title: Nucleosomes from normal and regenerating rat liver.
abstract: Micrococcal-nuclease digestion of rat liver nuclei selectively released mononucleosomes associated with ADP-ribosylated [Caplan, Ord & Stocken (1978) Biochem. J.174, 475-483] histone H1. Two classes of mononucleosome were detected, those that leaked out during digestion and those that were subsequently released by 5mm-sodium phosphate buffer (pH6.8)/0.2mm-NaEDTA. The former, from which histone H1 had been dissociated, contained 140-base-pair-length DNA and core histones;the latter contained core particles and mononucleosomes with histone H1 and 200-base-pair-length DNA. When normal liver nuclei were phosphorylated with [gamma-(32)P]ATP, dissociated histone H1, which could be separated from core particles with Sephadex G-200, showed (32)P uptake. (32)P uptake into histones H2A and poly(ADP-ribosyl)ated H3 was appreciable in core particles, but was less evident in nucleosomes still containing histone H1. When [(3)H]-thymidine was given to partially hepatectomized rats in S-phase, 5-10min pulses in animals of over 300g body wt. showed the presence of high-specific-radioactivity DNA in released core particles and mononucleosomes compared with DNA retained in the nuclear pellets. Mononucleosomes from rat livers in S-phase with new, [(3)H]lysine-containing histones, had higher (32)P incorporation in histones H1 and their core histones, than for di- or tri-nucleosomes. Thermal-denaturation properties of control and phosphorylated mononucleosomes and core particles were very similar; removal of histone H1 and non-histone chromosomal proteins in 0.5m-NaCl markedly increased the proportion of DNA ;melting' below 70 degrees C.
mesh_terms: D000818:Animals; D002453:Cell Cycle; D002467:Cell Nucleus / Q000378:metabolism*; D004247:DNA / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D006657:Histones / Q000378:metabolism; D006358:Hot Temperature; D066298:In Vitro Techniques; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008115:Liver Regeneration; D008297:Male; D010766:Phosphorylation; D051381:Rats; D013936:Thymidine / Q000378:metabolism
chemical_list: D006657:Histones; D004247:DNA; D013936:Thymidine