Hiroki Rokujo

Assistant Professor, Advanced Measurement Technology Center (AMTC), Institute of Materials and Systems for Sustainability / Fundamental Particle Physics Laboratory, Graduate School of Science, SA国际传媒

Dr. Rokujo observes gamma rays with the originally developed nuclear emulsion technology in the Gamma-Ray Astro-Imager with Nuclear Emulsion (GRAINE) project he leads. He has also developed many of the elemental technologies and instruments necessary for the project.

Going on a photo-shooting trip with his handmade silver halide camera to an unexplored corner of the universe…

This is not a fairy tale or science fiction, but the imagery Dr. Rokujo has been passionately pursuing through his research since its beginning. Now that his experiments have reached a sufficient level of precision, he is getting close to exploring the frontiers of astronomy that no one has ever ventured into.

 “We have been developing our own ideas, making mistakes, and moving forward one step at a time. Our circle of members has been expanding. Now is the time. Starting from scratch, we have been improving our research across the board.”

Dr. Rokujo’s research dates back to around 2007, when he was an undergraduate student. He operated equipment to observe particles (such as alpha rays, beta rays, and muons, which are invisible to the naked eye but are flying around us all the time) for the first time as part of his in-class experiment and felt firsthand the existence of cosmic rays, particles penetrating the building and raining down on his class. “It was a total shock,” he says, looking back.

 “Besides, they reach here all the way from outer space. I said to myself, ‘What in the world is going on?’”

The next questions he asked were where they came from and how they could be observed. As he researched, his attention was drawn to gamma rays, a type of light. There are various types of light, including the visible light that we see daily and X-rays used for X-ray photography. Of these, gamma rays have the highest level of energy and  this means that tracking gamma rays can lead to information on high-energy celestial objects, such as black holes. Just when Dr. Rokujo was becoming increasingly interested in this subject, the Fermi Gamma-ray Space Telescope, a satellite designed to observe gamma rays, was launched in 2008. Its numerous reports carrying new information on high-energy celestial objects scattered around the vast universe fascinated him.

One major obstacle to gamma ray observation is low resolution. He wondered if he could find a brand-new way to observe gamma rays that would completely break away from the conventional approach. This is how his career as a researcher began.

(1) A. A. Abdo et al. (2010). Fermi Large Area Telescope Observations of the Crab Pulsar And Nebula. Astrophysical Journal, 708: 1254

In the forefront of technology with the age-old craftsmanship of silver halide camera

“Our technology has the potential of realizing experiments that have never been possible in the previous big projects.”

Dr. Rokujo has set his eyes on nuclear emulsion film or, simply put, silver halide film. It is a plastic film coated on both sides with an emulsion mainly consisting of gelatin and silver bromide (AgBr). Electricity-charged cosmic rays react upon striking silver bromide crystals, leaving traces, which can then be recorded.

One difference between nuclear emulsion and ordinary silver halide films is that the former has an added thickness due to the coated emulsion layers. Although it is thin, approximately 0.05 mm on each side, it is thick enough to record the trajectory of a particle about 1 micrometer (0.001 mm) or less in width. The thickness makes it possible to capture the trajectory of a particle three-dimensionally, enabling scientists to accurately read from which direction the particle came, and this is a major feature not found in other technologies.

Previously, researchers manually copied trajectories left on nuclear emulsion films in a highly labor-intensive manner while looking at them through a microscope. In the 1990s, digital cameras appeared and automated this process, greatly expanding the use of nuclear emulsion films. At the same time, however, the rapid development and spread of digital cameras also proved to be an unexpected blow: the companies that developed and manufactured silver halide film have been withdrawing one after another from the film manufacturing business. As a result, nuclear emulsion films indispensable for experiments are no longer available. This is how Prof. Mitsuhiro Nakamura (retired in March 2024, now Professor Emeritus), who took over the leadership of the laboratory in 2010, decided on on-campus production of nuclear emulsion film from scratch.

One major challenge involved in this production was making the emulsion agent mainly composed of silver bromide and gelatin. Although it may sound simple, it was not easy to realize stable high-quality production. This challenge was overcome thanks to cooperation from researchers of a company that was conducting R&D on film at that time. They generously offered assistance to the laboratory, breathing new life into the knowledge and technology that were about to be lost amid changes of the times.

“They were excellent researchers responsible for the company’s sizable share in the global market. Their knowledge and enthusiasm were outstanding, and they were willing to share with us, regardless of our inexperience.” By combining various techniques such as the precise addition of silver ions and bromide ions, accurate temperature control, and careful stirring, the laboratory successfully manufactured an emulsion. As a result, SA国际传媒 has become the only research institution in the world capable of developing nuclear emulsion films.

