Characterization of the Intergenic Spacer rDNAs of Two Pig Nodule Worms,Oesophagostomum dentatumandO. quadrispinulatum

Abstract

The characteristics of the intergenic spacer rDNAs (IGS rDNAs) of Oesophagostomum dentatum and O. quadrispinulatum isolated from pigs in different geographical locations in Mainland China were determined, and the phylogenetic relationships of the two species were reconstructed using the IGS rDNA sequences. The organization of the IGS rDNA sequences was similar to their organization in other eukaryotes. The 28S-18S IGS rDNA sequences of both O. dentatum and O. quadrispinulatum were found to have variable lengths, that is, 759–762 bp and 937–1128 bp, respectively. All of the sequences contained direct repeats and inverted repeats. The length polymorphisms were related to the different numbers and organization of repetitive elements. Different types and numbers of repeats were found between the two pig nodule species, and two IGS structures were found within O. quadrispinulatum. Phylogenetic analysis showed that all O. dentatum isolates were clustered into one clade, but O. quadrispinulatum isolates from different origins were grouped into two distinct clusters. These results suggested independent species and the existence of genotypes or subspecies within pig nodule worms. Different types and numbers of repeats and IGS rDNA structures could serve as potential markers for differentiating these two species of pig nodule worms.

Cytochrome c oxidase subunit 1 gene reveals species composition and phylogenetic relationships of Oesophagostomum spp. infecting pigs in northeastern Brazil

“…Similarly, phylogenetic analyses on O. dentatum and O. quadrispinulatum recovered from pigs in different regions of China generated a cluster with two clades that formed a monophyletic group (Lin et al, 2012a). The last authors used ribosomal DNA targets, which resulted in similar formation of a monophyletic group, with different groupings in the species O. quadrispinulatum, thereby indicating the presence of distinct genotypes or subspecies (Lin et al, 2014). Four distinct and novel haplotypes were identified in our O. quadrispinulatum sequences.…”

“…Considering only the species with the greatest impact on public health and veterinary medicine, pigs can be infected with the species O. dentatum and O. quadrispinulatum (Lin et al, 2014). Oesophagostomum bifurcum, O. stephanostomum, O. brumpti and O. aculeatum have previously been described in human and non-human primates (Glen & Brooks, 1985); and O. columbianum, O. venulosum and O. asperum in sheep and goats (Gaddam et al, 2017).…”

Variation of 45S rDNA intergenic spacers in Arabidopsis thaliana

“…The rDNA ITS have become widely used for species identification and even the highly variable IGS can be utilized to distinguish among closely related species in phylogenetic studies (e.g. Cavallero et al 2015;Han et al 2016;Konstantinova and Yli-Mattila 2004;Lin et al 2014;Marcilla et al 2001).…”