Abstract
The antibiotic chloramphenicol selectively inhibited mitochondrial protein synthesis in the ciliate protozoan Tetrahymena pyriformis GL. Secondary to the inhibition of mitochondrial protein synthesis was an inhibition of nuclear RNA synthesis at a time before inhibition of cellular protein and DNA synthesis. Of the stable non-polyadenylated RNA species in Tetrahymena, the addition of chloramphenicol resulted specifically in the inhibition of synthesis of 28S + 17S and 5S rRNA transcripts. By contrast, syntheses of 4S tRNA and 21S mitochondrial rRNA were not as extensively inhibited. The addition of 60 microM hemin before the addition of chloramphenicol partially protected against the inhibition of RNA synthesis. These data indicate that continued synthesis of nucleus-directed rRNA is linked to the synthesis of mitochondrial proteins in Tetrahymena.