Meiotic mapping of yeast ribosomal deoxyribonucleic acid on chromosome XII.

We have used meiotic mapping techniques to locate the position of the repeating ribosomal DNA (rDNA) genes of the yeast Saccharomyces cerevisiae. We found that the rDNA genes are located on the right arm of chromosome XII, approximately 45 map units centromere distal to the gene gal2. Together with mapping data from previous studies, this result suggests that the tandem array of rDNA genes contains at least two junctions with the non-rDNA of the yeast chromosome. In addition, we observed segregation patterns of the rDNA genes consistent with meiotic recombination within the rDNA gene tandem array in 3 of the 59 tetrads examined.