Molecular characterization of pouched amphistome parasites (Trematoda: Gastrothylacidae) using ribosomal ITS2 sequence and secondary structures

Abstract

Members of the family Gastrothylacidae (Trematoda: Digenea: Paramphistomata) are parasitic in ruminants throughout Africa and Asia. In north-east India, five species of pouched amphistomes, namely Fischoederius cobboldi, F. elongatus, Gastrothylax crumenifer, Carmyerius spatiosus and Velasquezotrema tripurensis, belonging to this family have been reported so far. In the present study, the molecular phylogeny of these five gastrothylacid species is derived using the second internal transcribed spacer (ITS2) sequence and secondary structure analyses. ITS2 sequence analysis was carried out to see the occurrence of interspecific variations among the species. Phylogenetic analyses were performed for primary sequence data alone as well as the combined sequence-structure information using neighbour-joining and Bayesian approaches. The sequence analysis revealed that there exist considerable interspecific variations among the various gastrothylacid fluke species. In contrast, the inferred secondary structures for the five species using minimum free energy modelling showed structural identities, in conformity with the core four-helix domain structure that has been recently identified as common to almost all eukaryotic taxa. The phylogenetic tree reconstructed using combined sequence-structure data showed a better resolution, as compared to the one using sequence data alone, with the gastrothylacid species forming a monophyletic group that is well separated from members of the other family, Paramphistomidae, of the amphistomid flukes group. The study provides the molecular characterization based on primary sequence data of the rDNA ITS2 region of the gastrothylacid amphistome flukes. Results also demonstrate the phylogenetic utility of the ITS2 sequence-secondary structure data for inferences at higher taxonomic levels.

Molecular characterization of the Indian poultry nodular tapeworm, Raillietina echinobothrida (Cestoda: Cyclophyllidea: Davaineidae) based on rDNA internal transcribed spacer 2 region

“…In recent years, several molecular tools including sequence data related to conserved domains have unveiled their utility in molecular identification, taxonomy, systematics and phylogeny of floral, faunal and microbial species, too (Huang et al 2006;Prasad et al 2009a, b;Wiemers et al 2009;Yao et al 2010;Sharma et al 2012). Since Woese and Fox (1977), the nuclear ribosomal repeat cistrons have also been widely implied for parasites (Littlewood and Olson 2001;Waeschenbach et al 2007;Jyrwa et al 2009;Goswami et al 2009;Tandon et al 2010;Prasad et al 2011;Ghatani et al 2012). Molecular phylogeny has advanced our understanding of comparative studies in basic and applied biology and more generally of their position within the phylum Platyhelminthes (Brooks and Hoberg 2001;Tandon et al 2010).…”

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

“…Miura et al (2005) reported the absence of heterozygosity in ITS-1 genes, which did not provide any support of gene fl ow among different lineages. Some workers suggested the ITS-2 as effective marker for species identifi cation, phylogenetic relations and developmental stages as well as molecular epidemiology and infection control (Rinaldi et al, 2005;Curran et al, 2006;Bazsalovicsová et al, 2010;Lotfy et al, 2010;Shylla et al, 2011;Ghatani et al, 2012;Phalee et al, 2014;Bian et al, 2013;Portier et al, 2012). In helminth parasites, ITS pseudogenes and mitochondrial genes are present and identifi cation of ITS region is not easy due to non-protein coding nature as compared to mitochondrial genes (Benasson et al, 2001).…”

“…Ghatani et al (2012) established the molecular phylogeny of fi ve gastrothylacid species using ITS-2 and secondary structure predictions. Inter-specifi c variations were noticed among the fi ve species through sequencing results, whereas secondary structures analyses expressed structural similarities.…”

Morphological and molecular characterization of Posthodiplostomum sp. (Digenea: Diplostomidae) metacercaria in the muscles of snakeheads (Channa punctata) from Manipur, India

“…The identical nature of the ITS2 secondary structure can be attributed to similarity in rRNA biogenesis among eukaryotes; its folding pattern plays an important role in processing of mature rRNA (Joseph et al, 1999) and structures are maintained during evolution through transitions/transversions, although mutations occur frequently (Coleman, 2007;Keller et al, 2010). The utility of ITS2 secondary structure for characterizing parasites has also been demonstrated (Shylla et al, 2011;Ghatani et al, 2012). A high degree of similarity in the ITS2 secondary structures of Posthodiplostomum sp.…”