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Robin B Gasser - One of the best experts on this subject based on the ideXlab platform.
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phylogenetic relationships of species of the oesophageal parasitic nematode genera cyclostrongylus and spirostrongylus strongyloidea chabertiidae cloacininae with their wallaby hosts marsupialia macropodidae
Molecular and Cellular Probes, 2016Co-Authors: Robin B Gasser, Neil B. Chilton, Florence Hubychilton, Anson V Koehler, Ian BeveridgeAbstract:A phylogeny for seven species of Cyclostrongylus and the monotypic genus Spirostrongylus (Nematoda: Chabertiidae), all highly host specific parasites of the oesophagi of wallabies (Marsupialia: Macropodidae), was constructed using sequence data for the first and second Internal Transcribed Spacers (ITS-1 and ITS-2) of the nuclear ribosomal DNA. There was no evidence for co-speciation, or for the sympatric or synxenic speciation of Cyclostrongylus alatus and Cyclostrongylus perplexus, both of which are parasites of Macropus rufogriseus. Rather, host switching, correlating with geographical distributions, appeared to provide some explanation of the pattern of speciation observed.
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Genetic divergence between island and continental populations of the parasitic nematode Labiosimplex australis in Australia
Parasitology Research, 2009Co-Authors: Neil B. Chilton, Robin B Gasser, Florence Huby-chilton, Lesley R. Smales, Ian BeveridgeAbstract:Sequences of the first and second Internal Transcribed Spacers (ITS-1 and ITS-2) of nuclear ribosomal (r) DNA were characterised for Labiosimplex australis , a parasitic nematode of macropodid marsupials from continental Australia and from island populations which have been isolated from mainland Australia for relatively short periods of time (
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sscp based identification of members within the pseudoterranova decipiens complex nematoda ascaridoidea anisakidae using genetic markers in the Internal Transcribed Spacers of ribosomal dna
Parasitology, 2002Co-Authors: S Damelio, Mario Georgenascimento, Harry W. Palm, Lia Paggi, Robin B GasserAbstract:The anisakid nematodes morphologically corresponding with Pseudoterranova decipiens sensu lato ( s.l. ) (Krabbe, 1878) from different seal or sea lion hosts and geographical origins, previously identified as Pseudoterranova krabbei , P. decipiens ( s.s. ), P. bulbosa , P. azarasi and P. cattani by multilocus enzyme electrophoresis, were characterized using a DNA approach. Also a population of P. decipiens ( s.l. ) from Chaenocephalus aceratus , the blackfin icefish, from Antarctica and another from Osmerus eperlanus , the European smelt, from Germany were included in the study. The first (ITS-1) and second (ITS-2) Internal Transcribed Spacers (ITS) of ribosomal DNA (rDNA) were amplified by PCR from individual nematodes and analysed by single-strand conformation polymorphism (SSCP), followed by selective sequencing. While no variation in single-stranded ITS-1 and ITS-2 profiles was detected among samples representing each of the species or populations (with the exception of slight microheterogeneity), SSCP analysis of the ITS-2 amplicons allowed the unequivocal differentiation of all of the 5 sibling species of P. decipiens ( s.l. ) examined, which was supported by sequence differences in ITS rDNA. Samples representing the P. decipiens ( s.l. ) population from O. eperlanus had the same SSCP profile as those of P. decipiens ( s.s. ), which was supported by a lack of nucleotide difference in the ITS between them, suggesting that the former represented P. decipiens ( s.s. ). Based on SSCP results and ITS sequence data, P. decipiens ( s.l. ) from C. aceratus was genetically most distinct with respect to all other members of Pseudoterranova examined, which indicated that it may represent P. decipiens E (based on geographical origin) or a distinct species. These findings and the molecular approach taken should have important implications for studying the life-cycles, transmission patterns, epidemiology and population genetics of these anisakid nematodes, and the diagnosis of their infections.
