N-nitrosomorpholine and N-nitrosobutylamine-stimulated DNA synthesis in BHK-21/C13 cells.

Non-semiconservative DNA synthesis was examined in BHK-21/C13 cells after treatment with the aliphatic N-nitrosobutylamine (NB) and the heterocyclic N-nitrosomorpholine (NM). The extent of repair synthesis after alkylation was compared quentitatively and calculations were made of the amount of DNA damage per cell and number of bases inserted per damaged site. Of the chromosome aberrations caused by NM the most predominant were dicentrics. Other aberrations included fragments, gaps, breaks and exchanges of both the chromatid and chromosome type. Unlike NM, NB elicted a higher frequency of chromatid breaks.