Photo-induced DNA damage, DNA repair and cell lethality
DNA lesion induction and repair was measured in DNA repair proficient and deficient cells after exposures to far-UV, mid-UV, near-UV and visible light and an attempt was made to relate these molecular phenomena to the biological endpoint of cell lethality. Pyrimidine dimer and strand break induction, DNA repair and cell killing were measured after cell exposure to polychromatic but narrow bandwidth light sources with peak emissions at 254, 305, 353, 369, and 445 nm. Pyrimidine dimers were detected using specific endonuclease that nicks DNA adjacent to dimers, while strand breaks were measured using an alkaline unwinding assay. The induction efficiencies of both lesions declined with increasing wavelength; however, the decrease in strand break induction was not as rapid as that of dimer induction. The ratio of strand breaks to dimers following cell exposure to 254 or 369 nm radiation was, respectively, 1.8 x 10/sup -4/ or 0.19. The kinetics of dimer repair as well as the size of repair synthesized patches remained constant with increasing wavelength, indicating a similar repair mechanism for dimers induced by all wavelengths tested. However, consistent with the detected decline in dimer induction with increasing wavelength the proportion of dimer repair to total DNA repair decreased with increasing wavelength. The efficiency of cell killing, determined using chlonagenic survival assays, dropped rapidly, but not as rapidly as that of dimer induction, with increasing wavelength. In addition, dimer repair deficient xeroderma pigmentosum cells became less lethally hypersensitive with increasing wavelength. These data suggest a decline in dimer induced cell lethality and the existence of non-dimer lethal lesions at longer wavelengths.
- Research Organization:
- Pennsylvania Univ., Philadelphia (USA)
- OSTI ID:
- 5017047
- Resource Relation:
- Other Information: Thesis (Ph. D.)
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
CELL KILLING
RADIOINDUCTION
DNA REPAIR
PYRIMIDINE DIMERS
STRAND BREAKS
ANIMAL CELLS
EXPERIMENTAL DATA
MAN
MEASURING METHODS
ULTRAVIOLET RADIATION
VISIBLE RADIATION
ANIMALS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
DATA
ELECTROMAGNETIC RADIATION
INFORMATION
MAMMALS
NUMERICAL DATA
PRIMATES
RADIATIONS
RECOVERY
REPAIR
VERTEBRATES
560121* - Radiation Effects on Cells- External Source- (-1987)