[Polysomal apparatus as a reflection of function interactions between translation and transcription processes during...

Distribution of optical density and radioactivity in sucrose density gradient was studied for 14C-RNA and 3H-protein polysomal components isolated from normal rat liver 1, 3, 6 12 and 24 hrs after cycloheximide (CHI) treatment (sublethal dose--0,3 mg/100 g body weight). Soon after the antibiotic injection (1--3 hrs), when protein biosynthesis was strongly inhibited (more than 90%), the total quantity of "heavy" polyribosomes and 14C-mRNA associated with this fraction significantly increased. At the same time the amount of free ribosomes showed a decrease. On the contrary, after 6 hrs the amount of polysomes sharply decreased and that of ribosomes and their subunits was increased. In the middle period and at the end of experiment (12--24 hrs) when protein biosynthesis was continuously restored, the polysomes sedimentation pattern was restored as well. Specific radioactivity of 14-C-rRNA's and 3H-proteins in this fraction was also increased. The restoration of optimal protein biosynthesis level after its inhibition by a single cycloheximide injection (sublethal doses) is thought to be a complex process of consecutive interactions between translation and transcription cell systems.