Age-related changes of supranucleosomal structures and DNA-synthesizing properties of rat liver chromatin

The template activity, nucleosomal pattern and thermodenaturation parameters of transcriptionally low active (TLA) and transcriptionally active liver chromatin fractions were studied in adult (6-8 months) and old (26-28 months) rats. The following age-related changes of chromatin template properties were found: decrease of endogenous DNA polymerase alpha- and beta-activity in vitro in both chromatin fractions, and redistribution of newly synthetized RNA between mono- and oligonucleosomes in the TLA fraction. These changes are thought to be connected with age-related reorganization of chromatin structure, i.e. with increase of DNA-protein interactions, which stabilize association of chromatin supranucleosomal structures.