Effects of ultraviolet irradiation on the rate and sequence of DNA replication in synchronized Chinese hamster cells

Journal Article · Sat May 01 04:00:00 EDT 1976 · Biophys. J.; (United States)

DOI:https://doi.org/10.1016/S0006-3495(76)85706-2· OSTI ID:7118372

Meyn, R E; Hewitt, R R; Thomson, L F; Humphrey, R M

The effects of ultraviolet light (uv) irradiation on the rate of DNA replication in synchronized Chinese hamster ovary (CHO) cells were investigated. A technique for measuring semiconservative DNA replication was employed that involved growing the cells in medium containing 5-bromodeoxyuridine and subsequently determining the amount of DNA that acquired hybrid buoyant density in CsCl density gradients. One of the advantages of this technique was that it allowed a characterization of the extent of DNA replication as well as rate after irradiation. It was found that while there was a dose-dependent reduction in the rate of DNA replication following uv-irradiation, doses of up to 10 J/m/sup 2/ (which produce many dimers per replicon) did not prevent the ultimate replication of the entire genome. Hence, we conclude that dimers cannot be absolute blocks to DNA replication. In order to account for the total genome replication observed, a mechanism must exist that allows genome replication between dimers. The degree of reduction in the rate of replication by uv was the same whether the cells were irradiated at the Gl-S boundary or 1 h into S-phase. Previous work had shown that cells in early S-phase are considerably more sensitive to uv than cells at the G1-S boundary. Experiments specifically designed to test for reiterative replication showed that uv does not induce a second round of DNA replication within the same S-phase.

• Research Organization: Univ. of Texas, Houston
• OSTI ID: 7118372
• Journal Information: Biophys. J.; (United States), Journal Name: Biophys. J.; (United States) Vol. 16:5; ISSN BIOJA
• Country of Publication: United States
• Language: English

Related Subjects

560121* -- Radiation Effects on Cells-- External Source-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
ANIMAL CELLS
ANTIMETABOLITES
ANTIMITOTIC DRUGS
AZINES
BIOLOGICAL EFFECTS
BIOLOGICAL RADIATION EFFECTS
BROMOURACILS
BUDR
CELL CULTURES
CELL CYCLE
DIMERS
DNA REPLICATION
DOSE-RESPONSE RELATIONSHIPS
DRUGS
ELECTROMAGNETIC RADIATION
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
IRRADIATION
NUCLEIC ACID REPLICATION
NUCLEOSIDES
NUCLEOTIDES
ORGANIC BROMINE COMPOUNDS
ORGANIC COMPOUNDS
ORGANIC HALOGEN COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PYRIMIDINES
RADIATION EFFECTS
RADIATIONS
RIBOSIDES
SYNCHRONOUS CULTURES
ULTRAVIOLET RADIATION
URACILS