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At least 19 recordsLinked to original sources

PubMedDate not supplied

[Use of polymerase chain reaction for identifying helminth DNA from the species Trichinella, Fasciola, Echinococcus, Nematodirus, Taenia].

We have used the polymerase chain reaction (PCR) and random amplified polymorphic DNA (RAPD) method to identify DNA polymorphism in three classes of helminths, Cestoda, Nematoda and Trematoda. In this study, RAPD markers have been used for a description of the genetic variability between the families, genera, species and isolates of helminths. We optimized the conditions of the RAPD analysis and revealed the genetic variability of helminths belonging to different taxonomic groups. These results show that the RAPD-PCR method can be considered as a suitable technic for a phylogenetic study of helminths. The problem of an age variability and most specificity of RAPDs markers is discussed.

Animals↗

PubMed1998

Immunopathological mechanisms underlying the time-course of Trichinella spiralis cardiomyopathy in rats.

The present study shows that isolated, perfused hearts from rats orally infected with Trichinella spiralis have a reduced left ventricular developed pressure (LVDP), heart rate (HR) and coronary flow (CF). This reduction is considerably enhanced by a single bolus (100 pM) of PAF (platelet activating factor, an eosinophil activator), especially at 21 days post-infection (d.p.i.), which is the time of the maximum increase in blood and tissue eosinophilia. Helminthic DNA analysis shows that, from 21 d.p.i. onwards, the morphological and functional changes in the myocardium cannot be ascribed to the parasite's presence, whereas its antigens and the attendant immunopathological reactions might have a role in the induction of myocardial damage and dysfunction. Some perivascular inflammatory cells (eosinophils and mast cells) appear to undergo degranulation. All these data suggest a complex sequence of events, from acute myocarditis (21 d.p.i.) which may lead in time (48 d.p.i. onwards) to a dilating cardiomyopathy.

Animals↗

PubMed2005

Isolates of Trichuris muris elicit different adaptive immune responses in their murine host.

The J and S isolates of Trichuris muris have different infection profiles in C57BL/6 mice; J worms are expelled, S worms survive to chronicity. Building on this, the ability of the J and S isolates to survive, and the quality of the immune response induced was explored in three different strains of mouse. The resistant BALB/c mouse mounted a strong Th2 response against both isolates, which were quickly expelled. The susceptible AKR host mounted a Th1 response and retained both isolates. Despite equivalent worm exposure, mesenteric lymph node cells from AKR mice infected with the S isolate produced significantly higher levels of IL-12 and the intestinal mastocytosis was reduced. IgG1 and IgG2a from S-infected AKR mice recognized low molecular weight antigens not recognized by J-infected mice. Differential expulsion kinetics was observed in the slower-responding C57BL/6 strain; J worms were expelled but S isolate worms were retained. Survival of the S isolate was again associated with elevated IL-12 and decreased Th2 responses. In resistant mouse strains, the outcome of infection is thus dominantly influenced by host genetics. However, in the slower-responding host, isolate-derived factors may play a role in shaping the quality of the adaptive immune response, thus influencing parasite survival.

Animals↗

PubMed1998

Molecular phylogeny of the families Campulidae and Nasitrematidae (Trematoda) based on mtDNA sequence comparison.

Historically, the systematic arrangement of the genera within the family Campulidae, and its relationship with its allied family Nasitrematidae have been rather confused, particularly because only adult morphology has been available to classical taxonomic analysis. In this paper we provide a partial phylogeny of the genera of these families based on mtDNA from five campulid species: Campula oblonga, Zalophotrema atlanticum, Hadwenius tursionis, Oschmarinella rochebruni and Orthosplanchnus fraterculus; and one nasitrematid, Nasitrema globicephalae. Fasciola hepatica and Dicrocoelium dendriticum were used as outgroups. Maximum parsimony and neighbour-joining methods were applied. Both methods produced similar trees where H. tursionis appeared as the basal campulid, with a sequential divergence of Z. atlanticum, N. globicephalae, C. oblonga, O. rochebruni and O. fraterculus. Results suggest that Nasitrematidae as defined should loose its familial status and the current subfamilial division of the family Campulidae is at least partly artificial and should not be maintained.

