Genetic variation between and within Triodontophorus brevicauda and Triodontophorus nipponicus revealed by analyses of mtDNA and rDNA gene sequences.

The study explores genetic variation in two species of Triodontophorus parasites that afflict horses, based on five selected genetic markers. Results reflect variations both within and between species and offer essential data for further research in systematics and population genetics of this genus.

Study Background and Goals

• The research focuses on two species of parasites under the Triodontophorus genus, namely Triodontophorus brevicauda and Triodontophorus nipponicus. These parasites are notorious for infesting the large intestines of horses and causing strongylid diseases.
• The main objective of the study was to evaluate the genetic variation within and between these two species. This was achieved by analysing five gene regions, including three mitochondrial genes and two ribosomal RNA genes.

Methodology

• The parasites analysed were sourced from Heilongjiang Province and the Inner Mongolia Autonomous region.
• The three mitochondrial genes chosen for this study were cytochrome c oxidase subunit I (cox1), NADH dehydrogenase subunit 5 (nad5), and cytochrome b (cytb).
• The two ribosomal RNA genes were the internal transcribed spacer 1 (ITS1) and the internal transcribed spacer 2 (ITS2).
• These genes were PCR amplified from individual nematodes, and the amplicons were then subjected to sequencing in both directions to aid in decoding their genetic makeup.

Results and Conclusions

• The research found consistency in the size of the three mitochondrial genes in both species. Meanwhile, the lengths of the two ribosomal genes varied between the two.
• Intraspecific variation between the two species, T. brevicauda and T. nipponicus, ranged between 0-2.2% for the five examined genes.
• As for interspecific variation, it was a higher range of 11.5-18.7% within the nematodes for these genes.
• Based on the nucleotide sequences of these five genes, the species formed separate, distinct monophyletic groups in phylogenetic analyses. However, it was noteworthy that samples of different species from the same geographical origin did not always cluster together.
• The findings of the study will be useful for advancing research in the systematics and population genetics of the Triodontophorus genus, particularly in relation to parasite control and treatment strategies in equine health.