When YEp51-Bax is introduced into an appropriate yeast strain, the effect of Bax on yeast growth can be easily observed by plate tests. Yeast containing YEp51-Bax are maintained on glucose-containing SD-Leu plates. A single colony can be streaked on galactose-containing SD-Leu plates to induce Bax expression side by side with a control streak from a colony containing YEp51 lacking Bax ('empty'). This test of growth inhibition can also be performed by standard replica-plating, although it is less sensitive than streaking. The drastically reduced growth rate observed on galactose medium which induces the bax gene indicates that the gene product is either cytotoxic to yeast or induces cell cycle arrest. Two assays can be employed to distinguish between these possibilities: the clonogenic (or colony formation) assay and the vital dye exclusion assay.
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