Rejoining of x-ray induced chromosome breaks in human cells and its relationship to cellular repair

Thesis/Dissertation · Tue Jan 01 04:00:00 EST 1985

OSTI ID:6936390

Cornforth, M N

A method was developed to improve the resolution for measuring breaks produced in interphase chromosomes by X-rays following the induction of premature chromosome condensation (PCC). It is based on the principle of 5-BrdU incorporation into the DNA of HeLa mitotic cells, which act as inducers of PCC when they are fused to diploid human fibroblasts. After a modified Fluorescence Plus Giemsa (FPG) protocol, the PCC stain intensely, while the mitotic inducer chromosomes stain faintly. The dose response for density inhibited (G/sub 0/) human cells was linear from 10.9 to 600 rad, with a slope of 0.06 breaks per cell per rad. Upon incubation at 37/sup 0/C, half of the breaks disappeared in 2 hours. Following a dose of 600 rad the initial rate of break rejoining mirrored the rate of increase in survival from post-irradiation incubation, due to the repair of potentially lethal damage (PLD). The X-ray induced PCC rejoining characteristics from two ataxia telangiectasia (A-T) cell lines were compared to profiles obtained with normal cells. Both normal and A-T cells apparently sustained the same initial level of radiation damage, and both cell types rejoined breaks at the same rate. However, while normal cells eventually rejoined all but about 5% of the breaks produced by 600 rad, the A-T lines were left with 5-6 times the level of residual damage. These experiments demonstrate that progression of cells into S phase is not a necessary condition for the measured frequency of chromosome fragments observed in X-irradiated A-T cells.

• Research Organization: Colorado State Univ., Fort Collins (USA)
• OSTI ID: 6936390
• Country of Publication: United States
• Language: English

Related Subjects

560120* -- Radiation Effects on Biochemicals
Cells
& Tissue Culture
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANTIMETABOLITES
AZINES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
BROMOURACILS
BUDR
CELL CULTURES
CELL CYCLE
CELL DIVISION
CHROMOSOMAL ABERRATIONS
CHROMOSOME BREAKAGE
CONNECTIVE TISSUE CELLS
DNA
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ELECTROMAGNETIC RADIATION
FIBROBLASTS
FLUORESCENCE
HELA CELLS
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IONIZING RADIATIONS
LUMINESCENCE
MITOSIS
MUTATIONS
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
RIBOSIDES
SOMATIC CELLS
URACILS
X RADIATION