The complete mitochondrial genome of Orthocoelium streptocoelium (Digenea: Paramphistomidae) for comparison with other digeneans

Evolutionary affinities and morphological characterization of the enigmatic Zonocotyle bicaecata (Trematoda: Paramphistomoidea: Zonocotylidae) from the Upper Paraná River basin

Neotropical fish amphistomes represent a highly diverse group within the Paramphistomoidea, with wide distribution across major South American hydrological drainages. However, the limited molecular characterization of these taxa has impeded a comprehensive assessment of their evolutionary relationships and the systematic relevance of morphological features in classification schemes. Our study, based on the critical evaluation of the type material of both nominal species of Zonocotyle (type genus of the monotypic Zonocotylidae), and newly collected specimens of Zonocotyle bicaecata from Steindachnerina insculpta (Curimatidae) in the Upper Paraná River basin, Brazil, presents a morphological reappraisal of Z. bicaecata and provides molecular data (28S rDNA, ITS1-5.8S-ITS2 region, and COI mtDNA) to assess its phylogenetic relationships. Our phylogenetic analyses confirm this species belongs to the Paramphistomoidea. The most comprehensive analyses (based on 28S and COI) further indicate a close relationship with other fish amphistomes from the Neotropical region. Additionally, we emphasized the necessity for a new classification within Paramphistomoidea and briefly discussed the host range of Zonocotyle among curimatid fish hosts.

Characterization of the complete mitochondrial genomes of Diplodiscus japonicus and Diplodiscus mehari (Trematoda: Diplodiscidae): Comparison with the members of the superfamily Paramphistomoidea and phylogenetic implication

Diplodiscus japonicus and Diplodiscus mehari (Trematoda: Diplodiscidae) are two important parasites in wood frogs, which have large infection rates and essential importance of ecology, economy and society. In this study, the complete mitochondrial (mt) genomes of D. japonicus and D. mehari were sequenced, then compared with other related trematodes in the superfamily Paramphistomoidea. The complete circular mt sequence of D. japonicus and D. mehari were 14,210 bp and 14,179 bp in length, respectively. Both mt genomes comprised 36 functional subunits, consisting of 12 protein-coding genes (PCGs), two ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and one non-coding region. The mt genes of D. japonicus and D. mehari were transcribed in the same direction, and the gene arrangements were identical to those of Paramphistomoidea trematodes. In the 12 PCGs, GTG was the most common initiation codon, whereas TAG was the most common termination codon. All tRNAs had a typical cloverleaf structure except tRNA Ser1. A comparison with related Paramphistomoidea trematode mt genomes suggested that the cox1 gene of D. mehari was the longest in these trematodes. Phylogenetic analyses revealed that Paramphistomoidea trematodes formed a monophyletic branch, Paramphistomidae and Gastrothylacidae were more closely related than Diplodiscidae. And the further analysis with Pronocephalata branch found that the flukes parasitic in amphibians (frogs) formed one group, and the flukes from ruminants (cattle, sheep, ect) formed another group. Our study demonstrated the importance of sequencing mt genomes of D. japonicus and D. mehari, which will provide significant molecular resources for further studies of Paramphistomoidea taxonomy, population genetics and systematics.

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The complete mt genomes of Diplodiscus japonicus and D. mehari were determined first time.

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There is only one NCR in Diplodiscus japonicus and D. mehari complete mt genomes.

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Phylogenetic analyses revealed two monophyletic groups for the flukes parasitic in amphibians and ruminants.

Development of Cytochrome B, a new candidate gene for a high accuracy detection of Fasciola eggs in fecal specimens

Fasciolosis among domestic ruminants has resulted in a decrease in the production of milk products and has occasionally led to the deaths of young ruminants due to of acute infections. This study aimed to discriminate between the eggs of Fasciola gigantica and other trematode eggs in samples collected from ruminant feces specimens using PCR-based methods with the new candidate gene Cytochrome B (CYTB). A species-specific primer was developed with a high degree of sensitivity (3.285 pg). The primer was able to amplify the F. gigantica genomic DNA and there were no positive results with the other related trematodes (Paramphistomum sp., Orthocoelium sp., Fischoederius sp., Calicophoron sp., Echinostoma revolutum, E. cinetorchis, E. ilocanum and Isthmiophora hortensis), freshwater snails (Lymnaea auricularia, Bithynia siamensis, Indoplanorbis exustus, Melanoides tuberculata, Tarebia granifera) or definitive hosts (Bos primigenius and Bubalus bubalis). The minimum concentration of DNA from eggs that could be give a positive result was 3.285 pg. Moreover, the results of the study confirmed the existence of F. gigantica in Nakhon Pathom Province with a high prevalence (28.57%) and revealed the area of infection through epidemiological mapping. Thus, the species-specific primer and epidemiological data in this study may be helpful for use in epidemiological studies, phylogenetic studies and veterinary studies in the future.

The complete mitochondrial genome of Paragonimus ohirai (Paragonimidae: Trematoda: Platyhelminthes) and its comparison with P. westermani congeners and other trematodes

We present the complete mitochondrial genome of Paragonimus ohirai Miyazaki, 1939 and compare its features with those of previously reported mitochondrial genomes of the pathogenic lung-fluke, Paragonimus westermani, and other members of the genus. The circular mitochondrial DNA molecule of the single fully sequenced individual of P. ohirai was 14,818 bp in length, containing 12 protein-coding, two ribosomal RNA and 22 transfer RNA genes. As is common among trematodes, an atp8 gene was absent from the mitogenome of P. ohirai and the 5' end of nad4 overlapped with the 3' end of nad4L by 40 bp. Paragonimusohirai and four forms/strains of P. westermani from South Korea and India, exhibited remarkably different base compositions and hence codon usage in protein-coding genes. In the fully sequenced P. ohirai individual, the non-coding region started with two long identical repeats (292 bp each), separated by tRNAGlu . These were followed by an array of six short tandem repeats (STR), 117 bp each. Numbers of the short tandem repeats varied among P. ohirai individuals. A phylogenetic tree inferred from concatenated mitochondrial protein sequences of 50 strains encompassing 42 species of trematodes belonging to 14 families identified a monophyletic Paragonimidae in the class Trematoda. Characterization of additional mitogenomes in the genus Paragonimus will be useful for biomedical studies and development of molecular tools and mitochondrial markers for diagnostic, identification, hybridization and phylogenetic/epidemiological/evolutionary studies.