scholarly journals On the role of dauer in the adaptation of nematodes to a parasitic lifestyle

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Lieke E. Vlaar ◽  
Andre Bertran ◽  
Mehran Rahimi ◽  
Lemeng Dong ◽  
Jan E. Kammenga ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Meta Analysis ◽  
Nematode Species ◽  
Life Cycles ◽  
Signalling Pathway ◽  
Parasitic Nematodes ◽  
Wide Range ◽  
Free Living Nematode ◽  
Parasitic Lifestyle ◽  
Dauer Signalling Pathway

AbstractNematodes are presumably the most abundant Metazoa on Earth, and can even be found in some of the most hostile environments of our planet. Various types of hypobiosis evolved to adapt their life cycles to such harsh environmental conditions. The five most distal major clades of the phylum Nematoda (Clades 8–12), formerly referred to as the Secernentea, contain many economically relevant parasitic nematodes. In this group, a special type of hypobiosis, dauer, has evolved. The dauer signalling pathway, which culminates in the biosynthesis of dafachronic acid (DA), is intensively studied in the free-living nematode Caenorhabditis elegans, and it has been hypothesized that the dauer stage may have been a prerequisite for the evolution of a wide range of parasitic lifestyles among other nematode species. Biosynthesis of DA is not specific for hypobiosis, but if it results in exit of the hypobiotic state, it is one of the main criteria to define certain behaviour as dauer. Within Clades 9 and 10, the involvement of DA has been validated experimentally, and dauer is therefore generally accepted to occur in those clades. However, for other clades, such as Clade 12, this has hardly been explored. In this review, we provide clarity on the nomenclature associated with hypobiosis and dauer across different nematological subfields. We discuss evidence for dauer-like stages in Clades 8 to 12 and support this with a meta-analysis of available genomic data. Furthermore, we discuss indications for a simplified dauer signalling pathway in parasitic nematodes. Finally, we zoom in on the host cues that induce exit from the hypobiotic stage and introduce two hypotheses on how these signals might feed into the dauer signalling pathway for plant-parasitic nematodes. With this work, we contribute to the deeper understanding of the molecular mechanisms underlying hypobiosis in parasitic nematodes. Based on this, novel strategies for the control of parasitic nematodes can be developed.

scholarly journals The narrow-spectrum anthelmintic oxantel is a potent agonist of a novel acetylcholine receptor subtype in whipworms

2021 ◽  
Vol 17 (2) ◽  
pp. e1008982
Author(s):  
Tina V. A. Hansen ◽  
Susanna Cirera ◽  
Cédric Neveu ◽  
Elise Courtot ◽  
Claude L. Charvet ◽  
...  
Keyword(s):  
Acetylcholine Receptor ◽  
Animal Health ◽  
High Sensitivity ◽  
Nematode Species ◽  
Screening Tools ◽  
Parasitic Nematodes ◽  
Receptor Subtype ◽  
Narrow Spectrum ◽  
Wide Range ◽  
Free Living Nematode

In the absence of efficient alternative strategies, the control of parasitic nematodes, impacting human and animal health, mainly relies on the use of broad-spectrum anthelmintic compounds. Unfortunately, most of these drugs have a limited single-dose efficacy against infections caused by the whipworm, Trichuris. These infections are of both human and veterinary importance. However, in contrast to a wide range of parasitic nematode species, the narrow-spectrum anthelmintic oxantel has a high efficacy on Trichuris spp. Despite this knowledge, the molecular target(s) of oxantel within Trichuris is still unknown. In the distantly related pig roundworm, Ascaris suum, oxantel has a small, but significant effect on the recombinant homomeric Nicotine-sensitive ionotropic acetylcholine receptor (N-AChR) made up of five ACR-16 subunits. Therefore, we hypothesized that in whipworms, a putative homolog of an ACR-16 subunit, can form a functional oxantel-sensitive receptor. Using the pig whipworm T. suis as a model, we identified and cloned a novel ACR-16-like subunit and successfully expressed the corresponding homomeric channel in Xenopus laevis oocytes. Electrophysiological experiments revealed this receptor to have distinctive pharmacological properties with oxantel acting as a full agonist, hence we refer to the receptor as an O-AChR subtype. Pyrantel activated this novel O-AChR subtype moderately, whereas classic nicotinic agonists surprisingly resulted in only minor responses. We observed that the expression of the ACR-16-like subunit in the free-living nematode Caenorhabditis elegans conferred an increased sensitivity to oxantel of recombinant worms. We demonstrated that the novel Tsu-ACR-16-like receptor is indeed a target for oxantel, although other receptors may be involved. These finding brings new insight into the understanding of the high sensitivity of whipworms to oxantel, and highlights the importance of the discovery of additional distinct receptor subunit types within Trichuris that can be used as screening tools to evaluate the effect of new synthetic or natural anthelmintic compounds.

