Ribonucleic acid synthesis in regenerating and embryonic liver: I. The synthesis of new species of RNA during regeneration of mouse liver after partial hepatectomy

Abstract

Hybridization of RNA with DNA and the competitive effect of other RNA preparations have been used to analyze RNA synthesis following partial hepatectomy in the mouse. Control experiments are presented todemonstrate the sensitivity and repeatability of the methods. The efficiency of hybridization at a standard RNA/DNA ratio increases twofold during the first hour of regeneration and declines to that of normal liver by seven days, consistent with a dramatic increase in the number of active DNA sites following partial hepatectomy. The synthesis of new molecules of RNA not present in normal or sham-operated animals commences within the first hour of regeneration, although the RNA synthesis characteristic of normal liver continues. By comparing RNA isolated at various times during the regeneration process, it can be shown that the synthesis of different molecules is discontinued at various stages. Some of the molecules characteristic of one hour of regeneration are not labeled at six hours or later; indeed they are essentially absent. Other species of RNA disappear at later stages of regeneration, until at seven days the RNA synthesized is not distinguishable from that of normal individuals. Liver regeneration appears to be partly mediated by short-lived RNA molecules, the synthesis of which commences rapidly after partial hepatectomy and ceases at various times during the regenerative process.