title: Adaptive response to DNA and chromosomal damage induced by X-rays in human blood lymphocytes.
abstract: Nucleoid sedimentation, single-cell gel electrophoresis (comet assay) and premature chromosome condensation (PCC) technique were utilized to estimate the involvement of DNA strand breaks and chromosomal damage in radio-adaptive response of stimulated human lymphocytes. Conditioning of cells with 0.02 Gy X-rays rendered them more resistant to single- and double-strand DNA breaks produced by 1 Gy challenging treatment as revealed by the sedimentation behaviour of the nucleoids and the comet assay. Nucleoid sedimentation also demonstrated that adaptive reaction towards X-ray-induced DNA damage is favoured in the presence of oxygen. A concomitant decrease in the amount of interphase chromosomal breaks visualized by PCC under the same experimental conditions was observed. Data indicate that adaptation of human lymphocytes to X-rays is tightly linked to the reduced susceptibility towards generation of DNA and chromosomal breaks. It is proposed that the very persistence of DNA strand discontinuities might serve as a triggering signal for the adaptation of human lymphocytes against ionizing radiation exposure.
authors.affiliation: Department of Molecular Genetics, Institute of Genetics Acad. D. Kostoff BAS, Sofia 1113, Bulgaria. molgen@bas.bg
authors.forename: L M
authors.initials: LM
authors.lastname: Stoilov
authors.forename: L H F
authors.initials: LH
authors.lastname: Mullenders
authors.forename: F
authors.initials: F
authors.lastname: Darroudi
authors.forename: A T
authors.initials: AT
authors.lastname: Natarajan
mesh_terms: D000222:Adaptation, Physiological / Q000528:radiation effects*; D000818:Animals; D016466:CHO Cells; D002869:Chromosome Aberrations / Q000528:radiation effects*; D006224:Cricetinae; D003412:Cricetulus; D053904:DNA Breaks, Single-Stranded; D004249:DNA Damage; D006801:Humans; D008214:Lymphocytes / Q000378:metabolism* / Q000528:radiation effects*; D009584:Nitrogen / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D014965:X-Rays
chemical_list: D009584:Nitrogen; D010100:Oxygen