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Titolo:
Single- and double-strand breaks in solid pBR322 DNA induced by ultrasoft X-rays at photon energies of 388, 435 and 573 eV
Autore:
Yokoya, A; Watanabe, R; Hara, T;
Indirizzi:
Japan Atom Energy Res Inst, Dept Environm Safety, Tokai, Ibaraki 3191195, Japan Japan Atom Energy Res Inst Tokai Ibaraki Japan 3191195 aki 3191195, Japan Rikkyo Univ, Coll Sci, Tokyo 1718501, Japan Rikkyo Univ Tokyo Japan 1718501 kyo Univ, Coll Sci, Tokyo 1718501, Japan
Titolo Testata:
JOURNAL OF RADIATION RESEARCH
fascicolo: 2, volume: 40, anno: 1999,
pagine: 145 - 158
SICI:
0449-3060(199906)40:2<145:SADBIS>2.0.ZU;2-8
Fonte:
ISI
Lingua:
ENG
Soggetto:
MAMMALIAN-CELLS; ABSORPTION; SPECTROSCOPY; PHOSPHORUS; RADIATION;
Keywords:
monochromatic ultrasoft X-rays; DNA strand break; synchrotron radiation; nitrogen K-edge; oxygen K-edge;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
24
Recensione:
Indirizzi per estratti:
Citazione:
A. Yokoya et al., "Single- and double-strand breaks in solid pBR322 DNA induced by ultrasoft X-rays at photon energies of 388, 435 and 573 eV", J RADIAT R, 40(2), 1999, pp. 145-158

Abstract

We measured strand breaks of pBR322 plasmid DNA irradiated with ultrasoft X-rays using monochromatic synchrotron radiation as a light source. Three photon energies, 388, 435 and 573 eV, a value below and above the nitrogen K-edge and above the oxygen K-edge, respectively, were chosen for the irradiation experiments as they have an equivalent photon transmittance of the sample. Irradiated DNA was analyzed by agarose gel electrophoresis and the numbers of single-and double-strand breaks (ssb and dsb) were determined by measuring the band intensity on the gel after ethidium bromide staining. Theaction cross-sections for the ssb and dsb slightly increased with the photon energy. The ratio between 388 and 573 eV was about 1.5 for both forms ofstrand breaks. The absorbed energy required far a strand break was about 60 eV for ssb and 1 keV for dsb, less than one fifth of the values obtained previously in the 2 keV region. On the other hand, the absorbed energies per strand break, as well as the ratio of the action cross-section for the ssb to that for the dsb, were constant regardless of the photon energy used. The K-shell photoabsorption on carbon, nitrogen and oxygen atoms in the DNAmolecule, followed by an Auger cascade, induced DNA strand breaks with a constant efficiency in terms of the absorbed energy. These results indicate that the strand breaks of the DNA molecule in the solid state are mainly caused by the photo- and Auger-electrons and the efficiency of the strand breaks little depends on the atoms ejecting these secondary electrons.

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Documento generato il 01/10/20 alle ore 01:21:30