Cytological evidence for DNA chain elongation after UV irradiation in the S phase
Human cells irradiated with UV light synthesize lower molecular weight DNA than unirradiated cells. This reduction in molecular weight is greater in xeroderma pigmentosum (XP) cells than in normal cells. The molecular weight of DNA is further reduced by the addition of caffeine to XP cells. By several hours after irradiation, DNA fragments are barely detectable. Cells from excision-proficient and excision-deficient XP patients were studied autoradiographically to produce cytological evidence of DNA chain elongation. Replicate cultures with and without caffeine were synchronized and irradiated with UV light during the S phase. Caffeine was removed in G2, and the cells were labeled with /sup 3/H-thymidine. Results showed significantly increased labeling during G2 of excision-deficient XP cells. Labeling was dependent on the time of irradiation and presence of caffeine. The XP variant cells had no increase in labeling for any irradiation time.
- OSTI ID:
- 5307034
- Journal Information:
- Biochem. Genet.; (United States), Vol. 19:3-4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
59 BASIC BIOLOGICAL SCIENCES
DNA
CHEMICAL RADIATION EFFECTS
XERODERMA PIGMENTOSUM
AUTORADIOGRAPHY
BIOLOGICAL REPAIR
CAFFEINE
COMPARATIVE EVALUATIONS
CYTOLOGY
MOLECULAR WEIGHT
PATIENTS
QUANTITATIVE CHEMICAL ANALYSIS
RADIOSENSITIVITY
THYMIDINE
TIME DEPENDENCE
TRITIUM COMPOUNDS
ULTRAVIOLET RADIATION
ANALEPTICS
AZINES
BIOLOGICAL RECOVERY
BIOLOGY
CENTRAL NERVOUS SYSTEM AGENTS
CHEMICAL ANALYSIS
CHEMISTRY
DISEASES
DRUGS
ELECTROMAGNETIC RADIATION
HETEROCYCLIC COMPOUNDS
LABELLED COMPOUNDS
NUCLEIC ACIDS
NUCLEOSIDES
NUCLEOTIDES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
PURINES
PYRIMIDINES
RADIATION CHEMISTRY
RADIATION EFFECTS
RADIATIONS
RECOVERY
REPAIR
RIBOSIDES
SKIN DISEASES
XANTHINES
560111* - Radiation Effects on Biochemicals- In Vitro- (-1987)
550201 - Biochemistry- Tracer Techniques
550301 - Cytology- Tracer Techniques