Susumu Ohno, a geneticist and molecular biologist known for his work in genetic sex determination and evolution through gene duplication, has died at the age of 71.
Ohno, a leading researcher at Duarte's City of Hope National Medical Center and Beckman Research Institute from 1953 to 1996, died Thursday at the City of Hope of lung cancer.
A methodical scientist who loved classical music, Ohno toward the latter part of his career married chemical and musical composition, turning DNA sequences into musical pieces. To the delight of many scientists and the horror of others, he had the result recorded by a violinist and a pianist--turning the genetic code of a primitive protozoan, for example, into sounds.
But to earn the freedom to choreograph that scientific arabesque, Ohno had established himself with significant breakthroughs in two areas of genetic research.
* In the 1950s and early 1960s, he pioneered the theory that evolution occurred by the duplication, rather than the alteration, of genes. His research indicated that more genes, created through the lengthening or doubling of chromosomes, would produce more DNA in any given cell. Noting that all mammals--humans, horses, mice--had the same amount of DNA in each cell, while the genus of birds had half as much, Ohno suggested that humans and lesser species shared a common ancestor--a 48-chromosome fish. Revolutionary at that time, his work greatly influenced future research.
* From 1966 to 1981, as chairman of the City of Hope Division of Biology, Ohno focused his research on how genes determine sex. He discovered the mechanism that controls whether a mammal's embryo will develop as a male or female, involving the inactive form of one of the X chromosomes in females. (Each human cell has 46 chromosomes, 23 from each parent, with two of them called sex chromosomes because they determine sex. A female has two X chromosomes while a male has one X and one Y.) He found that all embryos begin as female, but the action of a substance called an H-Y antigen converts some to male.
"In a few well-thought-out experiments, Dr. Ohno's research changed conventional thinking in the field of genetics," said Dr. Ernest Beutler, chairman of the department of molecular and experimental medicine at the Scripps Research Institute in La Jolla, in the City of Hope statement announcing Ohno's death. "He was an extraordinary biologist and formulated theories that had eluded everyone else."
Ohno's work earned him the Amory Prize for Reproductive Biology from the American Academy of Arts and Sciences in 1981.
At City of Hope, he was honored in 1981 with the first Ben Horowitz chair in genetics research. Thus funded for independent research, he followed his basic belief that all of nature is characterized by repetition, and worked to link gene coding to musical scores.
Ohno discussed his genetic research--and played his music--at universities and conferences worldwide. He was unfazed when some scientists disputed his theory that a pervasive natural law governs everything from the chemistry of a gene to the music of Wolfgang Amadeus Mozart, and barely shrugged when a Caltech biologist called his musical findings "cute but not profound."
Born in Seoul, Ohno grew up in Japan and earned doctorates in pathology and cytogenetics from Hokkaido University and in in veterinary medicine from Tokyo University of Agriculture and Technology. He worked in pathology research at the Institute of Infectious Diseases at Tokyo University before joining the City of Hope.
He was elected to the National Academy of Sciences and the American Academy of Arts and Sciences, and in 1992 to the Royal Danish Academy of Sciences and Letters.
Ohno is survived by his wife of 48 years, Midori Aoyama, and their three children.
The family has asked that any memorial contributions be made to the Susumu Ohno Distinguished Scientist Fellowship at City of Hope Cancer Center, 1500 E. Duarte Road, Duarte, CA 91010-0269.