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H Bjorn - One of the best experts on this subject based on the ideXlab platform.
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distinguishing Oesophagostomum dentatum from Oesophagostomum quadrispinulatum developmental stages by a single strand conformation polymorphism method
International Journal for Parasitology, 1998Co-Authors: Robin B Gasser, Wayne G Woods, H BjornAbstract:Abstract At some life-cycle stages, it is impossible to distinguish between the two species of porcine nodular worm, Oesophagostomum dentatum and Oesophagostomum quadrispinulatum , using morphological features. A PCR-based single-strand conformation polymorphism technique was established to overcome this limitation. The rDNA region spanning the second internal transcribed spacer was amplified by PCR from genomic DNA from morphologically well-defined adult worms. The PCR products were then denatured and subjected to electrophoresis in a non-denaturing gel matrix. Single-strand conformation polymorphism analysis of the products generated characteristic and reproducible patterns for each of the two species and allowed their unequivocal delineation. The single-strand conformation polymorphism was also applied effectively to assess the purity of nine laboratory-maintained cultures of infective third-stage larvae believed to be monospecific for O. dentatum or O. quadrispinulatum . The analysis showed that all six O. dentatum cultures were indeed monospecific, whereas the three cultures believed to be monospecific for O. quadrispinulatum were either a mixture of O. dentatum and O. quadrispinulatum larvae or pure O. dentatum larvae. These findings demonstrated the usefulness of the single-strand conformation polymorphism approach for the routine monitoring of the purity of parasite lines and indicated its value for studies on the population biology of porcine nodular worms.
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an in vivo dose response study of fenbendazole against Oesophagostomum dentatum and Oesophagostomum quadrispinulatum in pigs
International Journal for Parasitology, 1997Co-Authors: J Praslicka, M Varady, H Bjorn, P Nansen, D R Hennessy, H TalvikAbstract:Abstract A dose-response study using fenbendazole (FBZ) was carried out in pigs infected with O. dentatum and O. quadrispinulatum to determine the minimum effective dose rate of the drug. Thirty pigs were randomly divided into 6 groups of 5 pigs and infected with 5000 infective larvae each. The animals were re-infected 5 days before treatment (Day 30 after the first infection) with the same number of larvae. On Day 35 the pigs in groups 1–5 were treated with FBZ at the following dose rates: 2.5 mg kg −1 (i.e. 50% of the registered dose level), 1.0 mg kg −1 (20%), 0.25 mg kg −1 (5%), 0.1 mg kg −1 (2%) and 0.05 mg kg −1 (1%), respectively. Pigs in group 6 served as non-treated controls. Seven days after treatment (Day 42 after infection) the pigs were slaughtered, worms recovered from the large intestine and counted. The species and sex of adult worms was determined. A high faecal egg count reduction (FECR) after treatment was observed in groups 1, 2 and 3 (98%, 88% and 91%, respectively), while in groups 4 and 5 the egg counts were not affected by treatment. The mean worm count reduction was high in groups 1, 2 and 3 (100%, 99.9% and 98.6%, respectively), but declined in groups 4 and 5 (77% and 40%, respectively). FBZ showed a high efficacy against immature worms in groups 1 and 2, while in groups 3, 4 and 5 counts were not reduced. Species differentiation revealed a higher effect of FBZ against O. dentatum than against O. quadrispinulatum . Sex differentiation indicated a slightly higher (not significant) efficacy against females than males in both species. This study demonstrated a high efficacy of FBZ against the nodular worms in pigs, even at 5% of the currently registered dose level.
