"Thus bacteriophage, Delbrück, and I were somehow brought together in that winter of 1938. I had been looking for some biological object on which to test Delbrück's ideas on the gene, something small enough to be like a gene and yet easy enough to work with. Bacteriophage was just that."
Pioneering microbial geneticist Salvador Edward Luria was born Salvatore Luria in Turin, Italy, on August 13, 1912, the second son of David Luria, an accountant, and his wife Esther. His school years coincided with the rise of fascism in Italy, and he was strongly influenced by several of his teachers who resisted the movement. Luria later noted that while he did well in math and literature courses, and had vague longings for an academic life, he developed no real passion for learning. Although his grades in chemistry and biology were only mediocre, he chose to attend medical school "because of my parents' wish and my own lack of alternative inclinations." He graduated from the University of Turin Medical School in 1935, near the top of his class.
Certain that he did not want to pursue medical practice, Luria sought training in radiology, hoping it would allow him to combine interests in biology and physics. His training was briefly interrupted in 1936-37, while he served his required time in the Italian army as a junior medical officer. Following this, he moved to the University of Rome to finish the radiology courses and, at the urging of his friend Ugo Fano, study physics. During his year among the physicists--including Enrico Fermi--Luria was introduced to radiation biology, and to Max Delbrück's recent theories about the gene as a molecule. These theories, he wrote later, seemed to "open the way to the Holy Grail of biophysics." Soon afterwards, Luria was introduced to bacteriophages--viruses that infect bacteria--by a bacteriologist friend, and quickly adopted "phage" as the ideal research organism for testing Delbrück's theories.
By late 1938 Italy had become increasingly aligned with Nazi Germany's anti-Semitic policies. As a Jew, Luria was barred from academic research fellowships or other awards, so he moved to Paris, where he obtained a fellowship in Fernand Holweck's laboratory at the Institute of Radium. When the German army invaded in June 1940, Luria traveled by bicycle to Marseilles to acquire an American immigration visa, then on to Lisbon, where he embarked for New York, arriving on September 12th.
In New York, assisted by Fermi, Luria got a Rockefeller Foundation fellowship, and worked at the College of Physicians and Surgeons at Columbia University. During his first months here, he also changed his name from Salvatore (which he had never liked) to Salvador E. Luria. Asked what the "E" was for, he told the official, "Edward."
Luria finally met Max Delbrück at the annual meeting of the American Physical Society in December 1940. They spent New Year's Day in Luria's lab, playing with bacteriophage and planning experiments to do the next summer at Cold Spring Harbor Laboratory on Long Island. That summer the two did their first investigations into how phage multiply within bacteria, and discovered that different phage strains interfere with each other when attacking bacteria. At the end of 1941, Luria worked with biophysicist Thomas Anderson to take some of the first electron microscope pictures of bacteriophage and accurately measure their size. This work helped win him a Guggenheim fellowship, which allowed him to spend much of 1942 at Vanderbilt University with Delbrück. In 1943 he took an instructorship at Indiana University; soon afterward he did one his most important studies, demonstrating that bacteria mutated spontaneously into phage-resistant forms. Again in collaboration with Delbrück, Luria developed the "fluctuation test" for calculating bacterial mutation rates. This work provided statistical evidence for the existence of genes in bacteria, and thus established microbes as suitable subjects for genetics research.
An informal meeting between Delbrück, Luria, and phage researcher Alfred Hershey later in 1943 led to the founding of the "phage group," a group of scientists working on genetics problems primarily with phage. During the next few years, meeting mainly at Cold Spring Harbor summer sessions, the group agreed on standard bacterial strains and phages for their research (so that results would be comparable) and developed a course on phage for the CSH program.
