Estimation of the single stranded region in the nuclear DNA of mouse tissues during aging with special reference to the brain.

The proportion of single stranded DNA in various tissues of mouse during aging was examined by measuring sensitivity to a single-strand specific nuclease. Brain DNA from mice of more than 15 mth old contained 3% of the single stranded regions while that from younger animals contained 2%. The DNAs from liver, kidney, heart and spleen did not show significant age-associated changes.