title: Premetazoan genome evolution and the regulation of cell differentiation in the choanoflagellate Salpingoeca rosetta.
abstract: BACKGROUND
  Metazoan multicellularity is rooted in mechanisms of cell adhesion, signaling, and differentiation that first evolved in the progenitors of metazoans. To reconstruct the genome composition of metazoan ancestors, we sequenced the genome and transcriptome of the choanoflagellate Salpingoeca rosetta, a close relative of metazoans that forms rosette-shaped colonies of cells.
  
  
  RESULTS
  A comparison of the 55 Mb S. rosetta genome with genomes from diverse opisthokonts suggests that the origin of metazoans was preceded by a period of dynamic gene gain and loss. The S. rosetta genome encodes homologs of cell adhesion, neuropeptide, and glycosphingolipid metabolism genes previously found only in metazoans and expands the repertoire of genes inferred to have been present in the progenitors of metazoans and choanoflagellates. Transcriptome analysis revealed that all four S. rosetta septins are upregulated in colonies relative to single cells, suggesting that these conserved cytokinesis proteins may regulate incomplete cytokinesis during colony development. Furthermore, genes shared exclusively by metazoans and choanoflagellates were disproportionately upregulated in colonies and the single cells from which they develop.
  
  
  CONCLUSIONS
  The S. rosetta genome sequence refines the catalog of metazoan-specific genes while also extending the evolutionary history of certain gene families that are central to metazoan biology. Transcriptome data suggest that conserved cytokinesis genes, including septins, may contribute to S. rosetta colony formation and indicate that the initiation of colony development may preferentially draw upon genes shared with metazoans, while later stages of colony maturation are likely regulated by genes unique to S. rosetta.
authors: Stephen R
authors: SR
authors: Fairclough
authors: Zehua
authors: Z
authors: Chen
authors: Eric
authors: E
authors: Kramer
authors: Qiandong
authors: Q
authors: Zeng
authors: Sarah
authors: S
authors: Young
authors: Hugh M
authors: HM
authors: Robertson
authors: Emina
authors: E
authors: Begovic
authors: Daniel J
authors: DJ
authors: Richter
authors: Carsten
authors: C
authors: Russ
authors: M Jody
authors: MJ
authors: Westbrook
authors: Gerard
authors: G
authors: Manning
authors: B Franz
authors: BF
authors: Lang
authors: Brian
authors: B
authors: Haas
authors: Chad
authors: C
authors: Nusbaum
authors: Nicole
authors: N
authors: King
mesh_terms: D056897:Choanoflagellata / Q000235:genetics* / Q000502:physiology; D048749:Cytokinesis / Q000235:genetics; D019143:Evolution, Molecular; D018503:Genome, Protozoan; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism; D058112:Septins / Q000235:genetics / Q000378:metabolism; D059467:Transcriptome
chemical_list: D015800:Protozoan Proteins; D058112:Septins