FIG. 1.
(A) Induction of PnfrA by different kinds of stress. β-Galactosidase (β-gal) expression in response to different stressors was determined. β-Galactosidase activity was plotted versus time. Filled bars, control at 37°C; empty bars, heat-shocked cells; shaded bars, salt-stressed cells; hatched bars, cells grown in the presence of 5% ethanol. Samples were collected at different times after stress was applied. All experiments were done in triplicate. (B) Influence of temperature on the heat shock response. Cells were grown at 37°C before an aliquot was shifted to a new temperature. Samples were collected at different times after stress was applied. β-Galactosidase activity was plotted versus time. Filled circles, control at 37°C; empty circles, 45°C; squares, 47°C; triangles, 49°C; inverted triangles, 51°C; diamonds, 53°C; hexagons, 55°C. (C) Western blot analysis of NfrA synthesis. Equal amounts of cell extracts were subjected to Western blot analysis. Samples were taken from stressed and unstressed cells at different times after stress was applied.