Analysis of rat liver chromatin and nuclear proteins after nutritional variation 1,2
Castro, C.E.; Sevall, J.S.
Journal of Nutrition 112(6): 1203-1211
1982
ISSN/ISBN: 0022-3166 PMID: 7086547 Document Number: 189749
Chemical composition of liver chromatin was determined for rats fed a complete stock diet or a diet lacking protein or fat. High carbohydrate, fat-free (diet 1) and low carbohydrate, protein-free (diet 2) diets were selected because they elicit structural alteration in chromatin as measured by incubation with micrococcal nuclease (EC 3.1.31.1). In the study, either dietary treatment caused an increase in mass ratios of RNA:DNA and nonhistone:DNA, relative to control ratios. The nonhistone:DNA ratios in liver of rats fed diet 1 or diet 2 were 2.4- and 3.5-fold, respectively, larger than control ratios. The histone-DNA ratio remained relatively constant among all 3 dietary treatments. Liver nuclei were purified from rats fed each dietary treatment and were solubilized in 9 M urea. The nuclear proteins were analyzed by 2-dimensional electrophoresis and visualized with a Ag treatment that stains proteins in color. The electrophoretograms presented show preferentially proteins with low MW and acidic pI , 2 characteristics of nonhistones. The 2-dimensional protein patterns are nearly identical for nuclear proteins from all 3 treatments. Analysis of the electrophoretograms indicates that the diet-induced increased nonhistone: DNA ratios are apparently not attributable to new species of protein, but rather to increased relative abundance of many proteins in the existing populations.