title: DNA damage in Chinese hamster cells repeatedly exposed to low doses of X-rays.
abstract: In a recent paper we reported the results of an experiment carried out by analysing chromosomal damage in Chinese hamster (CHO) cells exposed to low doses of X-rays. The present investigation was undertaken in order to validate those results using a different approach, the single cell gel electrophoresis assay (comet assay) immediately after irradiation. Cells were cultured during 14 cycles, irradiation treatment was performed once per cycle when the cells were at 90-95% of confluence. Doses of 2.5, 5.0 and 10.0 mSv were used. Sequential irradiation of CHO cells induced a decrease of cells without migration and an increase of cells showing DNA damage with the three doses employed. Significant increases of low-level damaged cells (p < 0.001) were found for the 14 exposures when compared to controls except for the first irradiations with 2.5 and 10 mSv, respectively. No significant increase of the frequency of cells with severe damage was observed in any case. These findings could be explained by assuming a complex interactive process of cell recovery, DNA damage and repair together with the induction of genomic instability, the incidence of bystander effects as well as some kind of radioadaptative response of the cells. If these phenomena are limited to the cell line employed deserves further investigation.
authors.affiliation: CIGEBA (Centro de Investigaciones en Genética Básica y Aplicada), Facultad de Ciencias Veterinarias, Universidad Nacional de La Plata, La Plata, Argentina.
authors.forename: A M
authors.initials: AM
authors.lastname: Güerci
authors.forename: F N
authors.initials: FN
authors.lastname: Dulout
authors.forename: A I
authors.initials: AI
authors.lastname: Seoane
mesh_terms: D000222:Adaptation, Physiological; D000818:Animals; D016466:CHO Cells / Q000528:radiation effects* / Q000648:ultrastructure; D002842:Chromatids / Q000528:radiation effects / Q000648:ultrastructure; D002869:Chromosome Aberrations; D019457:Chromosome Breakage; D002875:Chromosomes / Q000528:radiation effects / Q000648:ultrastructure; D020552:Comet Assay; D006224:Cricetinae; D003412:Cricetulus; D004247:DNA / Q000528:radiation effects; D004249:DNA Damage; D004260:DNA Repair; D004307:Dose-Response Relationship, Radiation; D007091:Image Processing, Computer-Assisted; D018499:Linear Energy Transfer; D008856:Microscopy, Fluorescence; D011836:Radiation Tolerance
chemical_list: D004247:DNA