title: The tiny eukaryote Ostreococcus provides genomic insights into the paradox of plankton speciation.
abstract: The smallest known eukaryotes, at approximately 1-mum diameter, are Ostreococcus tauri and related species of marine phytoplankton. The genome of Ostreococcus lucimarinus has been completed and compared with that of O. tauri. This comparison reveals surprising differences across orthologous chromosomes in the two species from highly syntenic chromosomes in most cases to chromosomes with almost no similarity. Species divergence in these phytoplankton is occurring through multiple mechanisms acting differently on different chromosomes and likely including acquisition of new genes through horizontal gene transfer. We speculate that this latter process may be involved in altering the cell-surface characteristics of each species. In addition, the genome of O. lucimarinus provides insights into the unique metal metabolism of these organisms, which are predicted to have a large number of selenocysteine-containing proteins. Selenoenzymes are more catalytically active than similar enzymes lacking selenium, and thus the cell may require less of that protein. As reported here, selenoenzymes, novel fusion proteins, and loss of some major protein families including ones associated with chromatin are likely important adaptations for achieving a small cell size.
authors: Scripps Institution of Oceanography, University of California at San Diego, La Jolla, CA 92093-0202, USA. bpalenik@ucsd.edu
authors: Brian
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authors: Palenik
authors: Jane
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authors: Grimwood
authors: Andrea
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authors: Aerts
authors: Pierre
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authors: Rouzé
authors: Asaf
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authors: Salamov
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authors: Putnam
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authors: Dupont
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authors: Jorgensen
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authors: Derelle
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authors: Rombauts
authors: Kemin
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authors: Zhou
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authors: Otillar
authors: Sabeeha S
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authors: Merchant
authors: Sheila
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authors: Podell
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authors: Gaasterland
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authors: Napoli
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authors: Gendler
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authors: Manuell
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authors: Tai
authors: Olivier
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authors: Vallon
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authors: Piganeau
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authors: Jancek
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authors: Heijde
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authors: Jabbari
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authors: Lohr
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authors: Robbens
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authors: Dubchak
authors: Gregory J
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authors: Pazour
authors: Qinghu
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authors: Paulsen
authors: Chuck
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authors: Delwiche
authors: Jeremy
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authors: Schmutz
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authors: Rokhsar
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authors: Van de Peer
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mesh_terms: D000222:Adaptation, Physiological; D005075:Biological Evolution; D002467:Cell Nucleus / Q000235:genetics; D000460:Chlorophyta / Q000235:genetics* / Q000378:metabolism; D002875:Chromosomes / Q000235:genetics; D004777:Environment; D005057:Eukaryotic Cells / Q000145:classification* / Q000378:metabolism*; D022761:Gene Transfer, Horizontal; D016678:Genome / Q000235:genetics*; D008670:Metals / Q000378:metabolism; D008969:Molecular Sequence Data; D010933:Plankton / Q000145:classification* / Q000235:genetics* / Q000378:metabolism; D051140:Selenoproteins / Q000378:metabolism; D014815:Vitamins / Q000378:metabolism
chemical_list: D008670:Metals; D051140:Selenoproteins; D014815:Vitamins