[14C-alanine incorporation into rat thymus nuclear proteins on actinomycin D administration at different times of day].

Actinomycin D was administered to rats at various day periods and it was observed that the levels of the nuclear protein synthesis in the thymus cells significantly lowered depending on the period of the drug administration. This was most pronounced with respect to histones H1 and nonhistone proteins. The antibiotic effect was determined by the stage of the lymphocyte living cycle: G1 period was most sensitive to the actinomycin block.