Posttreatment with sodium arsenite alters the mutational spectrum induced by ultraviolet light irradiation in Chinese hamster ovary cells
- Institute of Biomedical Sciences, Taipei (Taiwan, Province of China)
Arsenic, a potent carcinogen, fails to induce gene mutations in mammalian cells. However, posttreatment of ultraviolet light (UV)-irradiated cells with sodium arsenite synergstically enhances the mutation frequency on the hypoxanthine (Guanine) phosphoribosyltransferase locus. To investigate the molecular mechanism of the comutagenic effects of sodium arsenite, the authors characterized the alternations of nucleotide sequences in 30 UV-induced and 39 sodium arsenite enhanced hprt mutants from CHinese hamster ovary K1 cells by direct sequencing of mRNA-PCR amplified cDNA. The majority of sequence alterations derived from UV irradiation (80%) and from sodium arsenite posttreatment (70%) were single base substitutions. UV irradiation induced all types of base substitutions. Among them, 57% were transversions. The frequency of transversion increased to 70% in sodium arsenite enhanced mutants. While base substitutions observed in UV-induced mutants were evenly distributed along with the whole coding region, exons 3 and 8 were most frequently mutated in sodium arsenite enhanced mutants. Sodium arsenite posttreatment did not alter the strand bias for mutation induction, i.e., 73% and 78%, of the mutations were located on the non-transcribed strand in UV-induced and sodium arsenite enhanced mutants, respectively. In contrast to UV-induced mutations, bases at the 5' position of TT and the 3' position of CT sequences were the most frequent mutation sites observed in sodium arsenite enhanced mutants. The authors hypothesize that sodium arsenite may interfere with the process of mutation fixation of TT and CT dimers during DNA replication. 50 refs., 2 figs., 6 tabs.
- OSTI ID:
- 7159419
- Journal Information:
- Environmental and Molecular Mutagenesis; (United States), Vol. 20:3; ISSN 0893-6692
- Country of Publication:
- United States
- Language:
- English
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ANIMAL CELLS
GENETIC RADIATION EFFECTS
ARSENATES
BIOLOGICAL EFFECTS
ULTRAVIOLET RADIATION
ARSENIC COMPOUNDS
BIOLOGICAL RADIATION EFFECTS
ELECTROMAGNETIC RADIATION
GENETIC EFFECTS
OXYGEN COMPOUNDS
RADIATION EFFECTS
RADIATIONS
560120* - Radiation Effects on Biochemicals
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