Studies of poly(A+)-RNA in mouse hepatoma and cortisone-stimulated rat liver

The content of poly(A)-containing RNA in subcellar fractions has been investigated both in cortisone-treated rat liver and experimental hepatoma cells. The fractions included nuclei, cytoplasm, mitochondria, free and membrane-bound polyribosomes. 1) In both cases of genome activation (cortisone induction and hepatoma cells) an increase in poly(A) content of all subcellular fractions except free polyribosomes was observed. 2) Cortisone was found to induce elongation of poly(A) segments detected in both nuclei and cytoplasm. 3) An increase in the poly(A) block size also was found to be stimulated in nuclei and cytoplasm of hepatoma cells. 4) The observed elongation in poly(A) length occurred against the background of an increase of the population of of poly(A)-RNA's.