Irradiation damage in chromatin isolated from V-79 Chinese hamster lung fibroblasts

Journal Article · Wed Apr 01 04:00:00 EST 1987 · Radiat. Res.; (United States)

DOI:https://doi.org/10.2307/3576886· OSTI ID:6613500

Heussen, C; Nackerdien, Z; Smit, B J; Boehm, L

The effect of chromatin structure on the extent of radiation damage induced by low doses of 100 KeV X rays was investigated using a fluorescent assay for DNA unwinding. Chromatin was isolated from V-79 Chinese hamster lung fibroblast nuclei by partial digestion with micrococcal nuclease. Gel electrophoresis of the isolated DNA showed the molecular weight of the chromatin preparation to be 10.6 X 10(6) with a size range of 6.6-21.7 X 10(6) Da while a size of 10.2 +/- 0.9 X 10(6) Da was found by sedimenting the DNA in alkaline sucrose gradients. The repeat length of V-79 chromatin was found to be 194 +/- 3 bp. The typical nucleosomal repeat structure of the isolated chromatin and that of intact nuclei was identical. Irradiation with 50 and 100 Gy of 100 KeV X rays and analysis by alkaline sucrose density centrifugation indicated that V-79 chromatin sustained 0.56 +/- 0.19 and 0.69 +/- 0.09 single-strand breaks per 10 Gy per 10(8) Da of DNA, respectively. Irradiation with doses of 0.5-3.0 Gy of 100 KeV X rays and analysis by the fluorometric assay showed that the radiation sensitivity of V-79 chromatin decreases sharply on compaction with MgCl/sub 2/. Histone H1 depletion, which inhibits compaction and causes chromatin to expand by increasing the linker from 26 to 48 bp, results in a considerable increase in the radiation sensitivity. It is concluded that radiation damage sustained by DNA is greatly influenced by chromatin structure.

• Research Organization: Univ. of Stellenbosch, Tygerberg, Republic of South Africa
• OSTI ID: 6613500
• Journal Information: Radiat. Res.; (United States), Journal Name: Radiat. Res.; (United States) Vol. 1; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

560120* -- Radiation Effects on Biochemicals
Cells
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63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ALKALINE EARTH METALS
ANIMAL CELLS
ANIMALS
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BODY
CELL CONSTITUENTS
CELL NUCLEI
CENTRIFUGATION
CHROMATIN
CONNECTIVE TISSUE CELLS
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DOSE-RESPONSE RELATIONSHIPS
ELECTROMAGNETIC RADIATION
ELECTROPHORESIS
ELEMENTS
FIBROBLASTS
GENETIC EFFECTS
GENETIC RADIATION EFFECTS
HAMSTERS
HISTONES
IONIZING RADIATIONS
LUNGS
MAGNESIUM
MAMMALS
METALS
MOLECULAR STRUCTURE
MOLECULAR WEIGHT
NUCLEIC ACIDS
NUCLEOPROTEINS
NUCLEOSOMES
ORGANIC COMPOUNDS
ORGANS
PROTEINS
RADIATION EFFECTS
RADIATIONS
RADIOSENSITIVITY
RESPIRATORY SYSTEM
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SEPARATION PROCESSES
SOMATIC CELLS
STRAND BREAKS
ULTRACENTRIFUGATION
VERTEBRATES
X RADIATION