[No. 193] Natsuko Yamakawa

I am deeply honored to have been given this opportunity to write as I mark my 15th year since stepping into the world of "research."

Compared to other countries, the percentage of women in Japan who choose to major in science is still quite low. I hope this can serve as a reference for the future for everyone considering their career paths, not just women.

One of the things that sparked my interest in the Department of Biosciences and Informatics was the "Summer Bio College" I attended as a high school student. At Keio University's Institute for Advanced Biosciences (in Tsuruoka City, Yamagata Prefecture), I experienced bio-experiments alongside high school students from Tsuruoka. I remember the excitement of using a Pipetman for the first time and handling something invisible to the naked eye (DNA). Around the year 2000, when I was in high school, "bio" was becoming a hot topic, and it was an era when the entire human genome was being sequenced. As someone who loves new things, biology was a fascinating field of study for me.

At the time, topics like ES cells and cloning technology were also in the news, and there was dream-like talk of one day being able to create organs and transplant them into humans. Against this backdrop, I decided I wanted to go to university to conduct research in biology and medicine, which led me to choose the Faculty of Science and Technology.

As a first-year student who had entered the university from an affiliated high school, I struggled just to keep up with the required science courses. The Faculty of Science and Technology had many required lectures in large classrooms, which made it easy to make friends across different classes. By helping each other out, my friends and I managed to get through the coursework. When it came time to choose a department for my second year, I was able to get into my desired Department of Biosciences and Informatics.

When it was time to be assigned to a laboratory in my fourth year, I was able to get a feel for the research and atmosphere of each lab through interactions with the TAs, as each lab was in charge of a required experiment course. At that time, popular labs were decided by a lottery, and I was fortunate enough to be assigned to the laboratory of Professor Hiroshi Yanagawa.

Looking back now, after receiving the request to write this piece, I realize again how "fun" my three years in the Yanagawa lab, including my master's program, were. Before joining a research lab, you basically only experience experiments that have a known answer. But once you're in a lab, you formulate a hypothesis, and the results you obtain from your own experiments become the answer. As I repeated the cycle of planning the next experiment based on the results and consulting with Dr. Nobuhide Doi, my senior colleagues, and my peers when I got stuck, I began to think that I wanted to continue doing "research."

I was especially blessed with great classmates who became rivals in a good way, and I became engrossed in my research. In addition to research, it was an intense three years where I poured my energy into other activities as well, such as softball, birthday parties for lab members where we brought homemade sweets, and selling takoyaki at the Yagami Festival.

Around the time my lab mates started job hunting, I began to seriously consider pursuing a doctoral degree. At the Yanagawa lab, we could conduct experiments at the cellular level, but we couldn't do experiments involving mice. Around the same time, I became interested in immunology, so with these keywords in mind, I visited various graduate school laboratories. I visited about ten labs in total, spoke with professors and lab members, and ultimately decided to join the lab of Professor Kensuke Miyake in the Division of Innate Immunity at the Institute of Medical Science, The University of Tokyo. (Taking entrance exams again after a long time was very nerve-wracking).

After obtaining my degree, the first person I worked under was Professor Megumi Takiguchi at Tokai University. At the time, Dr. Takiguchi had just obtained tenure, so the lab was full of energy with a "let's do our best together" spirit. It was here that I first experienced experiments using humanized mice.

Amidst all this, I wanted to get involved in immunological research using human samples, something I had been interested in since I was a student. So, I began my research life under Dr. Eric Meffre in the Department of Immunobiology at Yale University's School of Medicine. I had wanted to study abroad someday ever since I was in elementary school, so I was truly fortunate to have the opportunity at that time. Having moved between several labs in Japan, I had the chance to learn the good and bad aspects of each, which allowed me to compare life in an American lab with a somewhat established style of my own. When I thought about returning to Japan, I felt it would be difficult to conduct research using human samples on the same scale as in the United States. That's when I wondered about research using monkeys and decided to join my current institution, the Primate Medical Science Research Center. Here, we mainly use cynomolgus monkeys to create and analyze pathogen infection models. COVID-19, which has been getting a lot of attention lately, is also one of our research subjects. I myself am working on evaluating a new tuberculosis vaccine, and I spend my days searching for experimental and analytical methods unique to monkeys, which are different from those for mice and humans.

Until now, the longest I have stayed in any single laboratory is four years. While my research themes are somewhat connected, they are relatively diverse. I think moving between labs is similar to changing jobs. You have to relearn the fundamental knowledge, so perhaps there is more "lost time" compared to someone who continues in one field. Nevertheless, I believe these experiences are what have shaped me into who I am.

Choice and decision have always been the keywords for me. There is no single "right" answer, so no matter what path you choose, and even if you end up on a path you didn't initially want, I hope you will believe in yourself and take the leap.