Double-strand break induction and repair in V79-4 hamster cells: the role of core ionisations, as probed by ultrasoft X-rays.
Int J Radiat Biol
; 86(3): 205-19, 2010 Mar.
Article
em En
| MEDLINE
| ID: mdl-20201649
ABSTRACT
PURPOSE:
To compare the induction of double-strand breaks (DSB) in cells irradiated by 250 and 350 eV ultrasoft X-rays and assess the residual yield of breaks 2 hours post irradiation in order to unravel the correlation between the sharp increase in cell-killing efficiency of ultrasoft X-rays above versus below the carbon-K threshold (284 eV) and the induction of core events in DNA atoms. MATERIALS ANDMETHODS:
V79-4 hamster cells were irradiated with synchrotron ultrasoft X-rays at isoattenuating energies of 250 eV and 350 eV. DSB were quantified using pulse field gel electrophoresis.RESULTS:
A significant increase in DSB induction was observed for 350 eV ultrasoft X-rays above the carbon-K threshold, compared to 250 eV below the threshold, per unit dose to the cell. The DSB induced by the 350 eV ultrasoft X-rays were less repaired 2 h after irradiation.CONCLUSION:
The increased DSB induction at 350 eV is attributed to the increase in the relative proportion of photon interactions in DNA resulting in significant dose inhomogeneity across the cell with a local increase in dose to DNA. It results from an increase in carbon-K shell interactions and the short range of the electrons produced. Core ionisations in DNA, through core-hole relaxation in conjunction with localised effects of spatially correlated low-energy photo- and Auger-electrons lead to an increase in number and the complexity of DSB.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Reparo do DNA
/
Quebras de DNA de Cadeia Dupla
Idioma:
En
Ano de publicação:
2010
Tipo de documento:
Article