Dataset Information

Genetic polymorphisms of Echinococcus tapeworms in China as determined by mitochondrial and nuclear DNA sequences.

ABSTRACT: The genetic polymorphisms of Echinococcus spp. in the eastern Tibetan Plateau and the Xinjiang Uyghur Autonomous Region were evaluated by DNA sequencing analyses of genes for mitochondrial cytochrome c oxidase subunit 1 (cox1) and nuclear elongation factor-1 alpha (ef1a). We collected 68 isolates of Echinococcus granulosus sensu stricto (s.s.) from Xinjiang and 113 isolates of E. granulosus s. s., 49 isolates of Echinococcus multilocularis and 34 isolates of Echinococcus shiquicus from the Tibetan Plateau. The results of molecular identification by mitochondrial and nuclear markers were identical, suggesting the infrequency of introgressive hybridization. A considerable intraspecific variation was detected in mitochondrial cox1 sequences. The parsimonious network of cox1 haplotypes showed star-like features in E. granulosus s. s. and E. multilocularis, but a divergent feature in E. shiquicus. The cox1 neutrality indexes computed by Tajima's D and Fu's Fs tests showed high negative values in E. granulosus s. s. and E. multilocularis, indicating significant deviations from neutrality. In contrast, the low positive values of both tests were obtained in E. shiquicus. These results suggest the following hypotheses: (i) recent founder effects arose in E. granulosus and E. multilocularis after introducing particular individuals into the endemic areas by anthropogenic movement or natural migration of host mammals, and (ii) the ancestor of E. shiquicus was segregated into the Tibetan Plateau by colonising alpine mammals and its mitochondrial locus has evolved without bottleneck effects.

SUBMITTER: Nakao M

PROVIDER: S-EPMC2823955 | biostudies-literature | 2010 Mar

REPOSITORIES: biostudies-literature

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Genetic polymorphisms of Echinococcus tapeworms in China as determined by mitochondrial and nuclear DNA sequences.

Nakao Minoru M Li Tiaoying T Han Xiumin X Ma Xiumin X Xiao Ning N Qiu Jiamin J Wang Hu H Yanagida Tetsuya T Mamuti Wulamu W Wen Hao H Moro Pedro L PL Giraudoux Patrick P Craig Philip S PS Ito Akira A

International journal for parasitology 20091001 3

The genetic polymorphisms of Echinococcus spp. in the eastern Tibetan Plateau and the Xinjiang Uyghur Autonomous Region were evaluated by DNA sequencing analyses of genes for mitochondrial cytochrome c oxidase subunit 1 (cox1) and nuclear elongation factor-1 alpha (ef1a). We collected 68 isolates of Echinococcus granulosus sensu stricto (s.s.) from Xinjiang and 113 isolates of E. granulosus s. s., 49 isolates of Echinococcus multilocularis and 34 isolates of Echinococcus shiquicus from the Tibet ...[more]

PMID: 19800346

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Project description:BACKGROUND:Cystic echinococcosis (CE) in humans and livestock is caused by Echinococcus granulosus (sensu lato). In China where CE is endemic, a number of studies have shown that Echinococcus granulosus (sensu stricto) is majorly responsible for CE. However, E. canadensis (G6) which is the second leading cause of CE is now being detected in most parts of the country. In this study, the species diversity and genetic variation of Echinococcus granulosus (s.l.) in four counties in Tibet Autonomous Region of China were investigated. METHODS:Infection with Echinococcus granulosus (s.s.) in yaks and sheep was identified using NADH dehydrogenase subunit 1 and 5 (nad1 and nad5) mitochondrial genes while the genotype G6 of E. canadensis initially diagnosed with NADH dehydrogenase subunit 1 (nad1) was further confirmed by analysis of the complete mitochondrial genome and a phylogenetic network constructed based on the nad2 and nad5 genes. RESULTS:Out of 85 hydatid cyst samples collected from slaughtered sheep (n = 54) and yaks (n = 31), 83 were identified as E. granulosus (s.s.) G1 (n = 77), G3 (n = 6) and 2 were identified as E. canadensis G6. Analysis of the nad1/nad5 genes revealed 16/17 mutations with 9/14 parsimony informative sites resulting in 15/14 haplotypes, respectively. Haplotype diversity (Hd) and nucleotide diversity (?) of E. granulosus (s.s.) population were 0.650 and 0.00127 for nad1 and 0.782 and 0.00306 for nad5, respectively, with an overall negative Tajima's D and Fu's Fs. A low FST indicated no genetic difference between isolates from sheep and yaks. CONCLUSION:Pockets of infection with E. canadensis (G6, G7, G8 and G10) have been previously reported in sheep, goats, yaks and/or humans in different parts of China. While the G6 genotype has been previously reported in sheep in the Tibet Autonomous Region, the detection in a yak in the present study represents the first to the best of our knowledge. Therefore, we recommend future surveys and control efforts to comprehensively investigate other potential intermediate hosts for the prevalence and genetic diversity of the E. canadensis group (G6, G7, G8 and G10) across the country and their inclusion into the existing CE control programme.

