Figure 3.—

Spot-test analysis reveals the temperature-dependent lethality of new1∷nat and tam7∷nat. Cells from cultures of the indicated strains grown to mid-log phase in rich YES liquid medium were plated in fivefold serial dilutions so that the final dilution plated around five cells on YES plates that were then incubated at the indicated temperatures. The limited ability of the plated new1∷nat cells to grow and divide at 32° is clear from a comparison of the magnified images, highlighting growth of the same strain on a YES plate at 25° (top right) and 32° (bottom right).