scholarly journals The genome ofStrongyloidesspp. gives insights into protein families with a putative role in nematode parasitism

Parasitology ◽  
2016 ◽  
Vol 144 (3) ◽  
pp. 343-358 ◽  
Author(s):  
VICKY L. HUNT ◽  
ISHENG J. TSAI ◽  
MURRAY E. SELKIRK ◽  
MARK VINEY
Keyword(s):  
Proteinase Inhibitors ◽  
Nematode Species ◽  
Life Cycles ◽  
Gastrointestinal Parasites ◽  
Parasitic Nematodes ◽  
Protein Families ◽  
Putative Role ◽  
Survival And Reproduction ◽  
Parasitic Lifestyle ◽  
Nematode Parasitism

SUMMARYParasitic nematodes are important and abundant parasites adapted to live a parasitic lifestyle, with these adaptations all aimed at facilitating their survival and reproduction in their hosts. The recently sequenced genomes of fourStrongyloidesspecies, gastrointestinal parasites of humans and other animals, alongside transcriptomic and proteomic analysis of free-living and parasitic stages of their life cycles have revealed a number of protein families with a putative role in their parasitism. Many of these protein families have also been associated with parasitism in other parasitic nematode species, suggesting that these proteins may play a fundamental role in nematode parasitism more generally. Here, we review key protein families that have a putative role inStrongyloides’ parasitism – acetylcholinesterases, astacins, aspartic proteases, prolyl oligopeptidases, proteinase inhibitors (trypsin inhibitors and cystatins), SCP/TAPS and transthyretin-like proteins – and the evidence for their key, yet diverse, roles in the parasitic lifestyle.

scholarly journals Molecular Diversity of Nematode Parasites in Afrotropical Reed Frogs (Hyperolius spp.)

Diversity ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 265
Author(s):  
Ulrich Sinsch ◽  
J. Maximilian Dehling ◽  
Patrick Scheid ◽  
Carsten Balczun
Keyword(s):  
Dna Sequences ◽  
Nematode Species ◽  
Sub Saharan Africa ◽  
Parasitic Nematodes ◽  
Marker Genes ◽  
Nematode Parasites ◽  
Diversity Assessment ◽  
Wide Range ◽  
Nematode Diversity ◽  
Sub Saharan

The diversity of nematodes infecting amphibians is understudied in tropical Africa and unknown in Rwanda. Diversity assessment is hampered by the fact that species descriptions refer mostly to morphological features that are unlinked to DNA sequences of marker genes available in public databases. In this paper, we explore the abundance and diversity of parasitic nematodes in reed frogs Hyperolius kivuensis (n = 115), H. parallelus (n = 45) and H. viridiflavus (n = 100) collected in Rwanda. Five nematode species were identified morphologically as Orneoascaris chrysanthemoides, O. schoutedeni, Gendria leberrei, Aplectana chamaeleonis and Rhabdias collaris. Corresponding DNA sequences of 18S and COI genes were determined and subsequently deposited in GenBank. Aplectana chamaeleonis showed the highest prevalence (8.7%), but O. chrysanthemoides the highest mean intensity of infection (6.0) and largest number (24) of individuals in H. kivuensis. To the best of our knowledge, all amphibian hosts are new records for these nematode species, which are known to infect a wide range of amphibian and reptile species. Our findings suggest that nematode diversity is probably lower than previously assumed due to low host specificity. As morphological species identification is often challenging, our data facilitate molecular identification of adult and specifically larval nematodes found in amphibians of Sub-Saharan Africa.

