Mitochondrial genomes of parasitic nematodes – progress and perspectives

doi:10.1016/j.pt.2005.12.003

Trends in Parasitology

Volume 22, Issue 2, February 2006, Pages 78-84

https://doi.org/10.1016/j.pt.2005.12.003 Get rights and content

Mitochondria are subcellular organelles in which oxidative phosphorylation and other important biochemical functions take place within the cell. Within these organelles is a mitochondrial (mt) genome, which is distinct from, but cooperates with, the nuclear genome of the cell. Studying mt genomes has implications for various fundamental areas, including mt biochemistry, physiology and molecular biology. Importantly, the mt genome is a rich source of markers for population genetic and systematic studies. To date, more than 696 mt genomes have been sequenced for a range of metazoan organisms. However, few of these are from parasitic nematodes, despite their socioeconomic importance and the need for fundamental investigations into areas such as nematode genetics, systematics and ecology. In this article, we review knowledge and recent progress in mt genomics of parasitic nematodes, summarize applications of mt gene markers to the study of population genetics, systematics, epidemiology and evolution of key nematodes, and highlight some prospects and opportunities for future research.

Introduction

Mitochondria are involved in oxidative phosphorylation (respiratory metabolism) in most eukaryotes. They are proposed to originate from free-living eubacteria undergoing endosymbiosis [1]. Mitochondrial (mt) genomes are usually small (∼13–26 kb), circular, compact and haploid (Figure 1). They contain 12–13 protein genes (cox1–cox3, nad1–nad6, nad4L, cob, atp6 and/or atp8) that encode enzymes required for oxidative phosphorylation, two ribosomal (r)RNA genes (rrnS and rrnL) encoding the RNA components of the mt ribosome, and 22 transfer (t)RNA genes required for translation of the different mt proteins. With the advent of new technologies, research on the structure and function of mt genomes has been progressing steadily. Currently, more than 696 mt genomes from metazoan organisms have been sequenced and are available in gene databases [e.g. see the Organelle Genome Resources of the National Center for Biotechnology Information (NCBI; http://www.ncbi.nlm.nih.gov/genomes/ORGANELLES/mztax_short.html) and the European Bioinformatics Institute (EBI) resource; http://www.ebi.ac.uk/genomes/organelle.html]. However, despite the socioeconomic importance of the study of nematodes, and recent evidence of idiosyncratic features and arrangements for some nematode mt genomes, <2% of mt sequences in the databases are from these organisms.

Section snippets

Mt genome sequences of parasitic nematodes

To date, complete mt genome sequences have been reported for 12 species of parasitic nematode (Table 1). The first complete mt genome sequence determined for any parasitic nematode was that of the ascaridoid Ascaris suum [2]. Complete or near-complete mt genome sequences became available for the filarioid Onchocerca volvulus 3, 4 and the ‘trichina’ Trichinella spiralis [5]. Using an improved long-PCR-based approach [6] for the sequencing from single nematodes representing three different

Selected examples of the use of mt genome datasets for studying nematodes

The availability of mt genome sequences for parasitic nematodes provides a rich source of markers for investigating their population genetics, epidemiology and systematics.

Concluding remarks

The variation in the mt genome structure among some species of nematodes studied to date indicates that mt genes in this group undergo relatively frequent rearrangement, which should facilitate studying mechanisms of mt gene rearrangements and mt genome evolution. Elucidating the mechanisms of mt gene rearrangements should also have implications for investigating the evolutionary relationships of nematodes. Concatenated nucleotide and amino acid sequence datasets (derived from full mt genome

Acknowledgements

We are grateful to several colleagues, in particular N.B. Chilton, X.Q. Zhu, I. Beveridge, Y.G. Abs EL-Osta, G. Schad and A.M. Polderman, for their contributions to previous studies referred to in this review. Funding support to R.B.G. from the Australian Academy of Science, Genetic Technologies Limited, Elchrom Scientific, the Australian Research Council and the University of Melbourne is gratefully acknowledged.

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Trends in Parasitology

Mitochondrial genomes of parasitic nematodes – progress and perspectives

Introduction

Section snippets

Mt genome sequences of parasitic nematodes

Selected examples of the use of mt genome datasets for studying nematodes

Concluding remarks

Acknowledgements

Adv. Parasitol.

Mol. Biochem. Parasitol.

Int. J. Parasitol.

Mol. Cell. Probes

Int. J. Parasitol.

Int. J. Parasitol.

Int. J. Parasitol.

Adv. Parasitol.

Int. J. Parasitol.

Vet. Parasitol.

Int. J. Parasitol.

Int. J. Parasitol.

Vet. Parasitol.

Acta Trop.

Int. J. Parasitol.

FEBS Lett.

Acta Trop.

The mitochondrial genomes of two nematodes, Caenorhabditis elegans and Ascaris suum

Genetics

Trichinella spiralis mtDNA: a nematode mitochondrial genome that encodes a putative ATP8 and normally structured tRNAs and has a gene arrangement relatable to those of coelomate metazoans

Genetics

Structure and organization of the mitochondrial genome of Dirofilaria immitis

Parasitology

A single nucleotide polymorphism map of the mitochondrial genome of the parasitic nematode Cooperia oncophora

Parasitology

Molecular characterization for lengthy mitochondrial DNA duplications from the parasitic nematode Romanomermis culicivorax

Genetics

Repeated sequence sets in mitochondrial DNA molecules of root knot nematodes (Meloidogyne): nucleotide sequences, genome location and potential for host race identification

Nucleic Acids Res.

Low, but strongly structural mitochondrial DNA diversity in root knot nematodes (Meloidogyne)

Genetics

Evolution of the AT-rich mitochondrial DNA of the root knot nematode, Meloidogyne hapla

Mol. Biol. Evol.