higher organisms, has two genes for every character, so dominant genes can mask recessives). Beadle and Tatum exposed Neurospora to X-rays to produce mutations and then examined the mutant strains to find their ability or inability to synthesize a nutrient needed for their own growth. They concluded that the function of a gene is to control production of a specific enzyme; they did not know that had reached the ‘one-gene-one-enzyme’ idea 30 years earlier by studying human metabolic disease. The value of their work was in providing an experimental method that allowed biochemical genetics to develop. It did so speedily, and their central idea remains unchallenged. More precisely, we would now say that one functional unit of DNA controls the synthesis of one peptide chain. Beadle, Tatum and shared a Nobel Prize in 1958.

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