title: Intron sequence of the taurocyamine kinase gene as a marker to investigate genetic variation of Paragonimus species in Japan and the origins of triploidy in P. westermani.
abstract: BACKGROUND
  Paragonimiasis is a foodborne parasitic infection caused by lung flukes of the genus Paragonimus. Several species of Paragonimus are endemic in Japan: P. westermani (diploid and triploid) P. miyazakii, P. ohirai and P. iloktsuenensis. The taxonomic status and genetic variability of these lung flukes remains poorly understood.
  
  
  METHODS
  The second intron of domain 1 of the taurocyamine kinase gene (TKD1int2) region was used to explore genetic variation and differentiation of diploid and triploid P. westermani, as well as P. miyazakii, P. ohirai and P. iloktsuenensis originating from Japan.
  
  
  RESULTS
  We found high levels of intraspecific variation in P. westermani, but only low levels of variation within the other species studied. Haplotype network and phylogenetic tree analyses demonstrated the sister-group relationship of P. ohirai and P. iloktsuenensis and the phylogenetically distant relationship of P. westermani with the other species. All individuals except for triploid P. westermani were homozygous. Each triploid contained at least one allele similar to that seen in most diploids from Chiba and one allele resembling that seen in diploids from Oita. One triploid contained three different sequences.
  
  
  CONCLUSIONS
  Our findings suggested that the TKD1int2 region is a suitable marker for use in studying the genetic variation and phylogenetics of Paragonimus species, as well as providing clues to the origins of triploidy in P. westermani.
authors.affiliation: Walai Rukhavej Botanical Research Institute (WRBRI), Mahasarakham University, Maha Sarakham 44150, Thailand.
authors.forename: Weerachai
authors.initials: W
authors.lastname: Saijuntha
authors.affiliation: Division of Cell Biology, Department of Preclinical Sciences, Faculty of Medicine, Thammasat University, Rangsit Campus, Pathum Thani 12121, Thailand talent3003@yahoo.com.
authors.forename: Chairat
authors.initials: C
authors.lastname: Tantrawatpan
authors.affiliation: Department of Immunology, Research Institute for Tropical Medicine (RITM), Department of Health Compound, FILINVEST Corporate City, Alabang, Muntinlupa City 1781, Philippines.
authors.forename: Blanca R
authors.initials: BR
authors.lastname: Jarilla
authors.affiliation: Division of Environmental Health Sciences, Kochi Medical School, Oko, Nankoku 783-8505, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Agatsuma
authors.affiliation: Department of Parasitology, Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand Imperial College London, Faculty of Medicine, St Mary's Campus, South Wharf Street, London W2 1NY, UK Cholangiocarcinoma Screening and Care Program (CASCAP), Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Ross H
authors.initials: RH
authors.lastname: Andrews
authors.affiliation: Institute of Zoology 1: Ecology and Parasitology, University of Karlsruhe, Kornblumen Strasse 13, Karlsruhe, Germany Cholangiocarcinoma Screening and Care Program (CASCAP), Faculty of Medicine, Khon Kaen University, Khon Kaen 40002, Thailand.
authors.forename: Trevor N
authors.initials: TN
authors.lastname: Petney
mesh_terms: D000818:Animals; D018509:DNA, Helminth / Q000235:genetics*; D005819:Genetic Markers; D014644:Genetic Variation / Q000235:genetics*; D007438:Introns / Q000235:genetics*; D007564:Japan; D010237:Paragonimiasis / Q000469:parasitology*; D010238:Paragonimus / Q000235:genetics*; D048492:Paragonimus westermani / Q000235:genetics; D017852:Phosphotransferases (Nitrogenous Group Acceptor) / Q000235:genetics*; D057885:Triploidy
chemical_list: D018509:DNA, Helminth; D005819:Genetic Markers; D017852:Phosphotransferases (Nitrogenous Group Acceptor); C022716:taurocyamine kinase
keywords: Genetic marker; Genetic variation; Heterozygosity; Intron; Paragonimus; Taurocyamine kinase