Reduced genetic variability within coding and non-coding 
regions of the <i>Echinococcus multilocularis</i> genome

Haag, Karen Luisa; Zaha, Arnaldo; Araújo, Aldo Mellender de‏; Gottstein, Bruno

doi:10.1017/s0031182097001649

Cited by 72 publications

(47 citation statements)

References 14 publications

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“…The degree of allele polymorphism found within E. multilocularis and within strains of E. granulosus was low, as shown in our previous studies (Haag et al 1997(Haag et al , 1998. Indeed, only one transversion and a single base deletion in the Hbx2 intron occurred among isolates of E. multilocularis (Haag et al 1997).…”

Section: Resultssupporting

confidence: 58%

“…Indeed, only one transversion and a single base deletion in the Hbx2 intron occurred among isolates of E. multilocularis (Haag et al 1997). Within the cattle, horse, pig and sheep strains of E. granulosus no allele polymorphism was found in the four coding and noncoding loci analysed in the present study.…”

Section: Resultscontrasting

confidence: 57%

“…For each isolate, four different targets were amplified by PCR, using primers specific for Echinococcus DNA (see procedures in Haag et al 1997). Two of them were partial intron sequences from an actin gene (ActII -266 bp) and from an homeobox containing gene (Hbx2 -331 bp).…”

Section: Methodsmentioning

confidence: 99%

“…The nucleotide variation within the PCR products obtained for the four targets was screened by the PCR-SSCP method (see procedures in Haag et al 1997). Subsequently, two isolates from each SSCP pattern (except in the case of E. vogeli) were chosen for direct fluorescence sequencing.…”

Section: Methodsmentioning

confidence: 99%

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Selection, Recombination and History in a Parasitic Flatworm (Echinococcus) Inferred from Nucleotide Sequences

Haag

Araújo²,

Gottstein

et al. 1998

Mem. Inst. Oswaldo Cruz

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Three species of flatworms from the genus Echinococcus (E. granulosus, E. multilocularis and E. vogeli) and four strains of E. granulosus (cattle, horse, pig and sheep strains) were analysed by the PCR-SSCP method followed by sequencing, using as targets two non-coding and two coding ( Four species within the genus are recognised: E. vogeli and E. oligarthrus, which occur in the neotropical region, E. multilocularis, that has an holartic geographic range and E. granulosus, that is world-wide distributed. Due to a low intermediate host specificity, E. granulosus has been subdivided in several strains, according to the host species used, or to the geographic range of the biological cycle. Some of the evolutionary questions concerning Echinococcus are: (1) is the adult mainly self-or cross-fertilising? (2) how do the strains within a species differentiate? (3) what is the true taxonomic status of these strains?The first question relates to the second one: depending on the breeding system, only one of two modes of strain differentiation can occur. If individual parasites would be mainly selfers (Smyth & Smyth 1964), purifying (negative) selection would quickly eliminate the non-adaptive mutations, due to increased homozygosis. In addition, selfing would lead to a high rate of linkage disequilibrium within parasite populations. In this situation, the genome would be selected as a whole, and not in pieces of recombining DNA. If, on the other hand, populations would undergo outcrossing (Rausch 1967(Rausch , 1985, free recombination would allow genes to be selected as individual units, and

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Section: Resultssupporting

confidence: 58%

Section: Resultscontrasting

confidence: 57%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Selection, Recombination and History in a Parasitic Flatworm (Echinococcus) Inferred from Nucleotide Sequences

Haag

Araújo²,

Gottstein

et al. 1998

Mem. Inst. Oswaldo Cruz

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“…examined Romanian isolates (0.0702) than for fi ve E. multilocularis isolates (0.0196). Lower genetic variability in E. multilocularis is putatively due to the facts that E. multilocularis has conservative host spectrum compared to E. granulosus adapted to a number of different host species and that E. multilocularis is phylogenetically young species (Haag et al, 1997;Bart et al, 2003). More effective public health policies to reduce E. granulosus s.l.…”

