Analysis of expressed Sequence Tags (ESTs) from the Haematococcus pluvialis

초록

The unicellular green alga Haematococcus pluvialis (Volvocales) is known for its massive accumulation of the ketocarotenoid astaxanthin in the esterified form in response to nutritional or light stress conditions. Partial sequencing of cDNA libraries to generate expressed sequence tags (ESTs) is an effective means of gene discovery, generation of molecular markers and characterization of transcription patterns. The present study is based on an astaxanthin induced cDNA library as a source of ESTs in H. pluvialis. Partial sequences were obtained from the 5' ends of 1858 individual cDNAs, which could be grouped into 1004 non-overlapping sequences. Of these, 752 sequences were singletons, while the remainder fell into 252 clusters. Approximately 79% of the EST sequences showed similarity to previously described sequences in public databases. H. pluvialis consisted of a relatively high percentage of genes involved genetic information processing (19%) and metabolism (14%) and a relatively low percentage of sequences in cellular process (4.0%), defense or stress resistance (3%) and environmental information process (3%). A relatively large fraction of H. pluvialis sequences was classified as genes involved in photosynthesis (9%), structure (9%) and signal transduction (8%). We will perform cDNA microarray analysis to isolate cDNA clones related to astaxanthin biosynthesis and to study their functional roles