Comparing the mitochondrial genomes of Wolbachia-dependent and independent filarial nematode species

BMC Genomics

Research Article

Vasyl V Tkach¹  Jefferson A Vaughan¹  Peter U Fischer²  Andrew S Mullin²  Samantha N McNulty²  Gary J Weil² 

[1] Department of Biology, University of North Dakota, 10 Cornell St, 58202, Grand Forks, ND, USA;Infectious Diseases Division, Department of Internal Medicine, Washington University School of Medicine, Campus Box 8051, 660 S. Euclid Avenue, 63110, St. Louis, MO, USA;

关键词: Mitochondrial Genome;    Codon Usage;    tRNA Gene;    Filariasis;    Wolbachia Infection;   

DOI  :  10.1186/1471-2164-13-145

 received in 2011-11-09, accepted in 2012-04-24,  发布年份 2012

来源: Springer

【 摘 要 】

BackgroundMany species of filarial nematodes depend on Wolbachia endobacteria to carry out their life cycle. Other species are naturally Wolbachia-free. The biological mechanisms underpinning Wolbachia-dependence and independence in filarial nematodes are not known. Previous studies have indicated that Wolbachia have an impact on mitochondrial gene expression, which may suggest a role in energy metabolism. If Wolbachia can supplement host energy metabolism, reduced mitochondrial function in infected filarial species may account for Wolbachia-dependence. Wolbachia also have a strong influence on mitochondrial evolution due to vertical co-transmission. This could drive alterations in mitochondrial genome sequence in infected species. Comparisons between the mitochondrial genome sequences of Wolbachia-dependent and independent filarial worms may reveal differences indicative of altered mitochondrial function.ResultsThe mitochondrial genomes of 5 species of filarial nematodes, Acanthocheilonema viteae, Chandlerella quiscali, Loa loa, Onchocerca flexuosa, and Wuchereria bancrofti, were sequenced, annotated and compared with available mitochondrial genome sequences from Brugia malayi, Dirofilaria immitis, Onchocerca volvulus and Setaria digitata. B. malayi, D. immitis, O. volvulus and W. bancrofti are Wolbachia-dependent while A. viteae, C. quiscali, L. loa, O. flexuosa and S. digitata are Wolbachia-free. The 9 mitochondrial genomes were similar in size and AT content and encoded the same 12 protein-coding genes, 22 tRNAs and 2 rRNAs. Synteny was perfectly preserved in all species except C. quiscali, which had a different order for 5 tRNA genes. Protein-coding genes were expressed at the RNA level in all examined species. In phylogenetic trees based on mitochondrial protein-coding sequences, species did not cluster according to Wolbachia dependence.ConclusionsThus far, no discernable differences were detected between the mitochondrial genome sequences of Wolbachia-dependent and independent species. Additional research will be needed to determine whether mitochondria from Wolbachia-dependent filarial species show reduced function in comparison to the mitochondria of Wolbachia-independent species despite their sequence-level similarities.

【 授权许可】

CC BY   
© McNulty et al.; licensee BioMed Central Ltd. 2012