DIFFERENCES IN THE RESPONSE TO MUTAGENS BETWEEN 2 V79 SUBLINES

Two V79 Chinese hamster sublines (V79-UL and V79-MZ) which differed ma rkedly with respect to their spontaneous pattern of mutations at the H PRT locus were comparatively investigated in genotoxicity tests with e thyl methanesulphonate (EMS). EMS-induced frequencies of HPRT mutation s and sister chromatid exchanges (SCEs) were much higher in V79-MZ tha n in V79-UL. V79-MZ were not hypersensitive against EMS and had normal frequencies of spontaneous gene mutations and chromosome aberrations. Baseline SCE frequencies at various BrdUrd concentrations were slight ly increased compared to V79-UL. EMS induced a similar amount of chrom osome aberrations in both cell lines but exchange figures occurred wit h lower frequency in V79-MZ. The results indicate that specific and si gnificant differences in the response to mutagens may exist between 'n ormal' Chinese hamster cell lines which might be relevant for genotoxi city testing.