Complementation analysis of PCNAs: a. YTS9 strains (trp+) containing various plasmids were selected on synthetic media without tryptophan and uracil. These transformants were grown only on liquid media omitting uracil at 30 °C to cure the resident plasmid as described in methods. After seven such consecutive sub-culturing, presence of the nutritional markers were tested by plating on SD agar plates lacing uracil alone, or tryptophan alone. Plates were incubated for 2 days at 30 °C and photographed. Sectors 1 & 7, empty vectors; 2, 2 μ, ADH1p-CaPCNA, URA3; 3, 2 μ, ADH1p-CaPCNA G178S, URA3; 4, 2 μ, ADH1p-ScPCNA, URA3; 5, 2 μ, CaPCNA gene, URA3; 6, 2 μ, CaPCNA gene G178S, URA3; 8, CEN, CaPCNAgene, URA3; and 9, CEN, CaPCNAgene G178S, URA3. b. The transformants of yeast strain YNA05 (ura+) containing various plasmids were selected on SD media w/o leucine and uracil. Isolated colonies were picked and re-streaked on SD-leucine plate but with or without 5-FOA. Sectors 1, empty vector; 2, 2 μ, ADH1p-ScPCNA G178S, LEU2; 3, 2 μ, ADH1p-ScPCNA, LEU2; 4, 2 μ, ADH1p-CaPCNA, LEU2; 5, 2 μ, CaPCNA G178S, LEU2; 6, 2 μ,CaPCNA gene, LEU2.