Osamu Shimomura

Osamu Shimomura
Born	下村 脩 27 8, 1928
Birthplace	Fukuchiyama, Empire of Japan
Died	Template:Death date and age Nagasaki, Japan
Nationality	Japanese
Occupation	Organic chemist, marine biologist
Employer	Marine Biological Laboratory, Boston University School of Medicine, Princeton University
Known for	Discovery of green fluorescent protein (GFP)
Education	Nagoya University (Ph.D., 1960)
Awards	Nobel Prize in Chemistry (2008), Asahi Prize, Pearse Prize, Golden Goose Award

Osamu Shimomura (下村 脩, Shimomura Osamu; August 27, 1928 – October 19, 2018) was a Japanese organic chemist and marine biologist whose decades-long study of bioluminescence in marine organisms led to one of the most consequential discoveries in modern biology: the isolation and characterization of green fluorescent protein (GFP) from the jellyfish Aequorea victoria. Born in the small city of Fukuchiyama in Japan's Kyoto Prefecture, Shimomura survived the atomic bombing of Nagasaki as a teenager, an experience that profoundly shaped his early life but did not deter his pursuit of scientific inquiry. Over a career spanning more than five decades, he worked at Princeton University, the Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts, and Boston University School of Medicine, where he held the title of professor emeritus of physiology. In 2008, Shimomura was awarded the Nobel Prize in Chemistry, shared jointly with American scientists Martin Chalfie of Columbia University and Roger Y. Tsien of the University of California, San Diego, for the discovery and development of GFP. GFP became an indispensable tool in cell biology, molecular biology, and medical research, enabling scientists to observe previously invisible biological processes in living cells and organisms.

Early Life

Osamu Shimomura was born on August 27, 1928, in Fukuchiyama, a city in the northern part of Kyoto Prefecture, Japan. His father was a military officer, and the family relocated multiple times during Shimomura's childhood as a consequence of his father's postings. The family eventually settled in Nagasaki on the island of Kyushu.

On August 9, 1945, when Shimomura was sixteen years old, the United States dropped an atomic bomb on Nagasaki. Shimomura was present in the city at the time and experienced the blast. He was temporarily blinded by the flash and exposed to the black rain that followed the explosion. The bombing and its aftermath left an indelible impression on the young Shimomura, though it did not diminish his intellectual curiosity. In the devastated postwar landscape of Nagasaki, educational and professional opportunities were severely limited, yet Shimomura pursued his studies with determination.

Shimomura enrolled at Nagasaki College of Pharmacy (which later became part of Nagasaki University), where he studied pharmaceutical sciences. It was during his time at Nagasaki that Shimomura first became interested in the chemistry of luminescent organisms — a subject that would define his entire career. After completing his undergraduate studies, he continued his research at Nagasaki University, where his early work on bioluminescent compounds caught the attention of established scientists in the field.

Education

Shimomura received his initial higher education at what would become Nagasaki University, graduating with a degree in pharmaceutical sciences. His early research focused on the biochemistry of luminescent compounds found in marine organisms. His talent and dedication drew the attention of Professor Yoshimasa Hirata at Nagoya University, one of Japan's leading organic chemists. Shimomura moved to Nagoya University to pursue doctoral studies under Hirata's supervision.

At Nagoya University, Shimomura completed his doctoral thesis in 1960. His dissertation research involved the study of luciferin, the light-emitting compound found in the sea firefly Cypridina hilgendorfii (now known as Vargula hilgendorfii), a small crustacean that produces a bright blue glow. Shimomura succeeded in crystallizing Cypridina luciferin, an achievement that was considered remarkable at the time and established his reputation as an exceptionally skilled biochemist. This accomplishment attracted the attention of Frank Johnson, a professor at Princeton University who was studying bioluminescence, and led directly to Shimomura's move to the United States.

Career

Princeton University and the Discovery of GFP

In 1960, Shimomura accepted an invitation from Frank Johnson to join his laboratory at Princeton University as a research associate. Johnson was studying the bioluminescence of the jellyfish Aequorea victoria, which is found in the waters of the Pacific Northwest off the coast of Washington state. Shimomura's task was to identify the substance responsible for the jellyfish's luminescence.

The work was painstaking and required enormous quantities of raw biological material. Shimomura and his colleagues traveled each summer to the Friday Harbor Laboratories at the University of Washington's marine station in the San Juan Islands, where they collected vast numbers of Aequorea victoria jellyfish by hand. Over the course of his career, Shimomura and his team collected and processed an estimated 850,000 jellyfish to obtain sufficient quantities of the luminescent proteins for study.

