title: Breaking DNA strands by extreme-ultraviolet laser pulses in vacuum.
abstract: Ionizing radiation induces a variety of DNA damages including single-strand breaks (SSBs), double-strand breaks (DSBs), abasic sites, modified sugars, and bases. Most theoretical and experimental studies have been focused on DNA strand scissions, in particular production of DNA double-strand breaks. DSBs have been proven to be a key damage at a molecular level responsible for the formation of chromosomal aberrations, leading often to cell death. We have studied the nature of DNA damage induced directly by the pulsed 46.9-nm (26.5 eV) radiation provided by an extreme ultraviolet (XUV) capillary-discharge Ne-like Ar laser (CDL). Doses up to 45 kGy were delivered with a repetition rate of 3 Hz. We studied the dependence of the yield of SSBs and DSBs of a simple model of DNA molecule (pBR322) on the CDL pulse fluence. Agarose gel electrophoresis method was used for determination of both SSB and DSB yields. The action cross sections of the single- and double-strand breaks of pBR322 plasmid DNA in solid state were determined. We observed an increase in the efficiency of strand-break induction in the supercoiled DNA as a function of laser pulse fluence. Results are compared to those acquired at synchrotron radiation facilities and other sources of extreme-ultraviolet and soft x-ray radiation.
authors.affiliation: Department of Radiation and Chemical Physics, Institute of Physics CAS, Na Slovance 2, Prague 8, 182 21, Czech Republic.
authors.forename: Eva
authors.initials: E
authors.lastname: Nováková
authors.affiliation: Department of Radiation and Chemical Physics, Institute of Physics CAS, Na Slovance 2, Prague 8, 182 21, Czech Republic.|Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, Prague 1, 115 19, Czech Republic.
authors.forename: Luděk
authors.initials: L
authors.lastname: Vyšín
authors.affiliation: Department of Radiation and Chemical Physics, Institute of Physics CAS, Na Slovance 2, Prague 8, 182 21, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Burian
authors.affiliation: Department of Radiation and Chemical Physics, Institute of Physics CAS, Na Slovance 2, Prague 8, 182 21, Czech Republic.
authors.forename: Libor
authors.initials: L
authors.lastname: Juha
authors.affiliation: Department of Radiation Dosimetry, Institute of Nuclear Physics CAS, Na Truhlářce 39/64, Prague 8, 180 86, Czech Republic.
authors.forename: Marie
authors.initials: M
authors.lastname: Davídková
authors.affiliation: Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, Prague 1, 115 19, Czech Republic.
authors.forename: Viliam
authors.initials: V
authors.lastname: Múčka
authors.affiliation: Department of Nuclear Chemistry, Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7, Prague 1, 115 19, Czech Republic.
authors.forename: Václav
authors.initials: V
authors.lastname: Čuba
authors.affiliation: NSF ERC for Extreme Ultraviolet Science and Technology, Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523-1373, USA.
authors.forename: Michael E
authors.initials: ME
authors.lastname: Grisham
authors.affiliation: NSF ERC for Extreme Ultraviolet Science and Technology, Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523-1373, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Heinbuch
authors.affiliation: NSF ERC for Extreme Ultraviolet Science and Technology, Department of Electrical and Computer Engineering, Colorado State University, Fort Collins, Colorado 80523-1373, USA.
authors.forename: Jorge J
authors.initials: JJ
authors.lastname: Rocca
mesh_terms: D001128:Argon; D053903:DNA Breaks, Double-Stranded / Q000528:radiation effects*; D053904:DNA Breaks, Single-Stranded / Q000528:radiation effects*; D004278:DNA, Superhelical / Q000528:radiation effects; D004587:Electrophoresis, Agar Gel; D004867:Equipment Design; D054020:Lasers, Gas; D010957:Plasmids / Q000235:genetics / Q000528:radiation effects; D014466:Ultraviolet Rays; D014618:Vacuum
chemical_list: D004278:DNA, Superhelical; D001128:Argon