Francis Ruddle, a Yale University geneticist who plumbed the DNA of mice and men, and from whose laboratory sprang the first transgenic mammal -- a mouse with added foreign DNA -- died on March 10 in New Haven. He was 83.
The cause was complications of a heart condition, said his wife, Nancy Ruddle.
Dr. Ruddle, who at his death was the Sterling professor emeritus of molecular, cellular and developmental biology at Yale, was a cartographer of genes, one of the first scientists to map their locations on specific human chromosomes.
His research, begun in the 1960s, helped lay the groundwork for the Human Genome Project, started in 1990 and concluded triumphantly in 2003 with the sequencing of the entire human genome, comprising more than three billion units of DNA.
"The greatest of his scientific efforts was in understanding the structure of the human genome -- and by that I mean where genes are located," Jon W. Gordon, a retired faculty member of the Mount Sinai School of Medicine in New York who was a postdoctoral student in Dr. Ruddle's lab in the early 1980s, said in a telephone interview on Monday.
"This has significance in two respects," Dr. Gordon said. "One, to understand where genes are located; and two, to understand the significance of their location to function. For example, if you have two genes on the same chromosome, then you can understand how chromosome breakage could affect both of them."
In 1980, Dr. Ruddle's lab attracted worldwide headlines with the announcement that researchers there -- including Dr. Gordon and another postdoctoral student, George A. Scangos -- had successfully implanted foreign DNA into mice, thereby altering their genetic makeup.
Dr. Ruddle's team had taken genetic material from two viruses (Herpes simplex, which can infect humans, and a monkey virus known as SV-40) and, using a glass tube finer than a human hair, injected it into newly fertilized mouse eggs. The eggs were then implanted into female mice, which carried them to term.
Tests of the 78 mice born as a result revealed the presence of the viral DNA in two of them, making the creatures part mouse and part non-mouse. In a 1981 article in the journal Science, Dr. Ruddle and Dr. Gordon coined the word "transgenic" to describe this introduction of genetic material from one species to another.
Soon afterward, Dr. Ruddle's lab succeeded in implanting mice with a human gene, one that instructs cells to produce the protein interferon. This work also determined that transgenic material was heritable: mice engineered by the technique could pass their newly acquired foreign genes on to their offspring.
The capacity to invest one organism with the genes of another has had enormous implications for medical research, as Dr. Scangos, now the chief executive of the biotechnology concern Biogen Idec, said on Monday.
"The ability has given us insight into many human diseases: cancer, Alzheimer's -- you name it," he said. "Mice and humans share most genes in common. So if you have a gene that you suspect might cause cancer, but you're not sure, you can introduce it into a mouse, and perhaps that mouse will develop cancer."
Francis Hugh Ruddle, known as Frank, was born on Aug. 19, 1929, in West New York, N.J., and reared in Mariemont, Ohio, near Cincinnati. An indifferent student, as he later described himself, he dropped out of high school to join the Army Air Forces, serving in postwar Japan.
After his discharge he entered Wayne State University, where he earned a bachelor's degree in 1953 and a master's two years later. He received a Ph.D. in zoology from the University of California, Berkeley, in 1960.
After postdoctoral work at the University of Glasgow, Dr. Ruddle joined the Yale faculty in 1961, going on to serve as the chairman of the biology department there.
In later years, Dr. Ruddle was occupied with research on homeobox genes, which are known to have been of immense importance in the evolution of species. A set of genes found in humans and many other species, homeobox genes govern the development of an organism's myriad constituent parts out of the single fertilized cell from which it began life.
Dr. Ruddle, who had homes in New Haven and on Block Island, R.I., is survived by his wife, the former Nancy Hartman, an emeritus professor in the Yale School of Public Health, whom he married in 1964; a sister, Mary Haenschke; two daughters, Kathlyn Ruddle and Amy Ruddle Shohet; and three grandchildren.
In an interview with The New York Times in 1988, Dr. Ruddle spoke enthusiastically of one of the great virtues of being able to pluck genes from one creature and deposit them into another: efficiency.
"One of the wonderful things about transgenesis," he said, "is that we can do all at once what evolution has taken millions of years to do."
This article originally appeared in The New York Times.