Influenza of age on chromatin transcription in murine tissues using a heterologous and an homologous RNA polymerase.

No gross changes in the compositions of chromatin prepared from liver, kidney and brain were noted with age. A decreased age-dependent in vitro chromatin template activity was observed using an Escherichia coli RNA polymerase. This was paralleled by a reduction in the number of initiation sites on the chromatin for the enzyme. However, using a homologous RNA polymerase definite age-related specificities in template activity were found. When chromatin and enzyme were 'age-matched', maximal activity was observed. This levle of activity was comparable in both 6 and 31-month-old mice, which suggested no impairment of function with age.