Molecular Analysis of Nematode Diversity and the Evolution of Parasitism

Dorris, Mark; Ley, Paul De; Blaxter, Mark

doi:10.1016/s0169-4758(99)01439-8

Cited by 157 publications

(118 citation statements)

References 27 publications

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“…Recent molecular characterization of rDNA and ribosomal internal transcribed spacer sequences 496 R.M. Kaplan suggests that genetic divergence between taxa in the Strongylida is remarkably low [13,26]. In contrast, studies comparing mDNA sequences suggest that the genetic diversity within-populations of individual trichostrongyle species is quite large [7].…”

Section: Resistance To Ivermectinmentioning

confidence: 99%

Anthelmintic resistance in nematodes of horses

2002

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-Suppressive anthelmintic treatment strategies originally designed to control Strongylus vulgaris in horses were extremely successful in reducing morbidity and mortality from parasitic disease. Unfortunately, this strategy has inadvertently resulted in the selection of drug-resistant cyathostomes (Cyathostominea), which are now considered the principal parasitic pathogens of horses. Resistance in the cyathostomes to benzimidazole drugs is highly prevalent throughout the world, and resistance to pyrantel appears to be increasingly common. However, there are still no reports of ivermectin resistance in nematode parasites of horses despite 20 years of use. It is unknown why resistance to ivermectin has not yet emerged, but considering that ivermectin is the single most commonly used anthelmintic in horses most parasitologists agree that resistance is inevitable. The fecal egg count reduction test is considered the gold standard for clinical diagnosis of anthelmintic resistance in horses, but diagnosis is complicated by lack of an accepted standard for the performance of this test or for the analysis and interpretation of data. Presently there is very little data available on the molecular mechanisms of anthelmintic resistance in cyathostomes; β-tubulin gene is the only anthelmintic-resistance associated gene that has been cloned. The increasingly high prevalence of anthelmintic-resistant cyathostomes must be taken into account when designing worm control programs for horses. Strategies to decelerate further selection for drug resistance thereby extending the lifetime of currently effective anthelmintics should be implemented whenever possible. Considering the nature of the equine industry in which horses often graze shared pastures with horses from diverse locations, transmission and widespread dispersal of resistant parasites is virtually assured. A proactive approach to this problem centered on understanding the molecular basis of anthelmintic resistance in cyathostomes is required if we are to expect chemical control of nematodes in horses to remain a viable element of parasite control in the future.cyathostome / anthelmintic / resistance / nematode / horse Résumé -La résistance aux anthelmintiques chez les nématodes des chevaux. Les stratégies des traitements anthelmintiques mises en place à l'origine pour contrôler Strongylus vulgaris chez les chevaux ont été extrêmement efficaces pour réduire la morbidité et la mortalité dues aux maladies 491

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Section: Resistance To Ivermectinmentioning

confidence: 99%

Anthelmintic resistance in nematodes of horses

2002

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“…We cannot preclude the possibility that nematodes were present in the mining water at the time the borehole was drilled a year prior to sampling, but this seems unlikely given the disinfection procedures are standard operating protocols. Because the nematodes were parthenogenetic, crossing with surface species was impossible, and nematode morphology and genetics cannot be used as indicators of long-term isolation 11,12 . Further evaluation of their indigeneity, therefore, relied upon environmental data.…”

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confidence: 99%

Nematoda from the terrestrial deep subsurface of South Africa

Borgonie

García-Moyano

Litthauer

et al. 2011

Nature

215

154

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Since its discovery over two decades ago, the deep subsurface biosphere has been considered to be the realm of single cell organisms, extending >3 km into the Earth's crust and comprising a significant fraction of the global biosphere 1,2,3,4 . The constraints of temperature, energy, O 2 and space seemed to preclude the possibility of more complex multi-cellular organisms from surviving at these depths. Here we report species of the phylum Nematoda that have been detected in or recovered from 0.9-3.6 km deep fracture water encountered in the deep mines of South Africa, but have not been detected in the mining water. These subsurface nematodes, including a new species Halicephalobus mephisto, tolerate high temperature, reproduce asexually and preferentially feed upon subsurface bacteria. 14 C data indicate that the fracture water in which the nematodes reside is 3-12 kyr old paleometeoric water. Our data suggest that nematodes should be found in other deep hypoxic settings where temperature permits and that they may control the microbial population density by grazing upon fracture surface biofilm patches. Our results expand the known Metazoan biosphere and demonstrate that deep ecosystems are more complex than previously accepted. The discovery of multi-cellular life in the deep subsurface of the Earth also has important implications for the search for subsurface life on other worlds in our solar system. . Halicephalobus mephisto

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“…A similar problem has been reported with the use of molecular data where identifying positional homology has been a major hindrance to their use in reconstructing phylogeny among taxa . Although it is evidently much easier to identify and quantify sequence evolution than morphological evolution (De Ley, 2000), DNA data when used alone may be subject to some amount of noise and artefact (Dorris et al, 1999). In view of this, Dayrat (2005) proposed a more holistic approach to describing biodiversity which involves the integration of as much data about the organism as possible.…”

Section: Classical Taxonomymentioning

confidence: 99%

Technological advancements and their importance for nematode identification

Ahmed

Sapp

Prior

et al. 2016

SOIL

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Abstract. Nematodes represent a species-rich and morphologically diverse group of metazoans known to inhabit both aquatic and terrestrial environments. Their role as biological indicators and as key players in nutrient cycling has been well documented. Some plant-parasitic species are also known to cause significant losses to crop production. In spite of this, there still exists a huge gap in our knowledge of their diversity due to the enormity of time and expertise often involved in characterising species using phenotypic features. Molecular methodology provides useful means of complementing the limited number of reliable diagnostic characters available for morphology-based identification. We discuss herein some of the limitations of traditional taxonomy and how molecular methodologies, especially the use of high-throughput sequencing, have assisted in carrying out large-scale nematode community studies and characterisation of phytonematodes through rapid identification of multiple taxa. We also provide brief descriptions of some the current and almost-outdated high-throughput sequencing platforms and their applications in both plant nematology and soil ecology.

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Molecular Analysis of Nematode Diversity and the Evolution of Parasitism

Cited by 157 publications

References 27 publications

Anthelmintic resistance in nematodes of horses

Anthelmintic resistance in nematodes of horses

Nematoda from the terrestrial deep subsurface of South Africa

Technological advancements and their importance for nematode identification

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