Tonegawa, Susumu, 1939–, Japanese molecular biologist, Ph.D. Univ. of California at San Diego, 1969. A member of the Basel Institute for Immunology in Switzerland (1971–81), he became a professor of biology at the Massachusetts Institute of Technology in 1981. Tonegawa discovered the general principle that underlies the body's ability to produce millions of antibodies from cells that contain a limited amount of genetic material. For his discovery, He was awarded the 1987 Nobel Prize in Physiology or Medicine.