Production and excision of thymine damage in the DNA of mammalian cells exposed to high-LET radiations

Journal Article · Sat Dec 01 04:00:00 EST 1979 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3574989· OSTI ID:5414463

Mattern, M R; Welch, G P

HeLa S3 and Chinese hamster ovary cells were irradiated with high doses of carbon ions having linear energy transfers (LETs) of 170 and 780 keV/..mu..m. The DNA was analyzed for 5,6-dihydroxydihydrothymine (t'-type) radiation products both before and after postirradiation incubation at 37/sup 0/C. In HeLa cells, 2.1 x 10/sup -5/ ring-damaged thymines were produced per kilorad per 10/sup 6/ daltons after irradiation with high-LET carbon ions - approximately one-fifth the efficiency of t' formation in HeLa cells exposed to low-LET x rays. t' products were also formed less efficiently in Chinese hamster ovary cells exposed to carbon ions than in those exposed to x rays. In both cell lines, up to 80% of the t' formed initially was excised selectively from the DNA during 60 min of postirradiation incubation at 37/sup 0/C. Product excision was accompanied by small amounts of DNA degradation (less than 1%). Radiation with LET of 170 keV/..mu..m - nearly the most effective LET for cell killing and the generation of unrejoined DNA strand breaks - produced ring-damaged thymines that were removed selectively from the DNA. This result is consistent with the conclusion that t'-type products do not contribute substantially to lethality after high-LET irradiation, although the alternative possibilities remain that t' is not excised as efficiently after biological doses, or that a particular subclass of t' or defective postexcision events contribute to cell killing.

• Research Organization: Univ. of California, San Francisco
• OSTI ID: 5414463
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 80:3; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

550200 -- Biochemistry
550400 -- Genetics
560121* -- Radiation Effects on Cells-- External Source-- (-1987)
59 BASIC BIOLOGICAL SCIENCES
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMALS
ATOMIC IONS
AZINES
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BODY
CARBON IONS
CELL CULTURES
CELL KILLING
CHARGED PARTICLES
CHEMICAL RADIATION EFFECTS
CHEMISTRY
DNA
ENERGY TRANSFER
FEMALE GENITALS
GONADS
HAMSTERS
HELA CELLS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IONS
LET
MAMMALS
METABOLITES
NUCLEIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANS
OVARIES
PYRIMIDINES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIOINDUCTION
RADIOSENSITIVITY
RECOVERY
REPAIR
RODENTS
STRAND BREAKS
THYMINE
URACILS
VERTEBRATES