Polyadenylated RNA molecules and polyribosomes in tumours of chemical and viral origin.

The distribution of poly(A)-enriched mRNA in nuclei, mitochondira, free and membrane-bound polyribosomes from normal C3HA mouse and Syrian hamster livers and normal chicken fibroblasts has been compared with that in corresponding subcellular fractions in a transplantable, chemically induced MD hepatoma, non-virus-producer hamster and virus-producer chicken Rous sarcomas. It has been shown that the content of poly(A)-RNA is increased in all tumour fractions except in free polyribosomes. The distribution of different classes of polysomes i.e. free, membrane-bound and mitochondrial outer-membrane-associated polysomes in tumour cells was changed in comparison to that in normal cells. It is concluded that in tumours of chemical and viral origin, the observed changes in the two components of the protein-synthesizing apparatus occur simultaneously.