Figure 2.

Determination of total nitric oxide synthase (NOS) activity in primmorphs, kept under dark (dark) or in the light (light). Six-day-old primmorphs that were formed in the dark remained for the subsequent 24 hr in the dark or were transferred to light. Then the total intracellular NOS activity was determined, as described in the Materials and Methods. In one control series, primmorphs were kept for 24 hr in the light and additionally exposed to 10 µM of the NOS inhibitor L-NMMA (light/L-NMMA). Results are means (± SD) from six separate experiments. RFU, relative fluorescent units.