Incorporation of N6-Benzyladenine into Messenger Poly(A)-RNA of Tobacco Cells Incubated at Stimulatory or Cytostatic Cytokinin Concentration

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Abstract
Poly(A)-RNA was purified from Nicotiana tabacum cell suspension cultures grown in the presence of N(6)-benzyladenine (BA). Cells were incubated with concentrations of 0.4 micromolar BA, optimal for cell division (OPT) or 10 micromolar BA, a cytostatic concentration (OVD), or without cytokinin (CTL) as a control. After 55 hours, total RNA was extracted from the cells and poly(A)-RNA was purified by oligo(dT)-cellulose binding. Similar yields of poly(A)-RNA were obtained for OPT or CTL cell samples; the compared recovery from the OVD cell samples was reduced by more than half. Poly(A)-RNA extracted from OPT or OVD cells contained BA nucleotide, inserted at the respective frequencies of 78 and 506 micromoles per mole conventional nucleotide. BA was inserted into the transcript as well as into the poly(A) segments. No qualitative or quantitative difference was observed between the in vitro translation activities of poly(A)-RNA extracted from OPT or CTL cells. The electrophoretic analysis of translation products from OVD mRNA showed a deficiency in proteins of molecular weight over 50 kilodaltons. This deficiency may be explained by a change in the coding properties of OVD mRNA rather than by a deficiency of the high molecular weight components in the mRNA population.