Extraction of rapidly labeled undegraded ribonucleic acid from isolated rat liver nuclei

Abstract

An important point in all investigations on nuclear RNA is the problem of isolation of pure nuclei. On the other hand, during the isolation of nuclei the nuclear RNA must be preserved from nucleases. In this connection it is not yet clear to what extent the different procedures for isolation of nuclei affect the nuclear RNA. Since there is strong evidence that the RNA is synthesized in the nucleus, all precursors of the cytoplasmic RNA's are expected to be found in the early labeled fractions of the nuclear RNA. It has been shown (1–3) that a RNA fraction having a higher turnover rate is not extractable by the usual phenol procedure. Although it accounts for only a few per cent of the total RNA it is of greatest biological importance, since it comprises both precursors of ribosomal RNA and of messenger RNA (4). The great lability of this RNA is possibly the reason why in different studies varying results were obtained concerning the heterogeneity and the localization of the early labeled RNA isolated from pure nuclei. In our experiments we have studied the electrophoretic and the labeling pattern of the nuclear RNA extracted from pure rat liver nuclei isolated by several different methods. A suitable procedure for isolation of rat liver nuclei with undegraded rapidly labeled RNA was established.