FY137 is a S. cerevisiae strain containing mutations in HIS4 and LYS2 that normally would make the strain auxotrophic for histidine and lysine. However, due to a recessive suppressor mutation in SPT6 (spt6-140), the phenotype of this strain is His+, Lys+. The strain also does not grow at 37°C. In the upper portion of the figure, growth of FY137 containing empty vector, S. cerevisiae (Sc) SPT6 or C. albicans (Ca) SPT6 under control of a galactose inducible promoter is depicted on His drop out media containing glucose or galactose at 30°C. Because wild-type SPT6 is not expressed on glucose, the strain grows normally. Induction of SPT6 expression by galactose leads to return to the His- phenotype, and the C. albicans gene has a similar effect to that seen with S. cerevisiae SPT6. In the lower portion of the figure, growth of the same strains on galactose at 37°C is shown. The temperature sensitive phenotype of FY137 is partially corrected by expression of C. albicans SPT6.