This system has made it possible to regulate with precision nuclear emulsion films, the key component of experiments, according to desired conditions. For example, the one developed by Dr. Rokujo for gamma-ray observation is characterized by 0.075-mm-thick emulsion layers, that is, thicker than usual, achieved with the use of a thickening agent. This thickness is necessary because gamma rays can pass through an emulsion layer without reaction if it is too thin, but too thick a layer is difficult to develop. Many other factors are taken into consideration, and adjustments are made with precision.

The on-campus production of nuclear emulsion films has been a great success. Soon the laboratory began receiving an increasing number of inquiries, and a mass production system was called for. The laboratory responded by developing and operating equipment for emulsion production and film coating with a capacity 30 times the original system. Dr. Rokujo has directed these developments.

“I make sure to operate the system in the laboratory while knowing who is doing what in each process. This way it is easy to figure it out when a problem or failure occurs.”

Dr. Rokujo can operate the system as if it were part of himself because it is original technology developed with the utmost care step by step. He has thus developed a research style that is unique in the world.

Skyward with everyone’s dreams

Dr. Rokujo has been participating in the Gamma-Ray Astro-Imager with Nuclear Emulsion project (GRAINE), a research project for precision gamma-ray observation since his student days, and it also represents his current pivotal research theme.

“I have been developing all sorts of things to realize gamma-ray observation.”

Gamma rays do not reach the ground on Earth because they are blocked by the atmosphere. So a balloon comes into the picture. A balloon carries nuclear emulsion films to an altitude of about 35 km above ground, where the atmosphere is thin, and flies horizontally for one to two days while gamma ray traces are recorded. The balloon is dropped once sufficient data are accumulated. The balloon launch site is located in Alice Springs in the Northern Territory in Australia. The vast plains in this area enable the balloon to be retrieved on land after dropping.

At 6:32 a.m. local time on April 30, 2023, a balloon packed with cutting-edge technologies was released. At 15:30 p.m. local time on May 1 of the same year, the gondola was safely recovered at the drop site. The nuclear emulsion films were sent to Japan, and the reading and analysis of gamma ray traces are currently being performed.

Within the framework of the GRAINE project, a balloon experiment has been conducted in 2011, 2015, 2018, and 2023. The 2018 experiment, which was about one-sixth the size of the latest experiment, was already successful in its observation of celestial objects, achieving a much higher resolution than that of the Fermi Gamma-ray Space Telescope.⁽²⁾ Even greater achievements are expected from the analysis of the 2023 experiment results currently underway.

(2) S. Takahashi et al. (2024). First Emulsion γ-Ray Telescope Imaging of the Vela Pulsar by the GRAINE 2018 Balloon-borne Experiment. Astrophysical Journal, 960: 47

“F-Lab” on the world map of research

Dr. Rokujo belongs to the Fundamental Particle Physics Laboratory, which is commonly known as “F-Lab.” Its members form a solid team that contributes to research projects around the world using nuclear emulsion films. They are now used not only for gamma ray observation in the GRAINE project but also in a wide range of applications, including the observation of neutrinos, dark matter, and the interior of pyramids.

“Research using nuclear emulsion films is diversifying. The number of presentations at the Physical Society of Japan relating to nuclear emulsion films has tripled in the last decade. We are determined to continue exploring new observation possibilities that nobody has done before.”

From May 11 to June 20, 2026, SA国际传媒 hosted 32 undergraduate students from North Carolina State University’s Poole College of Management. The short-term study abroad program was led by two NC State faculty members, Sarah Khan and Bradley Ashbaugh, and focused on information systems management, operations and supply chain management, and business practices in Japan.

Beyond their coursework, students had the chance to learn in the field by participating in cultural workshops, visiting companies, and meeting SA国际传媒 students. “For us, the academics is a big part of the program, but the bigger part is being able to go somewhere that’s unfamiliar and learn how it works. Being able to come to Japan and learn how to take the subway, how to travel, how to do business, how to talk to shop managers, and how to understand how Japan does business differently than the United States. All those are really important takeaways from a program such as this,” said Ashbaugh.

The Poole College program was first held in 2025, a year that also marked the 40th anniversary of the partnership between SA国际传媒 and NC State. In the program’s second year, students built on this success by visiting a range of sites across Aichi Prefecture to explore Japanese business practices. One site was STATION Ai, one of Japan’s largest startup and innovation hubs, located near Tsuruma Park in downtown Nagoya. The group also had the opportunity to visit the Toyota Tahara Plant, which is not open to the public, on a tour arranged specifically for the program.