Project description:BACKGROUND:Whipworms (Nematoda: Trichuridae), among the most common soil-transmitted helminths (STHs), can cause the socioeconomically important disease trichuriasis in various mammalian hosts including humans and non-human primates. For many years, Trichuris from non-human primates has been assigned to the same species as the one infecting humans Trichuris trichiura. More recently, several molecular reports challenged this assumption following recognition of a Trichuris species complex observed in humans and non-human primates. A refined concept for species limits within Trichuris contributes to an understanding of diversity and the potential (zoonotic) transmission among humans and non-human primates. In this study, we expanded previous investigations by exploring the diversity of Trichuris among eight primates including three Asian autochthonous species (i.e. Rhinopithecus roxellana, Rhinopithecus bieti and Nomascus leucogenys). Species-level identification, whether novel or assignable to known lineages of Trichuris, was based on analyses of nuclear internal transcribed spacers (ITS) and mitochondrial cytochrome c oxidase subunit 1 (cox1) genes. RESULTS:In total, seven genetically distinct subgroups of whipworms were determined to be present among the primates sampled. Most Trichuris lineages, including Subgroups 1, 1', 3, 5 and 6, showed a broad host range and were not restricted to particular primate species; in addition to T. trichiura, a complex of Trichuris species was shown infecting primates. Furthermore, it was assumed that Trichuris spp. from either N. leucogenys and P. hamadryas or R. roxellana and R. bieti, respectively, were conspecific. Each pair was indicated to be a discrete lineage of Trichuris, designated, respectively, as Subgroups 1 or 1' and 2, based on integrated genetic and phylogenetic evidence. CONCLUSION:These results emphasise that the taxonomy and genetic variations of Trichuris are more complicated than previously acknowledged. These cumulative molecular and phylogenetic data provide a better understanding of the taxonomy, genetics and evolutionary biology of the whipworms.

Project description:BACKGROUNDFasciolopsis buski is a zoonotic intestinal fluke infecting humans and pigs, but it has been seriously neglected. It is yet to know whether there is any genetic diversity among F. buski from different geographical locations, particularly in sequences of nuclear ribosomal DNA (rDNA) and mitochondrial (mt) DNA. Therefore, we determined the sequences of partial 18S, the complete internal transcribed spacer (ITS) rDNA and the complete mt genome of F. buski from China, compared the rDNA and mtDNA sequences with those of isolates from India and Vietnam, and assessed the phylogenetic relationships of this fluke and related fasciolid trematodes based on the mtDNA dataset.RESULTSThe complete mt genome sequence of F. buski from China is 14,833 bp, with 36 genes, including 12 protein-coding genes (PCGs), 22 tRNA genes, and two rRNA genes (rrnL and rrnS). The AT content of F. buski from China is 65.12%. The gene content and arrangement of the F. buski mt genome is similar to that of Fascioloides magna. Genetic distances between isolates of F. buski from China and India were high (28.2% in mtDNA, 13.2% in ITS-1 and 9.8% in ITS-2) and distinctly higher than the interspecific differences between Fasciola hepatica and Fasciola gigantica. The rDNA and mtDNA datasets for F. buski from China (isolate from pigs) and Vietnam (isolates from humans) were identical. The intergeneric differences in amino acid and nucleotide sequences among the genera Fasciolopsis, Fascioloides and Fasciola ranged between 24.64-25.56% and 26.35-28.46%, respectively.CONCLUSIONSOur results indicate that F. buski from China and India may represent distinct taxa, while F. buski in Vietnam and China represent the same species. These findings might have implications for the implementation of appropriate control strategies in different regions. Further studies are needed to decode mtDNA and rDNA sequences of F. buski from various geographical isolates for the better understanding of the species complex of F. buski.

Dataset Information

Genetic polymorphisms of Echinococcus tapeworms in China as determined by mitochondrial and nuclear DNA sequences.

Publications

Genetic polymorphisms of Echinococcus tapeworms in China as determined by mitochondrial and nuclear DNA sequences.

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