Ruth Sager devoted her career to the study and teaching of genetics. She conducted groundbreaking research in chromosomal theory, disproving nineteenth-century Austrian botanist Gregor Johann Mendel's once-prevalent law of inheritance —a principle stating that chromosomal genes found in a cell's nucleus control the transmission of inherited characteristics.
Through her research beginning in the 1950s, Ruth Sager revealed that a second set of genes (nonchrosomomal in nature) also play a role in one's genetic composition. In addition to advancing the science of nonchromosomal genetics, she has worked to uncover various genetic mechanisms associated with cancer.
Born on February 7, 1918, in Chicago, Illinois, Ruth Sager was one of three girls in her family. Her father worked as an advertising executive, while her mother maintained an interest in academics and intellectual discourse. As a child, Sager did not display any particular interest in science. At the age of sixteen, she entered the University of Chicago, which required its students to take a diverse schedule of liberal arts classes. Sager happened into an undergraduate survey course on biology, sparking her interest in the field. In 1938, she graduated with a B.S. degree. After a brief vacation from education, Sager enrolled at Rutgers University and studied plant physiology, receiving an M.S. in 1944. Sager then continued her graduate work in genetics at Columbia University and in 1946 was awarded a fellowship to study with botanist Marcus Rhoades. In 1948 she received her Ph.D. from Columbia, and in 1949 she was named a Merck Fellow at the National Research Council.
Two years later, Sager joined the research staff at the Rockefeller Institute's biochemistry division as an assistant, working at first in conjunction with Yoshihiro Tsubo. There she began her work challenging the prevailing scientific idea that only the chromosomal genes played a significant role in genetics. Unlike many of her colleagues of the time, Sager speculated that genes which lay outside the chromosomes behave in a manner akin to that of chromosomal genes. In 1953 Sager uncovered hard data to support this theory. She had been studying heredity in Chlamydomonas, an alga found in muddy ponds, when she noted that a gene outside the chromosomes was necessary for the alga to survive in water containing streptomycin, an antimicrobial drug. Although the plant—which Sager nicknamed "Clammy"—normally reproduced asexually, Sager discovered that she could force it to reproduce sexually by withholding nitrogen from its environment. Using this tactic, Sager managed to cross male and females via sexual fertilization. If either of the parents had the streptomycin-resistant gene, Sager showed, the offspring exhibited it as well, providing definitive proof that this nonchromosomal trait was transmitted genetically.
During the time she studied "Clammy," Sager switched institutional affiliations, taking a post as a research associate in Columbia University's zoology department in 1955. The Public Health Service and National Science Foundations supported her work. In 1960 Sager publicized the results of her nonchromosomal genetics research in the first Gilbert Morgan Smith Memorial Lecture at Stanford University and a few months later in Philadelphia at the Society of American Bacteriologists. Toward the end of the year, her observations were published in Science magazine. As she continued her studies, she expanded her knowledge of the workings of nonchromosomal genes. Sager's further work showed that when the streptomycin-resistant alga mutated, these mutations occurred only in the non-chromosomal genes. She also theorized that nonchromosomal genes differed greatly from their chromosomal counterparts in the way they imparted hereditary information between generations. Her research has led her to speculate that nonchromosomal genes may evolve before the more common DNA chromosomes and that they may represent more closely early cellular life.
Sager continued announcing the results of her research at national and international gatherings of scientists. In the early 1960s Columbia University promoted her to the position of senior research associate, and she coauthored, along with Francis J. Ryan, a scientific textbook titled Cell Heredity. In 1963 she travelled to the Hague to talk about her work, and the following year she lectured in Edinburgh on nonchromosomal genes. In 1966 she accepted an offer to become a professor at Hunter College of the City University of New York. She remained in New York for nine years, spending the academic year of 1972 to 1973 abroad at the Imperial Cancer Research Fund Laboratory in London. The following year she married. Harvard University's Dana-Farber Cancer Institute lured her away from Hunter in 1975 with an offer to become professor of cellular genetics and head the Institute's Division of Cancer Genetics.
In the past twenty years, Sager's work centered on a variety of issues relating to cancer, such as tumor suppressor genes, breast cancer, and the genetic means by which cancer multiplies. Along with her colleagues at the Dana Farber Institute, Sager researched the means by which cancer multiplies and grows, in an attempt to understand and halt the mechanism of the deadly disease. She has likened the growth of cancer to Darwinian evolution in that cancer cells lose growth control and display chromosome instability. In 1983 she told reporter Anna Christensen that if researchers discover a way to prevent the chromosomal rearrangements, "we would have a potent weapon against cancer." She speculated that tumor suppressor genes may be the secret to halting cancer growth.
Sager continued to publish and serve on numerous scientific panels. In 1992 she offered scientific testimony at hearings of the Breast Cancer Coalition. A member of the Genetics Society of America, the American Society of Bacteriologists, and the New York Academy of Sciences, Sager was appointed to the National Academy of Sciences in 1977. An avid collector of modern art, she was also a member of the American Academy of Arts and Sciences.
On March 29, 1997, Sager died of cancer. At her death, she was chief of cancer genetics at the Dana-Farber Cancer Institute in Boston, which is affiliated with the Harvard Medical School.
Christensen, Anna, Potential Weapon in War on Cancer, United Press International, February 7, 1983.
The New York Times, April 4, 1997, p. A28.