Alfred Hershey

Alfred Hershey
Unknown author · Public domain · source
Name	Alfred Hershey
Caption	Hershey in 1969
Birth date	4 December 1908
Birth place	Owosso, Michigan
Death date	22 May 1997
Death place	Syosset, New York
Nationality	American
Fields	Bacteriology, Genetics
Workplaces	Washington University in St. Louis, Carnegie Institution of Washington
Alma mater	Michigan State University
Doctoral advisor	Robert J. Anderson
Known for	Hershey–Chase experiment, Bacteriophage genetics
Prizes	Nobel Prize in Physiology or Medicine (1969)

Alfred Hershey was an American bacteriologist and geneticist whose pioneering work with bacteriophage viruses provided foundational evidence that DNA is the genetic material of life. His famous Hershey–Chase experiment, conducted with Martha Chase, was a landmark in molecular biology and helped redirect the field toward the study of nucleic acids. For this contribution, he was awarded the Nobel Prize in Physiology or Medicine in 1969, sharing the honor with Max Delbrück and Salvador Luria. Hershey spent much of his career at the Carnegie Institution of Washington's Department of Genetics, where he led the influential Phage Group.

Early life and education

Alfred Hershey was born in Owosso, Michigan, and developed an early interest in science. He completed his undergraduate studies in chemistry at Michigan State University, earning a Bachelor of Science degree in 1930. He remained at the same institution for his doctoral work, receiving a PhD in bacteriology in 1934 under the mentorship of Robert J. Anderson. His dissertation research focused on the chemistry of Brucella bacteria, which provided him with a strong foundation in microbiological techniques that would later prove crucial for his viral studies.

Career and research

After completing his doctorate, Hershey joined the faculty of the Washington University School of Medicine in St. Louis as a research associate. It was here he began his transformative work with bacteriophage, viruses that infect bacteria, shifting his focus from bacterial metabolism to genetics. In 1950, he moved to the Carnegie Institution of Washington's Department of Genetics at Cold Spring Harbor Laboratory in New York, where he became a central figure in the Phage Group. This informal network of scientists, which included Max Delbrück and Salvador Luria, used phage as a simple model system to uncover universal principles of heredity and viral reproduction. Hershey's meticulous quantitative experiments on phage growth and genetic recombination were highly influential, establishing many core methodologies in molecular genetics.

Hershey–Chase experiment

In 1952, Hershey and his assistant Martha Chase performed the definitive Hershey–Chase experiment, also known as the blender experiment. The design exploited the fact that phage are composed of a protein coat surrounding a DNA core. They labeled the phage protein with the radioactive isotope Sulfur-35 and the DNA with Phosphorus-32. After allowing the phage to infect Escherichia coli bacteria, they used a Waring blender to shear off the empty viral coats. Analysis revealed that the radioactive Phosphorus-32 from the DNA entered the bacterial cells to produce new phage, while the Sulfur-35 from the protein remained outside. This provided powerful physical proof that DNA, not protein, carried the genetic information, strongly supporting earlier indirect evidence from Oswald Avery's work and paving the way for the discovery of the DNA double helix by James Watson and Francis Crick.

Awards and honors

Hershey's contributions were recognized with numerous prestigious awards. The apex was the 1969 Nobel Prize in Physiology or Medicine, jointly awarded with Max Delbrück and Salvador Luria "for their discoveries concerning the replication mechanism and the genetic structure of viruses." He was also elected a member of the United States National Academy of Sciences in 1958. He received the Albert Lasker Award for Basic Medical Research in 1958 and was honored with the Kimber Genetics Award of the National Academy of Sciences. In 1965, he was awarded an honorary Doctor of Science degree from University of Michigan.

Personal life and legacy

Hershey was known as a intensely private, modest, and dedicated experimentalist who preferred the laboratory to the lecture hall. He married fellow bacteriologist Harriet Davidson in 1945, and they had one son. After retiring from the Carnegie Institution of Washington in 1974, he remained in Syosset, New York, until his death. His legacy is profound; the Hershey–Chase experiment is a cornerstone of molecular biology taught worldwide. His rigorous approach to phage genetics helped establish viruses as model organisms and directly enabled the explosive growth of genetic engineering and biotechnology. The American Society for Microbiology awards an annual award in his name for outstanding contributions to bacteriology.

Category:American geneticists Category:Nobel laureates in Physiology or Medicine Category:1908 births Category:1997 deaths