OBITUARY Setsuro EBASHI (1922–2006)

No. 6] Proc. Jpn. Acad., Ser. B 83 (2007) 179 OBITUARY Setsuro EBASHI (1922–2006) Professor Setsuro Ebashi, who was a Member of an ultracentrifuge or calcium isotope that was nec- the Japan Academy, Professor Emeritus, University essary to prove his hypothesis. Furthermore, when of Tokyo, and Professor Emeritus, National Insti- he obtained a series of chelating agents from Mr. tute for Physiological Sciences in Okazaki National Keihei Ueno, President of Dojindo Laboratories, and Research Institutes passed away on the morning of compared their calcium-binding activity with their July 17, 2006, at the age of 83. Prof. Ebashi had muscle-relaxing activity he could not find any cor- astroke six years ago in 2000. Thereafter, however, relation. He was disappointed by these results and his health remained relatively stable, and during an tentatively abandoned the idea of calcium being the international symposium in October 2005, celebrat- key substance. When he decided to go abroad to ing the 40th anniversary of his discovery of troponin, study in Prof. Fritz Lipmann’s laboratory of Rocke- he delivered a speech in English without a draft, as fellerInstitute in 1959, he considered changing his was his usual style, and impressed the scientists who research area. were assembled from all over the world. His condi- Prof. Lipmann, however, advised Ebashi to con- tion suddenly worsened a few days before his passing, tinue his research on the muscle. Around this period, which has been a deeply felt loss for his friends and Ebashi came across a paper in the library that sug- pupils. gested to him that the correlation between calcium- Prof. Ebashi was born in Koji-Machi, Tokyo on binding activity and muscle-relaxing activity of the August 31, 1922. He attended Tokyo Daiichi（first） chelating agents should be examined in the presence Middle School, Daiichi（first）High School, and then of magnesium ion. He then re-calculated the rela- graduated from Faculty of Medicine, University of tionship between the two activities and as a result Tokyo in 1944. He then served as a naval surgeon, found that they correlated exactly. This was an im- and was detained after the war in Shanghai. He re- portant turning point in his research career, and after turned to Japan in 1946, and joined Dr. Hiroshi that his research proceeded very smoothly. By fully Kumagai, who was his mentor when Ebashi was a utilizing an ultracentrifuge and calcium isotope, he medical student. Dr. Kumagai later became Profes- discovered that the activity of the relaxing factor was sor of Pharmacology, and then the Dean of the Fac- due to the removal of calciumion,andfurthermore ulty of Medicine, University of Tokyo. Thus, Ebashi that an extremely low concentration of calcium ion started his career as a scientist in the Department of directly acts on muscle proteins to induce a contrac- Pharmacology, University of Tokyo. tile change. Upon returning to Japan, he discovered After a relatively long time seeking to find his troponin, a calcium receptive protein that is essential specialization, Ebashi decided to concentrate his re- for the calcium sensitivity of muscle proteins. These search on the regulatory mechanism of muscular con- results altogether established the calcium theory of traction in the early 1950s. By this time, he was the regulation of muscularcontraction without any already almost 30 years old and it seems to be a rel- doubt. atively late start in contrast to the subsequent rapid Ebashi became a Professor of Pharmacology, progress in his research. Faculty of Medicine, University of Tokyo at the age Prof. Ebashi first investigated the relaxing fac- of only 36. Since 1971, he had been jointly appointed tor, which was the granularfractionextracted from as Professor of Biophysics, Faculty of Science, Uni- skeletal muscles, and in 1957, he began to perceive a versity of Tokyo. After retiring from the University relationship between the relaxing factor and calcium of Tokyo in 1983, he became Professor, National In- ions. However, the laboratory was in poor condi- stitute for Physiological Sciences in Okazaki National tion after the war, not being equipped with either Research Institutes, the Director-General of the Na- 180 Obituary [Vol. 83, Prof. Ebashi at the Rockefeller Institute in 1959. tional Institute for Physiological Sciences, and then thusiasm day after day until past midnight, and com- the President of Okazaki National Research Insti- pleted most of the important parts of his work either tutes. alone or together with his wife, Dr. Fumiko Ebashi, He became a Member of the Japan Academy we, the pupils, were at a loss and did not know how in 1978, served as the Chairman of the Section II to follow his ways of research. On the other hand, and the Secretary-GeneraloftheJapan Academy. he wholeheartedly took care of not only his pupils, He also served as Editor-in-Chief of the Proceedings but also his young friends who came in search of his of the Japan Academy, contributing greatly to the wisdom and advice. It is also well knownthatthe development of this journal over many years. conversation surrounding Ebashi was extremely en- Among the many prizes and honors given to joyable. I was looking forward, when he becomes less Prof. Ebashi for his achievements were the Impe- busy, to listening to his unique views about politics, rial Prize and the Japan Academy Prize, Order of culture and the history of science during the Taisho, Cultural Merit, Grand Cordon of the Order of the Showa and Heisei eras in which he lived. Sorrow- Sacred Treasure, International Prize for Biology, a fully, these wonderful opportunities are now forever Foreign Member of the RoyalSociety,London, and lost. It is regretful that Prof. Ebashi, who was ca- aForeign Associate of National Academy of Sciences, pable of doing anything, was somehow unconcerned USA. about his own health. Finally, I wish to touch upon Prof. Ebashi’s Iwishtoexpressmy deepest sorrow and condo- charming personality, which I observed within close lences to his family. range of him as one of his pupils. It was rather rare that he instructed his pupils to do some particular Masanori Otsuka, m.j.a. experiments or gave them some lessons. Instead, he showed us examples through his own actions. How- This obituary was translated from the message of con- dolence in Japanese by M. Otsuka, which was read at the ever, he had extraordinary intelligence and stamina. 1003rd General Meeting of the Japan Academy on November When he performedhisexperimentswithgreaten- 13, 2006..

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