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assessing sequence variation in the Internal Transcribed Spacers of ribosomal dna within and among members of the contracaecum osculatum complex nematoda ascaridoidea anisakidae
Parasitology Research, 2000Co-Authors: Xingquan Zhu, S Damelio, Lia Paggi, Robin B GasserAbstract:The anisakid nematodes of seals from different geographical origins, previously identified as Contracaecum osculatum A, C. osculatum B, C. osculatum C, C. osculatum D, C. osculatum E and C. osculatum baicalensis by multilocus enzyme electrophoresis, were characterised using a DNA approach. The first and second Internal Transcribed Spacers (ITS-1, ITS-2) of ribosomal DNA (rDNA) were individually amplified by polymerase chain reaction (PCR) and analysed by single-strand conformation polymorphism (SSCP) and sequencing. SSCP analyses allowed the unequivocal differentiation of all taxa except C. osculatum D from C. osculatum E. While C. osculatum D and C. osculatum E had identical ITS sequences, each of the other four taxa had distinct sequences, with interspecific differences ranging from 0.3% to 2.3%. C. osculatum C was genetically the most distinct taxon with respect to all other members of the species complex.
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Sequence differences in the Internal Transcribed Spacers of DNA among four species of hookworm (Ancylostomatoidea: Ancylostoma).
International Journal for Parasitology, 1999Co-Authors: Neil B. Chilton, Robin B GasserAbstract:Abstract The two ribosomal DNA Internal Transcribed Spacers (1 and 2) of the hookworms Ancylostoma caninum, A. tubaeforme, A. ceylanicum and A. duodenale were sequenced. The sequence lengths were similar among the four species, except that A. ceylanicum had slightly longer (by 5–7 bp) Internal Transcribed spacer 1 and 2 sequences. The predicted secondary structure of the Internal Transcribed spacer 2 precursor rRNA was similar for all species, despite interspecific differences in primary sequence ranging from 0.9% to 13.2%. Interspecific differences in Internal Transcribed spacer 1 sequence ranged from 0.9% to 7.5%. A cladistic analysis of the sequence data, using the human hookworm Necator americanus as the outgroup, provided little resolution of the phylogenetic relationships, except that A. ceylanicum occurred on a branch external to the other three species. Nonetheless, Internal Transcribed Spacers 1 and 2 may provide useful phylogenetic information at higher taxonomic levels within the superfamily Ancylostomatoidea.
Cristina Cutillas - One of the best experts on this subject based on the ideXlab platform.
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Phylogeography of Trichuris populations isolated from different Cricetidae rodents
Parasitology, 2012Co-Authors: Rocio Callejon, Ángela Marrugal, Francisco Balao, D. C. Guevara, Heikki Henttonen, Manuel De Rojas, Carlos Feliu, Cristina CutillasAbstract:SUMMARY The phylogeography of Trichuris populations (Nematoda) collected from Cricetidae rodents (Muroidea) from different geographical regions was studied. Ribosomal DNA (Internal Transcribed Spacers 1 and 2, and mitochondrial DNA (cytochrome c- oxidase subunit 1 partial gene) have been used as molecular markers. The nuclear Internal Transcribed Spacers (ITSs) 1 and 2 showed 2 clear-cut geographical and genetic lineages: one of the Nearctic region (Oregon), although the second was widespread throughout the Palaearctic region and appeared as a star-like structure in the minimum spanning network. The mitochondrial results revealed that T. arvicolae populations from the Palaearctic region were separated into 3 clear-cut geographical and genetic lineages: populations from Northern Europe, populations from Southern (Spain) and Eastern Europe (Croatia, Belarus, Kazahstan), and populations from Italy and France (Eastern Pyrenean Mountains). Phylogenetic analysis obtained on the basis of ITS1-5·8S-ITS2 rDNA sequences did not show a differential geographical structure; however, these markers suggest a new Trichuris species parasitizing Chionomys roberti and Cricetulus barabensis. The mitochondrial results revealed that Trichuris populations from arvicolinae rodents show signals of a post-glacial northward population expansion starting from the Pyrenees and Italy. Apparently, the Pyrenees and the Alps were not barriers to the dispersal of Trichuris populations.
