FIG. 6.

Restoration of growth on uridine by expression of heterologous uridine ribohydrolase and phosphorylase. Starting with yeast cultures with an optical density at 600 nm of 0.1, 4 serial 1:6 dilutions were spotted on SC-URA-HIS-LEU plates supplemented with either uracil or uridine, where only two dilutions are shown. Dilutions 3 and 4 on the uracil-containing plate indicate equal loading of cells. Dilution steps 1 and 2 are shown on the uridine-supplemented plate. See Table 1 and the text for details.