Transcriptional profile of Synechococcus in the dark or light with or without photosynthesis inhibitors

In the unicellular cyanobacterium, Synechococcus elongatus PCC 7942, dramatically reduces the transcription rate in the dark (dark repression), and its cellular functions enormously depend on light as an energy source through photosynthetic activity. Here, we employed high-density oligonucleotide arrays to investigate comprehensive profiles of genome-wide Synechococcus gene expression when illuminated or dark-acclimated cells are treated with photosynthesis inhibitors DCMU or DBMIB. In addition, we added rifampicin to the DBMIB-treated cells in the dark, and analyzed genome-wide expression profiles. Treatment with DCMU or DBMIB under illuminated condition mimicked dark-repression-like genome-wide transcription profiles. Addition of DBMIB under dark condition largely attenuated dark-repression and kept relatively large amount of transcripts, this high-transcripts level still kept when rifampicin was additionally administered. Wild type (WT) strain was analyzed under illuminated or dark condition with or without inhibitors using Affymetrix high-density oligonucleotide microarrays (GeneChip CustomExpress Arrays) representing predicted 2,515 protein-coding genes on the genome of Synechococcus elongatus PCC 6301, which can be used also to the almost homologous strain, S. elongatus PCC 7942: a duplicate experiments (except for light 0min samples, quadruplicate experiments) in WT under light, dark, light+DCMU, light+DBMIB, dark+DBMIB, and dark+DBMIB+rifampicin conditions. Samples were cultivated at 30min or 60min after addition of the stimuli (the timing at which each stimuli was added is ZT 12h) from Synechococcus elongatus PCC 7942 (WT strain). timecourse data (0~60 min under dark or light condition with or without DCMU, DBMIB and rifampicin) from Synechococcus elongatus PCC 7942 (WT) strains