Figure 3.

Time course of ntcA transcript levels in the dark and effect of re-illumination. A, Synechocystis sp. PCC 6803 cells were transferred to darkness and after 1 h the culture was re-illuminated. Samples for RNA isolation (10 μg) were taken at the indicated times and hybridized with the ntcA gene probe. The same RNA samples were hybridized with the trpA (Trp synthetase A subunit) and the rnpB (ribonuclease B subunit) housekeeping genes. B, Cell extracts (50 μg of protein) were obtained from Synechocystis sp. cultures incubated for 1 h in darkness or under illumination, separated by SDS-PAGE, and western blot was carried out using the polyclonal NtcA antiserum.