We are using FOA (5-floroorotic acid) for selection against URA-3 plasmids in yeast. FOA is expensive to buy and difficult to get into solution. Does anyone know of a non-toxic solvent (such as DMSO) in which a stable 100X FOA stock solution can be made? -- Scott Vande Pol Case Western Reserve University Department of Pathology Cleveland Oh. 44106 sbv at pop.cwru.edu