Study On Expressed Sequence Tags Of Griffithsia Japonica And Phylogenetic Of Antarctic Chlamydomonas

Both expressed sequence tags and phylogeny analysis are belonging to the field of bioinformatics. The application of bioinformatics will enhance the understanding on marine algae and explaining their origin and evolution. In this study, expressed sequence tags analysis on Griffithsia japonica and Phylogenetic analysis on Antarctic ice algae were performed.1 Expressed sequence analysis on Griffithsia japonicaMarine red alga G. japonica is a suitable model for basic research of phycology. To better understand the genetic information presented in it, a total of 465 expressed sequence tags are established, among them, 176 ESTs (38 %) show a signifcant similarity to registered sequences in database, 14 ESTs (3 %) are descried as unknown protein or hypothetical protein, 275 ESTs (59 %) are novel. The informative ESTs could be grouped into 7 categories according to the function: metabolism (29 %), protein synthesis and degradation (26 %), photosynthesis (14 %), transcription (14 %), signal transduction /membrane trafficking (9 %), cell strcture/division (4 %) and stress response (4 %). The coden usage of G. japonica is the same as that of Laminaria digitatain.In this study, several significance sequences including genes of 6 light-harvesting protein genes, 1 thioredoxin gene, 2 carbonic anhydrase genes, 2 polyubiquitin genes and 1 polyubiquitin conjunction enzyme gene were choosen from the known EST sequence for gene and deduced amino acid sequences analysis, Phylogenetic analysis and comparison with that from other organisms.Expressed sequence tag is a very powerful tool in finding functional genes in algae. Based on EST manipulation, we will have better understanding of genetics, biophysical and biochemical properties of the algae thoroughly and broadly.2 Phylogenetic analysis on Antarctic ChlamydomonasThe unique biology properties of Antarctic algae come from the extreme environment of South Pole. To ascertain their taxonomic and evolutional status will lay a ground for their futher study. The taxonomic characterization of two strains of Antarctic ice algae ICE-L and ICE-W were analyzed on morphological and molecular information. According to the morphological observation, they belong to Chlamydomonas. The analysis of 18S rDNA, rbcL and ITS sequence of ICE-L and ICE-W indicated that they are the same species, and are very close relatives if not the same as Chlamydomonas sp. Antarctic 2E9. ICE-L and ICE-W belong to the "monadina clade" in thelSS rDNA phylogenetic tree, they show close relationship to C. monadina. In the rbcL phylogenetic tree, ICE-L and ICE-W clustered with C. kuwadae with a bootstrap value of 100 %. The ITS sequence of ICE-L and ICE-W is 1 298 bps and 1 300 bps in length respectively, are the longest sequences of Volvocales ITS sequences that have ever been reported. Any close relatives to the Antarctic ice algae are not identified according to the 116 conserved sites of ITS2. The polyphyly of Chlamydomonas was testified by our phylogenetic analysis.The work of Antarctic ice algae phylogenetic analysis is attactive not only for the extreme environment in which they live, but also for the comparison of three major DNA sequences currently used to discern phylogenetic information among these groups of algae.