Identification of genes up -regulated ubder high light exposure in the unicelluar green alga Dunaliella salina

Abstract

The unicellular green alga Dunaliella salina is an attractive model for studying the photoacclimation responses of the photosynthetic apparatus. To identify genes specific to photoacclimation, a cDNA library was created from light stressed D. salina. From the cDNA library 1112 randomly chosen ESTs were analyzed. Because ESTs constitute the expressed part of the genome, the strategy of random sequencing cDNA clones at their 5`ends allowed us to obtain information on the transcript levels of numerous genes of light stressed D. salina cells. The results of a BLASTX search performed on the obtained total set of ESTs showed that approximately 1% of the ESTs could be assigned to genes of proteins that are acclimated by high-light stress. Specifically, an increase in expression of known antioxidant genes such as Fe-SOD and APX was detected. Further, the ATP-dependent Clp protease gene was also up-regulated in D. salina cells after 48 hours of exposure to high light. In addition, mRNA of light harvesting protein homologs such as the Cbr was more abundant in cells after 48 hours of high light exposure.