The use of Caenorhabditis elegans in parasitic nematode research

Parasitology ◽  
2004 ◽  
Vol 128 (S1) ◽  
pp. S49-S70 ◽  
Author(s):  
J. S. GILLEARD
Keyword(s):  
Caenorhabditis Elegans ◽  
Parasitic Nematode ◽  
Expression System ◽  
Nematode Species ◽  
Current Status ◽  
Evolutionary Development ◽  
Parasitic Nematodes ◽  
Free Living ◽  
C Elegans ◽  
Free Living Nematode

There is increasing interest in the use of the free-living nematode Caenorhabditis elegans as a tool for parasitic nematode research and there are now a number of compelling examples of its successful application. C. elegans has the potential to become a standard tool for molecular helminthology researchers, just as yeast is routinely used by molecular biologists to study vertebrate biology. However, in order to exploit C. elegans in a meaningful manner, we need a detailed understanding of the extent to which different aspects of C. elegans biology have been conserved with particular groups of parasitic nematodes. This review first considers the current state of knowledge regarding the conservation of genome organisation across the nematode phylum and then discusses some recent evolutionary development studies in free-living nematodes. The aim is to provide some important concepts that are relevant to the extrapolation of information from C. elegans to parasitic nematodes and also to the interpretation of experiments that use C. elegans as a surrogate expression system. In general, examples have been specifically chosen because they highlight the importance of careful experimentation and interpretation of data. Consequently, the focus is on the differences that have been found between nematode species rather than the similarities. Finally, there is a detailed discussion of the current status of C. elegans as a heterologous expression system to study parasite gene function and regulation using successful examples from the literature.

scholarly journals Influence of ecological factors on larvae hatching of cystogenous species of nematodes

2016 ◽  
Author(s):  
L. Pylypenko ◽  
K. Kalatur
Keyword(s):  
Control Strategies ◽  
Research Effort ◽  
Inorganic Compounds ◽  
Ecological Factors ◽  
Nematode Species ◽  
Control Measures ◽  
Parasitic Nematodes ◽  
Cyst Nematodes ◽  
Wide Range ◽  
Hatching Process

Understanding hatching process in plant parasitic nematodes has the potential to lead to new control strategies of these devistating pathogens, causing up to10–20% or $80 billion of crop loss globally (Nicol et al, 2011; Каплин, 2012). Although much research effort has been extended in elucidating the hatching factors, there has been no successful control strategy using their analogues to induce hatch in the field. This review examines development on this subject, focusing on the root diffusate, natural and inorganic compounds, as well as abiotic hatching factors (environmental temperature, moisture, aeration). They are assumed to have different impact on the hatching process of various cyst nematodes species despite of similarities in their biological features and life strategies. Notably, soil temperature and moisture play the vital role for species with a wide range of host plants whereas host plant diffusate is a key factor for highly specialized cyst nematode species. Appropriately investigated, it can favour development of control measures specified against targeted nematode species and boost their application in practice.

scholarly journals Molecular Aspects of Cancer Research Endometrium – The Prospect of Personalized Treatment

2021 ◽  
pp. 346-356
Author(s):  
Movchan Oksana
Keyword(s):  
Endometrial Cancer ◽  
Molecular Mechanisms ◽  
Selection Process ◽  
Meta Analysis ◽  
Treatment Options ◽  
Survival Rates ◽  
Molecular Processes ◽  
Pubmed Database ◽  
Wide Range ◽  
Molecular Aspects

Aims: Endometrial cancer is the most common gynaecological cancer, and there is a growing interest in identifying the molecular pathways involved and developing molecular-targeted treatment to prevent it. Present study was aimed to give an overview of the molecular processes involved in endometrial cancer development and treatment options. Methods: We conducted a comprehensive systematic literature review and meta-analysis. For that purpose, PubMed database was searched for related studies till June 2021 and a through selection process was adopted to select the eligible studies. Results: Endometrial malignancies are complicated molecularly, and their focused therapy has a wide range of outcomes, with median progressive survival rates ranging from 2.3 to 18 months. Conclusions: The effective treatment and therapy need a detailed understanding of the molecular mechanisms underlying the creation and progression of endometrial cancer, as well as the development of innovative targeted therapeutic agents.

scholarly journals Sensory cilia as the Achilles heel of nematodes when attacked by carnivorous mushrooms

