Dr. Ryuzo Yanagimachi is a Professor Emeritus at the University of Hawaii and a member of the National Academy of Sciences, USA. His many contributions to the study of vertebrate fertilization and assisted reproductive technologies, include the first discovery of sperm chemotaxis in vertebrates and sperm hyperactivation, cloning in mice, and the first intracytoplasmic sperm injection (ICSI) in mammals. Here, he shares his career history in his own words and advice for today’s SSR trainees.
I was born and raised in the capital city, Sapporo, of the northern island of Japan, Hokkaido, in 1928. None of my family members and relatives were scientists. I had a brother who was five years senior to me, and when I was in the 3rd or 4th grade of primary school, he and one of his friends took me to a nearby mountain to catch frog and newt eggs. It was springtime, perhaps early April. As Hokkido had (and still has) a long cold winter, walking along a snow-melting path was something entirely new and pleasant to me. This was the first time I was exposed to nature.
Over the next few years, I went to the same mountain by myself, while the interests of my brother and his friends shifted to other subjects like painting, model airplane making, music, and so on. Meanwhile, I became an "expert" in tadpole rearing (in spring) and insect collection (summer), which I did by myself. World War II started when I was in the 7th grade. We thought that all we Japanese, young and old, were going to die. We were sort of brainwashed. Dying for the emperor and country was the ultimate honor. It was something like today's North Korea. It was lucky for Japan to be beaten by the USA and to rebuild the country from ashes.
I remember that my father had a hard time finding nails to buy from stores to use to repair our home. A younger brother of my mother was the only person I knew who was involved in science and engineering. He was an engineer of a steel-manufacturing company with whom I shared interests in scientific subjects like star-gazing (astronomy), using a telescope handmade from grandfather's eye-glass. He told me that Japan's promising future would be in electronics and civil engineering. I did not like "electro" as I was electro-shocked several times when I played with a 100 V electric current. This was the reason why I first enrolled in civil engineering but soon realized that it was not what I really wanted to do. We can have life only once. I thought it would be great to have an occupation where I could work with Mother Nature. My memory went back to my childhood when I walked around mountains in spring and summer to catch frogs and insects.
So, after engineering school, I entered the College of Natural Science of Hokkaido University in Sapporo, majoring in zoology. My mentor for a guided research project in the last three years in the University was an embryology professor who asked me to study fertilization in fish (herring). While reading a textbook, Cell in Development and Heredity, written by E.B. Wilson (Univ. of Chicago Press, McMillan Co, 1925) I came across the theory of heredity by Nussbaum and Weismann: "The child does not inherit its characters from the parental body but from the germ cells. So far as heredity is concerned, the body is merely a carrier of germ cells." From this moment, this concept became the driving force of my entire research career.
I received a Doctor of Science degree (= Ph.D.) from Hokkaido University in 1960 after studying fish fertilization and reproduction in parasitic barnacles, rhizocephalans, and I wanted to be a researcher of fish aquaculture. At that time, research positions were obtained mainly through recommendations by mentors, not public job advertisements. My mentor, Professor Ichikawa, maybe thought that I was not good enough to be a researcher, and he recommended me as a high school teacher. In fact, I was a full-time high school teacher for one year, but I quit it. I thought I could not be a researcher as long as I remained in Japan.
A year before I finished my doctorate, I had written a letter to Dr. M.C. Chang of the Worcester Foundation for Experimental Biology, Shrewsbury, MA, USA asking him if I could be his postdoctoral fellow after obtaining a Ph.D. degree. In those days there were only a few people, including Dr. Chang, Dr. C.R. Austin in England, and Dr. Thibault in France, were studying mammalian fertilization and I thought this area would become important someday. I did not expect to receive a reply from Dr. Chang, but to my surprise, he accepted me as a postdoc fellow and so I started my work on mammalian fertilization in 1960 under his mentorship. I was curious for many years why he accepted me as a postdoc despite my total lack of experience working with mammals. Many years later, Dr. Chang and his wife Isabelle came to Hawaii. While traveling through the Hawaii Volcano National Park, I asked him why he accepted me as a postdoc despite my total lack of experience. His reply was short: "Well, you did good work with fish." I am grateful to him for accepting me as his student.
I returned to Hokkaido University, Sapporo, Japan, after 4 years in Massachusetts. Soon after, Dr. Robert Noyes of Vanderbilt University, Nashville, TN sent me a letter saying he was going to move to the University of Hawaii to join a newly established medical school, and he asked me if I was interested in joining the Department of Anatomy and Reproductive Biology as an Assistant Professor. My answer was, of course, yes. I had to stay outside of the USA for two years before I became eligible to re-enter. I thus moved to Hawaii in 1966. I was 38 years old. I was promoted to full professor in 1977 and retired in 2005.
Today, within the building of the Institute for Biogenesis Research (IBR) in the University of Hawaii Manoa Campus, I can use one office room and two small labs at my disposal. I have neither research grants nor students. I do not want to interfere with any other members of IBR. Instead, I visit some of my former postdoctoral fellows who now have their own laboratories and research teams. I visit them from time to time to conduct research together. I do not seek extramural funds anymore. In a sense, I work with my former postdocs as their free postdoc fellow/ research collaborator. I am now 92 years old. As of today, I can still walk without a cane. I can still drive, renewing my driving license every two years. I am thinking of writing a review, entitled “Enigmas and unsolved problems of mammalian fertilization and related subjects." Since no journal asked me to write it, and there is no deadline date, I do not know when and if I will finish it.
What impact has the pandemic had on your daily activities and your research?
I have reached the age when I live year by year. Waiting one year is like waiting 10 years or more. The COVID pandemic makes visiting my collaborators very difficult or impossible. I wish the pandemic to be over very soon while I am still able to stand on my own feet. I hope I can finish writing the review mentioned above within one year. One project related to mammalian fertilization and one project related to fish fertilization are in progress.
What words of inspiration would you like to share with the future generation of scientists?
Research is like a long-distance marathon. When others slow down or stop running, it is time one keeps running.