Hershey, Alfred Day

Hershey, Alfred Day,

1908–1997, American microbiologist, b. Owosso, Mich., Ph.D., Michigan State College (now Michigan State Univ.), 1934. Hershey was a professor at the Washington Univ. School of Medicine (1934–50), then joined the Carnegie Institution of Washington, Cold Spring Harbor, N.Y. He was director of the genetics research unit there from 1962 until he retired in 1974. In 1969 he shared the Nobel Prize in physiology or medicine with Max DelbrückDelbrück, Max Ludwig Henning
, 1906–1981, American biophysicist, b. Berlin, Germany. Ph.D, Univ. of Göttingen, 1930. He spent most of his career as a professor at the California Institute of Technology.
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 and Salvador LuriaLuria, Salvador Edward,
1912–1991, American physician, b. Turin, Italy, M.D., Univ. of Turin, 1935. He conducted research and taught at the Institute of Radium in Paris (1938–40), Columbia (1940–42), Indiana Univ. (1943–50), and the Univ.
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 for parallel work that led to new knowledge about the replication mechanism and genetic structure of viruses. Beginning in 1940, the three became interested in using bacteriophagesbacteriophage
, virus that infects bacteria and sometimes destroys them by lysis, or dissolution of the cell. Bacteriophages, or phages, have a head composed of protein, an inner core of nucleic acid—either deoxyribonucleic acid (DNA) or ribonucleic acid (RNA)—and a
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, a group of viruses that destroy bacteria, to study self-replication, mutation, and other fundamental life processes. Hershey built on Delbrück's finding that viruses infecting the same cell showed an unexpected interaction and demonstrated that this phenomenon was the result of genetic recombinationrecombination,
process of "shuffling" of genes by which new combinations can be generated. In recombination through sexual reproduction, the offspring's complete set of genes differs from that of either parent, being rather a combination of genes from both parents.
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 and, further, that it could be used to construct the genetic map of viruses. Collectively, the work of the three made significant contributions to the discipline of virology and to the progress of molecular biology.

Hershey, Alfred Day


Born Dec. 4, 1908, in Lansing, Mich. American virologist. Member of the American Academy of Arts and Sciences and the National Academy of Sciences (1958).

Hershey graduated from the University of Michigan in 1930; he received his Ph.D. there in 1934. He taught bacteriology at Washington University from 1934 to 1950. He joined the staff of the genetics department of the Carnegie Institution in 1950; he was made director of the department in 1962.

Hershey devoted most of his research to the genetics of bacteriophages and the chemistry of viral DNA. He discovered recombinants in bacteriophages and, together with the American scientist R. Rotman, constructed the first genetic map of the viruses. In 1952, Hershey and M. Chase used labeled atoms to show that the material carrier of bacteriophage heredity is DNA. Their experiments laid the groundwork for new advances in molecular genetics. Hershey discovered two phases in the reproduction of a bacteriophage before the appearance of infectious particles: the first phase is replication of phage DNA, and the second is synthesis of phage protein.

Hershey was awarded the Kimber Genetics Award in 1965 and the Nobel Prize in 1969 (jointly with M. Delbrück and S. Luria).

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