DNA microarray analysis of cyanobacterial gene expression during acclimation to high light

DNA microarrays bearing nearly all of the genes of the unicellular cyanobac terium Synechocystis sp PCC 6803 were used to examine the temporal program of gene expression during acclimation from low to high light intensity. A c omplete pattern is provided of gene expression during acclimation of a phot osynthetic organism to changing light intensity, More than 160 responsive g enes were identified and classified into distinct sets. Genes involved in l ight absorption and photochemical reactions were downregulated within 15 mi n of exposure to high light intensity, whereas those associated with CO2 fi xation and protection from photoinhibition were upregulated. Changes in the expression of genes involved in replication, transcription, and translatio n, which were induced to support cellular proliferation, occurred later. Se veral unidentified open reading frames were induced or repressed, The possi ble involvement of these genes in the acclimation to high light conditions is discussed.