title: Evolutionary patterns of RNA-based gene duplicates in Caenorhabditis nematodes coincide with their genomic features.
abstract: BACKGROUND
  RNA-based gene duplicates (retrocopies) played pivotal roles in many physiological processes. Nowadays, functional retrocopies have been systematically identified in several mammals, fruit flies, plants, zebrafish and other chordates, etc. However, studies about this kind of duplication in Caenorhabditis nematodes have not been reported.
  
  
  RESULTS
  We identified 43, 48, 43, 9, and 42 retrocopies, of which 6, 15, 18, 3, and 13 formed chimeric genes in C. brenneri, C. briggsae, C. elegans, C. japonica, and C. remanei, respectively. At least 5 chimeric types exist in Caenorhabditis species, of which retrocopy recruiting both N and C terminus is the commonest one. Evidences from different analyses demonstrate many retrocopies and almost all chimeric genes may be functional in these species. About half of retrocopies in each species has coordinates in other species, and we suggest that retrocopies in closely related species may be helpful in identifying retrocopies for one certain species.
  
  
  CONCLUSIONS
  A number of retrocopies and chimeric genes exist in Caenorhabditis genomes, and some of them may be functional. The evolutionary patterns of these genes may correlate with their genomic features, such as the activity of retroelements, the high rate of mutation and deletion rate, and a large proportion of genes subject to trans-splicing.
authors.affiliation: The key Laboratory of Aquatic Biodiversity and Conservation of Chinese Academy of Sciences, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan 430072, PR China.
authors.forename: Ming
authors.initials: M
authors.lastname: Zou
authors.forename: Guoxiu
authors.initials: G
authors.lastname: Wang
authors.forename: Shunping
authors.initials: S
authors.lastname: He
mesh_terms: D000818:Animals; D002107:Caenorhabditis / Q000235:genetics*; D019143:Evolution, Molecular; D023281:Genomics; D016133:Polymerase Chain Reaction; D012313:RNA / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D012313:RNA