Molecular events in liver regeneration and repair.
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Animals↗
Biomedical subjects
J L van Lancker
Publications and source records attributed to J L van Lancker.
Procainamide-DNA interaction.
The interactions of procainamide with DNA were studied by neutral and alkaline sucrose gradient sedimentation and sequential action of 2 enzymes: a mammalian repair endonuclease and bacterial DNA polymerase I. Sucrose gradient sedimentation shows that in the absence of photosensitization, the interaction of procainamide with DNA did not modify DNA sedimentation in alkaline or neutral sucrose gradients. In contrast, when a photosensitized DNA procainamide mixture was placed on sucrose gradients, the peak appearing on alkaline sucrose gradient after treatment with endonuclease was shifted toward the lower molecular weights, indicating that strand breaks had developed in the photosensitized procainamide DNA. Incubation of a [32P] labeled photosensitized procainamide-DNA complex with a repair endonuclease and DNA polymerase I released the label in the acid soluble fraction, indicating that only the photosensitized procainamide-DNA complex was susceptible to the endonucleolytic attack. There was only negligible release of the label in the acid soluble fraction without exposure of the DNA-procainamide mixture to light. The incorporation into DNA of [3H]-TTP (tritium labeled triphosphates) in presence of DNA polymerase I was inhibited when the photosensitized procainamide-DNA complex was used as substrate. However, after treatment of the photosensitized DNA complex with the repair endonuclease, the incorporation of [3H]-TTP was increased and reached values close to that observed with DNA unexposed to light, suggesting that the endonuclease functions as a repair enzyme.
Animals↗
The effect of a mammalian repair endonuclease on x-irradiated DNA.
DNA was extracted from rat liver of non-irradiated animals, and was irradiated in vitro, and from animals which received whole body doses of X-radiation. Sedimentation on neutral and alkaline sucrose gradients as well as measurements of 32P release after sequential treatment with endonuclease and alkaline phosphatase and determination of triphosphate incorporation after the sequential treatment with endonuclease, alkaline phosphatase and DNA polymerase indicated that DNA irradiated in vivo and in vitro were effective substrates for the mammalian repair endonuclease. The experiments suggest that in addition to strand breaks, X-radiation causes base damage and they have provided a plausible explanation for the formation of double strand breaks in DNA irradiated in vivo.
Alkaline Phosphatase↗