Amino Acid Sequence↗

PubMed1995

Intracellular promiscuity in Schistosoma mansoni: nuclear transcribed DNA sequences are part of a mitochondrial minisatellite region.

It has been shown that the mtDNA of the parasitic trematode Schistosoma mansoni is hypervariable in size. We report here that this length variation is due to a large polymorphic minisatellite composed of two types of repeated sequences of 558 bp and 62 bp. Each minisatellite repeat is made up of a large 558-bp component and a variable tandem array of the small 62-bp unit. Of more fundamental interest was the finding that both the 558-bp and 62-bp components have significant homology with a gene, SM750, previously identified in the nuclear genome of S. mansoni. The small 62-bp unit is identical to the nuclear polymorphic repeat element, which is apparently spread throughout the nuclear genome and is abundant among transcripts, in addition to being present in five tandem copies in SM750. The presence, in the S. mansoni mtDNA, of fragments of genes that are present in and transcribed from the nuclear genome raises the question of the origin of these sequences. The arrangement and the variability that the mtDNA minisatellite embodies were explored as an identity test for S. mansoni based on the use of PCR for tallying the relative abundance of the several repeat numbers of the tandem arrays of the 62-bp unit within the minisatellite structure.

Animals↗

PubMed1997

Phylogenetic analysis of the Monogenea and their relationships with Digenea and Eucestoda inferred from 28S rDNA sequences.

Platyhelminth phylogeny is controversial. Phylogenetic analyses of the partial domain C1 and the full domains D1 and C2 (358 nucleotides) from the 28S ribosomal RNA gene for 21 species from the Monogenea, Digenea, Cestoda, and, as the outgroup, Tricladida reveal major departures from prevailing theory. The Digenea and not the Monogenea (Monopisthocotylea and Polyopisthocotylea) form the sister group of the cestodes; the Monopisthocotylea and Polyopisthocotylea are each monophyletic, but the Monogenea do not form a monophylum; the sister group of the Digenea + Cestoda is the Polyopisthocotylea; and Monopisthocotylea are the sister group of all other parasitic flatworms.

Animals↗

PubMed2004

Nonisotopic single-strand conformation polymorphism analysis of sequence variability in ribosomal DNA expansion segments within the genus Trichinella (Nematoda: Adenophorea).

A nonisotopic single-strand conformation polymorphism (SSCP) approach was employed to 'fingerprint' sequence variability in the expansion segment 5 (ES5) of domain IV and the D3 domain of nuclear ribosomal DNA within and/or among isolates and individual muscle (first-stage) larvae representing all currently recognized species/genotypes of Trichinella. In addition, phylogenetic analyses of the D3 sequence data set, employing three different tree-building algorithms, examined the relationships among all of them. These analyses showed strong support that the encapsulated species T. spiralis and T. nelsoni formed a group to the exclusion of the other encapsulated species T. britovi and its related genotypes Trichinella T8 and T9 and T. murrelli, and T. nativa and Trichinella T6, and strong support that T. nativa and Trichinella T6 grouped together. Also, these eight encapsulated members grouped to the exclusion of the nonencapsulated species T. papuae and T. zimbabwensis and the three representatives of T. pseudospiralis investigated. The findings showed that nonencapsulated species constitute a complex group which is distinct from the encapsulated species and supported the current hypothesis that encapsulated Trichinella group external to the nonencapsulated forms, in accordance with independent biological and biochemical data sets.

Animals↗

PubMed2004

Cloning and characterization of the mitochondrial heat-shock protein 60 gene of Trichinella spiralis.

The full-length cDNA of mitochondrial heat-shock protein (hsp) 60 of the infective-stage larva of Trichinella spiralis was cloned by degenerative PCR and rapid amplification of cDNA end reactions. The 1,945 bp full-length cDNA sequence contained an open reading frame of 576 amino acids. A mitochondrial signal peptide was located at the N-terminal and a GGM motif at the C-terminal. The gene contained ten exons and nine introns. RT-PCR analysis indicated that thermal, cold, acidic and oxidative treatment did not elicit significant changes in the expression of mitochondrial hsp 60 in the larvae. Cluster analysis showed that the sequence of the hsp 60 gene of T. spiralis is closely related to that of Drosophila melanogaster.

