Screen of astaxanthin biosynthesis realted genes from Haematococcus pluvilais by cDNA microarray

Abstract

The induction and regulation of ketocarotenoid biosynthesis in the unicellular green alga Haematococcus pluvialis, which is known for its massive accumulation of the astaxanthin (3,3`-dihydroxy-b,b-carotene-4,4`-dione) under unfavorable culture conditions, recently received considerable attention due to the increasing use of the secondary carotenoid as a source of pigmentation for fish aquacultures and potential drug in cancer prevention, as a free radical quencher. Expression studies of several genes involved in carotenoid biosynthesis assumed that the accumulation of astaxanthin is a survival strategy of this organism and other related organisms in response to stressful environments. However, the molecular defense mechanisms of H. pluvialis in response to stress induction are incompletely known. Here we report the fabrication of cDNA chip using Haematococcus cDNA libraries. And fabricated cDNA chip was used to compare profiling between exponentially growing immature and astaxanthin accumulating mature cells of Haematococcus pluvialis. 965 genes were screened out that exhibited different expressions in dual chips, there were 68 up-regulated genes at immature cells and 57 down-regulated genes at immature cells in the gene expression profiles of Haematococcus pluvialis. Significant decrease of expression of photosynthesis related genes was shown at mature cells. And, defense or stress related genes and signal transduction genes were induced at mature cells. We validated differential expression of 30 selected genes related putative astaxanthin biosynthesis mechanism with fold scores >1.0 by quantitative real time PCR.