MITOCHONDRIAL-DNA AND NUCLEAR-DNA INDICATE THAT THE JAPANESE FASCIOLASPECIES IS FASCIOLA-GIGANTICA

For elucidation of the taxonomic status of the Japanese Fasciola speci es, whole mitochondrial DNA of Fasciola hepatica from Australia, F. gi gantica from Malaysia, and Fasciola sp. from Japan was digested with t hree four-base-cutting endonucleases: HinfI, MspI, and RsaI. The resul ting digestion patterns showed that for each enzyme there were some ba nds specific for each geographical isolate and that the Japanese Fasci ola sp, shared more bands with F. gigantica than with F. hepatica. Nuc leotide sequences of two regions, the second internal transcribed spac er (ITS2) of the nuclear ribosomal RNA cluster and mitochondrial cytoc hrome c oxidase subunit I (COI), were also compared among them. The IT S2 sequence was highly conserved among the three isolates. F. gigantic a and the Japanese Fasciola sp. were identical, but they differed from the Australian F. hepatica at six sites, one of which was a deletion. The COI sequence was less conserved but implied a similar relationshi p between the isolates. There seems no reason to regard the Japanese F asciola sp. as anything other than a strain of F. gigantica.