This culture landmark provides a general overview of Joshua Lederberg, an American molecular biologist who won the Nobel Prize in physiology.

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Joshua Lederberg

Joshua Lederberg was an American molecular biologist known for his work in microbial genetics, artificial intelligence, and the United States space program, he was just 33 years old when he won the 1958 Nobel Prize in Physiology or Medicine for discovering that bacteria can mate and exchange genes.

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.


Robert Boyle

Joshua Lederberg (1925-2008).
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Neurospora crassa

Neurospora crassa. Image from

Neurospora crassa

Escherichia coli. Image from

Lederberg was awarded the Nobel Prize for discovering that bacteria can mate and exchange genes.

Joshua Lederberg 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 Edward Tatum, his post-doctoral mentor, proposing 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. With this discovery and some mapping of the E. coli chromosome, Lederberg was able to receive his Ph. D. from Yale University in 1947.

Instead of returning to Columbia to finish his medical degree, Lederberg chose to accept an offer of an assistant professorship in genetics at the University of Wisconsin–Madison.

Edward Tatum

Edward Tatum, Lederberg's mentor.
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Joshua and Esther Lederberg

Joshua and Esther Lederberg.
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Joshua Lederberg and Norton Zinder showed in 1951 that genetic material could be transferred from one strain of the bacterium Salmonella typhimurium to another using viral material as an intermediary step. This process is called transduction. In 1956, M. Laurance Morse, Esther Lederberg and Joshua Lederberg also discovered specialized transduction. The research in specialized transduction focused upon lambda phage infection of E. coli. Transduction and specialized transduction explained how bacteria of different species could gain resistance to the same antibiotic very quickly.

Transduction. Image from




1. In 5 words, define the scientist Joshua Lederberg.

2. How old was Lederberg when he won his Nobel Prize?

3. What subject did he win his Nobel Prize in?

4. What did he discover that earned him the Nobel Prize?

5. How did Oswald Avery influence Lederberg?

6. What important discovery about the e-coli bacteria did he make?

7. What was the topic of his doctoral dissertation?

8. What is transduction?

Space exploration

In 1958, Joshua Lederberg 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 quarantine 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, an influential pioneer project in artificial intelligence (AI).

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 University, considering his extensive research and publications in these disciplines.


Sputnik I, launched by the Soviet Union in October 1957. Image from

Lederberg was concerned that extraterrestrial microbes could cause catastrophic diseases on earth.

Rockefeller University

Rockefeller University campus, Chicago.

9. What is specialized transduction?

10. When dealing with space investigation, what was he concerned about?

11. What is astrobiology?

12. What did the DENDRAL project deal with?

13. What is the Gulf War Syndrome?

14. Apart from the Nobel Prize, what other awards did he receive?

15. Lederberg conducted research in several sciences. Which ones can you identify in the text?

16. What kind of relationship did he have with the U.S. Government?

Scientific advisor

Throughout his career, Lederberg was active as a scientific advisor to the U.S. government. Starting in 1950, he was 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 the 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.

Learn the difference between transformation, conjugation, transposition, and transduction.

National medal of science

1989 National Medal of Science.
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1. Lederberg was an American microbiologist.
2. 33 years old.
3. Physiology or Medicine.
4. Bacteria can mate and exchange genes.
5. Avery emphasized the importance of DNA.
6. E. coli entered a sexual phase in which it could share genetic information through bacterial conjugation.
7. Conjugation and the mapping of the E. coli chromosome.
8. Genetic material can be transferred from one strain of a bacterium to another using viral material as an intermediary step.

9. The process by which a restricted set of bacterial genes is transferred to another bacterium.
10. During space exploration, extraterrestrial microbes might gain entry to Earth onboard spacecraft, causing catastrophic diseases.
11. A scientific field that studies the origins, evolution, distribution, and future of life in the universe.
12. Artificial intelligence.
13. A chronic disorder affecting military veterans of the 1990–1991 Persian Gulf War. Symptoms include fatigue, muscle pain, cognitive problems, insomnia, rashes and diarrhea.

14. The National Medal of Science.
15. Physiology/Medicine (Nobel Prize), Zoology (Bachelor), Genetics, (molecular) Biology, Computer Science/Informatics, Artificial Intelligence and Psychology (Gulf War Syndrome).
16. He was a science advisor to the U.S. government for many years.


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