Genetic polymorphisms of Echinococcus tapeworms in China as determined by mitochondrial and nuclear DNA sequences.
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.
Department of Parasitology, Asahikawa Medical College, Asahikawa, Hokkaido 078-8510, Japan. nakao@asahikawa-med.ac.jp
Minoru
M
Nakao
Tiaoying
T
Li
Xiumin
X
Han
Xiumin
X
Ma
Ning
N
Xiao
Jiamin
J
Qiu
Hu
H
Wang
Tetsuya
T
Yanagida
Wulamu
W
Mamuti
Hao
H
Wen
Pedro L
PL
Moro
Patrick
P
Giraudoux
Philip S
PS
Craig
Akira
A
Ito
D000818:Animals; D002681:China; D016000:Cluster Analysis; D018509:DNA, Helminth / Q000737:chemistry / Q000235:genetics; D004272:DNA, Mitochondrial / Q000737:chemistry / Q000235:genetics; D004443:Echinococcosis / Q000469:parasitology* / Q000662:veterinary*; D004446:Echinococcus / Q000145:classification* / Q000235:genetics / Q000302:isolation & purification*; D003576:Electron Transport Complex IV / Q000235:genetics*; D006239:Haplotypes; D015801:Helminth Proteins / Q000235:genetics; D006801:Humans; D008322:Mammals; D024101:Mitochondrial Proteins / Q000235:genetics; D008969:Molecular Sequence Data; D020648:Peptide Elongation Factor 1 / Q000235:genetics*; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D017385:Sequence Homology
D018509:DNA, Helminth; D004272:DNA, Mitochondrial; D015801:Helminth Proteins; D024101:Mitochondrial Proteins; D020648:Peptide Elongation Factor 1; D003576:Electron Transport Complex IV