A daily temporal program for rhythmic expression of protein-coding and non-coding genes in response to light and dark in Synechocystis sp. PCC 6803

We investigated Synechocystis high-density microarray data of three high-resolution time-series experiments with alternating light/dark rhythm, transition to continuous light, and transition to continuous darkness. Using ‘least oscillating set’ normalization and a clustering approach we found a daily temporal program for rhythmic expression of protein-coding and non-coding genes under light/dark conditions. All rhythms, however, damped out rapidly under continuous conditions. We quantified gene expression of wild type Synechocystis PCC 6083 over 48 hours under three different light regimes; 12:12-h light/dark cycle (LDLDL), transfer to continuous light (LDLLL), and transfer to continuous dark (LDDDD). Samples were taken every two hours starting at CT 5.5 with an extra sample 30 minutes after dawn. Before the transfer to continuous light/dark in the LDLLL and LDDDD experiment, samples were taken every 6 with an extra sample 30 minutes after dawn.