Abstract
The induction by r-7,t-8-dihydroxy-t-9,10-oxy-7,8,9,10-tetrahydrobenzo[a]pyrene (BPDE) of 8-azaguanine resistant (AGr) Chinese hamster V79 cell mutants was described, 40% of which contained material which cross-reacted (CRM) with antiserum to hypoxanthine-guanine phosphoribosyltransferase (HPRT) and whose AGr phenotype was ascribed to missense mutation. Any change in the HPRT gene in 11 CRM-negative mutants was not demonstrated by Southern blotting. HPRT mRNA of normal size and amount was found in most of these mutants. Examination of the revertants of one mutant indicates the probable occurrence of changes within an amino acid codon in the genesis of mutant and revertant. BPDE may function primarily as a point mutagen.