Amino Acid Sequence↗

PubMed1994

A trans-spliced leader RNA sequence in plant parasitic nematodes.

A trans-spliced leader gene has been identified in the genomes of the potato cyst nematodes Globodera rostochiensis and G. pallida. The gene contains a 22-nt sequence identical to that of the leader sequence of Caenorhabditis elegans, a consensus splice donor site and a putative Sm antigen binding site. In common with other nematodes the spliced leader gene is present in tandem repeating units together with the 5S ribosomal RNA gene. Variation in the length of the intergenic spacer region has permitted the design of polymerase chain reaction primers which can be used to reveal repeat length variants diagnostic for G. rostochiensis and G. pallida and the Pa1 pathotype of G. pallida.

Animals↗

PubMed1997

Molecular delineation of Cylicocyclus nassatus and C. ashworthi (Nematoda:Strongylidae).

The nucleotide sequences of the first internal transcribed spacer (ITS-1), 5.8S gene and second internal transcribed spacer (ITS-2) of ribosomal DNA have been determined for Cylicocyclus nassatus, C. ashworthi and C. insignis. Pairwise comparisons revealed sequence differences between the taxa ranging from 3.8 to 6.2% for the ITS-2 and 2.2-2.7% for the ITS-1. For the ITS-1, the level of the sequence difference between C. ashworthi and C. nassatus (2.2%) was equivalent to that between C. nassatus and C. insignis (2.2%), indicating that C. ashworthi and C. nassatus represent separate species. Theoretical restriction maps were constructed from the sequence data, and a polymerase chain reaction-linked restriction fragment length polymorphism (PCR-linked RFLP) technique was established to unequivocally distinguish C. ashworthi from C. nassatus.

Animals↗

PubMed1998

Differences in the 5.8S rDNA sequences among ascarid nematodes.

Sequences of the 5.8S rDNA were obtained for 14 species of nematode from different superfamilies and families within the order Ascaridida. All sequences were 157 bp in length. Sequence differences among species ranged from 0 to 18 bp (0-11.5%). A phenetic analysis of the sequence data groups the 14 taxa into their respective superfamilies and families, but does not discriminate fully at the subfamily level. A phylogenetic analysis of the sequence data failed to resolve the evolutionary relationships at the superfamily level. The 5.8S gene may be useful for phylogenetic studies of the phylum Nematoda at the ordinal level.

Animals↗

PubMed1995

Genetic markers for closely-related parasitic nematodes.

Seven species of closely-related nematode parasite (Trichostrongylus axei, T. colubriformis, T. probolurus, T. retortaeformis, T. rugatus, T. vitrinus and T. tenuis) were characterized using a polymerase chain reaction-linked restriction fragment length polymorphism technique (PCR-RFLP). The rDNA region spanning the first and second internal transcribed spacers as well as the 5.8S rDNA gene (ITS+) was amplified from isolates of each of the seven species, digested separately with six restriction endonucleases (Dra I, Hinf I, Rsa I, Vsp I, Nla III and Tsp 509 I) and the fragments separated by agarose gel electrophoresis. PCR-RFLP of ITS+ produced characteristic patterns for each Trichostrongylus species examined. No variation in RFLP patterns was observed among different isolates for species where multiple isolates were examined. The present study demonstrates that the ITS+ provides genetic markers for the species identification of closely-related parasitic nematodes, and indicates the usefulness of these markers for diagnostic purposes, and epidemiologic and molecular-systematic studies on parasites and other eukaryotic organisms.

Animals↗

PubMed2007

Characterization of the mitochondrial genome of Diphyllobothrium latum (Cestoda: Pseudophyllidea) - implications for the phylogeny of eucestodes.