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use of random amplified polymorphic dna polymerase chain reaction for the definition of genetic markers for species and strains of porcine Oesophagostomum
Parasitology Research, 1997Co-Authors: Anja Joachim, H Bjorn, A Daugschies, C M Christensen, P NansenAbstract:Nodular worms are common parasites of pigs, and research has recently started to focus on the biology of these nematodes. However, the methods for delineation of species at immature developmental stages and␣for␣differentiation of various lines of the same species␣remain limited. For differentiation of porcine Oesophagostomum species and strains by genomic fingerprinting, random amplified polymorphic DNA-polymerase chain reaction was performed on DNA derived from 20 larval batches of anthelmintic-susceptible and resistant strains and isolates of these nematodes and 2 ruminant Oesophagostomum spp. Polymorphic DNA markers could be amplified with 9 of the 33 primers tested. In all, 13 markers were species-specific and 6 markers could differentiate between strains or groups of strains. With a combination of the latter, artificially selected anthelmintic-resistant strains and the susceptible mother strain of O. dentatum could be delineated. When single adult worms were compared, considerable variations between strains of the same species and between individuals from the same strain could be detected. The differentiation of Oesophagostomum strains and species at all parasitic stages on the basis of genetic markers could greatly facilitate studies on the biology of these parasites.
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in vitro characterization of anthelmintic susceptibility of field isolates of the pig nodular worm Oesophagostomum spp susceptible or resistant to various anthelmintics
International Journal for Parasitology, 1996Co-Authors: M Varady, H Bjorn, P NansenAbstract:Abstract A larval development assay (LDA) and an egg hatch paralysis assay (EHPA) were used to measure the sensitivity to anthelmintics of eggs and larvae of nodular worms ( Oesophagostomum spp.) in pigs. The tests were carried out using in vivo defined resistant and susceptible isolates of Oesophagostomum dentatum, O. quadrispinulatum and Oesophagostomum spp. For measurement of pyrantei/morantel and levamisole sensitivity the LDA was found able to distingrich between susceptible or resistant isolates of Oesophagostomum . The EHPA was able to detect levamisole resistance, but the test failed to show differences in response to pyrantel between pyrantel susceptible and resistant lines. The possible routine application of LDA and EHPA in the diagnosis of anthelmintic resistance in Oesophagostomum spp. is discussed.
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associations ofascaris suum and Oesophagostomum spp infections of sows with management factors in 83 danish sow herds
Preventive Veterinary Medicine, 1996Co-Authors: Ashoka Dangolla, H Bjorn, Preben Willeberg, Allan RoepstorffAbstract:Associations of the occurrence of Ascaris suum and Oesophagostomum spp. in sows with herd management factors were examined using logistic-binomial regression. The information used was from 11 to 78 sows sampled from each of 83 breeding herds (2961 sows in total) and examined for eggs per gram of faeces (EPG). A sow excreting at least 20 EPG was defined as ‘infected’. Management factors of the study herds were recorded using a questionnaire. A total of 263 sows from 50 herds (8.9% of sows) and 375 sows from 20 herds (12.7% of sows) were infected with A. suum and Oesophagostomum spp., respectively. For A. suum, sows from herds with more than 85 sows had significantly higher odds of being infected compared with those from 30 to 85 sows (P < 0.05). When bedding was provided for sows, the odds of A. suum infection was 5.4 compared with sows from herds in which bedding was not provided (P < 0.05). For Oesophagostomum spp., sows from herds with different specific pathogen free status had about one tenth the odds of being infected compared with those from conventional herds (P < 0.05). Sows that had been treated with anthelmintics had very low odds of being infected with Oesophagostomum spp. compared with those that were not treated (P < 0.05). The effects of these management factors in both final models did not differ when the definition of an ‘infected’ sow was changed. The present results suggest the importance of disposal of bedding material from pens in reducing the prevalence of A. suum in larger sow herds. Anthelmintic treatment is important in reducing the prevalence of Oesophagostomum spp. infection of sows.
P Nansen - One of the best experts on this subject based on the ideXlab platform.
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the effect of fasting on ascaris suum and Oesophagostomum spp in growing pigs
International Journal for Parasitology, 1997Co-Authors: Saulius Petkevicius, P Nansen, L S StephensonAbstract:Abstract Experiments were conducted to study the possible influence of fasting on Ascaris suum and Oesophagostomum spp. in growing pigs. Forty young crossbred pigs naturally infected with A. suum and Oesophagostomum spp. were used. In one experiment 10 pigs were fasted and offered water ad libitum for 6 days, in another experiment for 10 days. Subsequently, these pigs, together with 10 non-fasted control pigs per experiment were slaughtered, and worm numbers, worm location, sex, developmental stage and female worm fecundity were determined. Pigs fasted for 10 but not for 6 days had decreased numbers of A. suum and Oesophagostomum spp. at slaughter vs controls, and worms were found in more distal locations in the gastrointestinal tract. Fasting for both 6 and 10 days significantly lowered the fecundity of both worm species.
