Reiji Okazaki
Encyclopedia
was a Japanese molecular biologist known for his research in DNA replication
and especially for describing the role of so-called Okazaki fragment
s which he discovered working with his wife Tsuneko Okazaki
in 1968.
, Japan
. He graduated in 1953 from Nagoya University
, and worked as a professor there after 1963.
Okazaki died of leukemia
seven years after his discovery; he had been heavily irradiated
in Hiroshima
when the first atomic bomb
was dropped.
Okazaki discovered the way in which the lagging strand of DNA is replicated via fragments by conducting an experiment using E. coli. After reacting E. coli with 3[H] Thymidine to synthesize DNA for only ten seconds, he placed the sample in a test tube of alkaline sucrose. The larger, heavier DNA flowed to the bottom of the test tube, while the smaller lighter DNA did not. When samples were taken from the bottom of the test tube, it was found that half were heavy and half were light, proving that half of the DNA was complete and half was in fragments. Then he took a sample of E.coli DNA that had been synthesized for an additional five seconds, and found all the activity now resulted in the larger molecular weight. Therefore, there were no longer any fragments. This proved that during the five second chase, the RNA primer was removed-using DNA Polymerase I- and the bases were joined together by DNA Ligase, leaving the new DNA fully mature and repaired.
DNA replication
DNA replication is a biological process that occurs in all living organisms and copies their DNA; it is the basis for biological inheritance. The process starts with one double-stranded DNA molecule and produces two identical copies of the molecule...
and especially for describing the role of so-called Okazaki fragment
Okazaki fragment
Okazaki fragments are short molecules of single-stranded DNA that are formed on the lagging strand during DNA replication. They are between 1,000 to 2,000 nucleotides long in Escherichia coli and are between 100 to 200 nucleotides long in eukaryotes....
s which he discovered working with his wife Tsuneko Okazaki
Tsuneko Okazaki
is a Japanese scientist known for her discovery and research of Okazaki fragments along with her husband Reiji.Okazaki graduated from Nagoya University, School of Science in 1956.-References:...
in 1968.
Biography
Reiji Okazaki was born in HiroshimaHiroshima
is the capital of Hiroshima Prefecture, and the largest city in the Chūgoku region of western Honshu, the largest island of Japan. It became best known as the first city in history to be destroyed by a nuclear weapon when the United States Army Air Forces dropped an atomic bomb on it at 8:15 A.M...
, Japan
Japan
Japan is an island nation in East Asia. Located in the Pacific Ocean, it lies to the east of the Sea of Japan, China, North Korea, South Korea and Russia, stretching from the Sea of Okhotsk in the north to the East China Sea and Taiwan in the south...
. He graduated in 1953 from Nagoya University
Nagoya University
Nagoya University is one of the most prestigious universities in Japan. It can be seen in the several rankings such as shown below.-General Rankings:...
, and worked as a professor there after 1963.
Okazaki died of leukemia
Leukemia
Leukemia or leukaemia is a type of cancer of the blood or bone marrow characterized by an abnormal increase of immature white blood cells called "blasts". Leukemia is a broad term covering a spectrum of diseases...
seven years after his discovery; he had been heavily irradiated
Radiation
In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. There are two distinct types of radiation; ionizing and non-ionizing...
in Hiroshima
Hiroshima
is the capital of Hiroshima Prefecture, and the largest city in the Chūgoku region of western Honshu, the largest island of Japan. It became best known as the first city in history to be destroyed by a nuclear weapon when the United States Army Air Forces dropped an atomic bomb on it at 8:15 A.M...
when the first atomic bomb
Little Boy
"Little Boy" was the codename of the atomic bomb dropped on Hiroshima on August 6, 1945 by the Boeing B-29 Superfortress Enola Gay, piloted by Colonel Paul Tibbets of the 393rd Bombardment Squadron, Heavy, of the United States Army Air Forces. It was the first atomic bomb to be used as a weapon...
was dropped.
Okazaki discovered the way in which the lagging strand of DNA is replicated via fragments by conducting an experiment using E. coli. After reacting E. coli with 3[H] Thymidine to synthesize DNA for only ten seconds, he placed the sample in a test tube of alkaline sucrose. The larger, heavier DNA flowed to the bottom of the test tube, while the smaller lighter DNA did not. When samples were taken from the bottom of the test tube, it was found that half were heavy and half were light, proving that half of the DNA was complete and half was in fragments. Then he took a sample of E.coli DNA that had been synthesized for an additional five seconds, and found all the activity now resulted in the larger molecular weight. Therefore, there were no longer any fragments. This proved that during the five second chase, the RNA primer was removed-using DNA Polymerase I- and the bases were joined together by DNA Ligase, leaving the new DNA fully mature and repaired.