During the 1940s, Luria continued his investigations into bacteriophage (usually those infecting E. coli or Shigella bacteria) and taught and mentored at Indiana, where his colleagues included geneticists Herman J. Muller and Tracy Sonneborn. Like several other researchers, he noted that phage killed by UV light can, when put into the same cell, often reconstitute themselves and produce normal progeny by exchanging damaged sections of genes. He set his first graduate student, James Watson, to work on similar experiments. After post-doctoral work in biochemistry, Watson went on to discover the structure of DNA with Francis Crick.
Luria married Zella Hurwitz, a psychologist, in 1945. Their only child, Daniel, was born in 1949. Luria became a U.S. citizen in 1947.
In 1950, Luria moved to the University of Illinois at Urbana. His work on host-induced bacteriophage modifications revealed a new phenomenon: restriction of the phage DNA expression by bacterial enzymes. (Such "restriction enzymes" later became a primary tool for recombinant DNA work.) He became an editor of the new journal Virology in 1955, a post he held until 1972. He also wrote a textbook, General Virology (1953), which became a standard for the field and went through three editions.
Luria spent a sabbatical year at the Massachusetts Institute of Technology (MIT) in 1958-59, and served as advisor for MIT's proposed reorganization of its biology department and development of a microbiology program. MIT asked him to be the first chair of the new program and he accepted, starting the new post in fall of 1959. Around the same time, Luria, feeling that the field of phage research had become overcrowded, turned his attention to related questions about cell membranes. He spent a year in Paris working with Jacques Monod, learning more about the mechanisms of enzymes within bacterial cell membranes. He and his research associates spent over a decade looking at colicins and the mechanisms by which these proteins could suddenly block the cell functions of other bacteria and kill them.
Luria shared the 1969 Nobel Prize in Physiology or Medicine with Max Delbrück and Alfred Hershey, for their "discoveries concerning the replication mechanism and the genetic structure of viruses." In 1972 he was asked to set up and direct a new center for cancer research at MIT, as a direct extension of the well-established molecular and cellular biology programs there. David Baltimore and Phillips Robbins were on the core staff of the center, which opened in 1973. Later researchers at the MIT cancer center also discovered messenger RNA splicing and isolated oncogenes. Luria retired as director in 1985, and was given the title of Institute Professor Emeritus.
Although he was not involved in resistance activities in Italy or France during the 1930s and 1940s, Luria was almost always politically engaged at some level after moving to the United States. With his early direct experience of fascism, he had strong sympathies for leftist movements, with their focus on reducing class inequalities and promoting social justice. He joined biochemist Linus Pauling and many others in protesting nuclear weapons testing during the 1950s and the building of new atomic power plants in the 1970s. He was also an active participant in the peace movement and was an outspoken critic of the Israeli invasion of Lebanon and the American intervention in Vietnam. He had a deep conviction that scientists had a responsibility to speak out against social injustice, bad policy, and irresponsible uses of technology. In 1969 this earned him a brief funding blacklisting at the National Institutes of Health. During the mid-1970s, he participated in discussions about limits on newly developed recombinant DNA technology.
Luria was also deeply engaged in the humanities. He encouraged his graduate students to read widely beyond the sciences, and for several years taught an informal course on world literature. In his later years he produced a number of reflective essays and talks on humanistic topics, completed his autobiography, and wrote a popular science book (Life: the Unfinished Experiment) which won the National Book Award in 1974.
During his career, Luria published over 150 scientific articles, numerous essays and editorials, and four books; served on editorial boards for Journal of Bacteriology, Virology, Experimental Cell Research, Journal of Molecular Biology, and other journals; held memberships in the American Academy of Arts and Sciences, American Society for Microbiology (serving as president 1968-69), and the National Academy of Sciences, among others. He became a non-resident fellow of the Salk Institute for Biological Studies in 1965.
Besides his 1969 Nobel Prize, Luria was honored with Columbia University's Louisa Gross Horwitz Prize (1969), the Lenghi Prize of the Accademia dei Lincei (1965) and several honorary doctorates.
Luria died in Lexington, Massachusetts, on February 6, 1991, of a heart attack.