ISOLATION AND CHARACTERIZATION OF EUGLENA GRACILIS CYTOPLASMIC AND CHLOROPLAST RIBOSOMES AND THEIR RIBOSOMAL RNA COMPONENTS

1. 1. Euglena gracilis cytoplasmic and chloroplast polysomes have been isolated and characterized by their s-values relative to rat-liver polysomes and Escherichia coli ribosomes. 2. 2. Euglena contains 87-S ribosomes in the cytoplasm and 68-S ribosomes in the chloroplasts. 3. 3. The Euglena cytoplasmic ribosome contains two rRNA components sedimenting as 24-S and 20-S molecules, while the chloroplast ribosome is composed of two slightly smaller rRNA molecules, 22 S and 17 S. The four rRNA molecules are sufficiently distinct to be separable in a sucrose gradient. 4. 4. When compared with other eucaryotic cytoplasmic ribosomes the Euglena cytoplasmic ribosome is unique in overall s values and RNA composition. The Euglena chloroplast ribosome is similar to other 70-S type ribosomes in both size and RNA content. 5. 5. These results are in contradiction to earlier reports regarding Euglena cytoplasmic and chloroplast ribosomes and their respective rRNA components. © 1969.