Nucleosome positioning and periodicity of satellite DNA in the liver of aging rats. Nucleosome positioning and periodicity of satellite DNA.

The positioning of nucleosomes has been analysed by comparing the pattern of cutting sites of a probing reagent on chromatin and naked DNA. For this purpose, high molecular weight DNA and nuclei from the liver of young (18 +/- 2 weeks) and old (100 +/- 5 weeks) Wistar male rats were digested with micrococcal nuclease (MNase) and hybridized with 32P-labelled rat satellite DNA probe. A comparison of the ladder generated by MNase with chromatin and nuclei indicates long range organization of the satellite chromatin fiber with distinct non-random positioning of nucleosomes. However, the positioning of nucleosomes on satellite DNA does not vary with age. For studying the periodicity and subunit structure of satellite DNA, high molecular weight DNA from the liver of young and old rats were digested with different restriction enzymes. Surprisingly, no noteworthy age-related change is visible in the periodicity and subunit structural organization of the satellite DNA. These results suggest that the nucleosome positioning and the periodicity of liver satellite DNA do not vary with age.