title: Cytosine methylation is a conserved epigenetic feature found throughout the phylum Platyhelminthes.
abstract: BACKGROUND
  The phylum Platyhelminthes (flatworms) contains an important group of bilaterian organisms responsible for many debilitating and chronic infectious diseases of human and animal populations inhabiting the planet today. In addition to their biomedical and veterinary relevance, some platyhelminths are also frequently used models for understanding tissue regeneration and stem cell biology. Therefore, the molecular (genetic and epigenetic) characteristics that underlie trophic specialism, pathogenicity or developmental maturation are likely to be pivotal in our continued studies of this important metazoan group. Indeed, in contrast to earlier studies that failed to detect evidence of cytosine or adenine methylation in parasitic flatworm taxa, our laboratory has recently defined a critical role for cytosine methylation in Schistosoma mansoni oviposition, egg maturation and ovarian development. Thus, in order to identify whether this epigenetic modification features in other platyhelminth species or is a novelty of S. mansoni, we conducted a study simultaneously surveying for DNA methylation machinery components and DNA methylation marks throughout the phylum using both parasitic and non-parasitic representatives.
  
  
  RESULTS
  Firstly, using both S. mansoni DNA methyltransferase 2 (SmDNMT2) and methyl-CpG binding domain protein (SmMBD) as query sequences, we illustrate that essential DNA methylation machinery components are well conserved throughout the phylum. Secondly, using both molecular (methylation specific amplification polymorphism, MSAP) and immunological (enzyme-linked immunoabsorbent assay, ELISA) methodologies, we demonstrate that representative species (Echinococcus multilocularis, Protopolystoma xenopodis, Schistosoma haematobium, Schistosoma japonicum, Fasciola hepatica and Polycelis nigra) within all four platyhelminth classes (Cestoda, Monogenea, Trematoda and 'Turbellaria') contain methylated cytosines within their genome compartments.
  
  
  CONCLUSIONS
  Collectively, these findings provide the first direct evidence for a functionally conserved and enzymatically active DNA methylation system throughout the Platyhelminthes. Defining how this epigenetic feature shapes phenotypic diversity and development within the phylum represents an exciting new area of metazoan biology.
authors.affiliation: Institute of Biological Environmental and Rural Sciences (IBERS), Aberystwyth University, Penglais Campus, Aberystwyth SY23 3FG, United Kingdom.
authors.forename: Kathrin K
authors.initials: KK
authors.lastname: Geyer
authors.forename: Iain W
authors.initials: IW
authors.lastname: Chalmers
authors.forename: Neil
authors.initials: N
authors.lastname: Mackintosh
authors.forename: Julie E
authors.initials: JE
authors.lastname: Hirst
authors.forename: Rory
authors.initials: R
authors.lastname: Geoghegan
authors.forename: Mathieu
authors.initials: M
authors.lastname: Badets
authors.forename: Peter M
authors.initials: PM
authors.lastname: Brophy
authors.forename: Klaus
authors.initials: K
authors.lastname: Brehm
authors.forename: Karl F
authors.initials: KF
authors.lastname: Hoffmann
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D017124:Conserved Sequence; D018899:CpG Islands / Q000235:genetics; D003596:Cytosine / Q000378:metabolism*; D004248:DNA (Cytosine-5-)-Methyltransferases / Q000737:chemistry / Q000378:metabolism; D019175:DNA Methylation / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism; D044127:Epigenesis, Genetic; D008969:Molecular Sequence Data; D010986:Platyhelminths / Q000201:enzymology / Q000235:genetics*
chemical_list: D004268:DNA-Binding Proteins; D003596:Cytosine; D004248:DNA (Cytosine-5-)-Methyltransferases