George Wells Beadle

Beadle and Tatum's key experiments involved exposing the bread mold Neurospora crassa to x-rays, causing mutations. In a series of experiments, they showed that these mutations caused changes in specific enzymes involved in metabolic pathways. These experiments led them to propose a direct link between genes and enzymatic reactions, known as the "one gene, one enzyme" hypothesis.

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Life and work

Beadle was born in Wahoo, Nebraska. He received his Bachelor of Science degree in agronomy from the University of Nebraska's College of Agriculture in 1926 where he was a member of FarmHouse fraternity. At the recommendation of his advisor, Franklin D. Keim, he then entered graduate school in agronomy at Cornell University, intending to study ecology. He soon switched his focus to genetics and cytology, pursuing research on maize (corn) genetics under Rollins Adams Emerson—including some collaboration with Barbara McClintock. He received his Ph.D. from Cornell in 1931.^[1]

For post-doctoral work, Beadle joined Thomas Hunt Morgan's "fly lab" at the California Institute of Technology, where he worked with Alfred Sturtevant and others on Drosophila genetics. There, working with Boris Ephrussi, he helped develop a technique for transplanting foreign cells in fly larvae (creating a third eye in flies' abdomens); this technique was used to demonstrate that some mutations affecting eye color involved genes that controlled specific metabolic steps in the production of eye pigment. In an effort to precisely characterize the reactions and substances involved, he recruited biochemist Edward Tatum to work on the pigment problem as well. They eventually isolated and identified the pigment precursor found in the "vermilion" mutant, but did so shortly after an independent German group. Over the course of his Drosophila work, Beadle was a professor at Harvard University, then Stanford University.^[2]

With Tatum, Beadle switched his focus to a model organism more suited to biochemical genetics: Neurospora. By constructing mutant strains that required specific nutritional elements (amino acids or vitamins), they established that individual gene mutations were responsible for individual steps in the metabolism and synthesis of vital nutrients. This led, in 1941, to propose the "one gene-one enzyme hypothesis," the idea that a gene specifies a single enzyme, rather than a complex set of characteristics (as was generally assumed).^[3]

In 1946, with the support of Linus Pauling, Beadle was recruited to head the newly reorganized biology division of Cal Tech; the department was one of the prototypes of what would become known as molecular biology. During the early Cold War, Beadle was outspoken in his defense of colleagues under investigation for suspected Communist ties, and also worked on defining and publicizing the potential dangers of nuclear weapons-related radiation. In 1958, Beadle and Tatum were awarded the Nobel Prize in Physiology and Medicine for their work on biochemical genetics. Beadle went on to serve as president of the University of Chicago from 1961-1968, helping—through fund-raising and recruitment—to re-establish its reputation as a top research university. He published a book, The Language of Life, in 1966.^[4]

Following his retirement as university president, returned to research, now on the evolutionary relationship between corn and teosinte. He continued research until the late 1970s, when Alzheimer's disease made continued intellectual work impossible. George Beadle died in 1989; his second wife Muriel Barnett Beadle died in 1994. He had one son, David (b. 1931), with his first wife Marion Hill Beadle.^[5]

Notes and references

• Paul Berg and Maxine Singer. George Beadle: An Uncommon Farmer. The Emergence of Genetics in the 20th Century. Cold Springs Harbor Laboratory Press, 2003. ISBN 0-87969-688-5
• Nobel Lectures, Physiology or Medicine 1942-1962, Elsevier Publishing Company, Amsterdam, 1964