Characterization of the complete mitochondrial genome of Spirocerca lupi: sequence, gene organization and phylogenetic implications

Abstract

BackgroundSpirocerca lupi is a life-threating parasitic nematode of dogs that has a cosmopolitan distribution but is most prevalent in tropical and subtropical countries. Despite its veterinary importance in canids, the epidemiology, molecular ecology and population genetics of this parasite still remain unexplored.MethodsThe complete mitochondrial (mt) genome of S. lupi was amplified in four overlapping long fragments using primers designed based on partial cox1, rrnS, cox2 and nad2 sequences. Phylogenetic re-construction of 13 spirurid species (including S. lupi) was carried out using Bayesian inference (BI) based on concatenated amino acid sequence datasets.ResultsThe complete mt genome sequence of S. lupi is 13,780 bp in length, including 12 protein-coding genes, 22 transfer RNA genes and two ribosomal RNA genes, but lacks the atp8 gene. The gene arrangement is identical to that of Thelazia callipaeda (Thelaziidae) and Setaria digitata (Onchocercidae), but distinct from that of Dracunculus medinensis (Dracunculidae) and Heliconema longissimum (Physalopteridae). All genes are transcribed in the same direction and have a nucleotide composition high in A and T. The content of A + T is 73.73% for S. lupi, in accordance with mt genomes of other spirurid nematodes sequenced to date. Phylogenetic analyses using concatenated amino acid sequences of the 12 protein-coding genes by BI showed that the S. lupi (Thelaziidae) is closely related to the families Setariidae and Onchocercidae.ConclusionsThe present study determined the complete mt genome sequence of S. lupi. These new mt genome dataset should provide novel mtDNA markers for studying the molecular epidemiology and population genetics of this parasite, and should have implications for the molecular diagnosis, prevention and control of spirocercosis in dogs and other canids.

Analysis of the genetic diversity of the nematode parasite Baylisascaris schroederi from wild giant pandas in different mountain ranges in China

“…MtDNA markers have higher Fst values than nuclear sequences, and the mtDNA of nematodes evolves more quickly than the mtDNA of other parasites [8,20,21]. Recently, some mt genes (e.g., mt Cytb ) have been widely applied for analysis of the phylogenetic relationships between nematodes at the subspecies, species, genus and order levels [9,22,23]. Here, the complete Cytb gene was sequenced in 48 B .…”

Mitochondrial genome of Hypoderaeum conoideum – comparison with selected trematodes

“…These worms were washed in physiological saline and identified morphologically according to existing morphological descriptions [ 11 ]. A reference specimen was stained and mounted [ 12 ] and the remaining specimens were fixed in 70% (v/v) ethanol and stored at −20°C until use [ 8 ]. Total genomic DNA was extracted from one specimen using E.Z.N.A.® Tissue DNA Kit.…”

“…For instance, PCR-based techniques using genetic markers in nuclear ribosomal (r) and mitochondrial (mt) DNA have been widely used [ 7 ]. The sequences of the first and second internal transcribed spacers (ITS-1 and ITS-2 = ITS) of nuclear rDNA have been particularly useful for specific identification, based on consistent levels of sequence difference between species and little variation within individual species [ 7 ], while the mitochondrial gene cox 1 has been used for studying genetic variation and relationships among different species [ 8 - 10 ]. As a basis for the development of molecular tools to study H. conoideum populations (irrespective of developmental stage), we have characterized the complete mt genome of this parasite, compared this genome with those of selected trematodes and undertaken a phylogenetic analysis of concatenated amino acid sequence data for 12 protein-coding genes to assess the genetic relationship of H. conoideum with these other trematodes.…”

The complete mitochondrial genome of Toxascaris leonina: Comparison with other closely related species and phylogenetic implications

“…Each PCR reaction yielded a single band (of the expected sizes at approximately 9 kb and 6 kb respectively) detected in a 0.8% (w/v) agarose gel upon ethidium-bromide staining (not shown). PCR products were sent to Sangon Company (Shanghai, China) for sequencing using a primer walking strategy (Hu et al, 2007;Liu et al, 2013a).…”