Section: Discussionmentioning

confidence: 99%

Genetic survey of alveolar and cystic echinococcoses in Romania: first molecular evidence of Echinococcus multilocularis in humans in the country

et al. 2017

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SummaryCystic echinococcosis (CE) and alveolar echinococcosis (AE) are considered as one of the most important zoonotic diseases in Romania, where they are subject to mandatory reporting. To obtain more knowledge about the genetic diversity of Echinococcus causative agents of these diseases, 11 isolates from humans and ungulate intermediate hosts from the two regions of Romania were genotyped using mitochondrial markers. In clinical samples of fi ve patients from north-eastern Romania (Iasi, Botosani, Vaslui counties), Echinococcus multilocularis was identifi ed as causal agent by cox1 sequence analysis. To the best of our knowledge this fi nding presents the fi rst molecular evidence of E. multilocularis in humans from Romania. Only two cases of AE in patients were previously documented in the country by serological methods. In our four patients the most widespread European variant E5 of E. multilocularis was recorded, whereas in isolate from Vaslui county three nucleotide substitutions were detected as compared to the most related E5 haplotype. One of these mutations (411T/G) matched N1 and N2 haplotypes described previously from North America. In six CE samples retrieved from western Romania (Caras-Severin and Timis counties), two human isolates were diagnosed as Echinococcus canadensis G7, one as E. granulosus s.s. G1 and one as E. granulosus s.s. G3 using atp6 and rrnS sequencing. In ungulates, the cattle isolate was allocated to E. granulosus s.s. G1 and pig isolate to E. canadensis G7. The two G7 fi ndings in humans reinforced the recent view that G7 was underestimated as compared to the E. granulosus s.s. regarding human CE threat that can be further employed for identifying sources of infections and establishing suitable preventive measures.

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Single‐strand conformation polymorphism (SSCP)‐based mutation scanning approaches to fingerprint sequence variation in ribosomal DNA of ascaridoid nematodes

Zhu

Gasser

1998

Electrophoresis

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In this study, we assessed single-strand conformation polymorphism (SSCP)-based approaches for their capacity to fingerprint sequence variation in ribosomal DNA (rDNA) of ascaridoid nematodes of veterinary and/or human health significance. The second internal transcribed spacer region (ITS-2) of rDNA was utilised as the target region because it is known to provide species-specific markers for this group of parasites. ITS-2 was amplified by PCR from genomic DNA derived from individual parasites and subjected to analysis. Direct SSCP analysis of amplicons from seven taxa (Toxocara vitulorum, Toxocara cati, Toxocara canis, Toxascaris leonina, Baylisascaris procyonis, Ascaris suum and Parascaris equorum) showed that the single-strand (ss) ITS-2 patterns produced allowed their unequivocal identification to species. While no variation in SSCP patterns was detected in the ITS-2 within four species for which multiple samples were available, the method allowed the direct display of four distinct sequence types of ITS-2 among individual worms of T. cati. Comparison of SSCP/sequencing with the methods of dideoxy fingerprinting (ddF) and restriction endonuclease fingerprinting (REF) revealed that also ddF allowed the definition of the four sequence types, whereas REF displayed three of four. The findings indicate the usefulness of the SSCP-based approaches for the identification of ascaridoid nematodes to species, the direct display of sequence variation in rDNA and the detection of population variation. The ability to fingerprint microheterogeneity in ITS-2 rDNA using such approaches also has implications for studying fundamental aspects relating to mutational change in rDNA.

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Reduced genetic variability within coding and non-coding regions of the Echinococcus multilocularis genome

Cited by 72 publications

References 14 publications

Selection, Recombination and History in a Parasitic Flatworm (Echinococcus) Inferred from Nucleotide Sequences

Selection, Recombination and History in a Parasitic Flatworm (Echinococcus) Inferred from Nucleotide Sequences

Genetic survey of alveolar and cystic echinococcoses in Romania: first molecular evidence of Echinococcus multilocularis in humans in the country

Single‐strand conformation polymorphism (SSCP)‐based mutation scanning approaches to fingerprint sequence variation in ribosomal DNA of ascaridoid nematodes

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