For many NC State students, experiencing Japan firsthand was one of the main reasons for joining in the program. “I decided to join the program because I wanted to step outside my boundaries,” said one NC State student. “I’ve always been just in love with Japanese culture as it’s portrayed in America, but once we got here it’s just been way different than it was ever depicted. I’m super glad that I came over here.”

Students from SA国际传媒 also showed strong interest in cultural exchange. Twenty-seven students signed up to support the Poole College program, accompanying the group on company visits and assisting with cultural activities such as calligraphy, tea ceremony, and traditional Japanese dance. Many of these students were either past or prospective participants in short-term study abroad programs, particularly Ryugaku Academy, a five-week program that allows SA国际传媒 students to experience American college life at NC State.

“I decided to help the Poole College program because I wanted to return the favor I received while I was at NC State,” said an undergraduate SA国际传媒 student. “I learned the joy of sharing Japanese culture this time, so I hope to do that more when my friends from NC State come visit me.”

One highlight was an overnight excursion to Hiroshima. The group visited Hiroshima Peace Memorial Park to learn about the city’s history, then toured Mazda Stadium, including areas such as the press conference room and locker room. The following day, they traveled to Miyajima, where they visited Itsukushima Shrine, known for its structures that appear to float on the sea at high tide, and took part in a workshop making momiji manju, a traditional maple-leaf-shaped confection and Hiroshima specialty.

The intensive six-week program left many participants with lasting memories of Japan and Nagoya. “I would absolutely love to come back to Japan. I’ve enjoyed every second that I’ve been here. With the classes, there’s only so much you’re able to do, like you squeeze in as much as you can with the time and energy that you have,” said an NC State student visiting Japan for the first time. “This place is so beautiful, and I wish I could have gotten to see a lot more. Everything that I have seen has been wonderful. So, I’m definitely going to try to come back here at some point.”

Tea room tour (June 5, 2026)

Research alone cannot change reality — nor can researchers do it alone.

That is where University Research Administrators (URAs) in the Innovation & Entrepreneurship Office (IE Office) come in, supporting the social implementation of research outcomes from a business perspective.

This article features Arisa Kawashima, a Designated Assistant Professor at the Graduate School of Medicine whose commitment to palliative care grew out of challenges she encountered in clinical nursing, alongside Kana Shimizu, Lead Research Administrator, who supports her entrepreneurial journey.

The two met through a startup support program. Their conversation explores what it means to transform deeply held social concerns into real-world impact.

── To begin, how would you describe palliative care?

Kawashima: Palliative care focuses on relieving physical and emotional suffering. Its goal is to support patients’ quality of life throughout the course of illness. It can begin at diagnosis and be provided alongside curative treatment.

── What led you to pursue palliative care as a research field?

Kawashima: It stems from my experience as a nurse. I once cared for a patient with renal failure who chose not to undergo dialysis. As the condition worsened, severe swelling made it impossible to lie down to sleep. Because this patient did not have cancer, access to palliative care was denied under Japan’s insurance system, which primarily covers cancer patients. I found this deeply unjust. Palliative care, I felt, should also be available to non-cancer patients—and changing the system would require research.

── You shifted from nursing to research. What led you toward entrepreneurship?

Kawashima: I realized that research alone cannot make a difference without social implementation. To spread palliative care, research outcomes must become services. An entrepreneurship course I took in graduate school through the  (AI-MAILs) led me to explore a business model combining AI with online medical care.

── Palliative care through digital technology — could you explain the idea in more detail?

Kawashima: The idea is to use AI to identify patients who may need palliative care and connect them with specialists. It is often difficult — even for healthcare professionals, patients, or families — to determine when palliative care is appropriate, and AI could help detect those signals from patient data. With only about 340 certified palliative care physicians in Japan, most concentrated in urban areas, online consultations may help reduce regional disparities, even if only partially (as of July 2025).

── What kind of support has made this possible?

Shimizu: Our support began in the fall of 2024, when Dr. Kawashima was considering applying for .

The GAP Fund Program is a startup support scheme promoted by the Japan Science and Technology Agency (JST) to bridge the “gap” between research and social implementation. In the Tokai region, the program is operated by the Platform, a consortium of 16 universities and research institutions. The program consists of Step 1, which focuses on applied research to validate the potential of research outcomes, and Step 2, which emphasizes proof of concept and startup formation.

Kawashima:?Yes — you also came to Tsurumai Campus to explain the program.