In 1962, Shimomura achieved a landmark breakthrough. He isolated two proteins from the jellyfish: aequorin, a calcium-dependent bioluminescent protein that emits blue light, and a second protein that he initially described as a "green protein" — later named green fluorescent protein (GFP). Shimomura observed that while aequorin emitted blue light in the presence of calcium ions, the jellyfish itself glowed green. He determined that GFP absorbed the blue light emitted by aequorin and re-emitted it as green light through fluorescence. This energy transfer mechanism explained the green glow of the living jellyfish.

At the time, the significance of GFP as a research tool was not immediately apparent. Shimomura himself was primarily interested in the basic chemistry and physics of bioluminescence rather than in potential applications. He meticulously characterized the spectral properties of GFP and determined its chromophore structure — the part of the molecule responsible for its fluorescence. In 1979, Shimomura reported that the GFP chromophore was formed by a chemical modification of three amino acids within the protein, a process that occurred spontaneously without the need for any external enzyme or cofactor. This finding would later prove critical: it meant that GFP could potentially glow in any organism into which its gene was introduced, without requiring any additional jellyfish-specific machinery.

Shimomura worked at Princeton University from 1960 until 1982, conducting research under the auspices of Johnson's laboratory and later independently. During this period, he also studied the bioluminescence of numerous other marine organisms, contributing to the broader understanding of how living creatures produce light.

Marine Biological Laboratory and Boston University

In 1982, Shimomura moved to the Marine Biological Laboratory (MBL) in Woods Hole, Massachusetts, where he continued his research on bioluminescent organisms. He also held a concurrent appointment as a professor at Boston University School of Medicine. At MBL, Shimomura had access to the rich marine biodiversity of the New England coast and continued his summers collecting jellyfish in the Pacific Northwest.

At MBL and Boston University, Shimomura expanded his investigations into bioluminescence beyond Aequorea victoria. He studied the luminescent mechanisms of a wide variety of organisms, including other species of jellyfish, the sea pansy Renilla reniformis, and various deep-sea creatures. His work contributed to the identification and characterization of numerous bioluminescent proteins and their associated chemical mechanisms.

Shimomura also continued to refine his understanding of aequorin, which became widely used as a calcium indicator in cell biology. Because aequorin emits light in the presence of calcium ions, it provided researchers with a way to monitor intracellular calcium levels in living cells — a capability that had broad implications for the study of cellular signaling, muscle contraction, and neural activity.

Throughout his career, Shimomura was known for his meticulous experimental technique and his preference for basic science over applied research. He described himself as driven by curiosity about the natural world rather than by the pursuit of practical applications. In an interview following his Nobel Prize, Shimomura reflected on the serendipitous nature of his discovery, noting that he had never anticipated that GFP would become one of the most widely used tools in modern biology.

Impact of GFP on Biological Research

While Shimomura's contribution was the foundational discovery and characterization of GFP, the transformation of the protein into a practical biological tool was the work of his co-laureates and many other scientists. In 1994, Martin Chalfie demonstrated that the GFP gene could be expressed in other organisms — specifically the bacterium Escherichia coli and the nematode Caenorhabditis elegans — and that the protein would fluoresce without any additional cofactors from jellyfish. This confirmed the implication of Shimomura's earlier finding that the GFP chromophore forms spontaneously.

Roger Y. Tsien subsequently engineered variants of GFP that fluoresced in different colors, expanding the palette available to researchers and enabling simultaneous tracking of multiple proteins or processes within the same cell. Tsien's work also improved the brightness and stability of GFP variants, making them more practical for a wide range of experimental applications.

Together, the work of Shimomura, Chalfie, and Tsien revolutionized cell biology and molecular biology. GFP and its derivatives enabled researchers to tag specific proteins with fluorescent markers, making it possible to watch proteins move within living cells, observe how cells divide, track how nerve cells develop and extend connections, and monitor the progression of diseases such as cancer and Alzheimer's disease in real time. The Nobel Committee described GFP as having become "one of the most important tools used in contemporary bioscience" and likened its impact to the development of the microscope itself.

Later Career and Retirement

Shimomura retired from active research at the Marine Biological Laboratory and became a senior scientist emeritus at MBL and professor emeritus at Boston University School of Medicine. Even after retirement, he continued to write about bioluminescence and contributed to the scientific literature on the subject. He authored a comprehensive book on bioluminescence that drew on his decades of experience in the field.

