Cultures of fibroblasts from newborn rats and successive subcultures of these cells were treated with 4-nitroquinoline-1-oxide to induce DNA repair. DNA from the cultures was examined by velocity sedimentation in alkaline sucrose gradients immediately after drug treatment and after a post-treatment incubation period of 3 h. Early passage cells were able to repair the damage that appeared as single strand breaks, however, by the seventh subculture this activity was not apparent. Measurements of repair synthesis showed a partial loss of this capacity with successive subculture. The results fit a model in which 4NQO causes two kinds of DNA modification, one of which is alkali labile and appears as a single-strand break. Both modifications are subject to excision repair, but each is recognized initially by a specific endonuclease. In the late passage cells, the endonuclease specific for the alkali labile modification is absent.
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Article| August 01 1977
Loss of DNA repair capacity during successive subcultures of primary rat fibroblasts.
A C Chan
I G Walker
Online ISSN: 1540-8140
Print ISSN: 0021-9525
J Cell Biol (1977) 74 (2): 365–370.
A C Chan, I G Walker; Loss of DNA repair capacity during successive subcultures of primary rat fibroblasts.. J Cell Biol 1 August 1977; 74 (2): 365–370. doi: https://doi.org/10.1083/jcb.74.2.365
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