PERSISTENCE OF RADIATION-INDUCED DOUBLE-STRAND BREAKS IN THE DNA OF HEATED CHO CELLS

Authors
Citation
Rl. Warters, PERSISTENCE OF RADIATION-INDUCED DOUBLE-STRAND BREAKS IN THE DNA OF HEATED CHO CELLS, International journal of radiation biology, 64(6), 1993, pp. 669-676
Citations number
39
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Radiology,Nuclear Medicine & Medical Imaging","Nuclear Sciences & Tecnology
ISSN journal
0955-3002
Volume
64
Issue
6
Year of publication
1993
Pages
669 - 676
Database
ISI
SICI code
0955-3002(1993)64:6<669:PORDBI>2.0.ZU;2-5
Abstract
Chinese hamster ovary cells were either heated at 45-degrees-C for 15 min or left unheated immediately prior to irradiation and incubation a t 37 or 41-degrees-C for 5 h. When cellular DNA was analysed by electr ophoresis of double-stranded DNA through agarose gels 5 h after irradi ation, DNA fragments presumably resulting from unrepaired DNA double-s trand breaks (dsbs) were observed in the DNA of all cells. The frequen cy of the putative unrepaired dsbs was greater in cells heated at 45-d egrees-C for 15 min before, or incubated at 41-degrees-C for 5 h after irradiation, than in unheated, control cells. Gel electrophoresis res ults were consistent with a failure of irradiated cells to rejoin dsb completely when heated at 45-degrees-C before, or incubated at 41-degr ees-C for 5 h after irradiation. In contrast, nuclear DNA accessibilit y studies using either an exogenous or an endogenous endonuclease dete cted no change in the accessibility of DNA in nuclei from 41-degrees-C -heated cells. These DNA accessibility studies indicate that the dsbs observed in the DNA of 41-degrees-C-heated cells may not result from a n actual failure of irradiated cells to repair radiation-induced dsbs during incubation at 41-degrees-C.