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an in vivo dose response study of fenbendazole against Oesophagostomum dentatum and Oesophagostomum quadrispinulatum in pigs
International Journal for Parasitology, 1997Co-Authors: J Praslicka, M Varady, H Bjorn, P Nansen, D R Hennessy, H TalvikAbstract:Abstract A dose-response study using fenbendazole (FBZ) was carried out in pigs infected with O. dentatum and O. quadrispinulatum to determine the minimum effective dose rate of the drug. Thirty pigs were randomly divided into 6 groups of 5 pigs and infected with 5000 infective larvae each. The animals were re-infected 5 days before treatment (Day 30 after the first infection) with the same number of larvae. On Day 35 the pigs in groups 1–5 were treated with FBZ at the following dose rates: 2.5 mg kg −1 (i.e. 50% of the registered dose level), 1.0 mg kg −1 (20%), 0.25 mg kg −1 (5%), 0.1 mg kg −1 (2%) and 0.05 mg kg −1 (1%), respectively. Pigs in group 6 served as non-treated controls. Seven days after treatment (Day 42 after infection) the pigs were slaughtered, worms recovered from the large intestine and counted. The species and sex of adult worms was determined. A high faecal egg count reduction (FECR) after treatment was observed in groups 1, 2 and 3 (98%, 88% and 91%, respectively), while in groups 4 and 5 the egg counts were not affected by treatment. The mean worm count reduction was high in groups 1, 2 and 3 (100%, 99.9% and 98.6%, respectively), but declined in groups 4 and 5 (77% and 40%, respectively). FBZ showed a high efficacy against immature worms in groups 1 and 2, while in groups 3, 4 and 5 counts were not reduced. Species differentiation revealed a higher effect of FBZ against O. dentatum than against O. quadrispinulatum . Sex differentiation indicated a slightly higher (not significant) efficacy against females than males in both species. This study demonstrated a high efficacy of FBZ against the nodular worms in pigs, even at 5% of the currently registered dose level.
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the effect of concurrent or sequential Oesophagostomum dentatum and o quadrispinulatum infections on the worm burdens of the two species in pigs
Parasitology, 1997Co-Authors: C M Christensen, P Nansen, E H BarnesAbstract:The interaction between the 2 nodular worm species in the pig, Oesophagostomum dentatum ( O.d. ) and Oesophagostomum quadrispinulatum ( O.q. ), was studied by comparing the development and distribution of the species following single or mixed infections. The faecal egg excretion levels were assessed at regular intervals from week 3 post-inoculation, and indicated a strong negative impact of the introduction of O.q. on the continued egg excretion of O.d. All pigs were killed 9 weeks after the first inoculations to determine the composition and location of the worm burdens in the large intestine. O.q. was found more anteriorly located in the intestine than O.d. , thus confirming previous descriptions. When both species were present, the distribution of O.d. was moved further posteriorly and was more spread out than in single-species infections. There appeared to be no adverse effect of O.d. on the establishment and fecundity of O.q. However, the worm recoveries corroborated the egg excretion observations, namely reduced worm burdens of O.d. if O.q. was introduced, or if O.q. was already present. It is uncertain whether this effect is caused by differences in host reaction against the two species, or whether a more specific competition occurs between the two nodular worm species in pigs.
