Osamu Shimomura: A Life of Persistence, from Nagasaki to the Glowing Jellyfish

Osamu Shimomura (27 August 1928 – 19 October 2018) was a Japanese organic chemist and marine biochemist who spent his career in Japan and the United States. He discovered the bioluminescent protein aequorin and green fluorescent protein (GFP) in the jellyfish Aequorea victoria, a discovery that changed the way biologists look at living cells. He shared the 2008 Nobel Prize in Chemistry with Martin Chalfie and Roger Tsien.

Early Life and Family

Shimomura was born in Fukuchiyama, in Kyoto Prefecture, Japan. His father was an army officer, and the family moved several times in his childhood, to Manchuria and different parts of Japan. The war disrupted his schooling. As a teenager he was sent to work at a munitions factory near Isahaya, about 20 km from Nagasaki. On 9 August 1945 he was there when the atomic bomb exploded over Nagasaki, and he saw the flash and felt its effects, becoming a survivor of the bombing. He later said that the experience of the war left him with a lasting interest in doing work that was peaceful and useful. Japan after the war was a land of hunger and ruins, and his family had to rebuild their lives.

Education and Mentors

Because his school had been destroyed, Shimomura entered the Nagasaki Medical College's pharmacy school (later Nagasaki University) and graduated in 1951. He then worked as an assistant at Nagasaki University for several years. A decisive step was joining the laboratory of Yoshimasa Hirata at Nagoya University, one of Japan's leading natural-product chemists. He was given a hard task: to purify and crystallise the luminous substance of Cypridina (Vargula hilgendorfii), a tiny crustacean that glows in the sea. Shimomura succeeded in 1956 in obtaining crystals of Cypridina luciferin, impressing the scientific community. He received his doctorate from Nagoya University in 1960. Meanwhile Frank Johnson, a Princeton University biologist, invited him to join his laboratory.

Career Timeline

Major Scientific Contributions

Shimomura isolated aequorin, a calcium-triggered photoprotein, and GFP from Aequorea victoria, and explained that aequorin emits blue light on binding Ca²⁺ while GFP converts this to green light by energy transfer. He then proposed the chromophore of GFP as a cyclised and oxidised Ser-Tyr-Gly tripeptide. These findings meant that GFP forms its light-absorbing group within the protein without extra enzymes, and so it can be expressed in other organisms. The complete chemistry, including the reaction scheme, is in our discovery article.

Besides this, he worked on the chemistry of many other bioluminescent systems, including Cypridina, the sea firefly, and the bioluminescent mushroom and earthworm, publishing work on the luciferins of multiple species. Aequorin became a standard way to measure intracellular calcium, long before GFP became popular.

Awards, Honours and Nobel Prize

• Nobel Prize in Chemistry 2008: shared by Osamu Shimomura, Martin Chalfie and Roger Y. Tsien "for the discovery and development of the green fluorescent protein, GFP". It was a Chemistry prize.
• Honours in Japan after the Nobel Prize.
• Emeritus professorships at the Marine Biological Laboratory and Boston University.

Personality, Struggles and Lesser-Known Facts

• Survivor of Nagasaki: He remembered the blinding flash of the explosion.
• Jellyfish by the thousands: Each summer the family participated in collecting jellyfish; his wife Akemi and their children helped with cutting and processing. Together they handled hundreds of thousands of jellyfish across the years.
• Home laboratory: After retiring he set up a small laboratory in his own basement in Falmouth, Massachusetts, to continue research, and he continued experimenting with modest resources.
• Curiosity first: He said he was never trying to make a tool; he wanted to know why the jellyfish glows. The use of GFP in biology came later, through others.
• The sink moment: The story that the extract glowed in the sink when seawater was added has been told often to illustrate serendipity.

Legacy and Influence on Modern Chemistry

GFP and its colour variants, red, yellow and cyan, are now used in thousands of laboratories worldwide, including Indian research institutes such as NCBS, IISc and the IISERs. Their use led to a revolution in imaging, drug screening, neuroscience and developmental biology, and the field of super-resolution microscopy, itself awarded the Nobel Prize in Chemistry in 2014, depends heavily on fluorescent proteins. In classrooms GFP is also a favourite example of a conjugated chromophore and of how protein structure protects an excited state.

Lessons for Students

1. Basic curiosity about nature, "why does the jellyfish glow?", can lead to technology that no one planned.
2. Be patient: years of collecting and purifying preceded the result.
3. Skills in organic chemistry (isolation, structure determination) make you valuable in biology.
4. Life setbacks, even war and loss, do not close your future.
5. Credit those who extend your work: Chalfie and Tsien turned GFP into a tool.

FAQ

Where did Shimomura find GFP?

In the jellyfish Aequorea victoria, collected at Friday Harbor in Washington State.

Was he a survivor of the atomic bombing?

Yes. As a teenager he was near Nagasaki when the bomb was dropped in 1945.

Did he share the prize in Medicine or Chemistry?

Chemistry, in 2008, along with Martin Chalfie and Roger Tsien.

Which substance did he crystallise before GFP?

Cypridina luciferin, the light-producing compound of a small marine crustacean.

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