title: Analysis of expressed sequence tags from the marine microalga Pseudochattonella farcimen (Dictyochophyceae).
abstract: Pseudochattonella farcimen (Eikrem, Edvardsen, et Throndsen) is a unicellular alga belonging to the Dictyochophyceae (Heterokonta). It forms recurring blooms in Scandinavian coastal waters, and has been associated to fish mortality. Here we report the sequencing and analysis of 10,368 expressed sequence tags (ESTs) corresponding to 8,149 unique gene models from this species. Compared to EST libraries from other heterokonts, P. farcimen contains a high number of genes with functions related to cell communication and signaling. We found several genes encoding proteins related to fatty acid metabolism, including eight fatty acid desaturases and two phospholipase A2 genes. Three desaturases are highly similar to Δ4-desaturases from haptophytes. P. farcimen also possesses three putative polyketide synthases (PKSs), belonging to two different families. Some of these genes may have been acquired via horizontal gene transfer by a common ancestor of brown algae and dictyochophytes, together with genes involved in mannitol metabolism, which are also present in P. farcimen. Our findings may explain the unusual fatty acid profile previously observed in P. farcimen, and are discussed from an evolutionary perspective and in relation to the ichthyotoxicity of this alga.
authors.affiliation: Program for Marine Biology, Department of Biology, University of Oslo, P.O. Box 1066 Blindern, 0316 Oslo, Norway. simon.dittami@bio.uio.no
authors.forename: Simon M
authors.initials: SM
authors.lastname: Dittami
authors.forename: Ingvild
authors.initials: I
authors.lastname: Riisberg
authors.forename: Uwe
authors.initials: U
authors.lastname: John
authors.forename: Russell J S
authors.initials: RJ
authors.lastname: Orr
authors.forename: Kjetill S
authors.initials: KS
authors.lastname: Jakobsen
authors.forename: Bente
authors.initials: B
authors.lastname: Edvardsen
mesh_terms: D056890:Eukaryota / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D005068:Eutrophication; D020224:Expressed Sequence Tags; D058086:Microalgae / Q000145:classification / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D010802:Phylogeny; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D012623:Seawater
chemical_list: D011506:Proteins