Slot-blot transcript analysis of the genes encoding the putative enzymes of the L-arginine oxidase/dehydrogenase pathway in Synechocystis sp. PCC 6803. Synechocystis sp. PCC 6803 cells were grown for 24, 48, or 72 h with nitrate or L-arginine as sole N-source and with a constant illumination of 50 photons m-2 s-1. Steady state transcript pools were investigated with gene-specific probes of equal length and equal GC% content to assure equal labeling with Dig-dUTP. An rnpB-specific probed was used to assure equal loading. The figure allows for the direct comparison of transcript levels between cells grown with L-arginine to that grown with nitrate.