Japanese scientist who won Nobel Prize

By the Editorial Team · Tuesday, July 28, 2026

Susumu Tonegawa, the Japanese molecular biologist who won the 1987 Nobel Prize for uncovering how genetic recombination generates antibody diversity, died at age 86. His pioneering work not only transformed immunology but also laid the groundwork for advances in vaccine development and memory research, impacting treatments for diseases like PTSD and Alzheimer’s.

Susumu Tonegawa, a Japanese molecular biologist renowned for his groundbreaking work on antibody diversity and memory formation, died on July 11 at his home in San Mateo, California. He was 86. The Massachusetts Institute of Technology (MIT), where Tonegawa served as a professor and founded the Picower Institute for Learning and Memory, confirmed his passing.

In 1987, Tonegawa became the first Japanese Nobel laureate in Physiology or Medicine for his discovery of the genetic mechanisms enabling the immune system to produce a vast array of antibodies. His work resolved a longstanding scientific puzzle: how can the body generate enough distinct antibodies to defend against countless pathogens despite having a limited number of genes?

Before Tonegawa’s research, two primary hypotheses were debated. One proposed that antibody diversity was genetically inherited and fixed at birth, while the other suggested that the body could modify antibody-producing genes in white blood cells known as B lymphocytes over time. Using hybrid DNA-RNA probes in experiments with mouse tissues, Tonegawa demonstrated that the body creates antibody diversity through somatic recombination—cutting and rejoining gene segments in B cells to produce new protein chains. This discovery fundamentally changed immunology by showing that antibody genes undergo rearrangement to generate variety.

Published initially in 1976, his findings laid the foundation for improved vaccine development and immunotherapies, and advanced understanding of autoimmune diseases.

In 1994, after joining MIT, Tonegawa shifted his focus to neuroscience. He established the Center for Learning and Memory (now the Picower Institute) and studied how memories form and are stored in the brain. His research identified "engram" cells in the hippocampus that encode different elements of memory, such as experiences, spatial information, and sensory details. Experiments manipulating these cells in mice illustrated how memories can be created or altered, offering potential pathways for treating conditions like post-traumatic stress disorder and Alzheimer’s disease.

Born on September 5, 1939, in Nagoya, Japan, Tonegawa was the son of Tatsumio and Miyoko Tonegawa. He earned his undergraduate degree from Kyoto University and his doctorate from the University of California, San Diego. He completed postdoctoral work at the Salk Institute before joining the Basel Institute for Immunology in Switzerland, where he conducted his Nobel-winning research.

Recruited to MIT in 1981 by Nobel laureate Salvador E. Luria, Tonegawa served as a mentor and innovator throughout his career. Colleagues praised his intellectual curiosity and interdisciplinary approach, which combined immunology and neuroscience.

Reflecting on creativity in science, Tonegawa once described it as a combination of intense curiosity, determination to solve a question, and integrating knowledge from diverse fields.

Tonegawa is survived by his wife, Mayumi Yoshinari, whom he married in 1985.

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