title: DNA fragmentation by gamma radiation and electron beams using atomic force microscopy.
abstract: Double-stranded pBS plasmid DNA was irradiated with gamma rays at doses ranging from 1 to 12 kGy and electron beams from 1 to 10 kGy. Fragment-size distributions were determined by direct visualization, using atomic force microscopy with nanometer-resolution operating in non-tapping mode, combined with an improved methodology. The fragment distributions from irradiation with gamma rays revealed discrete-like patterns at all doses, suggesting that these patterns are modulated by the base pair composition of the plasmid. Irradiation with electron beams, at very high dose rates, generated continuous distributions of highly shattered DNA fragments, similar to results at much lower dose rates found in the literature. Altogether, these results indicate that AFM could supplement traditional methods for high-resolution measurements of radiation damage to DNA, while providing new and relevant information.
authors.affiliation: Departamento de Ciência e Tecnologia, Universidade Estadual de Santa Cruz, Ilhéus, BA Brazil.
authors.forename: Luis Nieto
authors.initials: LN
authors.lastname: González
authors.forename: João D T
authors.initials: JD
authors.lastname: Arruda-Neto
authors.forename: Monica A
authors.initials: MA
authors.lastname: Cotta
authors.forename: Helaine
authors.initials: H
authors.lastname: Carrer
authors.forename: Fermin
authors.initials: F
authors.lastname: Garcia
authors.forename: Ricardo A S
authors.initials: RA
authors.lastname: Silva
authors.forename: Antonio L D
authors.initials: AL
authors.lastname: Moreau
authors.forename: Henriette
authors.initials: H
authors.lastname: Righi
authors.forename: Godofredo C
authors.initials: GC
authors.lastname: Genofre
keywords: AFM; Electron beams; Fragment-size distributions; Gamma radiation; Plasmid DNA