X-irradiation of cells on glass slides has a dose doubling impact

Kegel, P., Riballo, M.E., Kuhne, M., Jeggo, P.A. and Lobrich, M. (2007) X-irradiation of cells on glass slides has a dose doubling impact. DNA Repair, 6 (11). pp. 1692-1697. ISSN 1568-7864

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Abstract

Immunofluorescence detection of gammaH2AX foci is a widely used tool to quantify the induction and repair of DNA double-strand breaks (DSBs) induced by ionising radiation. We observed that X-irradiation of mammalian cells exposed on glass slides induced twofold higher foci numbers compared to irradiation with gamma-rays. Here, we show that the excess gammaH2AX foci after X-irradiation are produced from secondary radiation particles generated from the irradiation of glass slides. Both 120kV X-rays and (137)Cs gamma-rays induce approximately 20 gammaH2AX foci per Gy in cells growing on thin ( approximately 2mum) plastic foils immersed in water. The same yield is obtained following gamma-irradiation of cells growing on glass slides. However, 120kV X-rays produce approximately 40 gammaH2AX foci per Gy in cells growing on glass, twofold greater than obtained using cells irradiated on plastic surfaces. The same increase in gammaH2AX foci number is obtained if the plastic foil on which the cells are grown is irradiated on a glass slide. Thus, the physical proximity to the glass material and not morphological differences of cells growing on different surfaces accounts for the excess gammaH2AX foci. The increase in foci number depends on the energy and is considerably smaller for 25kV relative to 120kV X-rays, a finding which can be explained by known physical properties of radiation. The kinetics for the loss of foci, which is taken to represent the rate of DSB repair, as well as the Artemis dependent repair fraction, was similar following X- or gamma-irradiation, demonstrating that DSBs induced by this range of treatments are repaired in an identical manner.

Item Type: Article
Depositing User: Gee Wheatley
Date Deposited: 30 Sep 2008
Last Modified: 13 Mar 2017 11:03
URI: http://sro.sussex.ac.uk/id/eprint/1853
Google Scholar:31 Citations

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