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use of random amplified polymorphic dna polymerase chain reaction for the definition of genetic markers for species and strains of porcine Oesophagostomum
Parasitology Research, 1997Co-Authors: Anja Joachim, H Bjorn, A Daugschies, C M Christensen, P NansenAbstract:Nodular worms are common parasites of pigs, and research has recently started to focus on the biology of these nematodes. However, the methods for delineation of species at immature developmental stages and␣for␣differentiation of various lines of the same species␣remain limited. For differentiation of porcine Oesophagostomum species and strains by genomic fingerprinting, random amplified polymorphic DNA-polymerase chain reaction was performed on DNA derived from 20 larval batches of anthelmintic-susceptible and resistant strains and isolates of these nematodes and 2 ruminant Oesophagostomum spp. Polymorphic DNA markers could be amplified with 9 of the 33 primers tested. In all, 13 markers were species-specific and 6 markers could differentiate between strains or groups of strains. With a combination of the latter, artificially selected anthelmintic-resistant strains and the susceptible mother strain of O. dentatum could be delineated. When single adult worms were compared, considerable variations between strains of the same species and between individuals from the same strain could be detected. The differentiation of Oesophagostomum strains and species at all parasitic stages on the basis of genetic markers could greatly facilitate studies on the biology of these parasites.
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in vitro characterization of anthelmintic susceptibility of field isolates of the pig nodular worm Oesophagostomum spp susceptible or resistant to various anthelmintics
International Journal for Parasitology, 1996Co-Authors: M Varady, H Bjorn, P NansenAbstract:Abstract A larval development assay (LDA) and an egg hatch paralysis assay (EHPA) were used to measure the sensitivity to anthelmintics of eggs and larvae of nodular worms ( Oesophagostomum spp.) in pigs. The tests were carried out using in vivo defined resistant and susceptible isolates of Oesophagostomum dentatum, O. quadrispinulatum and Oesophagostomum spp. For measurement of pyrantei/morantel and levamisole sensitivity the LDA was found able to distingrich between susceptible or resistant isolates of Oesophagostomum . The EHPA was able to detect levamisole resistance, but the test failed to show differences in response to pyrantel between pyrantel susceptible and resistant lines. The possible routine application of LDA and EHPA in the diagnosis of anthelmintic resistance in Oesophagostomum spp. is discussed.
A M Polderman - One of the best experts on this subject based on the ideXlab platform.
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distribution and clustering of Oesophagostomum bifurcum and hookworm infections in northern ghana
Parasitology, 2006Co-Authors: Juventus B Ziem, Pascal Magnussen, E Agongo, Annette Olsen, J Horton, Ronald B Geskus, A M PoldermanAbstract:Human Oesophagostomum infections are locally common in northern Ghana. The present study describes the results of a cross-sectional survey involving 1011 subjects, selected by a compound-based random sampling method from 1227 compounds in 24 villages. Selected persons were examined by both Kato and coproculture methods. Hookworm-like eggs, representing ova of Oesophagostomum bifurcum and hookworm were detected in 87·5% of the Kato smears. The geometric mean egg count of the infected subjects was 1018. Upon coproculture, third-stage larvae of O. bifurcum and hookworm were detected in 53·0% and 86·9% of subjects respectively. Oesophagostomum infections were clustered but no clear explanation for aggregation of infections could be found as yet. Subjects infected with hookworm had a 5-fold higher risk of being infected with O. bifurcum . Infection rates in adult women were higher than in adult men. No association was found with family size, level of hygiene or with the presence of animals in the compounds. Representatives of the Bimoba-tribe were significantly more infected than those of the other tribes. It appears, however, that this tribal association is a geographical phenomenon: Bimoba are mostly living in villages with the highest infection rates.
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distribution of human Oesophagostomum bifurcum hookworm and strongyloides stercoralis infections in northern ghana
Transactions of The Royal Society of Tropical Medicine and Hygiene, 2005Co-Authors: Lawrence Yelifari, P Bloch, Pascal Magnussen, L Van Lieshout, G Dery, S Anemana, E Agongo, A M PoldermanAbstract:Summary A cross-sectional study was carried out in 216 randomly selected, representative rural villages in the northeastern part of Ghana from March 1995 to May 1998. Inhabitants of randomly selected households, stratified by age and gender, were included. The geographical position of villages was recorded with a global positioning system (GPS). The prevalence of Oesophagostomum, hookworm and Strongyloides stercoralis infections in a study population of 20 250 people was determined by microscopic examination of larvae in stool cultures. The overall prevalence was 10.2, 50.6 and 11.6% for the three nematodes, respectively. Hookworm infections were seen in all but one (99.5%) and S. stercoralis in 88.4% of the 216 villages, while Oesophagostomum infections were found to be common in a limited area with prevalences varying from 0 to 75%. An association was found between Oesophagostomum and hookworm infection, both at the individual and at the village level. Spatial analysis of the prevalence data indicated that the endemic area is relatively clearly demarcated to the south of the study area.
