Ruth Sager

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Ruth Sager
BornFebruary 7, 1918
DiedMarch 29, 1997(1997-03-29) (aged 79)
Alma materUniversity of Chicago
Rutgers University
Columbia University
Known forPioneering cytoplasmic genetics
AwardsGilbert Morgan Smith Medal (1988)
Scientific career
FieldsGenetics, extranuclear inheritance
InstitutionsRockefeller Institute, Columbia University, Hunter College, Harvard Medical School, Dana–Farber Cancer Institute
Doctoral advisorMarcus Morton Rhoades

Ruth Sager (February 7, 1918 – March 29, 1997) was an American geneticist.[1] In the 1950s and 1960s she pioneered the field of cytoplasmic genetics by discovering transmission of genetic traits through chloroplast DNA,[2] the first known example of genetics not involving the cell nucleus. The academic community did not acknowledge the significance of her contribution until after the second wave of feminism in the 1970s.[3] Her second career began in the early 1970s and was in cancer genetics; she proposed and investigated the roles of tumor suppressor genes.


Sager was born on February 7, 1918, in Chicago, Illinois, one of three daughters of Leon B. Sager, an advertising executive, and Deborah Borovik Sager. Following Sager's birth, her mother died from the influenza epidemic of the time. Sager and her sisters, Esther and Naomi, were raised by their step mother Hannah. At 16 Sager had graduated from New Trier High school. After, she attended the University of Chicago and earned her S.B. in mammalian physiology in 1938. Following, she attended the Rutgers University and received her M.S. in plant physiology in 1944.[4] During World War II Sager had left academia to work as a secretary and an apple farmer. Following the war Sager had received her Ph.D. in maize genetics from Columbia University under Marcus M. Rhodes.[5] In 1944 she married Seymour Melman; in 1973 she married Arthur Pardee. She died of bladder cancer in Brookline, Massachusetts in 1997.


Sager matriculated at the University of Chicago at the age of 16, to study liberal arts but switched her major to biology, initially with the intention of attending medical school, after finding she enjoyed science classes the most.[4] She received her undergraduate degree in 1938, then, deciding she would prefer research to practicing medicine, she sought a master's degree in plant physiology from Rutgers University. Here she performed wartime research on the growth of tomato seedlings and received a master's degree in 1944.[4] She received a doctorate in maize genetics from Columbia University in 1948, for work performed under Marcus Rhoades, and with Barbara McClintock.[3]

Research and career[edit]

Sager was awarded a Merck Fellowship from the National Research Council in 1949, and worked as a postdoctoral fellow at the Rockefeller Institute on the chloroplast from 1949 to 1951 in the laboratory of Sam Granick.[6] 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.[7] 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.[4] This research provided evidence for non-Mendelian uniparental inheritance; it also showed that there are multiple independent genetic systems in Chlamydomonas.[2] 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.[4] She was the first person to publish extensive genetic mapping of a cellular organelle.[6]

She joined Columbia University's zoology department as a research associate in 1955, supported by funding from the United States Public Health Service and the National Science Foundation.[7] She was promoted to senior research associate in the early 1960s, but she had difficulty obtaining a faculty position due to initial skepticism surrounding cytoplasmic inheritance from the scientific community, as well as gender discrimination.[7][8] It wasn't until 1966, 18 years after receiving her doctorate, that Hunter College invited her to be a professor of biology.[2]

Sager changed her research focus to cancer biology in the 1970s, with a specific focus on breast cancer, and spent time researching at London's Imperial Cancer Research Fund Laboratory from 1972 to 1973, where she met her future husband, Arthur Pardee.[6] In 1975 she joined the Department of Microbiology and Molecular Genetics at Harvard Medical School as a professor of cellular genetics, where she served as chief of the Division of Cancer Genetics at the affiliated Dana–Farber Cancer Institute. Her research there focused on the genetic and molecular causes of cancer, including investigation of the roles of tumor suppressor genes, DNA methylation, and chromosomal instability in tumor growth and spread.[7] Sager was one of the first people to emphasize the importance of such genes.[6] She identified over 100 potential tumor suppressor genes and performed extensive research into a specific tumor suppressor gene called maspin (mammary serine protease inhibitor)[6] She developed cell culture methods to study normal and cancerous human and other mammalian cells in the laboratory and pioneered the research into "expression genetics," the study of altered gene expression.[5]

For more than half a century she demonstrated vision, insight and determination to develop novel scientific concepts in the face of established dogmas. Her pioneering research and original ideas continue to make contributions to biology

Mary J.C. Hendrix, Mapsin, 2002[9]

She was elected a fellow of the National Academy of Sciences in 1977 and the American Academy of Arts and Sciences in 1979.[5][10] In 1988 Sagar was awarded the Gilbert Morgan Smith Medal from the National Academy of Sciences.[11]

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).[8]

Selected honors and awards[edit]

Selected publications[edit]

  • Sager, Ruth; Ryan, Francis J. (1961). Cell Heredity. New York: Wiley.
  • Sager, Ruth (1972). Cytoplasmic Genes and Organelles. Academic Press.


  1. ^ "Ruth Sager, HMS Geneticist, Dies". Harvard Gazette. April 10, 1997. Archived from the original on February 5, 2012. Retrieved February 21, 2012.
  2. ^ a b c "Ruth Sager: Faculty of Medicine - Memorial Minute". Harvard Gazette. November 4, 2004. Archived from the original on February 8, 2012. Retrieved February 21, 2012.
  3. ^ a b Oakes, Elizabeth. International Encyclopedia of Women Scientists. 2002. Facts on File.
  4. ^ a b c d e Ogilvie, Marilyn Bailey; Harvey, Joy Dorothy, eds. (2000). The biographical dictionary of women in science : pioneering lives from ancient times to the mid-20th century. New York: Routledge. ISBN 0415920388. OCLC 40776839.
  5. ^ a b c d e Pardee, Arthur. "Ruth Sager 1918-1997" (PDF). National Academy of Science. Retrieved 27 Mar 2014.
  6. ^ a b c d e f g h Davison., Reynolds, Moira (2004). American women scientists : 23 inspiring biographies, 1900-2000. Jefferson, N.C.: McFarland. ISBN 9780786421619. OCLC 60686608.{{cite book}}: CS1 maint: multiple names: authors list (link)
  7. ^ a b c d Notable women scientists. Proffitt, Pamela, 1966-. Detroit: Gale Group. 1999. ISBN 9780787639006. OCLC 41628188.{{cite book}}: CS1 maint: others (link)
  8. ^ a b Jan., Sapp (1987). Beyond the gene : cytoplasmic inheritance and the struggle for authority in genetics. New York: Oxford University Press. ISBN 0195042069. OCLC 236342637.
  9. ^ Maspin (PDF). Hendrix, Mary. Georgetown, Tex.: Landes Bioscience. 2002. ISBN 1587060973. OCLC 47790803. Archived from the original (PDF) on 2018-04-05. Retrieved 2018-04-04.{{cite book}}: CS1 maint: others (link)
  10. ^ a b "Book of Members, 1780–2010: Chapter S" (PDF). American Academy of Arts and Sciences. Retrieved July 25, 2014.
  11. ^ a b "Gilbert Morgan Smith Medal". National Academy of Sciences. Archived from the original on 10 February 2011. Retrieved 16 February 2011.

Further reading[edit]