Exploring the "strictness" and "flexibility" of yeast mutual recognition and investigating the mechanisms behind speciation, evolution, and environmental adaptation

Q1. What inspired you to become a researcher?

A1. Guidance from my advisor's "5-year plan"

Looking back, I realized I had naturally become a researcher. In high school, I only studied biology during my first year, but I became fascinated by the stories shared by a student teacher, which led me to major in biology at university.

As a senior, I intentionally chose a laboratory that had a reputation for being the most demanding. Core hours were from 10:00 to 19:00, six days a week. To improve our English proficiency, Thursdays were strictly English-only for all conversations. Additionally, our daily routine included translating a short Japanese text left on our desks each morning into English and submitting it. It was a rigorous yet deeply supportive environment.

It was there that I encountered yeast research, and my specific research theme was decided based on an interview when I joined the lab. Thereafter, my advisor handed me a three-page, A4-sized research proposal titled "5-Year Plan." In hindsight, that plan likely mapped out my path all the way through the doctoral program. Although I engaged in job-hunting activities during my master's program, a lingering feeling of having unfinished business drove me to pursue a Ph.D. I feel that the "5-Year Plan" naturally guided my steps onto the path of becoming a scientist.

Q2. What research are you currently working on?

A2. Exploring diversity and evolution through wild yeast

Using fission yeast as a model organism, I am investigating the mechanisms of sexual reproduction evolution and environmental adaptation. Yeast cells also have sexes, and two distinct mating types recognize each other via pheromones to mate. The pheromone secreted by each cell and the receptor located on the cell membrane of the opposite mating type share a "lock-and-key" relationship. Even a minor alteration in the pheromone's structure prevents them from binding. During my student days, I engineered a "new species" that does not mate with conventional yeast by genetically modifying these pheromones and receptors.

While the mechanism by which yeast recognize each other is extraordinarily strict, the birth of a new species in nature also requires a certain level of "flexibility" to allow mating between different species. Believing that this dual nature holds the key to environmental adaptation and evolution, I am dedicating significant effort to fieldwork. Focusing on the ecological trait where fruit flies (Drosophila) feed on yeast, I collect fruit flies across various regions in Japan to analyze the genetics of wild yeast. The pH level within a fly's gut changes depending on the section, and the environmental shifts yeast experience while passing through the digestive tract temporarily loosen the pheromone recognition mechanism. In turn, the gut is transformed into a "mating ground" where diverse yeast strains can encounter one another. This is my hypothesis of the formation of the mating ground.

To date, I have collected more than 2,000 strains of wild yeast and created a catalog visualizing the characteristics of selected strains. In Okinawa, I discovered a promising new yeast species capable of breaking down unique sugars and exhibiting high-temperature tolerance. Yeast is a microorganism deeply intertwined with our daily lives, playing an essential role not only in bread and liquor but also, surprisingly, in the manufacturing of chocolate. Joint research projects with food and liquor companies are already underway to develop new products using these novel yeast strains. Harnessing the diverse potential of yeast and returning those benefits to society is one of my primary goals.

Q3. What is your message to aspiring researchers?

A3. Research is not just a profession, but a "way of life"

Life presents us with countless turning points, such as choosing further education or entering the workforce. Everyone wonders which path to take, but there is no single "right" answer, no matter which one you choose. What truly matters is making your own decision and possessing the mindset to turn that chosen path into the right answer.

Research is a series of failures, but since I believe that is its very nature, I don't really feel it's a struggle. Even when favorable results do not emerge, I try to think that it was simply a matter of bad luck. To me, being a researcher is not just a profession, but a "way of life." As long as someone is driven by the desire to uncover or understand something, they're a researcher, whether they're affiliated with a university or research institution. I hope people aspire to be researchers not merely as a profession, but as a way of life.

(Article: Yasuhiro Hatabe)