Complete mitochondrial genomes of the ‘intermediate form’ of Fasciola and Fasciola gigantica, and their comparison with F. hepatica

Abstract

BackgroundFascioliasis is an important and neglected disease of humans and other mammals, caused by trematodes of the genus Fasciola. Fasciola hepatica and F. gigantica are valid species that infect humans and animals, but the specific status of Fasciola sp. (‘intermediate form’) is unclear.MethodsSingle specimens inferred to represent Fasciola sp. (‘intermediate form’; Heilongjiang) and F. gigantica (Guangxi) from China were genetically identified and characterized using PCR-based sequencing of the first and second internal transcribed spacer regions of nuclear ribosomal DNA. The complete mitochondrial (mt) genomes of these representative specimens were then sequenced. The relationships of these specimens with selected members of the Trematoda were assessed by phylogenetic analysis of concatenated amino acid sequence datasets by Bayesian inference (BI).ResultsThe complete mt genomes of representatives of Fasciola sp. and F. gigantica were 14,453 bp and 14,478 bp in size, respectively. Both mt genomes contain 12 protein-coding genes, 22 transfer RNA genes and two ribosomal RNA genes, but lack an atp8 gene. All protein-coding genes are transcribed in the same direction, and the gene order in both mt genomes is the same as that published for F. hepatica. Phylogenetic analysis of the concatenated amino acid sequence data for all 12 protein-coding genes showed that the specimen of Fasciola sp. was more closely related to F. gigantica than to F. hepatica.ConclusionsThe mt genomes characterized here provide a rich source of markers, which can be used in combination with nuclear markers and imaging techniques, for future comparative studies of the biology of Fasciola sp. from China and other countries.

Biomphalaria straminea (Mollusca: Planorbidae) as an intermediate host of Drepanocephalus spp. (Trematoda: Echinostomatidae) in Brazil: a morphological and molecular study

“…(1.27-1.42) (Lie and Basch 1967;Ostrowski de Núñez 1968;Rietschel and Werding 1978;Našincová et al 1993; and Isthmiophora hortensis (Asada, 1926) (1.23-1.3) Cho et al 2003). Similarly, the (Le et al 2000) i KF543342 (Liu et al 2014) metacercaria found in Astyanax fasciatus (Cuvier, 1819) from Mexico and identified as Echinostomatinae gen. sp. (Scholz et al 1995), presented collar spine morphology, including the ratio between the dorsal angle and first lateral spine, consistent with morphological characteristics similar to metacercariae obtained in the present study.…”

The complete mitochondrial genome of Gastrothylax crumenifer (Gastrothylacidae, Trematoda) and comparative analyses with selected trematodes

“…Parasites used in the analysis included Clonorchis sinensis (NC_012147) (Shekhovtsov et al 2010), Fasciola gigantica (NC_024025) (Liu et al 2014), F. hepatica ( N C _ 0 0 2 5 4 6 ) ( L e e t a l . 2 0 0 1 ) , F. e l o n g a t u s (KM_397348), Haplorchis taichui (NC_022433.1), Metagonimus yokogawai (KC330755.1), O. viverrini ( J F 7 2 9 3 0 4 .…”

A review on the molecular characterization of digenean parasites using molecular markers with special reference to ITS region

“…According to Vilas et al (2005) and Al-Kandari et al (2011) ITS-1 is more variable than ITS-2 due to variable nucleotide repeats (Warberg et al, 2005 in microphallid species) and accretion of substitutions at higher rate (Morgan & Blair, 1995;van Herwerden et al, 1999;Tkach et al, 2000). Slow rate of concerted evolutionary processes (hybridization, incomplete lineage sorting and retention of ancestral polymorphism) can cause the sharing of various ITS regions among trematodes (Vilas et al, 2005) and reveal the possible existence of intermediate genotypes (Huang et al, 2004;Itagaki et al, 2005a;Itagaki et al, 2005b;Liu et al, 2014;Mufti et al, 2014). Sequence length variations, due to mutations (Tkach & Kinsella, 2011) or polymorphism (Liu et al 2007) in ITS-1 region point towards the differentiation of species on the basis of genetic diversity (Presswell et al, 2014).…”

“…The phylogenetic analyses disclosed that isolates of Fasciola represented single species of F. hepatica. Liu et al (2014) …”