PLoS ONE (Jan 2013)

Genetic diversity and distribution of the ciguatera-causing dinoflagellate Gambierdiscus spp. (Dinophyceae) in coastal areas of Japan.

  • Tomohiro Nishimura,
  • Shinya Sato,
  • Wittaya Tawong,
  • Hiroshi Sakanari,
  • Keita Uehara,
  • Md Mahfuzur Rahman Shah,
  • Shoichiro Suda,
  • Takeshi Yasumoto,
  • Yohsuke Taira,
  • Haruo Yamaguchi,
  • Masao Adachi

DOI
https://doi.org/10.1371/journal.pone.0060882
Journal volume & issue
Vol. 8, no. 4
p. e60882

Abstract

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BackgroundThe 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.Methods/principal findingA 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/significanceThis 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.