Base Composition of Fractions of Nuclear and Nucleolar Ribonucleic Acid Obtained by Sedimentation and Chromatography

Purification and properties of nuclear and cytoplasmic deoxyribonucleic acidlike ribonucleic acid from Ehrlich ascites cells

“…In contrast, the ndRNA showed the characteristic high U base composition and the broad pattern of more rapidly sedimenting RNA which have been found for the ndRNA from a number of different sources (Muramatsu et al, 1966;Attardi et al, 1966; Houssais and Attardi, 1966; Soeiro et al, 1966; Willems etal., 1968).…”

“…Several types of evidence have indicated that there exists in the nuclei of animal cells a species of RNA whose function is restricted to the nucleus. These include DNA-RNA hybridization experiments (Shearer and McCarthy, 1967), base ratios of very short pulselabeled RNA from the nucleus and cytoplasm of duck erythrocytes (Attardi et al, 1966) and HeLa cells (Houssais and , the properties of nuclear and cytoplasmic RNA from cells labeled in the presence of low concentrations of actinomycin D Penman et al, 1968) and the properties of ndRNA isolated by nuclear fractionation techniques (Muramatsu et al, 1966;Soeiro et al, 1966;Willems et al, 1968). The argument could be made that the unique base composition of ndRNA was due, in the case of the pulse-labeled RNA experiments, to nonequilibration of 32P pools and, in the case of the actinomycin experiments, to the "unnatural" influence of actinomycin on RNA synthesis within the nucleus.…”

“…This ndRNA,* 1 therefore, is distinct from the rRNA, rpRNA (Scherrer et at., 1963), tRNA, and 5S RNA (Knight and Darnell, 1967) which are also found in the nucleus. The ndRNA represents a large fraction of the rapidly labeled RNA in the cell and can be isolated from nuclei in amounts which are readily detectable by optical density measurements (Muramatsu et al, 1966).…”

“…Several procedures have been used for the isolation of ndRNA. These include nuclear fractionation (Soeiro et al, 1966;Willems et al, 1968) and nuclear fractionation in combination with methylated albumin kieselguhr chromatography (Muramatsu et al, 1966). Of the various methods of RNA fractionation which are presently available, chromatography on methylated albumin kieselguhr columns is potentially one of the most useful, since the procedure is convenient, the recovery can be made quantitative, and large amounts of RNA can be fractionated.…”

Fidelity of ribosomal ribonucleic acid synthesis by nucleoli and nucleolar chromatin

“…h Nucleotide composition of nucleolar 45S RNA determined by ultraviolet spectra analyses (Muramatsu et al, 1966). ' The endogenous incorporation by chromatin was 0.46 pmol of |'H]GMP per Mg of DNA per 10 min.…”