Action of FdUrD and dCyd on the incorporation of BrdUrd in chinese hamster somatic cell DNA and the isolation of auxotrophic mutants.

Chinese hamster somatic cells grown in the presence of bromodeoxyuridine, deoxycytidine and fluorodeoxyuridine incorporate more bromodeoxyuridine in the DNA than cells grown in the presence of bromodeoxyuridine alone. Thus they become more sensitive to light irradiation. Our data suggest that 0.05 mM--0.2 mM bromodeoxyuridine, 0.05 mM deoxyctidine and 10 mmug/ml fluorodeoxyuridine is one of the best possible combinations for the selection of Chinese hamster somatic cells mutants. Auxotrophs for proline, inositol or both were thus isolated at high frequency.