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screening for haplotypic variability within Oesophagostomum bifurcum nematoda employing a single strand conformation polymorphism approach
Molecular and Cellular Probes, 2002Co-Authors: J M De Gruijter, A M Polderman, Robin B GasserAbstract:Abstract Genetic markers in the mitochondrial genome have proven useful for population genetic studies because of their maternal inheritance and relatively high evolutionary rates. In this study, we exploited the high resolution capacity of PCR-coupled single-strand conformation polymorphism (SSCP) to screen for sequence variation in part of the cytochrome c oxidase subunit 1 gene (p cox 1) among individuals of the parasitic nematode, Oesophagostomum bifurcum from human or Mona monkey hosts from Africa. SSCP analysis revealed distinct profiles among some of the individuals, and subsequent sequence analysis of representative samples defined 10 different haplotypes. For comparative purposes, the p cox 1 sequences for representatives of four other species of Oesophagostomum from livestock were included. While there were high levels (11·5–13·7%) of sequence difference among the latter species, there was no fixed nucleotide difference between O. bifurcum individuals from humans and those from monkeys. The data support the proposal that O. bifurcum from the two primate hosts represents a single species and that the haplotypic variability in p cox 1 represents population variation. The results reinforce the usefulness of the SSCP-sequencing approach for studying genetic variation in nematode populations using mitochondrial markers.
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experimental Oesophagostomum bifurcum in monkeys
Journal of Helminthology, 2001Co-Authors: M L Eberhard, J Blotkamp, E Kovacsnace, J J Verwij, V A A Asigri, A M PoldermanAbstract:: Oesophagostomum BIFURCUM: larvae, cultured from human stools collected in northern Ghana, were used to establish experimental infections in monkeys. A patent infection was established in a rhesus monkey (Macaca mulatta) and this infection was used to generate larvae to inoculate additional monkeys. In all, 17 animals were inoculated. Thirteen of 15 animals developed antibodies to the infection between 19 and 62 days post inoculation (PI); two animals had a positive response before inoculation. Four of ten animals developed patent infections between 88 and 134 days and passed eggs in the faeces. Egg shedding was consistent in only one animal, but at low levels of one or two eggs per 2 mg direct smear, and extended over a 400 day period. In the other three animals, egg shedding was sporadic and of only 2-4 weeks duration. In seven animals necropsied between 19 and 22 days PI, one to 17 early fourth-stage larvae were recovered from nodules in the bowel wall; in an eighth animal examined at 314 days, six immature adult worms (early fifth stage) were recovered from nodules in the bowel wall. The morphological features and growth of these recovered larvae are described. Three animals were inoculated with larvae that had been dried for one week at 28 degrees C; two animals began shedding eggs at 128 and 134 days PI, respectively. The present results suggest that the parasite obtained from humans is poorly adapted to lower primate hosts, and supports the concept that Oesophagostomum bifurcum found in humans and monkeys in the same geographical region of northern Ghana and Togo are distinct and that the infections in humans are not likely to represent zoonotic infections acquired from monkeys.
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the capacity of the third stage larvae of Oesophagostomum bifurcum to survive adverse conditions
Annals of Tropical Medicine and Parasitology, 2000Co-Authors: J Blotkamp, S Baeta, A M Polderman, Mark L EberhardAbstract:Human infections with the intestinal nematode Oesophagostomum bifurcum are commonly found in the Sudan savannah of northern Togo and Ghana. Apparently, the long and hot dry season in this region does not prevent transmission, which is believed to take place through ingestion of the infective, third-stage larvae (L 3 ). Oesophagostomum L 3 cultured from human stools, unlike the larvae of Necator americanus, were shown to survive desiccation. In addition, 93% of the O. bifurcum L 3 frozen for 24 h at - 15°C regained motility when brought back into ambient temperatures. The L 3 also survived the acidity of an artificial mixture made to resemble the gastric juices of humans. Desiccated larvae could even be rehydrated in this mixture, indicating the possibility of dust-borne infections. The sturdiness of the L 3 is likely to contribute to the high transmission intensity in northern Togo and Ghana.
