Changes in content of nuclear proteins and nucleic acids in regenerating liver

Abstract

At various intervals following partial hepatectomy in the rat, nuclei were isolated from homogenates of the regenerating liver, and they were analyzed for content of DNA and various protein fractions. A peak of mitosis was found at 28 hr after hepatectomy. With the exception of Histone Fractions II and III, each of the nuclear protein fractions had decreased in amount per nucleus at 15 hr. From 19 to 26.5 hr, all nuclear protein fractions increased in content per nucleus to values above those for normal liver with the exception of Protein III (residual lipo-protein) which returned only to normal. Average nuclear contents of all protein fractions declined shaply from 26.5 to 28 hr at which the average nucleus isolated probably was immediately post-mitotic. Only Histone Fraction II (derived from the deoxyribonucleoproteins readily extracted from the nuclei with 1 M NaCl) showed close correlation with the increase in DNA content between 15 and 26.5 hr. However, the increase in Histone II was relatively greater than the increase in total DNA in comparison with corresponding values for normal liver nuclei.