Figure 5.

Guanylate cyclase participates in the NO-induced activation of the tobacco PAL gene. (A) Accumulation of PAL mRNA in suspension cells after treatment with either the NO donor GSNO or cGMP in the absence or presence of the guanylate cyclase inhibitors LY 83583 and ODQ. Total RNA was isolated from cells after incubation for the indicated times. Treatments are indicated. Concentrations were 350 μM GSNO, 200 μM LY 83583, 200 μM ODQ, and 100 μM 8-Br-cGMP. The control was untreated cells. Equal loading of RNA was confirmed by ethidium bromide staining for rRNA (data not shown). (B) PAL enzyme activity in cells treated as described for A. At the indicated times, extracts of suspension cells were prepared and PAL activity in each was determined. Data represent the mean of duplicate measurements. Standard errors are indicated.