Robin B Gasser - One of the best experts on this subject based on the ideXlab platform.
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screening for haplotypic variability within Oesophagostomum bifurcum nematoda employing a single strand conformation polymorphism approach
Molecular and Cellular Probes, 2002Co-Authors: J M De Gruijter, A M Polderman, Robin B GasserAbstract:Abstract Genetic markers in the mitochondrial genome have proven useful for population genetic studies because of their maternal inheritance and relatively high evolutionary rates. In this study, we exploited the high resolution capacity of PCR-coupled single-strand conformation polymorphism (SSCP) to screen for sequence variation in part of the cytochrome c oxidase subunit 1 gene (p cox 1) among individuals of the parasitic nematode, Oesophagostomum bifurcum from human or Mona monkey hosts from Africa. SSCP analysis revealed distinct profiles among some of the individuals, and subsequent sequence analysis of representative samples defined 10 different haplotypes. For comparative purposes, the p cox 1 sequences for representatives of four other species of Oesophagostomum from livestock were included. While there were high levels (11·5–13·7%) of sequence difference among the latter species, there was no fixed nucleotide difference between O. bifurcum individuals from humans and those from monkeys. The data support the proposal that O. bifurcum from the two primate hosts represents a single species and that the haplotypic variability in p cox 1 represents population variation. The results reinforce the usefulness of the SSCP-sequencing approach for studying genetic variation in nematode populations using mitochondrial markers.
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molecular separation of Oesophagostomum stephanostomum and Oesophagostomum bifurcum nematoda strongyloidea from non human primates
International Journal for Parasitology, 1999Co-Authors: Robin B Gasser, J Blotkamp, Wayne G Woods, Michael A Huffman, A M PoldermanAbstract:Abstract The ITS-2 sequences for adult specimens of Oesophagostomum stephanostomum from the common chimpanzee and Oesophagostomum bifurcum from the Mona monkey were determined. For both species, the length and GC content of the ITS-2 sequences were 216 bp and 43%, respectively. While there was no unequivocal sequence difference among individual worms representing each of the two species, five (2.3%) interspecific nucleotide differences were detected. These differences were associated with the presence of unique restriction sites in the ITS-2 sequence of O. stephanostomum for multiple endonucleases of diagnostic value for the differentiation of the two taxa by restriction analysis. Pairwise comparisons of the ITS-2 sequences of O. stephanostomum and O. bifurcum with published ITS-2 sequences for five different congeners indicated that these species from the subgenus Conoweberia are closely related, in accordance with previous morphological studies.
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distinguishing Oesophagostomum dentatum from Oesophagostomum quadrispinulatum developmental stages by a single strand conformation polymorphism method
International Journal for Parasitology, 1998Co-Authors: Robin B Gasser, Wayne G Woods, H BjornAbstract:Abstract At some life-cycle stages, it is impossible to distinguish between the two species of porcine nodular worm, Oesophagostomum dentatum and Oesophagostomum quadrispinulatum , using morphological features. A PCR-based single-strand conformation polymorphism technique was established to overcome this limitation. The rDNA region spanning the second internal transcribed spacer was amplified by PCR from genomic DNA from morphologically well-defined adult worms. The PCR products were then denatured and subjected to electrophoresis in a non-denaturing gel matrix. Single-strand conformation polymorphism analysis of the products generated characteristic and reproducible patterns for each of the two species and allowed their unequivocal delineation. The single-strand conformation polymorphism was also applied effectively to assess the purity of nine laboratory-maintained cultures of infective third-stage larvae believed to be monospecific for O. dentatum or O. quadrispinulatum . The analysis showed that all six O. dentatum cultures were indeed monospecific, whereas the three cultures believed to be monospecific for O. quadrispinulatum were either a mixture of O. dentatum and O. quadrispinulatum larvae or pure O. dentatum larvae. These findings demonstrated the usefulness of the single-strand conformation polymorphism approach for the routine monitoring of the purity of parasite lines and indicated its value for studies on the population biology of porcine nodular worms.
