Incorporation of Unnatural Pyrimidine Bases into Deoxyribonucleic Acid of Mammalian Cells

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Science  05 Jun 1959:
Vol. 129, Issue 3362, pp. 1550-1551
DOI: 10.1126/science.129.3362.1550


When a mammalian cell strain was incubated with 5-iododeoxyuridine and 5-bromodeoxyuridine, DNA thymine was partially replaced by the halogen-containing pyrimidines. The extent of incorporation of the unnatural bases increased when amethopterin and hypoxanthine were added to the medium. It is thus evident that the replacement of DNA thymine by selected structural analogs, a phenomenon previously reported for bacterial systems, is applicable to cells of higher organisms.