Neutron and cobalt-60 γ irradiation produce similar changes in DNA supercoiling

Andrew T M Vaughan, D. J. Gordon, D. R. Chettle, S. Green

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

The effects of 60Co γ-ray and d(20 MeV)Be neutron irradiation on DNA supercoiling have been studied using a nucleoid rewinding technique. Irradiation of viable CHO AA8 cells on ice with from 4 to 25 Gy of either radiation produced a similar resistance to rewinding of nuclear supercoils after treatment with ethidium bromide. The restitution from the effects of 12 Gy of either radiation was also similar, leaving no detectable residual damage. The discrepancy between these data and the reduced ability of neutrons to produce DNA breaks, as defined by the alkaline elution assay, is explained by the discontinuous deposition of dose associated with neutron irradiation. It is suggested from a microdosimetric analysis that the neutron radiation interacts with DNA at sites on average 5-10 times further apart than the interactions with γ rays. The long DNA sequences which result after neutron irradiation are consequently eluted inefficiently during alkaline elution, giving a reported RBE of approximately 0.3. Restrictions in the rewinding of individual supercoils are not dependent on the interionization distance and thus give rise to an RBE of approximately 1. Furthermore, the complete removal of DNA damage, as measured by this technique, supports the hypothesis that neutron toxicity is associated with incorrect, not incomplete, rejoining of the DNA molecule.

Original languageEnglish (US)
Pages (from-to)19-23
Number of pages5
JournalRadiation Research
Volume127
Issue number1
StatePublished - 1991
Externally publishedYes

Fingerprint

cobalt 60
Neutrons
cobalt
Cobalt
deoxyribonucleic acid
irradiation
neutrons
DNA
neutron irradiation
Radiation Dosage
elution
rays
radiation
damage
DNA Breaks
Ethidium
CHO Cells
Ice
toxicity
DNA damage

ASJC Scopus subject areas

  • Agricultural and Biological Sciences (miscellaneous)
  • Radiology Nuclear Medicine and imaging
  • Biophysics
  • Radiation

Cite this

Neutron and cobalt-60 γ irradiation produce similar changes in DNA supercoiling. / Vaughan, Andrew T M; Gordon, D. J.; Chettle, D. R.; Green, S.

In: Radiation Research, Vol. 127, No. 1, 1991, p. 19-23.

Research output: Contribution to journalArticle

Vaughan, ATM, Gordon, DJ, Chettle, DR & Green, S 1991, 'Neutron and cobalt-60 γ irradiation produce similar changes in DNA supercoiling', Radiation Research, vol. 127, no. 1, pp. 19-23.
Vaughan, Andrew T M ; Gordon, D. J. ; Chettle, D. R. ; Green, S. / Neutron and cobalt-60 γ irradiation produce similar changes in DNA supercoiling. In: Radiation Research. 1991 ; Vol. 127, No. 1. pp. 19-23.
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