Synthesis of RNA and protein in relation to oral regeneration in the ciliate Stentor coeruleus

The effects of actinomycin D, puromycin, and cycloheximide on oral regeneration and macromolecular syntheses in the ciliate Stentor coeruleus were investigated. At concentrations which significantly reduced the rate of RNA synthesis (actinomycin D) and protein synthesis (puromycin and cycloheximide), these inhibitors prevented the completion of development of most cells treated prior to stage “late 4” of regeneration. Cells exposed to the inhibitors in stages “late 4” or 5 were, for the most part, delayed or not affected. Cells treated after stage 5 were unaffected. The oral primordia of many cells arrested in stages “2–3” through 4 were subsequently resorbed, whereas cells blocked in stage 5 retained their oral organelles for the period of the block. The results suggest that both RNA and protein syntheses are essential to regeneration and that the final synthesis of essential macromolecules occurs during stage 5.