Mitochondrial genomes of human helminths and their use as markers in population genetics and phylogeny.
ABSTRACT To date, over 100 complete metazoan mitochondrial (mt) genomes of different phyla have been reported. Here, we briefly summarise mt gene organisation in the Metazoa and review what is known of the mt genomes of nematodes and flatworms parasitic in humans. The availability of complete or almost complete mtDNA sequences for several parasitic helminths provides a rich source of genetic markers for phylogenetic analysis and study of genetic variability in helminth groups. Examples of the application of mtDNA in studies on Ascaris, Onchocerca, Schistosoma, Fasciola, Paragonimus, Echinostoma, Echinococcus and Taenia are described.
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ABSTRACT: Abstract Paleoparasitology has contributed to resume,the debate about the peopling of the Americas. The finding of parasites in human coprolites has allowed tracing pre-historic human,migrations. Hookworm,and whipworm,infections have been recorded in pre-ColumbianA merica. These intestinal parasites originated inAfrican pre-hominids and have accompanied humans across continents. However, when humans crossed the Beringia cold climate conditions probably eliminated from the traveling human,populations. Both hookworms,and whipworms,can only be transferred via development,in the soil where temperature and humidity conditions are essential to maintain transmission. Therefore, transpacific contacts have been proposed to explain their presence in pre-Columbian populations. Chagas disease points also to ancient human,movements,and cultural diffusion in the past. It is
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ABSTRACT: Adult tapeworms of the genus Echinococcus (family Taeniidae) occur in the small intestines of carnivorous definitive hosts and are transmitted to particular intermediate mammalian hosts, in which they develop as fluid-filled larvae (cysts) in internal organs (usually lung and liver), causing the disease echinococcosis. Echinococcus species are of major medical importance and also cause losses to the meat and livestock industries, mainly due to the condemnation of infected offal. Decisions regarding the treatment and control of echinococcosis rely on the accurate identification of species and population variants (strains). Conventional, phenetic methods for specific identification have some significant limitations. Despite advances in the development of molecular tools, there has been limited application of mutation scanning methods to species of Echinococcus. Here, we briefly review key genetic markers used for the identification of Echinococcus species and techniques for the analysis of genetic variation within and among populations, and the diagnosis of echinococcosis. We also discuss the benefits of utilizing mutation scanning approaches to elucidate the population genetics and epidemiology of Echinococcus species. These benefits are likely to become more evident following the complete characterization of the genomes of E. granulosus and E. multilocularis.Electrophoresis 07/2013; 34(13):1852-62. · 3.26 Impact Factor
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ABSTRACT: Taenia multiceps is a widely distributed zoonotic tapeworm of canids. The larval stage of the parasite (Coenurus) occurs in sheep, goat and cattle and has been rarely reported from humans. This study investigated genetic variability of two mitochondrial genes in 102 isolates of T. multiceps. Metacestodes were collected from brains and hearts of sheep in Tehran and Qom provinces of Iran. DNA of each isolate was extracted and used for PCR amplification of cytochrome c oxidase subunit I (CO1) and 12S ribosomal DNA (12S rRNA) genes. All amplicons were sequenced and the sequence data were analyzed using NCBI Blast and BioEdit. Phylogenetic trees and pairwise calculations were obtained by using Mega5 software. In total 7 and 25 representative haplotypes were differentiated for CO1 and 12S rRNA genes, respectively. For CO1 sequences 11 segregation sites within 7 haplotypes were observed. For 12S rRNA sequences a total of 32 segregation sites were observed in 25 haplotypes. CO1 gene displayed lower diversity than 12S rRNA gene with an overall nucleotide variation of 3.0% for CO1 vs. 7.2% for 12S rRNA. Pairwise comparisons among 7 haplotypes in CO1 and 12S rRNA genes showed the level of nucleotide differences 0.3-2.5% and 0.2-4.0%, respectively. A high degree of genetic variation was found in the isolates of T. multiceps in Iran. Additional molecular studies are required on the parasite from other intermediate hosts.Veterinary Parasitology 07/2013; · 2.38 Impact Factor