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16s partial gene mitochondrial dna and Internal Transcribed Spacers ribosomal dna as differential markers of trichuris discolor populations
Veterinary Parasitology, 2012Co-Authors: Rocio Callejon, Ángela Marrugal, M Rojas, Ali Halajian, D. C. Guevara, Cristina CutillasAbstract:Abstract Comparative morphological, biometrical and molecular studies of Trichuris discolor isolated from Bos taurus from Spain and Iran was carried out. Furthermore, Trichuris ovis isolated from B. taurus and Capra hircus from Spain has been, molecularly, analyzed. Morphological studies revealed clear differences between T. ovis and T. discolor isolated from B. taurus but differences were not observed between populations of T. discolor isolated from different geographical regions. Nevertheless, the molecular studies based on the amplification and sequencing of the Internal Transcribed Spacers 1 and 2 ribosomal DNA and 16S partial gene mitochondrial DNA showed clear differences between both populations of T. discolor from Spain and Iran suggesting two cryptic species. Phylogenetic studies corroborated these data. Thus, phylogenetic trees based on ITS1, ITS2 and 16S partial gene sequences showed that individuals of T. discolor from B. taurus from Iran clustered together and separated, with high bootstrap values, of T. discolor isolated from B. taurus from Spain, while populations of T. ovis from B. taurus and C. hircus from Spain clustered together but separated with high bootstrap values of both populations of T. discolor. Furthermore, a comparative phylogenetic study has been carried out with the ITS1and ITS2 sequences of Trichuris species from different hosts. Three clades were observed: the first clustered all the species of Trichuris parasitizing herbivores (T. discolor, T. ovis, Trichuris leporis and Trichuris skrjabini), the second clustered all the species of Trichuris parasitizing omnivores (Trichuris trichiura and Trichuris suis) and finally, the third clustered species of Trichuris parasitizing carnivores (Trichuris muris, Trichuris arvicolae and Trichuris vulpis).
Claudia Sorlini - One of the best experts on this subject based on the ideXlab platform.
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16S–23S rRNA Internal Transcribed Spacers as molecular markers for the species of the 16S rRNA group I of the genus Bacillus
Fems Microbiology Letters, 1998Co-Authors: Daniele Daffonchio, Sara Borin, Arianna Consolandi, Diego Mora, P.l. Manachini, Claudia SorliniAbstract:Abstract The Internal Transcribed Spacers between the 16S and the 23S ribosomal RNA genes were used to discriminate species of the 16S rRNA group I of the genus Bacillus by PCR. The spacer-PCR fingerprints clearly discriminated the different species, except those closely related like the members of the ` B. cereus group' ( B. cereus , B. thuringiensis and B. mycoides ) and the species of the ` B. subtilis group' ( B. amyloliquefaciens and B. licheniformis ). Examining in more detail the shortest Internal Transcribed Spacers, B. subtilis group species were distinguished by single-strand conformation polymorphism analysis, whereas B. mycoides was differentiated from B. cereus / B. thuringiensis by restriction analysis.
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16s 23s rrna Internal Transcribed Spacers as molecular markers for the species of the 16s rrna group i of the genus bacillus
Fems Microbiology Letters, 1998Co-Authors: Daniele Daffonchio, Sara Borin, Arianna Consolandi, Diego Mora, P.l. Manachini, Claudia SorliniAbstract:Abstract The Internal Transcribed Spacers between the 16S and the 23S ribosomal RNA genes were used to discriminate species of the 16S rRNA group I of the genus Bacillus by PCR. The spacer-PCR fingerprints clearly discriminated the different species, except those closely related like the members of the ` B. cereus group' ( B. cereus , B. thuringiensis and B. mycoides ) and the species of the ` B. subtilis group' ( B. amyloliquefaciens and B. licheniformis ). Examining in more detail the shortest Internal Transcribed Spacers, B. subtilis group species were distinguished by single-strand conformation polymorphism analysis, whereas B. mycoides was differentiated from B. cereus / B. thuringiensis by restriction analysis.
Patrick P Edger - One of the best experts on this subject based on the ideXlab platform.
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secondary structure analyses of the nuclear rrna Internal Transcribed Spacers and assessment of its phylogenetic utility across the brassicaceae mustards
PLOS ONE, 2014Co-Authors: Patrick P Edger, Michelle Tang, Kevin A Bird, Dustin R Mayfield, Gavin C Conant, Klaus Mummenhoff, Marcus A Koch, Chris J PiresAbstract:The Internal Transcribed Spacers of the nuclear ribosomal RNA gene cluster, termed ITS1 and ITS2, are the most frequently used nuclear markers for phylogenetic analyses across many eukaryotic groups including most plant families. The reasons for the popularity of these markers include: 1.) Ease of amplification due to high copy number of the gene clusters, 2.) Available cost-effective methods and highly conserved primers, 3.) Rapidly evolving markers (i.e. variable between closely related species), and 4.) The assumption (and/or treatment) that these sequences are non-functional, neutrally evolving phylogenetic markers. Here, our analyses of ITS1 and ITS2 for 50 species suggest that both sequences are instead under selective constraints to preserve proper secondary structure, likely to maintain complete self-splicing functions, and thus are not neutrally-evolving phylogenetic markers. Our results indicate the majority of sequence sites are co-evolving with other positions to form proper secondary structure, which has implications for phylogenetic inference. We also found that the lowest energy state and total number of possible alternate secondary structures are highly significantly different between ITS regions and random sequences with an identical overall length and Guanine-Cytosine (GC) content. Lastly, we review recent evidence highlighting some additional problematic issues with using these regions as the sole markers for phylogenetic studies, and thus strongly recommend additional markers and cost-effective approaches for future studies to estimate phylogenetic relationships.
