Taxonomic status of Fasciola in Japan : Comparison of mitochondrial NDI and COI sequences and ribosomal ITS2 sequence with Fasciola hepatica and Fasciola gigantica

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The purpose of the study is to compare nucleotide sequences of mitochondrial NDI and COI and ribosomal ITS2 among Fasciola species, and to detect DNA polymorphism within triploid form of Fasciola in Japan. The analysis of restriction fragment length polymorphism shows that triploid Japanese Fasciola species is composed of at least two populations possessing respective type of mitochondrial DNA.It is probable that maternal origin of triploid Japanese species of the two populations is not F.hepatica, but rather F.gigantica. The one population of triploid Japanese species and diploid Korean species, both reproducing off spring parthenogenetically, would originate from the same ancestral F.gigantica. The ND1 and COI sequences of Japanese triploid forms of Fasciola were nearly identical to those found in F.gigantica, but were different from those of F.hepatica. Thus, the Japanese triploid forms of Fasciola are thought to be categorized to F.gigantica. The ITS-2 sequences of the Japanese triploid worms were divided into two distinct types, one of which was almost identical to that of F.hepatica and the other to F.gigantica from Indonesia.