Isolation of and ribonucleic acid synthesis in nuclei of rat fetal liver.

Abstract Nuclei were prepared from rat fetal liver by a modified sucrose procedure and their properties were determined. Electron micrographs of these nuclei indicated the relative purity and the preservation of the morphological characteristics. The RNA:DNA and acid-soluble nuclear protein (ASNP): DNA of these nuclei were 0.5 and 2.2, respectively. The DNA content of these nuclei was 4.8 pg/nucleus compared to 9.6 for adult rat liver nuclei. The fetal liver nuclei were also prepared by a citric acid procedure. The nucleic acid and protein contents of these nuclei were lower. Electron micrographs of citric acid-concentrated nuclei suggested either an extraction or clumping of the nuclear contents. The activities of ATP'ase, glucose-6-phosphatase, NADH- and NADPH-cytochrome c reductases in the preparations of the fetal liver nuclei concentrated by the modified sucrose method were very low. Ribonuclease activity was higher in the nuclei from fetal rat liver than from adult liver. The properties of these nuclear ribonucleases were compared. Sedimentation analysis of the nuclear RNA from fetal and adult liver was qualitatively similar with absorbancy peaks at 4, 18, 28 and 45 S and a shoulder at 35 S.