Effect of 5-bromodeoxyuridine on the appearance of cytoplasmic poly-A containing RNA

Cytoplasmic poly‐A containing RNA, synthesized by cultured chick embryo cells, was examined during growth in 5‐bromodeoxyuridine. The kinetics of 3H‐adenosine incorporation into this species of RNA, when compared to the rest of the cytoplasmic RNA, and to control cells, indicates that the rate of synthesis of this RNA is slower in BrdU treated cells. An examination of the rate at which a steady state distribution of radioactivity, between the poly‐A segment and non‐poly‐A portion of poly‐A containing RNA is reached also indicated that this species is synthesized at a lower rate in BrdU treated cells.