Mapping of the rib5 gene in Saccharomyces cerevisiae using UV light as an enhancer of rad52-mediated chromosome loss.

Rib5 mutants of S. cerevisiae are blocked at the end of the riboflavin biosynthetic pathway. Using UV light to increase rad52-mediated chromosome loss, we have assigned the rib5 mutation to chromosome II. Tetrad analysis of crosses between rib5 and other markers on chromosome II shows that the RIB5 gene is located on the right arm of this chromosome, closely linked to HIS7.