title: The genome of Romanomermis culicivorax: revealing fundamental changes in the core developmental genetic toolkit in Nematoda.
abstract: BACKGROUND
  The genetics of development in the nematode Caenorhabditis elegans has been described in exquisite detail. The phylum Nematoda has two classes: Chromadorea (which includes C. elegans) and the Enoplea. While the development of many chromadorean species resembles closely that of C. elegans, enoplean nematodes show markedly different patterns of early cell division and cell fate assignment. Embryogenesis of the enoplean Romanomermis culicivorax has been studied in detail, but the genetic circuitry underpinning development in this species has not been explored.
  
  
  RESULTS
  We generated a draft genome for R. culicivorax and compared its gene content with that of C. elegans, a second enoplean, the vertebrate parasite Trichinella spiralis, and a representative arthropod, Tribolium castaneum. This comparison revealed that R. culicivorax has retained components of the conserved ecdysozoan developmental gene toolkit lost in C. elegans. T. spiralis has independently lost even more of this toolkit than has C. elegans. However, the C. elegans toolkit is not simply depauperate, as many novel genes essential for embryogenesis in C. elegans are not found in, or have only extremely divergent homologues in R. culicivorax and T. spiralis. Our data imply fundamental differences in the genetic programmes not only for early cell specification but also others such as vulva formation and sex determination.
  
  
  CONCLUSIONS
  Despite the apparent morphological conservatism, major differences in the molecular logic of development have evolved within the phylum Nematoda. R. culicivorax serves as a tractable system to contrast C. elegans and understand how divergent genomic and thus regulatory backgrounds nevertheless generate a conserved phenotype. The R. culicivorax draft genome will promote use of this species as a research model.
authors.affiliation: Zoologisches Institut, Universität zu Köln, Cologne, NRW, Germany. philipp.schiffer@googlemail.com.
authors.forename: Philipp H
authors.initials: PH
authors.lastname: Schiffer
authors.forename: Michael
authors.initials: M
authors.lastname: Kroiher
authors.forename: Christopher
authors.initials: C
authors.lastname: Kraus
authors.forename: Georgios D
authors.initials: GD
authors.lastname: Koutsovoulos
authors.forename: Sujai
authors.initials: S
authors.lastname: Kumar
authors.forename: Julia I R
authors.initials: JI
authors.lastname: Camps
authors.forename: Ndifon A
authors.initials: NA
authors.lastname: Nsah
authors.forename: Dominik
authors.initials: D
authors.lastname: Stappert
authors.forename: Krystalynne
authors.initials: K
authors.lastname: Morris
authors.forename: Peter
authors.initials: P
authors.lastname: Heger
authors.forename: Janine
authors.initials: J
authors.lastname: Altmüller
authors.forename: Peter
authors.initials: P
authors.lastname: Frommolt
authors.forename: Peter
authors.initials: P
authors.lastname: Nürnberg
authors.forename: W Kelley
authors.initials: WK
authors.lastname: Thomas
authors.forename: Mark L
authors.initials: ML
authors.lastname: Blaxter
authors.forename: Einhard
authors.initials: E
authors.lastname: Schierenberg
mesh_terms: D000818:Animals; D005075:Biological Evolution; D017173:Caenorhabditis elegans / Q000235:genetics; D017158:Enoplida / Q000235:genetics* / Q000254:growth & development; D015723:Gene Library; D049751:Genome, Helminth; D059467:Transcriptome; D014231:Tribolium / Q000235:genetics; D017160:Trichinella spiralis / Q000235:genetics