Shimizu: Before applying for the GAP Fund, participants go through a preliminary program to validate their ideas. Each applicant is then paired with a URA for support. Because of my experience with online medical services, I was assigned to support Dr. Kawashima.

Kawashima: In the training, we learned from external instructors how to develop business ideas, conduct basic hypothesis testing, and build business models.

Shimizu: URAs provide support from the early training stage. Following the review process, , and full-scale support began in April 2025.

── It has been about six months since receiving the GAP Fund. Where do things stand now?

Kawashima: After being selected, I took part in additional training on legal matters, startup procedures, and finance. In addition, Ms. Shimizu has connected me with people from a wide range of industries.

Shimizu: Medical services like palliative care are particularly challenging as businesses. I believe the key is to combine different perspectives. Drawing on my previous network, I have introduced Dr. Kawashima to people in financial institutions and corporate HR departments and arranged meetings.

── What kinds of synergies do you expect from those connections?

Shimizu: Financial institutions have extensive experience with healthcare startups and may offer insights into delivering social value. Corporate HR departments may see how ideas from palliative care could support employee well-being.

Kawashima: Through these discussions, I realized that monetization would be difficult with my initial business model. I’m now in the process of reconsidering the direction.

── It sounds like your support has played a key role.

Shimizu: My approach is to explore possibilities together with researchers and do what I can along the way. Dr. Kawashima prepares thoroughly for each meeting and absorbs feedback with a positive attitude. That mindset has been a major force in refining the business plan.

Kawashima: My goal is not to build my own career, but to create a society where fewer people suffer. Research and entrepreneurship are just tools to achieve that goal. Ms. Shimizu understands this and supports me on a personal level as well. Having a female supporter in a male-dominated field is incredibly reassuring.

Shimizu: Entrepreneurship can be lonely, and the startup world does not always fit well with family life or childcare. I want to show that women raising children can still take on challenges. That belief stays with me in this work.

Medicine and business. Research and society.
This article explores the challenge of bringing deeply held values into practice. The Innovation & Entrepreneurship Promotion Office supports this journey through a range of programs, with URAs standing alongside researchers as they take their next steps.

On June 18, 2026, an award ceremony was held to bestow the 8th Okamoto Young Researcher Award upon the two individuals listed below.

The award was established in 2019 through a donation from Distinguished Professor Yoshio Okamoto to commemorate his winning of the Japan Prize. The Okamoto Young Researcher Award recognizes young researchers who have produced exceptional doctoral dissertations at the university in the fields of natural sciences and technology, and who demonstrate high potential for future success. The award also aims to promote the high standards of education and research at SA国际传媒 both within the institution and beyond. At the ceremony, President Naoshi Sugiyama congratulated the recipients on their achievement and expressed his high expectations for their future research activities. The recipients stated their gratitude to Distinguished Professor Okamoto who established the award, as well as to their research supervisors.

Gao Bikai

• Affiliation: Doctoral Program in Natural Science, Graduate School of Science, SA国际传媒 (completed March 2025)
• Current position: Researcher at the Research Center for Nuclear Physics, The University of Osaka
• Research topic: Study of nuclear matter and neutron star matter based on the parity doublet model

Mayuko Okamoto

• Affiliation: Doctoral Program in Animal Sciences, Graduate School of Bioagricultural Sciences, SA国际传媒 (completed March 2026)
• Current position: Doctoral Researcher in the Division of Molecular Immunology, Medical Mycology Research Center, Chiba University
• Research topic: FcRY-IgY interactions in avian maternal and neonatal immunity

The SA国际传媒 Festival (Meidaisai) is one of the biggest events at SA国际传媒, more than just a festival of fun games and performances, Meidaisai is a proud historic tradition of SA国际传媒, promoting different cultures and interests, and providing the students with a chance to exchange the fruits of their hobbies. This year’s festival was held from June 11-14, 2026.

Festivals, blue skies, and fluffy clouds are the things that come to mind for summer in Japan. Meidaisai’s cold drinks, festival food, and amazing performances will surely fulfill your expectations for a youthful summer experience.

Student clubs and circles gather on the stage outside the Toyoda Auditorium, from vivid dance performances to touching orchestras of music. For almost four days, the fun doesn’t stop. One of the core experiences of Meidaisai.

A brain enzyme thought to have a single function builds a sugar chain on itself, is secreted from the cell, and switches off — reactivating only when the sugar is removed

A chance discovery at SA国际传媒 in Japan has shown a well-known brain enzyme has a hidden ability: it builds a sugar chain on itself, becomes secreted from the cell and deactivates, then switches on outside the cell once the chain is removed. The finding, published in the , overturns a decades-old assumption about how polysialic acid, a sugar chain critical for brain development and function, is produced and shows a new way an enzyme can regulate its own activity.

