Changes in structural integrity of heart DNA from aging mice

Abstract

The state of the structural integrity of the DNA from mouse myocardial cells has been investigated by utilizing both CaCl density gradient sedimentation and digestion by S 1 eadonucleasa from Aspergillus orzae. The DNA from myocardial cells of young mice 3 sedimeated in â narrow peak at the ezpected density of 1 .701 g/cm , while the DNA from the heart cells of senescent mice became broadly distributed is CaCl gradients, banding even more multimodally is alkaline sucrose gradients. This mode of sedimentation indicates that old mouse DNA becomes partially fragneated. When the native DNA of myocardial calls from 6, 20 and 30 month old mice was treated with single-strand specific S endonuclease, it was the DNA from the senescent mice that showéd a progressive increase in sensitivity to digestion by the enzyme. The results indicate that the heart DNA of aging mice develops single-stranded gaps in addition to a breakdown into differently sized fragments .