Rocio Callejon - One of the best experts on this subject based on the ideXlab platform.
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Phylogeography of Trichuris populations isolated from different Cricetidae rodents
Parasitology, 2012Co-Authors: Rocio Callejon, Ángela Marrugal, Francisco Balao, D. C. Guevara, Heikki Henttonen, Manuel De Rojas, Carlos Feliu, Cristina CutillasAbstract:SUMMARY The phylogeography of Trichuris populations (Nematoda) collected from Cricetidae rodents (Muroidea) from different geographical regions was studied. Ribosomal DNA (Internal Transcribed Spacers 1 and 2, and mitochondrial DNA (cytochrome c- oxidase subunit 1 partial gene) have been used as molecular markers. The nuclear Internal Transcribed Spacers (ITSs) 1 and 2 showed 2 clear-cut geographical and genetic lineages: one of the Nearctic region (Oregon), although the second was widespread throughout the Palaearctic region and appeared as a star-like structure in the minimum spanning network. The mitochondrial results revealed that T. arvicolae populations from the Palaearctic region were separated into 3 clear-cut geographical and genetic lineages: populations from Northern Europe, populations from Southern (Spain) and Eastern Europe (Croatia, Belarus, Kazahstan), and populations from Italy and France (Eastern Pyrenean Mountains). Phylogenetic analysis obtained on the basis of ITS1-5·8S-ITS2 rDNA sequences did not show a differential geographical structure; however, these markers suggest a new Trichuris species parasitizing Chionomys roberti and Cricetulus barabensis. The mitochondrial results revealed that Trichuris populations from arvicolinae rodents show signals of a post-glacial northward population expansion starting from the Pyrenees and Italy. Apparently, the Pyrenees and the Alps were not barriers to the dispersal of Trichuris populations.
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16s partial gene mitochondrial dna and Internal Transcribed Spacers ribosomal dna as differential markers of trichuris discolor populations
Veterinary Parasitology, 2012Co-Authors: Rocio Callejon, Ángela Marrugal, M Rojas, Ali Halajian, D. C. Guevara, Cristina CutillasAbstract:Abstract Comparative morphological, biometrical and molecular studies of Trichuris discolor isolated from Bos taurus from Spain and Iran was carried out. Furthermore, Trichuris ovis isolated from B. taurus and Capra hircus from Spain has been, molecularly, analyzed. Morphological studies revealed clear differences between T. ovis and T. discolor isolated from B. taurus but differences were not observed between populations of T. discolor isolated from different geographical regions. Nevertheless, the molecular studies based on the amplification and sequencing of the Internal Transcribed Spacers 1 and 2 ribosomal DNA and 16S partial gene mitochondrial DNA showed clear differences between both populations of T. discolor from Spain and Iran suggesting two cryptic species. Phylogenetic studies corroborated these data. Thus, phylogenetic trees based on ITS1, ITS2 and 16S partial gene sequences showed that individuals of T. discolor from B. taurus from Iran clustered together and separated, with high bootstrap values, of T. discolor isolated from B. taurus from Spain, while populations of T. ovis from B. taurus and C. hircus from Spain clustered together but separated with high bootstrap values of both populations of T. discolor. Furthermore, a comparative phylogenetic study has been carried out with the ITS1and ITS2 sequences of Trichuris species from different hosts. Three clades were observed: the first clustered all the species of Trichuris parasitizing herbivores (T. discolor, T. ovis, Trichuris leporis and Trichuris skrjabini), the second clustered all the species of Trichuris parasitizing omnivores (Trichuris trichiura and Trichuris suis) and finally, the third clustered species of Trichuris parasitizing carnivores (Trichuris muris, Trichuris arvicolae and Trichuris vulpis).