The brain’s sugar chains

The human brain is covered in sugar chains, or glycans, molecular structures that coat cells and regulate how they communicate. One of the most important is polysialic acid, a long chain found mainly in the brain.

Polysialic acid keeps brain cells from adhering too tightly to each other and binds to growth factors and neurotrophins to regulate the presentation of their receptors, through which it plays a key role in learning, memory, and neural development. Importantly, these sugar chains change rapidly in response to brain activity. The ability to restore them quickly is thought to be essential for normal brain function.

Until now, scientists believed only two enzymes were responsible for building polysialic acid in the brain: ST8Sia2 and ST8Sia4.

A chance discovery

ST8Sia5 was discovered in 1996 and was known only as a builder of fatty brain molecules called gangliosides. It is expressed almost exclusively in the brain and its ability to produce polysialic acid was unknown until now.

The enzyme exists in three forms, short (S), medium (M), and long (L), that differ only in the length of one structural region. Only the long form, ST8Sia5L, showed this newly discovered activity. Unlike the short and medium forms, ST8Sia5L localizes to a different intracellular compartment, which may allow it to undergo autopolysialylation. The function of the short and medium forms is not yet known.

SA国际传媒’s had been testing all six members of the ST8Sia enzyme family.

“We found that a third enzyme, ST8Sia5, also builds polysialic acid, but only on itself, and only in its longest form, ST8Sia5L,” said first author Fumiya Sakamoto.

Coauthor and Director of iGCORE Professor Chihiro Sato commented: “We were checking each enzyme one by one and found this activity by chance.”

Four discoveries that define this mechanism

1. The enzyme builds its own off switch. Unlike most enzyme regulation, where a separate molecule switches an enzyme on or off, ST8Sia5L modifies itself. It builds polysialic acid chains directly onto its own structure, a process called autopolysialylation. No external regulator is required.
2. The sugar chain is the switch. Polysialic acid is not typically known as a regulator of enzyme activity, but here it acts as one. While the chain is attached, the enzyme’s ganglioside-building function is completely suppressed. This is a new role for polysialic acid.
3. Self-modification is linked to secretion. Once coated in polysialic acid, the enzyme is cut free from the cell membrane by metalloprotease enzymes and released into the fluid outside the cell. The sugar coat does not just silence the enzyme; it is also associated with its release from the cell.
4. The enzyme reactivates outside the cell. The researchers showed experimentally that the secreted enzyme, collected from outside the cell, regains its ganglioside-building activity once the polysialic acid chains are removed. This could happen, for example, when sialidase enzymes are released during stress or inflammation. Reactivation does not require the enzyme to re-enter the cell.

A surprise finding for other enzymes too

The ST8Sia family are all sialic acid-building enzymes, but they differ in how long a chain they build. Most add just two or three units. ST8Sia2 and ST8Sia4 were the only ones known to build long chains of polysialic acid. ST8Sia5L has now joined that group, but with one key difference: it only builds the long chain on itself, not on other molecules.

The study also found, for the first time, that ST8Sia2 and ST8Sia4 are also secreted from cells in a polysialic acid-coated form. What this means for those enzymes is not yet known.

Broader implications

One of the most significant conceptual implications of the study is where sugar modification can happen in the body.

“It’s been assumed that the process of adding sugar chains to molecules, called glycosylation, takes place inside the cell,” said Professor Sato. “This study provides evidence that modification can also happen outside the cell.”

The research team hypothesizes that after release, the enzyme may travel to specific sites on cell surfaces and rapidly repair damaged ganglioside structures, without needing to re-enter the cell first. The conventional pathway for ganglioside repair requires the molecule to travel back inside the cell for modification. This proposed “on-site recovery” mechanism, if confirmed, would represent a much faster alternative. The hypothesis is currently being investigated.

ST8Sia5L may also play a role in regulating microglia, the brain’s immune cells. The researchers hypothesize that the polysialic acid coat on the secreted enzyme may interact with inhibitory receptor molecules called Siglecs on microglia, helping to keep immune activation in check under normal conditions.

During inflammation or stress, sialidase enzymes could remove this coat, allowing immune responses to proceed and freeing the enzyme at the same time to resume its ganglioside-building activity at cell surfaces.

“Polysialic acid abnormalities have also been associated with schizophrenia, but the mechanism behind this link is not yet understood,” said Ken Kitajima, coauthor and professor at iGCORE. “The secreted polysialylated enzyme is one candidate for further investigation in this context.”