2020 ◽  
Vol 117 (11) ◽  
pp. 6014-6022 ◽  
Author(s):  
Ching-Han Lee ◽  
Han-Wen Chang ◽  
Ching-Ting Yang ◽  
Niaz Wali ◽  
Jiun-Jie Shie ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Calcium Influx ◽  
Muscle Cells ◽  
Nematode Species ◽  
Predatory Behavior ◽  
Parasitic Nematodes ◽  
Loss Of Function ◽  
Genetic Screens ◽  
Predator Prey ◽  
C Elegans

Fungal predatory behavior on nematodes has evolved independently in all major fungal lineages. The basidiomycete oyster mushroomPleurotus ostreatusis a carnivorous fungus that preys on nematodes to supplement its nitrogen intake under nutrient-limiting conditions. Its hyphae can paralyze nematodes within a few minutes of contact, but the mechanism had remained unclear. We demonstrate that the predator–prey relationship is highly conserved between multiplePleurotusspecies and a diversity of nematodes. To further investigate the cellular and molecular mechanisms underlying rapid nematode paralysis, we conducted genetic screens inCaenorhabditis elegansand isolated mutants that became resistant toP. ostreatus. We found that paralysis-resistant mutants all harbored loss-of-function mutations in genes required for ciliogenesis, demonstrating that the fungus induced paralysis via the cilia of nematode sensory neurons. Furthermore, we observed thatP. ostreatuscaused excess calcium influx and hypercontraction of the head and pharyngeal muscle cells, ultimately resulting in rapid necrosis of the entire nervous system and muscle cells throughout the entire organism. This cilia-dependent predatory mechanism is evolutionarily conserved inPristionchus pacificus, a nematode species estimated to have diverged fromC. elegans280 to 430 million y ago. Thus,P. ostreatusexploits a nematode-killing mechanism that is distinct from widely used anthelmintic drugs such as ivermectin, levamisole, and aldicarb, representing a potential route for targeting parasitic nematodes in plants, animals, and humans.

Effects of plant phenylpropanoid pathway products and selected terpenoids and alkaloids on the behaviour of the plant-parasitic nematodes Radopholus similis, Pratylenchus penetrans and Meloidogyne incognita

Nematology ◽  
2006 ◽  
Vol 8 (1) ◽  
pp. 89-101 ◽  
Author(s):  
Nathalie Wuyts ◽  
Rony Swennen ◽  
Dirk De Waele
Keyword(s):  
Meloidogyne Incognita ◽  
Chemical Defence ◽  
Nematode Species ◽  
Biologically Active ◽  
Parasitic Nematodes ◽  
Pratylenchus Penetrans ◽  
Radopholus Similis ◽  
Irreversible Inhibitor ◽  
Wide Range

AbstractPlants produce a wide range of biologically active chemicals which have been extensively explored for nematode-antagonistic properties. Although phenylpropanoids are part of the chemical defence system of plants against pests and diseases, including parasitic nematodes, no comprehensive study exists which relates (levels of) phenylpropanoid compounds in roots to actual effects on nematode behaviour. Therefore, a broad spectrum evaluation was made of the effects of phenylpropanoids (simple phenolics and flavonoids) and selected monoterpenoids and alkaloids on the behaviour of the migratory endoparasites Radopholus similis and Pratylenchus penetrans and the sedentary endoparasite Meloidogyne incognita. In vitro bioassays assessed effects on chemotaxis, motility, viability and hatch. Compared with the other two nematode species, P. penetrans was remarkably insensitive to the test compounds. Only phloretin was (limited) hatch inhibitive. This property was shared by other chalcone-related compounds for R. similis. Repellents and motility inhibitors for R. similis and M. incognita were found among the simple phenolic compounds. Flavonols stood out as repellent compounds for both these nematode species, while they were, in their degraded form, also motility inhibitors for M. incognita. Dopamine was an attractant for R. similis, while ferulic acid was strongly motility inhibitive and toxic (LC50 of 120 μg ml−1) for this nematode species. Salicylic acid was a strong attractant for M. incognita. The compound was also nematicidal (LC50 of 46 μg ml−1) and an irreversible inhibitor of hatch.

scholarly journals FMRFamide-like peptides expand the behavioral repertoire of a densely connected nervous system

