[Intracellular distribution of RNA in Acetabularia mediterranea]

RNA synthesis and distribution in cytoplasm of Acetabularia mediterranea cell were studied by radiochemical and ultramicrobiochemical methods. Existance of an apico-basal gradient of RNA concentration in the cytoplasm was shown. Variations in the rate of the RNA synthesis in different regions of the cytoplasm are of great importance for the formation of this gradient whereas a contribution of nuclear RNA transport is insignificant. Sedimentation coefficients of about 23S and 16S were detected for the most part of the synthesized cytoplasmic RNAs. Evidently these RNAs represent rRNA of chloroplast ribosomes. Basal region of cytoplasm contains a relatively large amount of low molecular weight RNA. The differences in stability of newly-synthesized RNA were found in cytoplasmic regions under examination.