POLYMERASE CHAIN REACTION-BASED DELETION ANALYSIS OF SPONTANEOUS AND ARSENITE-ENHANCED GPT MUTANTS IN CHO-AS(52) CELLS

In this study, we have examined the mutagenicity of sodium arsenite at the xanthine-guanine phosphoribosyltransferase locus (ypt) in a pSV2 gpt-transformed CHO cell line, AS52. Our results provide very weak evi dence for arsenite as a gene mutagen because the chemical at high dose s and at high cytotoxicity enhances barely a doubling of mutant freque ncy (MF) and a doubling of the gpt gene deletion frequency compared to controls. We suggest that the increase in MF in arsenite-treated cell s results from arsenic, as comutagen, enhancing the induction effect o f any unknown endogenous or exogenous factors on the spontaneous mutag enesis of AS52 cells. Nested PCR analysis mutants has a total deletion of the gpt gene. For the spontaneous, 50 mu M arsenite- and 100 mu M arsenite-enhanced spontaneous mutants in AS52 cells, the percentages o f total deletion of the gpt gene are 36.00%, 54.72% and 66.67%, respec tively. We suggest that a high proportion of the gene deletion in arse nite-enhanced mutants may be due to the high cytotoxicity of the chemi cal.