title: Insights into metazoan evolution from Alvinella pompejana cDNAs.
abstract: BACKGROUND
  Alvinella pompejana is a representative of Annelids, a key phylum for evo-devo studies that is still poorly studied at the sequence level. A. pompejana inhabits deep-sea hydrothermal vents and is currently known as one of the most thermotolerant Eukaryotes in marine environments, withstanding the largest known chemical and thermal ranges (from 5 to 105°C). This tube-dwelling worm forms dense colonies on the surface of hydrothermal chimneys and can withstand long periods of hypo/anoxia and long phases of exposure to hydrogen sulphides. A. pompejana specifically inhabits chimney walls of hydrothermal vents on the East Pacific Rise. To survive, Alvinella has developed numerous adaptations at the physiological and molecular levels, such as an increase in the thermostability of proteins and protein complexes. It represents an outstanding model organism for studying adaptation to harsh physicochemical conditions and for isolating stable macromolecules resistant to high temperatures.
  
  
  RESULTS
  We have constructed four full length enriched cDNA libraries to investigate the biology and evolution of this intriguing animal. Analysis of more than 75,000 high quality reads led to the identification of 15,858 transcripts and 9,221 putative protein sequences. Our annotation reveals a good coverage of most animal pathways and networks with a prevalence of transcripts involved in oxidative stress resistance, detoxification, anti-bacterial defence, and heat shock protection. Alvinella proteins seem to show a slow evolutionary rate and a higher similarity with proteins from Vertebrates compared to proteins from Arthropods or Nematodes. Their composition shows enrichment in positively charged amino acids that might contribute to their thermostability. The gene content of Alvinella reveals that an important pool of genes previously considered to be specific to Deuterostomes were in fact already present in the last common ancestor of the Bilaterian animals, but have been secondarily lost in model invertebrates. This pool is enriched in glycoproteins that play a key role in intercellular communication, hormonal regulation and immunity.
  
  
  CONCLUSIONS
  Our study starts to unravel the gene content and sequence evolution of a deep-sea annelid, revealing key features in eukaryote adaptation to extreme environmental conditions and highlighting the proximity of Annelids and Vertebrates.
authors.affiliation: Department of Structural Biology and Genomics, Institut de Génétique et de Biologie Moléculaire et Cellulaire, CERBM F-67400 Illkirch, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Gagnière
authors.forename: Didier
authors.initials: D
authors.lastname: Jollivet
authors.forename: Isabelle
authors.initials: I
authors.lastname: Boutet
authors.forename: Yann
authors.initials: Y
authors.lastname: Brélivet
authors.forename: Didier
authors.initials: D
authors.lastname: Busso
authors.forename: Corinne
authors.initials: C
authors.lastname: Da Silva
authors.forename: Françoise
authors.initials: F
authors.lastname: Gaill
authors.forename: Dominique
authors.initials: D
authors.lastname: Higuet
authors.forename: Stéphane
authors.initials: S
authors.lastname: Hourdez
authors.forename: Bernard
authors.initials: B
authors.lastname: Knoops
authors.forename: François
authors.initials: F
authors.lastname: Lallier
authors.forename: Emmanuelle
authors.initials: E
authors.lastname: Leize-Wagner
authors.forename: Jean
authors.initials: J
authors.lastname: Mary
authors.forename: Dino
authors.initials: D
authors.lastname: Moras
authors.forename: Emmanuel
authors.initials: E
authors.lastname: Perrodou
authors.forename: Jean-François
authors.initials: JF
authors.lastname: Rees
authors.forename: Béatrice
authors.initials: B
authors.lastname: Segurens
authors.forename: Bruce
authors.initials: B
authors.lastname: Shillito
authors.forename: Arnaud
authors.initials: A
authors.lastname: Tanguy
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Thierry
authors.forename: Jean
authors.initials: J
authors.lastname: Weissenbach
authors.forename: Patrick
authors.initials: P
authors.lastname: Wincker
authors.forename: Franck
authors.initials: F
authors.lastname: Zal
authors.forename: Olivier
authors.initials: O
authors.lastname: Poch
authors.forename: Odile
authors.initials: O
authors.lastname: Lecompte
mesh_terms: D000222:Adaptation, Physiological / Q000187:drug effects / Q000235:genetics; D000596:Amino Acids / Q000235:genetics; D000818:Animals; D001482:Base Composition / Q000235:genetics; D001499:Bayes Theorem; D018076:DNA, Complementary / Q000235:genetics*; D030541:Databases, Genetic; D019143:Evolution, Molecular; D020224:Expressed Sequence Tags; D005786:Gene Expression Regulation; D015723:Gene Library; D020407:Internet; D019216:Metals, Heavy / Q000633:toxicity; D058977:Molecular Sequence Annotation; D008969:Molecular Sequence Data; D018384:Oxidative Stress / Q000187:drug effects / Q000235:genetics; D010802:Phylogeny; D011077:Polychaeta / Q000187:drug effects / Q000235:genetics*; D017434:Protein Structure, Tertiary; D012270:Ribosomes / Q000235:genetics; D013696:Temperature; D014714:Vertebrates / Q000235:genetics
chemical_list: D000596:Amino Acids; D018076:DNA, Complementary; D019216:Metals, Heavy