Metabolism of naturally occurring homopolymers

The half-life of polyadenylated polysomal RNA from normal and transformed cells in monolayer culture

The small genotypic differences between normal and transformed cells are insufficient to account directly for all their wide phenotypic differences, which probably in some cases at least involve alterations in control of gene expression. To ascertain whether such alterations involved changes in mRNA stability, RNA half-lives were estimated in five monolayer cell lines, including two pairs of normal cells and their transformed counterparts. The results for the polyadenylated fractions in all cases fit with those expected from a model in which the whole fraction has a single half-life, of less than one generation time. From both the transformed/untransformed cell pairs, there is evidence that a relationship exists between cell generation time and the half-life of the polyadenylated polysomal RNA fraction, which persists even through the process of transformation. Considerable alteration in the pattern of RNA stability is therefore unlikely to be obligatory in in vitro transformation.

Release of nuclear DNA template restrictions by specific polyribonucleotides

Certain synthetic homo- and copolyribonucleotide polymers are capable of releasing the DNA template restriction of isolated nuclei of rat liver cells when assayed with an excess of or in the absence of exogenous DNA polymerase. The purine homopolyribonucleotides are far more effective than are the pyrimidine polymers.