Effect of 5-BUdR on RNA synthesis in Dictyostelium discoideum under growth and starvation conditions

Abstract Amoebae of Dictyostelium discoideum , treated with 0.2 mM 5-bromodeoxyuridine (5-BUdR) for one generation, display an altered differentiation pattern. In this work we analysed the consequence of this treatment on the RNA synthesis during growth and during the first 7 h of starvation. The results show that 1 . The rate of ribosomal RNA (rRNA) synthesis of exponentially growing treated cells decreases by 25%. 2 . Nutrient starvation by itself induces an immediate 70% decrease in the rate of rRNA synthesis. When amoebae are pretreated with 5-BUdR, the inhibition of rRNA synthesis observed during the growth phase occurs also during starvation and therefore lowers the residual activity normally observed during that period.