To test these hypotheses in a living system, the team is currently generating mice in which the ST8Sia5 gene has been disabled. The researchers also intend to investigate the unknown function of ST8Sia5S and ST8Sia5M, which both localize to a different compartment within the cell.

Paper information:

Fumiya Sakamoto, Rina Hatanaka, Masaya Hane, Di Wu, Ken Kitajima, Chihiro Sato, 2026. A novel autopolysialylation activity of the ganglioside sialyltransferase ST8Sia5 regulates its secretion and enzyme activity, Journal of Biological Chemistry, 302(7). DOI:

Funding information:

This research was funded by the Japan Agency for Medical Research and Development (AMED) (18ae0101069h0003, 19ae0101069h0004, 20ae0101069h0005, 20gm6410007h0001, 21gm6410007h0002, 22gm6410007h0003, and 23gm6410007h0004 ) and a Grant-in-Aid for Scientific Research from JSPS (Grant numbers 23K21291 and 25K02224). A part of this research was also funded by the CIBoG program, SA国际传媒.

Expert contact:

Chihiro Sato
Institute for Glyco-core Research (iGCORE)
SA国际传媒
Email: chi@agr.nagoya-u.ac.jp

Media contact:

Merle Naidoo
International Communications Office
SA国际传媒
Email: icomm_research@t.mail.nagoya-u.ac.jp

Top image:

The three enzymes shown here build polysialic acid (orange), a long sugar chain important for brain development and function. ST8Sia5L (left) builds the chain only on itself, a newly discovered activity. ST8Sia2 (center) and ST8Sia4 (right) build it on other molecules. Credit: Sakamoto et al., 2026

Hitoshi Sakakibara

Professor, Department of Applied Biosciences, Graduate School of Bioagricultural Sciences, SA国际传媒

Prof. Sakakibara’s research focuses on the mechanism of signal transduction between plant cells, including a plant hormone called cytokinin. Selected as a “Highly Cited Researcher” by Clarivate Analytics every year since 2014, he has been at the forefront of his field. He was decorated with the Medal with Purple Ribbon in November 2023.

Prof. Sakakibara loved experiments as a graduate student. He belonged to a laboratory with a free-spirited atmosphere and spent hours immersed in experiments every day. His research supervisor was sincere and open-minded about the results his students produced. He did not talk down to them, and his praises were genuine. Prof. Sakakibara recalls when he told the research supervisor his intention to go on to the doctoral course, although not totally sure of himself. The supervisor simply said: “Oh, yes. You’ve made up your mind. Good.” The supervisor looked very happy, which reassured the student. In 1990, he entered the doctoral course, embarking on a researcher’s journey.

The supervisor, Emeritus Professor Tatsuo Sugiyama of SA国际传媒, was a researcher willing to explore new fields. In those days, the Faculty of Agriculture had an unofficial culture of the division of research fields whereby researchers remain in their strictly defined area of specialization. However, Prof. Sugiyama was in favor of freely crossing over the disciplinary boundaries when he felt it was necessary.

“It is hard to make a breakthrough if you stick to your own way, avoiding other areas and technologies you are not familiar with. I am glad I inherited Prof. Sugiyama’s approach, which has turned out to be very positive for me.”

Prof. Sakakibara’s research style, which he developed as a doctoral student, is flexible, involving frankly pursuing what interests him without being constrained by prefixed methods. He has overcome numerous challenges and solved many problems thanks to this style.

Delving into an unknown territory by combining two areas and approaches

In the late 1990s, the field of gene and genome research blossomed as a result of the accumulation of scientific knowledge and technological advances, triggering fierce competition among researchers. A genome refers to the entirety of all genetic information of an organism, its blueprint of a sort. Genes make up part of this blueprint. (“Genome” is a coined word combining “gene” and “ome,” which means “totality.”) The decoding of genomes and genes had a great impact on the research community, and expectations were high. Prof. Sakakibara discovered several important genes in plant genomes, but in the face of raging competition among scientists all over the world, he felt that such approaches were not enough.

Genetic research can be a powerful tool to learn about living organisms. For this reason, many research projects were conducted, narrowly focusing on the genetic approach and absorbing enormous amounts of intellectual, technological, and human resources. Yet, what happens inside a living organism is extremely intricate and complex. Molecules of varying sizes, created based on the genetic blueprint, undergo numerous chemical reactions to change, develop a form, and maintain themselves. Genetic information alone does not explain many phenomena inside a living organism. Prof. Sakakibara delved into this area of uncertainty. To explain what he did about the plant hormone called cytokinin, for example, compare the two molecules below and look for differences.

