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Reiji Okazaki

Reiji Okazaki
岡崎 令治
Born
Okazaki Reiji

(1930-10-08)October 8, 1930
Hiroshima, Japan
DiedAugust 1, 1975(1975-08-01) (aged 44)
Japan
EducationNagoya University
Known forOkazaki Fragments
SpouseTsuneko Okazaki
Scientific career
FieldsMolecular biology
InstitutionsNagoya University, Washington University, Stanford University

Reiji Okazaki (岡崎 令治, Okazaki Reiji, October 8, 1930 – August 1, 1975) was a pioneer Japanese molecular biologist, known for his research on DNA replication and especially for describing the role of Okazaki fragments along with his wife Tsuneko.

Okazaki was born in Hiroshima, Japan. He graduated in 1953 from Nagoya University, and worked as a professor there after 1963. He died of leukemia in Japan in 1975 at the age of 44 after traveling to the United States and Canada; he had been heavily irradiated in Hiroshima when the first atomic bomb was dropped.[1]

Okazaki Fragments

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In 1968, Reiji and Tsuneko Okazaki discovered the way in which the lagging strand of DNA is replicated via fragments, now called Okazaki fragments.[2][3][4][5]

Their experiments used E. coli. After introducing 3T-thymidine for only ten seconds to E. coli during DNA replication, they placed the sample in a test tube of alkaline sucrose.[3] 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.[5] This complete replacement of fragments was later identified as RNA primers being replaced with DNA nucleotides by DNA polymerase I and Okazaki fragments being joined by DNA ligase.[6]

References

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  1. ^ Okazaki, Tsuneko (11 May 2017). "Days weaving the lagging strand synthesis of DNA — A personal recollection of the discovery of Okazaki fragments and studies on discontinuous replication mechanism". Proceedings of the Japan Academy. Series B, Physical and Biological Sciences. 93 (5): 322–338. Bibcode:2017PJAB...93..322O. doi:10.2183/pjab.93.020. PMC 5489436. PMID 28496054.
  2. ^ Okazaki, R.; Okazaki, T.; Sakabe, K.; Sugimoto, K.; Sugino, A. (1968). "Mechanism of DNA chain growth. I. Possible discontinuity and unusual secondary structure of newly synthesized chains". Proceedings of the National Academy of Sciences of the United States of America. 59 (2): 598–605. Bibcode:1968PNAS...59..598O. doi:10.1073/pnas.59.2.598. PMC 224714. PMID 4967086.
  3. ^ a b Sugimoto, K.; Okazaki, T.; Okazaki, R. (1968). "Mechanism of DNA chain growth, II. Accumulation of newly synthesized short chains in E. Coli infected with ligase-defective T4 phages". Proceedings of the National Academy of Sciences of the United States of America. 60 (4): 1356–1362. Bibcode:1968PNAS...60.1356S. doi:10.1073/pnas.60.4.1356. PMC 224926. PMID 4299945.
  4. ^ Sugimoto, K.; Okazaki, T.; Imae, Y.; Okazaki, R. (1969). "Mechanism of DNA chain growth. 3. Equal annealing of T4 nascent short DNA chains with the separated complementary strands of the phage DNA". Proceedings of the National Academy of Sciences of the United States of America. 63 (4): 1343–1350. Bibcode:1969PNAS...63.1343S. doi:10.1073/pnas.63.4.1343. PMC 223470. PMID 5260937.
  5. ^ a b Okazaki, T.; Okazaki, R. (1969). "Mechanism of DNA chain growth. IV. Direction of synthesis of T4 short DNA chains as revealed by exonucleolytic degradation". Proceedings of the National Academy of Sciences of the United States of America. 64 (4): 1242–1248. Bibcode:1969PNAS...64.1242O. doi:10.1073/pnas.64.4.1242. PMC 223275. PMID 4989398.
  6. ^ "11.2 DNA Replication - Microbiology | OpenStax". openstax.org. November 2016. Retrieved 2 October 2021.


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