Joshua Lederberg

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Joshua Lederberg speaking at a conference in 1997

Joshua Lederberg (born May 23, 1925) is an American molecular biologist who is known for his work in genetics, artificial intelligence, and space exploration. He was awarded half of the Nobel Prize in 1958 for his research in genetic structure and function in microorganisms. The other half of that year's prize was shared by Edward Lawrie Tatum and George Wells Beadle.

In addition to his contributions to biology, Lederberg did extensive research in artificial intelligence. This included work in the NASA experimental programs seeking life on Mars and the chemistry expert system Dendral.

[edit] Early life and education

Lederberg was born in Montclair, New Jersey, to Esther Goldenbaum Schulman Lederberg and Rabbi Zwi H. Lederberg, in 1925. He had two younger brothers. Lederberg graduated from Stuyvesant High School in New York City at the age of 15 in 1940. After graduation, he was allowed lab space as part of the American Institute Science Laboratory, a forerunner of the Westinghouse Science Talent Search. He enrolled in Columbia University in 1941, majoring in zoology. Under the mentorship of Francis J. Ryan, he conducted biochemical and genetic studies on the bread mold Neurospora crassa. Intending to receive his MD and fulfill his military service obligations, Lederberg worked as a hospital corpsman during 1943 in the clinical pathology laboratory at St. Albans Naval Hospital, where he examined sailors' blood and stool samples for malaria. He went on to receive his undergraduate degree in 1944.

[edit] Bacterial genetics

He began medical studies at Columbia's College of Physicians and Surgeons while continuing to perform experiments. Inspired by Oswald Avery's discovery of the importance of DNA, Lederberg began to investigate his hypothesis that, contrary to prevailing opinion, bacteria did not simply pass down exact copies of genetic information, making all cells in a lineage essentially clones. After making little progress at Columbia, Lederberg wrote to Tatum, Ryan's post-doctoral mentor, proposing a collaboration. In 1946 and 1947, Lederberg took a leave of absence to study under the mentorship of Tatum at Yale University. Lederberg and Tatum showed that the bacterium Escherichia coli entered a sexual phase during which it could share genetic information through bacterial conjugation ^[1]. With this discovery and some mapping of the E. coli chromosome, Lederberg was able to receive his Ph. D. from Yale University in 1947.

Intending to return to Columbia to finish his medical degree, Lederberg instead chose to accept an offer of an assistant professorship in genetics at the University of Wisconsin-Madison. Lederberg and his graduate student Norton Zinder went on to show in 1952 that bacteriophages could transfer genetic information between bacteria in Salmonella ^[2]. This process, called transduction, explained how bacteria of different species could gain resistance to the same antibiotic very quickly. Lederberg and his then-wife Esther Lederberg also developed the replica plating technology in 1952. In 1957, he founded the Department of Medical Genetics at the University of Wisconsin-Madison.

[edit] Post Nobel Prize research

Joshua Lederberg (right) receiving The National Medal of Science from George H. W. Bush.

In 1958, he received the Nobel Prize and moved to Stanford University where he was the founder and chairman of the Department of Genetics. He collaborated with Frank Macfarlane Burnet to study viral antibodies. With the launching of Sputnik in 1957, Lederberg became concerned about the biological impact of space exploration. In a letter to the National Academies of Sciences, he outlined his concerns that extraterrestrial microbes might gain entry to Earth onboard spacecraft, causing catastrophic diseases. He also argued that, conversely, microbial contamination of manmade satellites and probes may obscure the search for extraterrestrial life. He advised quarrentine for returning astronauts and equipment and sterilization of equipment prior to launch. Teaming up with Carl Sagan, his public advocacy for what he termed exobiology helped expand the role of biology in NASA. In the 1960s, he collaborated with Edward Feigenbaum in Stanford's computer science department to develop DENDRAL.

In 1978, he became the president of Rockefeller University, until he stepped down in 1990 and became professor-emeritus of molecular genetics and informatics at Rockefeller.

Throughout his career, Lederberg was active as a scientific advisor to the U.S. government. Starting in 1950, he has been a member of various panels of the Presidential Science Advisory Committee. In 1979, he became a member of the U.S. Defense Science Board and the chairman of President Jimmy Carter's President's Cancer Panel. In 1989, he received National Medal of Science for his contributions to the scientific world. In 1994, he headed the Department of Defense's Task Force on Persian Gulf War Health Effects, which investigated Gulf War Syndrome.

In 2006, Lederberg was awarded the Presidential Medal of Freedom.

[edit] Personal

He married fellow scientist Esther Zimmer (later Lederberg) in 1946; they divorced in 1966. He married Dr. Marguerite Stein Kirsch in 1968. Lederberg and Kirsch have two children, David Kirsch and Anne Lederberg.

[edit] References

• ↑ Lederberg, Joshua, and Edward L. Tatum. "Gene Recombination in Escherichia coli." Nature 158, (19 October 1946): 558.
• ↑ Zinder, Norton D., and Joshua Lederberg. "Genetic Exchange in Salmonella." Journal of Bacteriology 64, 5 (November 1952): 679-699.
• U.S. National Libraries of Medicine. NIH Profiles in Science

[edit] External links

• Nobel biography
• The Joshua Lederberg Papers