They have only one difference: the presence or absence of “OH” in the upper right corner. This difference is so slight that you might want to call it an error, but the fact is that plants cannot grow normally unless these molecules are produced differently. They are produced in the plant root and signal the absorption of nutrients to the leaves, stems, and flower buds, thus giving the green light for growth. The signaling does not go well without the function of “OH.”

The plants are known to have a gene to produce a protein that serves as a tool to attach “OH.” However, it was impossible to tell which one was the “tool” simply by looking at the genes. Even if the gene for the “OH”-attaching tool protein were identified, that alone would not lead to the elucidation of the mechanism in detail, discovering the specific molecular form and when and where in the body the protein works. Today, the tool protein is known as and named “CYP735A.” Prof. Sakakibara’s research group is credited with both its discovery and the elucidation of its mechanism. This research achievement was possible because the group was able to combine the knowledge of genetics with high-precision chemical analysis.

“In the Department of Agricultural Chemistry, I had already learned the basics of chemical analysis. As a research scientist, I had learned not to be complacent about the results without solid confirmation at the material level. I have been able to stay in a leading position in my field probably because I have been able to combine genetics and chemical analysis well.”

Prof. Sakakibara also thinks that his affiliation with RIKEN at that time greatly helped the development of his chemical analysis method. Full-time specialized technicians at the institute made it easy to accumulate know-how through collaboration. The researchers’ ideas coupled with the technicians’ high-precision skills enabled the birth of a method that was needed at the forefront of research. To illustrate how essential precision is, note that enhancing accuracy with which molecules, such as cytokinin, are extracted and detected leads to the reduction of the quantity of samples needed for experiments. This improvement is highly significant for scientists in the laboratory because cytokinin, although essential for plant growth, is only present in trace amounts, and the preparation of plant samples in large quantities can be difficult if the target plant section is a part of the stem tip. Around the year 2000, plant samples were required for research in the quantities between 10 and 100 grams, whereas by 2009 technical improvement changed the unit of quantity required to 10 to 100 mg.⁽²⁾ Further improvement is still being made today, reducing the required quantity to 0.1 to 1 mg in some cases.

“I am grateful that RIKEN provided me with the research environment that enabled us to develop a technology that can be properly reproduced by any researchers. We still work with people there, and we still maintain the highest technical standards.”

(1) Takatoshi Kiba, Kentaro Takei, Mikiko Kojima, and Hitoshi Sakakibara (2013). Side-Chain Modification of Cytokinins Controls Shoot Growth in Arabidopsis. Developmental Cell, 27: 452-461

(2) Mikiko Kojima, Tomoe Kamada-Nobusada, Hirokazu Komatsu, Kentaro Takei, Takeshi Kuroha, Masaharu Mizutani, Motoyuki Ashikari, Miyako Ueguchi-Tanaka, Makoto Matsuoka, Koji Suzuki, and Hitoshi Sakakibara (2009). Highly Sensitive and High-Throughput Analysis of Plant Hormones Using MS-Probe Modification and Liquid Chromatography–Tandem Mass Spectrometry: An Application for Hormone Profiling in Oryza sativa. Plant & Cell Physiology, 50: 1201–1214

A paper opened the door to a major discovery—all that has been done so far converged in a moment of déjà-vu.

Prof. Sakakibara explains the fun he experiences doing his research saying, “Cytokinins tell neat stories.” He has read numerous papers related to cytokinins, including ones whose immediate connection to his own research is unclear. He can recall some parts of such papers without even trying, probably because they represent the body of information he has amassed purely out of genuine curiosity. In fact, he launched his research on CYP735A, the tool molecule that attaches “OH,” because he remembered a phenomenon that had previously been reported in only one paper.

“Looking back now, I think it was like a gamble. But I don’t think its success was 100% luck, either.”

Prof. Sakakibara shares with us an impressive episode, a story of a major discovery, a dramatic turnabout that got the paper he jointly wrote with other scientists to be published in Nature in 2007, his first Nature publication.⁽³⁾

It concerns a rice mutant named LOG (short for “Lonely Guy”), which was isolated by Dr. Junko Kyozuka (now at Tohoku University), a member of the joint research team. The flower of this mutant has no pistil and has only one stamen. The LOG gene that causes this had been sequenced, but the molecule produced from the LOG gene and its functions were not yet known. The only clue was that the characteristics of the flower bud formation suggested the phenomenon resembled what happens when the cytokinin function is weakened.

Prof. Sakakibara began by searching the database of genes of various organisms for any with a structure similar to that of the LOG gene. There were about 100 hits, sorted in order of similarity from the top. He began going through the list from the bottom for no special reason and immediately felt there was something familiar to him.

