A partial sequence of nuclear events in regenerating rat liver (gene regulation-chromosomal RNA)

When two lobes of the liver of the adult rat are removed, the cells of the remaining lobe are aroused to renewed cell division. We have studied the early events in such regeneration. The first observable response to such partial hepatectomy is the production in the liver nuclei of rapidly-labeled high-molecular-weight RNA of sequences not produced by normal liver. This is followed, with a lag of about 1 hr, by the appearance of increased (above normal) amounts of chromosomal RNA, again of sequences not produced by normal liver. With a lag of another hour, the template activity in support of RNA synthesis of the liver chromatin increases substantially. These events occur before initiation of DNA synthesis in the cells of the regenerating liver.