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Lederberg, Joshua

bacterial genetics bacteria genes

[lay derberg] (1925– ) US geneticist: pioneer of bacterial genetics.

A New Yorker almost from birth, Lederberg graduated in biological science at Columbia University and then enrolled there in 1944 as a medical student during his service in the US Naval Reserve. At that time bacteria were not thought to have genes, or sex. During his course on medical bacteriology, Lederberg began experiments to test this and in 1946 went to Yale to work on it with the experienced microbiologist E L Tatum (1909–75). They were skilful and lucky in the choice of the intestinal bacterium Escherichia coli strain K-12 for their work, and within weeks showed that mutants of this strain crossed; in a large colony, a few reproduced by sexual mating (‘conjugation’). Lederberg went on to show that this is not uncommon and can be used to map bacterial genes; bacterial genetics had begun and its methods became valuable to geneticists, as had earlier use of the fruit fly Drosophila and the fungus Neurospora .

His next major discovery, made with in 1952, was that bacteriophage (a bacteria-infecting virus) could transfer genetic material between strains of bacteria (‘transduction’) to produce recombinant types. For the first time genes had been deliberately inserted into cells, a basis for ‘genetic engineering’. In 1957, with G Nossal (1931– ), Lederberg showed that immune cells produce single types of antibody, a result which was basic to the development of monoclonal antibodies by others. With his first wife, Lederberg obtained the first firm evidence that adaptive mutations in bacteria can occur spontaneously; this had been an unproved assumption in the theory of evolution. After Yale, Lederberg taught genetics at Wisconsin and at Stanford and became president of Rockefeller University in 1978. At age 33, he had shared a Nobel Prize with and Tatum in 1958. Aside from his work on bacterial genetics, he researched on artificial intelligence and the specific problem of computerizing some of the work of organic chemists by devising a linear notation for organic molecular structures. In collaboration with E A Feigenbaum, these studies pioneered the development of ‘expert systems’.

Lee, Canada (1907–1951) [next] [back] Lebra, Joyce Chapman (1925–) - History of Japan, India

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