George Wells Beadle Biography

George W. Beadle's innovative and diverse research with corn, fruit flies, and bread mold helped to demystify the activities of genes, making it possible to reduce the inheritance of a particular characteristic to a series of steps needed for the manufacture of biochemicals, notably enzymes. For his work on the "one gene-one enzyme" concept, Beadle shared the Nobel Prize for physiology or medicine with Edward Lawrie Tatum and Joshua Lederberg in 1958.

Beadle was born in Wahoo, Nebraska, to Chauncey Elmer and Hattie Albro Beadle. Beadle may have made a career on the family farm if not for a high school science teacher who advised him to go to college. At the College of Agriculture at the University of Nebraska, Beadle gained an interest in genetics, especially that of corn. Beadle received his undergraduate degree in biology in 1926, then left for Cornell University in New York where he earned his doctorate in genetics.

In 1931, Beadle worked in the genetics laboratory of Thomas Hunt Morgan at the California Institute of Technology (Caltech) in Pasadena, California. Morgan had pioneered genetics work on the fruit fly, Drosophila melanogaster. As Beadle studied inherited characteristics such as eye color, considered whether genes might influence heredity by chemical means. When Beadle left California for Paris in 1935, he continued this line of work with Boris Ephrusi at the Institut de Biologie Physico-Chimique. Carefully transplanting eye buds from the larvae of one type of mutant fruit fly to larvae of another, Beadle showed that eye color in the insects is not a quirk of nature, but the result of a long chain of chemical reactions. For all the relative ease of working with fruit flies, however, Beadle sought a simpler rganism and a simpler set of chemical reactions to study.

Several years later, Beadle found what he was looking for. When Beadle returned from Paris in 1936, he briefly taught genetics at Harvard University, then moved to Stanford University in California, where he remained from 1937 to 1946. As a professor of biology at Stanford, Beadle began working with a red bread mold, Neurospora crassa. Beadle would work with neurospora for seventeen years. In 1941, he began collaborating with Edward Tatum, and their work eventually won hem--with Joshua Lederberg, who later worked with Tatum at Yale--the Nobel Prize.

Neurospora crassa, once the bane of bakers, became a boon for geneticists Beadle and Tatum. Not only does the mold have a short life cycle and grow on a basic sugar medium, but it reproduces both sexually and asexually. Also, the final cell division that produces its reproductive cells, known as ascospores, leaves them in a linear arrangement along the pod-like ascus (spore case), making the trail of inherited characteristics clear to follow.

Taking a hint from fellow geneticist Hermann Joseph Muller, who in themid-1920s had shown that the rate of mutation increases with exposure to X rays, Beadle and Tatum grew thousand of cultures of molds in which they had induced mutations. The wild strain of the mold can grow on a medium containing very few nutrients. With just some sugar sprinkled with a little biotin (a growth vitamin) and inorganic salts, a wild-type mold can synthesize all the proteins it needs to live. A mold with a mutation, however, loses the ability to make a particular compound it needs to grow, such as a specific amino acid(amino acids are the building blocks of proteins such as those used to construct DNA). Beadle expected that a missing amino acid would have to be supplied to the mold, but found to his surprise the mold was sometimes able to convert a similar compound to the necessary amino acid. Through a process of trial and error, Beadle was able to deduce the sequence of chemical steps involved in the work of conversion.

Once Beadle had pieced together the pathways of chemical production, his ideas could be applied to other molds. One immediate application was to use his techniques to mass-produce the antibiotic penicillin. Penicillin and other antibiotics are derived from compounds produced naturally by certain molds, which uses them as a defense against invading bacterial cells.

Beadle also crossed two different mutant strains of mold and found that the resulting hybrid could produce a particular amino acid that neither parent strain could produce alone. This was because one mutant lacked genetic coding for a certain enzyme (a protein that can encourage or inhibit chemical reactions), causing a breakdown in the chemical synthesis along one spot in the sequence, while the other mutant lacked different coding for an enzyme from another spot along the sequence. When crossed, the resulting mold could produce the missing amino acid because it had inherited both genetic patterns, one from each parent. Beadle concluded that specific genes (sequences of protein groups in DNA serving as functional units of inheritance) controlled each step in the sequence. Each gene held the information for the manufacture of a single enzyme, a concept that became known as "one gene, one enzyme."

Extended to other plants and animals, Beadle's theory could be used to explain all of genetic inheritance in terms of chemical reactions. Different genes control the different stages of chemical reactions. For example, cells must be able to produce the pigment that gives an animal's eyes their color. The production of pigment might occur in several steps, with enzymes used to hasten each chemical reaction. If the gene for any one of the enzymes is missing, the cells cannot produce the pigment.

The one gene-one enzyme concept caused a breakthrough in genetic research during the 1940s by shifting the study of genetics away from physical haracteristics of organisms to the production of biochemicals. On the heels of this line of research, the compound deoxyribonucleic acid (DNA) was analyzed, and the mechanism of the genetic code was pieced together in the early 1950s. Beadle and Tatum parted ways when Tatum left for Yale University in 1945. Using the same mutation induction techniques on bacteria, Tatum worked along with Joshua Lederberg to show how genetic information can be transferred from one bacterium to another.

Beadle became professor and chairman of the division of biology at Caltech in 1946 and stayed on until 1961. For his work in genetics he won the Lasker Award of the American Public Health Association in 1950. With his wife, Beadle wrote several books on genetics for a general audience. Recognition for years of work came in 1958 when Beadle, Tatum and Lederberg won the Nobel Prize. In that same year Beadle won the Albert Einstein Commemorative Award in Science, and in the following year he received the National Award from the American Cancer Society.

In the 1960s Beadle renewed his interest in the genetics of corn. Beadle became a player in the "corn wars," a debate among geneticists and archaeologists over the domestication of corn or maize in the Americas. Beadle contended that modern corn comes from a Mexican wild grass rather than a now-extinct species of maize. Beadle drew his conclusion from the corn remains that show that domestication occurred at the time of the Mayans and Aztecs.

In 1961, Beadle left California for Chicago, Illinois, where he became the sixth chancellor of the University of Chicago. Beadle remained at chicago until he retired in 1968. By then he had accumulated over thirty honorary degrees from many universities around the country and been awarded memberships into several prestigious academic societies. For their work in popularizing genetics, he and his wife Muriel won the Edison Award in 1967. In the late 1960s Beadle became director of the American Medical Association's Institute for Biomedical Research. Beadle died in Pomona, California, at age eighty-five from complications of Alzheimer's disease.