Reiji Okazaki

Reiji Okazaki (岡崎 令治, Okazaki Reiji, October 8, 1930 – August 1, 1975) was a Japanese molecular biologist known for his research in DNA replication and especially for describing the role of so-called Okazaki fragments which he discovered working with his wife Tsuneko Okazaki in 1966.

Biography

Reiji Okazaki was born in Hiroshima, 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.