Nucleic Acid Synthesis in the Chloroplasts of Acetabularia mediterranea

Abstract

Radioautographic and radiochemical techniques were used to establish the presence of replicating DNA and the synthesis of RNA in these chloroplasts. Radioautography with thymidine-H3 showed the chloroplasts to be the primary site of cytoplasmic label uptake. The use of C14-labeled thymidine allowed a more accurate determination of the amount of label that was incorporated into DNA and RNA. This method showed that incorporation was unaffected even when cells had been enucleated for over 3 months prior to incubation with the labeled compound. Duplicate experiments also showed that label from thymine was also incorporated into DNA and RNA in these chloroplasts.