The complete nucleotide sequence of the mitochondrial genome was determined for the fish tapeworm Diphyllobothrium latum. This genome is 13,608 bp in length and encodes 12 protein-coding genes (but lacks the atp8), 22 transfer RNA (tRNA) and 2 ribosomal RNA (rRNA) genes, corresponding to the gene complement found thus far in other flatworm mitochondrial (mt) DNAs. The gene arrangement of this pseudophyllidean cestode is the same as the 6 cyclophyllidean cestodes characterized to date, with only minor variation in structure among these other genomes; the relative position of trnS2 and trnL1 is switched in Hymenolepis diminuta. Phylogenetic analyses of the concatenated amino acid sequences for 12 protein-coding genes of all complete cestode mtDNAs confirmed taxonomic and previous phylogenetic assessments, with D. latum being a sister taxon to the cyclophyllideans. High nodal support and phylogenetic congruence between different methods suggest that mt genomes may be of utility in resolving ordinal relationships within the cestodes. All species of Diphyllobothrium infect fish-eating vertebrates, and D. latum commonly infects humans through the ingestion of raw, poorly cooked or pickled fish. The complete mitochondrial genome provides a wealth of genetic markers which could be useful for identifying different life-cycle stages and for investigating their population genetics, ecology and epidemiology.

Animals↗

PubMed1995

Increased frequency of deletions in the mitochondrial genome with age of Caenorhabditis elegans.

We have developed a long-extension-PCR strategy which amplifies approximately half of the mitochondrial genome (6.3 kb) of Caenorhabditis elegans using an individual worm as target. We analyzed three strains over their life span to assess the number of detectable deletions in the mitochondrial genome. Two of these strains are wild-type for life span while the third is mutant in the age-1 gene, approximately doubling its maximum life span. At the mean life span in wild-type strains, there was a significant difference between the frequency of deletions detected in the mitochondrial genome compared with the mean number of deletions in young animals. In addition, deletions in the mitochondrial genome occur at a significantly lower rate in age-1 mutants as compared with wild type. We cloned and identified the breakpoints of two deletions and found that one of the deletions had a direct repeat of 8 bp at the breakpoint. This is the largest single study (over 900 individual animals) characterizing the frequency of deletions in the mitochondrial genome as a function of age yet carried out.

Aging↗

PubMedDate not supplied

Genetic divergence of Asiatic Bdellocephala (Turbellaria, Tricladida, Paludicola) as revealed by partial 18S rRNA gene sequence comparisons.

Polymerase chain reaction (PCR) and direct sequencing of small ribosomal RNA genes were used for analysis of genetic differences among Asiatic species of freshwater triclad genus Bdellocephala. Representatives of four species and four subspecies of this genus were used to establish homology between nucleotides in the 5'-end portion of small ribosomal RNA gene sequences. Within 552 nucleotide sites of aligned sequences compared, six variable base positions were discovered, dividing Bdellocephala into five different genotypes. Sequence data allow to distinguish two groups of these genotypes. One of them unites species from Kamchatka and Japan, another one unites Baikalian taxa. Agreement between available morphological, cytological and sequence data is discussed.

Animals↗

PubMed2006

The radiation of Haliotrema (Monogenea: Dactylogyridae: Ancyrocephalinae): molecular evidence and explanation inferred from LSU rDNA sequences.