2017 ◽  
Vol 114 (50) ◽  
pp. E10726-E10735 ◽  
Author(s):  
James Siho Lee ◽  
Pei-Yin Shih ◽  
Oren N. Schaedel ◽  
Porfirio Quintero-Cadena ◽  
Alicia K. Rogers ◽  
...  
Keyword(s):  
Nervous System ◽  
Single Cells ◽  
Meta Analysis ◽  
Reproductive Development ◽  
Parasitic Nematodes ◽  
Behavioral Repertoire ◽  
C Elegans ◽  
Free Living Nematode ◽  
Transcriptional Changes ◽  
Carrier Animal

Animals, including humans, can adapt to environmental stress through phenotypic plasticity. The free-living nematode Caenorhabditis elegans can adapt to harsh environments by undergoing a whole-animal change, involving exiting reproductive development and entering the stress-resistant dauer larval stage. The dauer is a dispersal stage with dauer-specific behaviors for finding and stowing onto carrier animals, but how dauers acquire these behaviors, despite having a physically limited nervous system of 302 neurons, is poorly understood. We compared dauer and reproductive development using whole-animal RNA sequencing at fine time points and at sufficient depth to measure transcriptional changes within single cells. We detected 8,042 genes differentially expressed during dauer and reproductive development and observed striking up-regulation of neuropeptide genes during dauer entry. We knocked down neuropeptide processing using sbt-1 mutants and demonstrate that neuropeptide signaling promotes the decision to enter dauer rather than reproductive development. We also demonstrate that during dauer neuropeptides modulate the dauer-specific nictation behavior (carrier animal-hitchhiking) and are necessary for switching from repulsion to CO2 (a carrier animal cue) in nondauers to CO2 attraction in dauers. We tested individual neuropeptides using CRISPR knockouts and existing strains and demonstrate that the combined effects of flp-10 and flp-17 mimic the effects of sbt-1 on nictation and CO2 attraction. Through meta-analysis, we discovered similar up-regulation of neuropeptides in the dauer-like infective juveniles of diverse parasitic nematodes, suggesting the antiparasitic target potential of SBT-1. Our findings reveal that, under stress, increased neuropeptide signaling in C. elegans enhances their decision-making accuracy and expands their behavioral repertoire.

Two new free-living nematode species (Comesomatidae) from the continental slope of New Zealand, with keys and notes on distribution

Zootaxa ◽  
2012 ◽  
Vol 3348 (1) ◽  
pp. 40 ◽  
Author(s):  
LEDUC D. ◽  
PROBERT P. K. ◽  
NODDER S. D.
Keyword(s):  
Continental Slope ◽  
Nematode Species ◽  
Intestinal Wall ◽  
Free Living ◽  
Related Factors ◽  
Interspecific Differences ◽  
Food Quantity ◽  
Wide Range ◽  
Free Living Nematode ◽  
Effect Of Food

Two new free-living marine nematode species of the family Comesomatidae are described from the continental slope of NewZealand, and their distributions at 32 sites are investigated in relation to environmental factors. Vasostoma aurata n. sp. is char-acterised by a distinctly set-off head, amphideal fovea with 4.5 turns, conspicuous chords consisting of two bands fusing atbody extremities, with outline of cell bodies usually golden-coloured, and relatively short spicules. Setosabatieria conicauda n.sp. is characterised by an amphid with 4.25–4.5 turns, the presence of only 1–3 sub-cephalic setae per file, several clusters ofintracellular inclusions, sometimes brown-coloured, in the intestinal wall, and a conical tail. Keys to all known species of Seto-sabatieria and Vasostoma are provided. Both species were mostly restricted to subsurface (1–5cm depth) sediments. The abun-dance of V. aurata n. sp. and S. conicauda n. sp. was significantly correlated with food quantity and quality, but the patternsdiffered between species. The effect of food-related factors may be directly linked to interspecific differences in food require-ments, or mediated by biogeochemical processes (i.e., tolerance of sub-surface oxygen and sulphide concentrations). No signif-icant correlations were found between sediment granulometry and abundances, despite the wide range of sediment grain-sizes (6–93% silt and clay) at the sampling sites.

Sign in / Sign up

Export Citation Format

Share Document