[Effects of different concentrations of chloramphenicol on RNA synthesis in E. coli]

In the presence of 2 microgram/ml chloramphenicol the rate of total RNA synthesis increases 1,6-fold, while that of rRNA synthesis--2,5--3,0-fold. Other ribosomal antibiotics, e.g. oxytetracycline, neomycin and puromycin, as well as chloramphenicol stimulate the synthesis of RNA while not causing a complete inhibition of the protein synthesis. Intensive stimulation of the rate of rRNA synthesis with low concentrations of chloramphenicol may be due to a decrease of intracellular concentration of guanosine-5'-diphosphate, 3'-diphosphate, as well as to the maintenance of a sufficiently high level of protein synthesis under these conditions.