Figure 2.

Loss of ornithine decarboxylase activity after spermidine addition to a spe2–4 culture (strain 28-8D) is accompanied by a parallel loss in the amount of ornithine decarboxylase protein (measured immunologically). The conditions for this experiment were essentially the same as those used for the experiment presented in Fig. 1; namely, the culture was grown on a minimal SD medium, and 100 μM spermidine (final concentration) was added at the position indicated as 0. The values for the ornithine decarboxylase protein represent the scanned values (in arbitrary units) for the Western blot analysis.