ON REGULATION OF RIBOSOMAL RNA SYNTHESIS IN YEAST

The DNA and RNA contents of a diploid strain of Saccharomyces cerevisiae were measured during aerobic growth on various media. The ratio of RNA DNA was found to be a function of the growth rate. A comparison of a haploid strain with a series of polyploid cultures grown under the same conditions revealed that the RNA DNA and RNA/protein ratios were ploidy-independent. rRNA-DNA hybridization experiments demonstrated that a constant percentage of the genome (2.4%) was homologous to ribosomal RNA. No evidence for specific rRNA gene amplification was found. © 1969.