title: Genetic diversity and distribution of the ciguatera-causing dinoflagellate Gambierdiscus spp. (Dinophyceae) in coastal areas of Japan.
abstract: BACKGROUND
  The marine epiphytic dinoflagellate genus Gambierdiscus produce toxins that cause ciguatera fish poisoning (CFP): one of the most significant seafood-borne illnesses associated with fish consumption worldwide. So far, occurrences of CFP incidents in Japan have been mainly reported in subtropical areas. A previous phylogeographic study of Japanese Gambierdiscus revealed the existence of two distinct phylotypes: Gambierdiscus sp. type 1 from subtropical and Gambierdiscus sp. type 2 from temperate areas. However, details of the genetic diversity and distribution for Japanese Gambierdiscus are still unclear, because a comprehensive investigation has not been conducted yet.
  
  
  RESULTS
  A total of 248 strains were examined from samples mainly collected from western and southern coastal areas of Japan during 2006-2011. The SSU rDNA, the LSU rDNA D8-D10 and the ITS region were selected as genetic markers and phylogenetic analyses were conducted. The genetic diversity of Japanese Gambierdiscus was high since five species/phylotypes were detected: including two reported phylotypes (Gambierdiscus sp. type 1 and Gambierdiscus sp. type 2), two species of Gambierdiscus (G. australes and G. cf. yasumotoi) and a hitherto unreported phylotype Gambierdiscus sp. type 3. The distributions of type 3 and G. cf. yasumotoi were restricted to the temperate and the subtropical area, respectively. On the other hand, type 1, type 2 and G. australes occurred from the subtropical to the temperate area, with a tendency that type 1 and G. australes were dominant in the subtropical area, whereas type 2 was dominant in the temperate area. By using mouse bioassay, type 1, type 3 and G. australes exhibited mouse toxicities.
  
  
  CONCLUSIONS
  This study revealed a surprising diversity of Japanese Gambierdiscus and the distribution of five species/phylotypes displayed clear geographical patterns in Japanese coastal areas. The SSU rDNA and the LSU rDNA D8-D10 as genetic markers are recommended for further use.
authors.affiliation: Faculty of Agriculture, Kochi University, Nankoku, Kochi, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Nishimura
authors.forename: Shinya
authors.initials: S
authors.lastname: Sato
authors.forename: Wittaya
authors.initials: W
authors.lastname: Tawong
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Sakanari
authors.forename: Keita
authors.initials: K
authors.lastname: Uehara
authors.forename: Md Mahfuzur Rahman
authors.initials: MM
authors.lastname: Shah
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Suda
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yasumoto
authors.forename: Yohsuke
authors.initials: Y
authors.lastname: Taira
authors.forename: Haruo
authors.initials: H
authors.lastname: Yamaguchi
authors.forename: Masao
authors.initials: M
authors.lastname: Adachi
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D001681:Biological Assay; D002922:Ciguatoxins / Q000378:metabolism* / Q000633:toxicity; D004275:DNA, Ribosomal / Q000235:genetics; D003710:Demography; D004141:Dinoflagellida / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D005819:Genetic Markers; D014644:Genetic Variation; D007564:Japan; D051379:Mice; D008957:Models, Genetic; D010802:Phylogeny; D058974:Phylogeography
chemical_list: D004275:DNA, Ribosomal; D005819:Genetic Markers; D002922:Ciguatoxins