THE SEVERITY OF ALPHA-PARTICLE-INDUCED DNA-DAMAGE IS REVEALED BY EXPOSURE TO CELL-FREE-EXTRACTS

Citation
Ps. Hodgkins et al., THE SEVERITY OF ALPHA-PARTICLE-INDUCED DNA-DAMAGE IS REVEALED BY EXPOSURE TO CELL-FREE-EXTRACTS, Radiation research, 146(6), 1996, pp. 660-667
Citations number
37
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging
Journal title
ISSN journal
0033-7587
Volume
146
Issue
6
Year of publication
1996
Pages
660 - 667
Database
ISI
SICI code
0033-7587(1996)146:6<660:TSOADI>2.0.ZU;2-9
Abstract
The rejoining of single-strand breaks induced by alpha-particle and ga mma irradiation in plasmid DNA under two scavenging conditions has bee n compared. At the two scavenger capacities used of 1.5 x 10(7) and 3 x 10(8) s(-1) using Tris-HCl as the scavenger, the ratio of single- to double-strand breaks for alpha particles is fivefold less than the co rresponding ratios for gamma irradiation. The repair of such radiation -induced single-strand breaks has been examined using a cell-free syst em derived from human whole-cell extracts. We show that the rejoining of single-strand breaks for both alpha-particle- and gamma-irradiated plasmid is dependent upon the scavenging capacity and that the efficie ncy of rejoining of alpha-particle-induced single-strand breaks is sig nificantly less than that observed for gamma-ray-induced breaks. In ad dition, for DNA that had been irradiated under conditions that mimic t he cellular environment with respect to the radical scavenging capacit y, 50% of alpha-particle-induced single-strand breaks are converted to double-strand breaks, in contrast with only similar to 12% conversion of gamma-ray-induced single-strand breaks, indicating that the initia l damage caused by alpha particles is more severe. These studies provi de experimental evidence for increased clustering of damage which may have important implications for the induction of cancer by low-level a lpha-particle sources such as domestic radon. (C) 1996 by Radiation Re search Society