The D1-D2 domains of LSU rDNA were used to reconstruct the phylogenetic relationships within the Ancyrocephalinae (Monogenea: Dactylogyridae) utilizing maximum-parsimony (MP), maximum-likelihood (ML), minimum evolution (ME) and neighbour-joining (NJ) methods. A total of 32 monogenean taxa were examined in the present study, including 9 Haliotrema species and 13 other species representing the Ancyrocephalinae, 4 Thaparocleidus species representing the Ancylodiscoididae, and 6 species representing the Diplectanidae which were used as multiple outgroups. All 4 analyses (i.e. MP, ML, ME and NJ) inferred the same interrelationship pattern: (Diplectanidae, (Ancylodiscoididae, Dactylogyridae)) with high bootstrap support. However, 9 Haliotrema species were dispersed to form 4 clades together with species from other genera, indicating the apparent non-monophyly of Haliotrema. Three major groups were defined based on reconstructed phylogenetic trees to explain the radiation of Haliotrema species. The morphology of the reproductive organ, particularly the male copulatory organ (MCO), was discussed to further understand the formation of each group. (1) Results of the present study indicated an intimate relationship among Metahaliotrema (2 species), Protogyrodactylus (4 species) and Haliotrema (2 of 9 species), and notably, all these species share vagina-absence. (2) Based on the present molecular analyses and the morphological characters of the MCO, we propose to transfer H. spirotubiforum and the undetermined Haliotrema sp. ZHDDb to Euryhaliotrema as new combinations. (3) We propose to erect a new genus to accommodate the Haliotrema species with horn-like shaped MCO. Taxonomic implications of the present molecular phylogenetic analyses are discussed. A wider range of taxa and more DNA markers displaying various evolutionary rates should be used to estimate phylogenetic relationships among species within the Ancyrocephalinae and Ancylodiscoididae in further studies.

Animals↗

PubMed2006

Paraphyly of the Pseudophyllidea (Platyhelminthes: Cestoda): circumscription of monophyletic clades based on phylogenetic analysis of ribosomal RNA.

Phylogenetic relationships of cestodes of the order Pseudophyllidea (Platyhelminthes: Cestoda) were examined using sequences of complete small subunit and partial (D1-D3 region) large subunit nuclear rDNA of members of all pseudophyllidean families. The results provide evidence of paraphyly of the order as indicated by previous molecular phylogenetic analyses based on a much lower number of species sequenced. Pseudophyllidean tapeworms represent an artificial assemblage comprising two unrelated clades. "Bothriocephalidea" is formed by four families sensu Bray et al. (1994), namely Bothriocephalidae, Echinophallidae, Philobythiidae and Triaenophoridae, whereas two other families, Diphyllobothriidae and Cephalochlamydidae, give rise to the "Diphyllobothriidea". The present results indicate that "Bothriocephalidea" forms the most derived clade of all difossate and tetrafossate/bothriate tapeworm lineages which are considered to be basal relative to the rest of tetrafossate/bothridiate and acetabulate cestodes. By contrast, "Diphyllobothriidea", which includes medically important parasites (Diphyllobothrium and Spirometra), appeared more basal, without a clearly resolved position within other difossate tapeworm lineages.

Animals↗

PubMed2000

Mitochondrial genetic code in cestodes.

The flatworm mitochondrial genetic code, which has been used for all species of the Platyhelminthes, is mainly characterized by AUA codon for isoleucine, AAA codon for asparagine and UAA codon for tyrosine. In eight species of cestodes (Echinococcus multilocularis, Echinococcus granlosus, Taenia solium Taenia saginata, Taenia hydatigena, Taenia crassiceps, Hymenolepis nama and Mesocestoides corti), the cytochrome c oxidase subunit I (COI) genes were partially sequenced to verify this genetic code. Comparison of the COI-encoding nucleotide sequences with those of human, sea urchin, fruit fly, nematode and yeast indicated that the assignments of AUA and AAA codons are adequate for cestodes. In addition, the nucleotide sequences of ATPase subunit 6 (ATP6) gene and its flanking region were compared to examine initiation and stop codons. In the related species of T. solium and T. saginata, the deduced amino acid sequences of ATP6 were homogeneous; however, the conversion of initiation codon AUG into GUG was observed in T. saginata. We also found the similar conversion in T. crassiceps. The C-terminal sequences of putative ATP6 proteins were highly conserved among the eight species and the stop codon UAG was altered to UAA in all Taenia species. The features of the gene-junctional region between NADH dehydrogenase subunit 4 (ND4) and glutamine tRNA (tRNAGln) genes also supported that UAA serves as a stop codon. Based on these results, we propose that the flatworm mitochondrial code should be modified for cestodes, particularly, in an initiating methionine codon (GUG) and a terminating codon (UAA).

Animals↗