The repair of DNA in the alveolar macrophages of the baboon has been investigated after treatment of the cells in vitro with ultraviolet light and with the alkylating agent, methyl methanesulfonate. Repair replication has been observed to occur after ultraviolet-light irradiation of macrophages attached to plastic dishes. The two different techniques used for measuring repair replication were a standard density-gradient procedure which separates normal-density, repair-replicated, preexisting DNA from semiconservatively synthesized DNA containing sufficient [3H]bromodeoxyuridine to cause a density shift; and an alternative procedure applicable to nonproliferating cell systems wherein residual semiconservative synthesis is inhibited by hydroxyurea, and the increased incorporation of the DNA precursor [3H]thymidine due to repair replication is measured. The latter technique was applied to the investigation of the concentration dependence of repair replication both after and during the treatment of the cells with the alkylating agent, methyl methanesulfonate. The labeling after treatment measures the repair of damage still present at the end of the treatment interval, while the labeling during treatment allows for greater sensitivity and detection of all repair occurring during the treatment period.
ASJC Scopus subject areas
- Environmental Science(all)