Alfred Day Hershey
Biography of Alfred Day Hershey
Alfred Day Hershey graduated from Owosso High School in 1925 and subsequently studied at the Michigan State College, where he obtained a B. S. in chemistry in 1930, and in 1934 his Ph. D. in bacteriology for a thesis describing separations of bacterial constituents.
From 1934 to 1950 he was engaged in teaching and research at the Department of Bacteriology, Washington University School of Medicine, St. Louis, where he held an instructorship in bacteriology and immunology from 1936. Here he collaborated with Professor J. J. Bronfenbrenner. From 1936 to 1939 their papers reported studies on the growth of bacterial cultures. He became assistant professor in 1938 and associate professor in 1942.
Most of the basic facts about the gene and how it functions were learned through studies of bacteriophages, the viruses that infect bacteria. Such studies were done in wartime United States by the German physicist, Max Ludwig Henning Delbrück at Vanderbilt University, and the Italian biologist, Salvador Luria, who was a colleague of Delbrück. They believed that in studying how a single phage particle multiplies within a host bacterium to form many identical progeny phages, they were in effect studying naked genes in action.
Hershey received a letter from Max Delbrück, who said he had been reading Hershey's papers and was quite interested in a joint effort. And thus, in 1943, Hershey, Delbrück and Luria organised the "Phage Group", a team of bacteriophage researchers who met every year at Cold Spring Harbor to discuss their work and advances.
While Hershey and Delbrück were working together in 1946, they observed that when two different strains of bacteriophages have infected the same bacteria, the two viruses may exchange genetic information. They then produce offspring with different infective natures than either parent had. This was the first example of genetic recombination in viruses.
In 1950 Hershey became a Staff Member at the Department of Genetics, Carnegie Institution of Washington in Cold Spring Harbor on Long Island, New York. There, in 1952, he performed and published the famous "blender experiment" that would secure him a Nobel Prize. Hershey and his assistant, the geneticist Martha Chase, showed that only DNA, and not protein, was injected into a bacterial cell by an infecting phage particle. The DNA was sufficient to transfer to the bacteria all the genetic information needed to produce more phage. Using a kitchen blender, they separated the protein coating from the bacteriophage's nucleic acid core. They injected nucleic acid into the bacterial cell and found that the acid itself caused replication and transmission of genetic information, not its protein components. One year later James Watson and Francis Crick announced the double-helix structure of DNA and a theory on how genetic material is passed.
In 1962 he was appointed Director of the Genetics Research Unit of the Carnegie Institution, Cold Springs Harbor.
Hershey's later research helped the development of vaccines for polio, measles and mumps. In 1965 he demonstrated that the DNA molecule (chromosome) of bacteriophage l had 20-base-long single-stranded tails at each end. The base sequences of these tails were complementary, allowing them to find each other and circular l DNA molecules. This was a bombshell result, because circular molecules had 2 years before been hypothesized as an intermediate in the integration of l DNA molecules into bacterial chromosomes.
In 1967 he received an honorary D. Sc. at the University of Chicago.
Hershey shared the Nobel Prize in 1969 with Salvador Edward Luria (1912-1991) and Max Ludwig Henning Delbrück (1906-1981), "for their discoveries concerning the replication mechanism and the genetic structure of viruses. Salvador Edward Luria then worked at the Massachusetts Institute of Technology (MIT), Cambridge MA, while Max Delbrück was affiliated with the California Institute of Technology, Pasadena, California.
Michigan State University honoured him with an M.D.h.c. in 1970. He retired from active research in 1972 but was a constant figure around the lab until his death in 1997.
Alfred Hershey married Harriet Davidson in 1945. They got one son, Peter. Hershey was Member of the American Society for Microbiology, the National Academy of Sciences, and the American Academy of Arts and Sciences. He was the Recipient of the Kimber Genetics Award of the National Academy of Sciences in 1965.
- "His economy of speech was greater even than his economy of writing. If we asked him a question in a social gathering, we could usually get an answer like “yes” or “no.” However, at a scientific meeting one might get no answer at all, which was probably Al’s way of saying, in the fewest possible words, that he had no thoughts on that subject suitable for communication at this time.
Encounters with Al were rare, considering that he worked at Cold Spring Harbor, which hosted hundreds of visitors every summer. That’s because Al spent his summers sailing in Michigan, and except at occasional symposia or the annual phage meetings, which came early and late in the season, he was not to be seen.
Thus, most of us who valued Al as a colleague and acquaintance, didn’t really know him. I am one of those, and I suppose that status qualifies me for this assignment: The Al about whom I write is the same Al that most other people did not really know, either. (Some who worked with Al say that his lab functioned well because Laura Ingraham, Al’s long-time associate, really did know his mind.)"
Franklin W. Stahl: Alfred Day Hershey, 1909-1997.
Biographical Memoirs, Volume 80. The National Academy Press, Washington DC.
- Franklin W. Stahl:
We Can Sleep Later: Alfred D. Hershey and the Originsof Molecular Biology.
New York: Cold Spring Harbor Laboratory Press. 2000.