Relationship Between Sporulation-Specific 20 S Ribonucleic Acid and Ribosomal Ribonucleic Acid Processing in Saccharomyces cerevisiae

Abstract

The nature and properties of the 20 S ribonucleic acid which accumulates only during the sporulation of Saccharomyces cerevisiae were examined. The 20 S ribonucleic acid (RNA) has a base composition considerably different from ribosomal RNA species and is virtually unmethylated. The 20 S RNA did, however, exhibit approximately 70% homology with 18 S RNA by RNA-deoxyribonucleic acid filter hybridization competitions. The 20 S RNA showed a hybridization saturation plateau level 30 to 40% higher than 18 S , consistent with measurements of the size difference in polyacrylamide gels. Pulse-chase experiments in the presence and absence of cycloheximide indicate that the 20 S RNA has a presumptive relationship to the 20 S ribosomal RNA precursor normally observed only in short pulse-labeling in vegetative cells.