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Trematodes of the genus Dicrocoelium are one of the most common parasites in ruminant animals; however, their life cycles in Japan are unclear. To find the sporocysts of D. chinensis in the natural field, we sampled 269 land snails (14 species) at a location with high level infection of sika deer in Gifu Prefecture, Honshu Island, Japan in autumn between 2017 and 2019. During the sampling period, we found mother sporocysts in the hepatopancreas of Aegista vulgivaga and Cyclophorus herklotsi. DNA barcoding based on the sequences of cytochrome c oxidase subunit 1 showed that the sporocysts from A. vulgivaga belonged to D. chinensis, indicating that this snail has potential as the first intermediate host of D. chinensis at this location. [ABSTRACT FROM AUTHOR]

We carried out phylogenetic analyses of the relationships between Dicrocoelium chinensis populations in Japan and China using molecular markers. One hundred nine lancet flukes collected from Japan and China were identified as D. chinensis based on their testis orientation and the nucleotide sequences of their ribosomal ITS2. These flukes were analyzed phylogenetically using mitochondrial nad1 gene sequences. An analysis of molecular variance found that the percentage of variation between the countries was extremely high, indicating that the D. chinensis populations in Japan and China are differentiated genetically. D. chinensis mainly parasitizes wild sika deer, which is thought to originate in northeast Asia and to have colonized into Japan from the Eurasia continent in the Pleistocene glaciations. In addition, phylogenic analyses indicated that Japanese sika deer is genetically differentiated from Chinese population; therefore, we hypothesize that D. chinensis might have been introduced into Japan along with the migration of infected wild ruminants in the Pleistocene, and then the population became differentiated from the Chinese population. This study provides the nucleotide sequences of the nad1 gene of D. chinensis in Japan for the first time and shows that these sequences are useful for elucidating the phylogenetic relationships of the Dicrocoelium species prevalent in Asia. [ABSTRACT FROM AUTHOR]

Lancet flukes parasitize the bile ducts and gall bladder of a range of mammals, including humans, causing dicrocoeliosis. In the present study, we sequenced and characterized the complete mitochondrial (mt) genomes as well as the first and second internal transcribed spacers (ITS-1 and ITS-2 = ITS) of nuclear ribosomal DNA (rDNA) of two lancet flukes, Dicrocoelium chinensis and D. dendriticum . Sequence comparison of a conserved mt gene and nuclear rDNA sequences among multiple individual lancet flukes revealed substantial nucleotide differences between the species but limited sequence variation within each of them. Phylogenetic analysis of the concatenated amino acid and multiple mt rrn S sequences using Bayesian inference supported the separation of D. chinensis and D. dendriticum into two distinct species-specific clades. Results of the present study support the proposal that D. dendriticum and D. chinensis represent two distinct lancet flukes. While providing the first mt genomes from members of the superfamily Plagiorchioidea, the novel mt markers described herein will be useful for further studies of the diagnosis, epidemiology and systematics of the lancet flukes and other trematodes of human and animal health significance. [ABSTRACT FROM AUTHOR]

Dicrocoelium chinensis is commonly known as the 'lancet fluke' or 'small liver fluke' which lives in the bile ducts and gall bladder of domestic and wild ruminants. In this study, we examined sequence variability in two mitochondrial (mt) genes, namely cytochrome c oxidase subunit 1 ( cox1) and NADH dehydrogenase subunit 1 ( nad1) genes, among D. chinensis isolated from domestic yaks in Gansu and Sichuan provinces, China. A portion of the cox1 (p cox1) and nad1 (p nad1) genes was amplified by PCR separately from the individual adult D. chinensis, and the amplicons were subjected to sequencing from both directions. The lengths of the sequences of p cox1 and p nad1 were 358 and 458 bp, respectively. The A+T contents of the sequences were 58.94-59.22% for p cox1 and 60.04-60.48% for p nad1, respectively. The intra-specific sequence variations within D. chinensis were 0-0.84% for p cox1 and 0-0.87% for p nad1. The inter-specific sequence differences among members of the examined trematodes were significantly higher, being 22.9-29.3% and 33.6-41.5% for p cox1 and p nad1, respectively. Phylogenetic analysis utilizing combined sequences of p cox1 and p nad1 using Bayesian inference revealed that all of the D. chinensis isolates grouped together with high statistical support. These findings demonstrated the existence of low intra-specific variation in mitochondrial DNA (mtDNA) sequences among the D. chinensis isolates from domestic yaks in China and had implications for studying the molecular epidemiology and population genetics of D. chinensis. [ABSTRACT FROM AUTHOR]

Abstract: Dicrocoelium dendriticum () and Dicrocoelium hospes () are recognised to affect the liver of domestic and wild ruminants. A third species, Dicrocoelium orientalis which was described from musk deer in the Baikal region of the former Soviet Union and re-named to Dicrocoelium chinensis (Sudarikov and Ryjikov, 1951) Tang and Tang, 1978 was isolated from other species of deer in Asian countries and from mouflon and roe deer in Europe. Scant information is available for D. chinensis, including the range of species that act as definitive and intermediate hosts. To provide morphological and molecular evidences differentiating D. chinensis versus D. dendriticum, 239 Dicrocoelium spp. specimens were collected from sheep, cattle and sika deer from different localities in Austria, Germany and Italy. Specimens were morphologically identified based on the testes orientation, overall size, and level of maximum body width and other morphometric measurements. From this sample, 10 specimens of D. chinensis and 25 of D. dendriticum from different hosts and geographical localities were characterized molecularly through sequencing of partial 18S rDNA (∼1400bp) and ITS-2 (including the 5.8S and 28S flanking regions; ∼600bp). Interspecific differences between D. dendriticum and D. chinensis of 0.14% and 3.8% were recorded in 18S rRNA and ITS-2 sequences, respectively. Phylogenetic analyses via Bayesian inference were conducted using sequences of ITS-2 (276bp) and partial 28S (221bp) of the above species of Dicrocoelium together with 20 species belonging to the Xiphidiata within the Plagiorchiida available in GenBank. Both gene regions were strongly concordant in differentiating the Dicrocoeliidae, Gorgoderidae and Plagiorchiidae and were in agreement with their current classification. Morphological and molecular characterization clearly differentiate D. dendriticum and D. chinensis as two distinct digeneans infecting ruminants. The implications on the separate status of D. chinensis on the etiology, biology and diagnosis of dicrocoeliosis are discussed. [Copyright &y& Elsevier]