RNA-SYNTHESIS IN GROWING AND STATIONARY CELLS OF A CULTURE OF SCARLET ROSE - DISPROPORTIONATE SYNTHESIS OF RIBOSOMAL-SUBUNITS IN THE STATIONARY STATE

RNA synthesis has been investigated in resting and growing cells of a culture of Scarlet rose. The rates of messenger RNA (mRNA) and ribosomal RNA (rRNA) synthesis are five‐ and ten‐fold higher, respectively, in the growing culture. In stationary phase cultures, newly synthesized 26S and 18S rRNA do not appear in the cytoplasm in equimolar amounts. Rather, the 26S/18S ratio of [3H]‐uridine labeled rRNA of stationary cells ranged from 0.9 to 1.3 while the ratio of the corresponding fraction from growing cells was 1.6 to 2.0. A similar result was obtained when cells were labeled with [3H‐CH3] methionine. Pulse chase experiments demonstrated that the nascent pre‐rRNA in resting cells could be chased into polysomes. These data are interpreted to indicate that a major part of the regulation of rRNA synthesis in stationary cells is at the level of the processing of the rRNA transcript. Copyright © 1979 Wiley‐Liss, Inc.