In his later years, Shimomura expressed concern about the environmental status of Aequorea victoria and other bioluminescent organisms, noting that the jellyfish populations he had relied upon for his research had become harder to find in the waters around Friday Harbor.

Personal Life

Osamu Shimomura was known for his quiet, modest demeanor and his deep dedication to laboratory work. He was married to Akemi Shimomura, who assisted him extensively in his research, particularly during the laborious summer jellyfish-collecting expeditions in the San Juan Islands. Akemi's contribution to the work was acknowledged by Shimomura and by colleagues who observed the couple working side by side for decades.

The Shimomuras had a son, Tsutomu Shimomura, who became known in the field of computer security.

Shimomura held both Japanese nationality and permanent residency in the United States. He maintained strong ties to Japan throughout his life and returned frequently. He spent his final years in Nagasaki, the city where he had survived the atomic bombing as a teenager.

Osamu Shimomura died on October 19, 2018, in Nagasaki, Japan, at the age of 90.

Recognition

Shimomura received numerous awards and honors over the course of his career, though widespread recognition came relatively late, reflecting the gap between his fundamental discovery of GFP in the 1960s and its explosion as a research tool in the 1990s and 2000s.

His most prominent honor was the Nobel Prize in Chemistry in 2008, which he shared with Martin Chalfie and Roger Y. Tsien "for the discovery and development of the green fluorescent protein, GFP." The Royal Swedish Academy of Sciences credited Shimomura specifically for the initial discovery and characterization of GFP from Aequorea victoria.

Shimomura was also awarded the Pearse Prize by the Royal Microscopical Society in recognition of his contributions to the field of light microscopy and bioluminescence. He received the Asahi Prize, one of Japan's most distinguished awards for contributions to academics and the arts.

In addition, Shimomura was honored with the Golden Goose Award, which recognizes federally funded research that may have seemed obscure or impractical at the time it was conducted but later yielded significant benefits to society. The award was fitting for Shimomura's work, which began as basic curiosity-driven research into why jellyfish glow and ultimately transformed biomedical science.

Nagoya University, Shimomura's doctoral alma mater, celebrated his Nobel Prize and recognized him as one of the university's most distinguished alumni. Boston University awarded him an honorary degree in 2010.

Shimomura was elected a Fellow of the American Association for Cancer Research Academy in recognition of the impact of GFP on cancer research, where fluorescent protein technology has been used to study tumor biology, track metastasis, and evaluate therapeutic interventions.

Legacy

Osamu Shimomura's discovery of green fluorescent protein is considered one of the most significant contributions to the biological sciences in the twentieth century. GFP and its engineered variants have become ubiquitous tools in laboratories worldwide, used in tens of thousands of research studies across virtually every field of biology and medicine. The protein's unique property — the ability to fluoresce without any cofactor other than molecular oxygen — means that its gene can be inserted into the genome of virtually any organism, from bacteria to mammals, to serve as a visible marker of gene expression, protein localization, and cellular processes.

The applications of GFP technology have been vast. Researchers have used GFP to visualize the development of nerve cells in the brain, to track the spread of cancer cells through the body, to monitor the infection process of viruses, and to study the behavior of stem cells. In developmental biology, GFP has made it possible to observe in real time how embryos develop and how tissues form. The "brainbow" technique, which uses multiple fluorescent protein variants to label individual neurons in distinct colors, is a direct descendant of the work initiated by Shimomura's discovery.

Shimomura's approach to science — patient, curiosity-driven, focused on fundamental understanding rather than immediate application — has been cited as a model for the value of basic research. His career demonstrated how investigation motivated purely by scientific curiosity can yield transformative practical benefits that are impossible to predict at the outset. The Nobel Committee, in awarding the 2008 prize, emphasized that the story of GFP illustrated the importance of supporting basic science even when its applications are not immediately apparent.

At the Marine Biological Laboratory in Woods Hole, Shimomura's legacy endures both in the continued use of GFP technology and in the institution's tradition of marine biology research. His meticulous work ethic, his collaborative partnership with his wife Akemi, and his modesty in the face of extraordinary scientific achievement left a lasting impression on colleagues and students who encountered him over his long career.

Shimomura devoted his career to understanding how creatures of the sea produce light. In doing so, he gave scientists everywhere the ability to illuminate the hidden workings of life itself.