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Systematic relationships of some members of the genera Oesophagostomum and Chabertia (Nematoda: Chabertiidae) based on ribosomal DNA sequence data.
International Journal for Parasitology, 1998Co-Authors: Lisa A. Newton, Neil B Chilton, Ian Beveridge, Robin B GasserAbstract:Abstract The present study characterised seven species of the Chabertiidae (Nematoda: Strongyloidea) belonging to either the subfamily Oesophagostominae ( Oesophagostomum radiatum, Oesophagostomum venulosum, Oesophagostomum dentatum, Oesophagostomum quadrispinulatum, Oesophagostomum columbianum, Oesophagostomum bifurcum ) or to the subfamily Chabertiinae ( Chabertia ovina ) by their second internal transcribed spacer rDNA sequence, assessed the extent of intraspecific variation and interspecific differences in the sequence, and inferred the phylogenetic relationship of C. ovina with respect to members of the Oesophagostominae. In both the phenetic and cladistic analyses of the sequence data, Chabertia was nested within Oesophagostomum , suggesting either that the species examined represent members of the same genus, or alternatively, that Oesophagostomum may represent more than one genus.
Wayne G Woods - One of the best experts on this subject based on the ideXlab platform.
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molecular separation of Oesophagostomum stephanostomum and Oesophagostomum bifurcum nematoda strongyloidea from non human primates
International Journal for Parasitology, 1999Co-Authors: Robin B Gasser, J Blotkamp, Wayne G Woods, Michael A Huffman, A M PoldermanAbstract:Abstract The ITS-2 sequences for adult specimens of Oesophagostomum stephanostomum from the common chimpanzee and Oesophagostomum bifurcum from the Mona monkey were determined. For both species, the length and GC content of the ITS-2 sequences were 216 bp and 43%, respectively. While there was no unequivocal sequence difference among individual worms representing each of the two species, five (2.3%) interspecific nucleotide differences were detected. These differences were associated with the presence of unique restriction sites in the ITS-2 sequence of O. stephanostomum for multiple endonucleases of diagnostic value for the differentiation of the two taxa by restriction analysis. Pairwise comparisons of the ITS-2 sequences of O. stephanostomum and O. bifurcum with published ITS-2 sequences for five different congeners indicated that these species from the subgenus Conoweberia are closely related, in accordance with previous morphological studies.
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distinguishing Oesophagostomum dentatum from Oesophagostomum quadrispinulatum developmental stages by a single strand conformation polymorphism method
International Journal for Parasitology, 1998Co-Authors: Robin B Gasser, Wayne G Woods, H BjornAbstract:Abstract At some life-cycle stages, it is impossible to distinguish between the two species of porcine nodular worm, Oesophagostomum dentatum and Oesophagostomum quadrispinulatum , using morphological features. A PCR-based single-strand conformation polymorphism technique was established to overcome this limitation. The rDNA region spanning the second internal transcribed spacer was amplified by PCR from genomic DNA from morphologically well-defined adult worms. The PCR products were then denatured and subjected to electrophoresis in a non-denaturing gel matrix. Single-strand conformation polymorphism analysis of the products generated characteristic and reproducible patterns for each of the two species and allowed their unequivocal delineation. The single-strand conformation polymorphism was also applied effectively to assess the purity of nine laboratory-maintained cultures of infective third-stage larvae believed to be monospecific for O. dentatum or O. quadrispinulatum . The analysis showed that all six O. dentatum cultures were indeed monospecific, whereas the three cultures believed to be monospecific for O. quadrispinulatum were either a mixture of O. dentatum and O. quadrispinulatum larvae or pure O. dentatum larvae. These findings demonstrated the usefulness of the single-strand conformation polymorphism approach for the routine monitoring of the purity of parasite lines and indicated its value for studies on the population biology of porcine nodular worms.
