Ruth Sager

Ruth Sager (February 7, 1918 – March 29, 1997) was an American plant geneticist, cell physiologist and cancer researcher. In the 1950s and 1960s she pioneered the field of cytoplasmic genetics by discovering transmission of genetic traits through chloroplast DNA, Her second career began in the early 1970s and was in cancer genetics; she proposed and investigated the roles of tumor suppressor genes.

Early life and education Ruth Sager was born in Chicago on February 7, 1918, the only child of Leon B. Sager, an advertising executive, and Deborah Borovik Sager. Her mother died from the influenza epidemic in March 1919. Her widowed father married Hannah Shulman and had two more daughters, Esther and Naomi. At age 16, Ruth graduated from New Trier High School.

She then enrolled at the University of Chicago with plans to study liberal arts and major in English. A physiology course taught by Anton Carlson awakened her interest in biology. Since she enjoyed her science classes the most, Sager switched her major to biology, aiming to attend medical school. She earned her Bachelor of Science degree in 1938 and was elected to Phi Beta Kappa.

Middle East connection Aiming to give their three daughters a wide-ranging education, Sager’s parents took them on a trip through Europe and the Middle East from February to May 1938. While in Palestine, Sager visited a kibbutz, whose members’ self-sufficiency in creating a life in the desert impressed her. She wanted to return to Palestine, but ran into harsh emigration restrictions. Over the next few years, she spent time working on several American training farms of Hashomer Hatzair, a Zionist movement for young secular Jews. While doing so, she became interested in the scientific aspects of desert farming.

Graduate studies Attending graduate school at Rutgers University, Sager opted for scientific research instead of medical practice. She carried out wartime research on the growth of tomato seedlings, receiving her M.S. in plant physiology in October 1944 with a thesis on the mineral nutrition of tomato plants. She spent the next academic year working on the horticulture department farm at the University of Maryland.

Sager’s wartime correspondence with Seymour Melman, an army officer stationed in California, led to their marriage in 1944. Both were accepted at Columbia University, where they began their graduate studies in 1945. Sager studied maize (corn) genetics under Marcus Rhoades, sometimes doing fieldwork for Barbara McClintock, who served as a reader of Sager’s dissertation. Sager earned her PhD in 1948. She was promoted to a staff position (assistant in the biochemistry division) in 1951, working in this capacity until 1955, using the alga Chlamydomonas reinhardtii as a model organism. She performed breeding experiments with the algae, mating strains that were resistant to the chloroplast inhibiting agent streptomycin with strains that were streptomycin-sensitive. Unlike what would be expected if the trait were passed down following traditional Mendelian inheritance, she found that the offspring only showed the streptomycin sensitivity/resistance trait of one of their parents. She found further evidence when she mapped the streptomycin sensitivity/resistance trait and found a stable, nonchromosomal inheritance system that she proposed may have arisen before chromosomes. It wasn't until 1966, 18 years after receiving her doctorate, that Hunter College invited her to be a professor of biology.

She was elected a fellow of the National Academy of Sciences in 1977, and the American Academy of Arts and Sciences in 1979. In 1988 Sagar was awarded the Gilbert Morgan Smith Medal from the National Academy of Sciences.

Sager published two classic textbooks: Cell Heredity (1961), co-written by Francis Ryan and considered by some to be the first molecular biology textbook; and Cytoplasmic Genes and Organelles (1972). Elected fellow of the National Academy of Sciences, 1977. Elected fellow of the American Academy of Arts and Sciences, 1979. Outstanding Investigator Award, National Cancer Institute, 1985. Gilbert Morgan Smith Medal, National Academy of Sciences, 1988. Princess Takamatso Lecturer in Japan, 1990. Alumna of the Year, University of Chicago, 1994.

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