Where does this déjà-vu come from? Looking around, his eyes fell on a paper⁽⁴⁾ casually placed on the desk. It was a paper about a pathogen that deforms plants with the use of the cytokinin function. The paper described a mysterious gene that works with the cytokinin-producing gene like its partner, without which the pathogen’s cytokinin does not function. He noticed that this “partner” gene had a sequence similar to that of the LOG gene.

 “Looking back, I am amazed at the mysterious way human memory and consciousness work. At that crucial moment, I suddenly recalled something that would have been completely forgotten under normal circumstances.”

It completely deviated from the conventionally established theory, but he thought, “This can’t be a mere coincidence.”  “At that moment, we had everything working for us. We had become quite advanced in our analysis technology by then. We combed through the data and reached the conclusion in two weeks. Our paper was accepted as if we had a free pass.”

(3) Takashi Kurakawa, Nanae Ueda, Masahiko Maekawa, Kaoru Kobayashi, Mikiko Kojima, Yasuo Nagato, Hitoshi Sakakibara, and Junko Kyozuka (2007). Direct control of shoot meristem activity by a cytokinin-activating enzyme. Nature, 445: 652-655

(4) Marin Crespi, Danny Vereecke, Wim Temmerman, Marc Van Montagu, and Jan Desomer (1994). The fas Operon of Rhodococcus fascians Encodes New Genes Required for Efficient Fasciation of Host Plants. Journal of Bacteriology, 176: 2492-2501

Vast knowledge and technical expertise that do not allow easy imitation

Prof. Sakakibara’s team continues to lead the field of research on plant hormones, especially cytokinin.

“The information that appears in our papers is only a small fraction of the total body of knowledge we possess. We have already tried everything that we can think of, having that much knowledge. I don’t think it’s easy to close the gap.”

Having undergone fierce competition in genetic research, the team has been making dedicated efforts to improve the chemical analysis method. Prof. Sakakibara says that he no longer feels the intensity of the competition as strongly as before. Nevertheless, he has not slowed down. As soon as he perceives the need for new technology, he avidly works to adopt it by making full use of the network of scientists he has built.

 “You can’t make new discoveries without continuously adopting key technologies. Being capable of quick moves is also essential for researchers.”

With pure curiosity at the heart and free from conventional approaches, Prof. Sakakibara continues to explore new research in his flexible style.

On June 3, 2026, the University of Freiburg hosted a delegation from SA国际传媒 for a celebration of two milestones in their shared academic relationship: the opening of the SA国际传媒 Global Campus at the University of Freiburg and the renewal of the Joint Degree Program in Medical Science.

Held at the historic Haus zur Lieben Hand in central Freiburg, the ceremony represented the latest step forward in the two universities’ partnership, building on the expanded strategic partnership agreement signed in 2023. The SA国际传媒 Global Campus at the University of Freiburg, which extends the legacy of the SA国际传媒 European Center (2010-2023), will serve as a hub for advancing international education, research collaboration, and academic exchange between the two institutions.

“These initiatives are our promise that the most curious students and the most ambitious researchers from Nagoya and Freiburg will continue to be part of a single, shared academic community,” said SA国际传媒 President Naoshi Sugiyama. “Our partnership stretches back more than 50 years, which is quite remarkable when you consider that SA国际传媒 was only established 87 years ago.”

University of Freiburg Rector Kerstin Krieglstein also praised the collaboration between the two universities:

Today’s signing of the Joint Doctoral Program and the opening of the Global Campus send a strong signal of our reliable and active partnership with SA国际传媒. With the Joint Doctoral Program, we are creating a clear pathway for joint PhDs and fostering talent working at the intersections of our research fields. The SA国际传媒 Global Campus in Freiburg will act as a catalyst in this regard: it makes exchange faster, easier, and more visible while generating momentum that extends into research, teaching, and knowledge transfer.

The ceremony was held during a visit to Freiburg in early June by a delegation from SA国际传媒, including President Sugiyama, Vice President Yoshiyuki Suto, Graduate School of Medicine Dean Masahisa Katsuno, and faculty members involved with the joint degree program. Other highlights of the visit included a joint symposium by the SA国际传媒 Graduate School of Medicine and University of Freiburg Faculty of Medicine, as well as a lecture by Vice President Suto at the Archaeological Collection at the University of Freiburg.

As both universities look to the future, the Global Campus and renewed joint degree program lay the groundwork for deeper collaboration in research, education, and student exchange, ensuring that the Nagoya-Freiburg partnership remains a model for international academic cooperation for decades to come.