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PubMed1999

Actions of nematode FMRFamide-related peptides on the pharyngeal muscle of the parasitic nematode, Ascaris suum.

The endogenous nematode peptides known as FMRFamide-related peptides (FaRPs) and various "classical" transmitters have a range of effects on nematodes that result in changes in behavior, particularly locomotion, including paralysis and inhibition of feeding. This study describes the application of an in vitro pharmacological approach to further delineate the action of a number of FaRP neurotransmitters on feeding behavior. Contraction of Ascaris suum pharyngeal muscle was monitored using a modified pressure transducer system that detects changes in intrapharyngeal pressure and therefore contraction of the radial muscle of the pharynx. The pharynx did not contract spontaneously. However, serotonin (5-HT, 100 microM) stimulated rhythmic contractions and relaxations (pumping) at a frequency of 0.5 Hz. The native nematode peptide, KNEFIRFamide (AF1), inhibited the pumping elicited by 5-HT. The duration of inhibition was concentration-dependent (1-1000 nM) with a threshold of 1 nM (n = 7). KSAYMRFamide (AF8/PF3) also inhibited pharyngeal pumping. There was no observable effect of any of the following nematode peptides on pharyngeal pumping behavior (1-1000 nM; n = 8): AF2, AF3, AF4, AF6, AF16, PF1/CF1, PF2/CF2, or PF4. Thus, interruption of pharyngeal processes, such as feeding, regulation of hydrostatic pressure, and secretion, may provide a new site of anthelmintic action.

Amino Acid Sequence↗
PubMed1999

Comparison of FaRP immunoreactivity in free-living nematodes and in the plant-parasitic nematode Heterodera glycines.

The family of FMRFamide-related peptides (FaRPs) is widely distributed among invertebrates, where the peptides serve as neuromodulators. Published reports indicate that numerous FaRP sequences exist in free-living and animal parasitic nematodes. Using a FMRFamide ELISA, FaRP immunoreactivity was detected in extracts of the soybean cyst nematode, Heterodera glycines, in both sexes and at all developmental stages. HPLC-ELISA results revealed a number of immunoreactive components in H. glycines preparations, and a comparison with extracts of the free-living nematodes Caenorhabditis elegans and Panagrellus redivivus showed significant qualitative differences in FaRP immunoreactivity between the plant parasite and the two free-living nematodes. Total and specific immunoreactivities varied during H. glycines development, with the highest specific activity in juveniles and males, and the highest total activity in mature females. Total female immunoreactivity was located primarily within the mature eggs. A significant portion, however, was associated with the female body, perhaps with egg laying.

Animals↗
PubMed1993

Biochemistry of the nematode cuticle: relevance to parasitic nematodes of livestock.

The cuticle of nematodes is a thin, flexible outer covering composed primarily of protein with trace amounts of lipid and carbohydrate. There has been considerable recent interest in the biochemistry, immunology and molecular biology of the cuticle of parasitic nematodes because of its role as an interface between parasite and host. The cuticle consists of: (1) collagen-like proteins that form the medial and basal layers; (2) non-collagen proteins that form the epicuticular and external cortical regions; (3) non-structural proteins associated with the external surface. The collagen-like proteins are solubilized by reducing agents, have molecular weights of 30-120 kDa and exhibit stage and species variations. Nematode collagen genes, however, code only for proteins with molecular weights of 30 kDa. The non-collagenous proteins, referred to as cuticlin, exhibit unusual chemical properties as indicated by their resistance to solubilization even under strongly denaturing conditions. Recent studies of Ascaris suum have demonstrated the presence of tyrosine-derived cross-links, dityrosine and isotrityrosine, that may form the linkage between subunits in assemblage of the collagenous and noncollagenous structural components of the cuticle. A peroxidase enzyme has been implicated in the synthesis of these cross-links. Recent 125I labeling studies of Haemonchus contortus have identified and characterized stage-specific proteins on the cuticular surface.

Animals↗
PubMed1981

[Comparative immunofluorescent-histological investigations on 7 nematode species in respect to its antigenic properties for differential diagnosis of nematode infections (author's transl)].

Five nematode species of the Onchocercidae family and one from the Strongylidae and Trichuridae family were tested as antigen in the immunofluorescence test (IIFT) against reference sera from six nematode infections. The localisation of the cytosomal antigen antibody-reaction in the IIFT which was described on D. Viteae, was found to be the same for B. malayi, B. pahangi, L. carinii, O. volvulus and A. caninum. This test, just as egg membrane crude preparations of 5 nematodes from the Onchocercidae family, could not differentiate between W. bancrofti, onchocerciasis, loiasis and D. perstans sera. The cuticular fluorescence of five Onchocercidae species, which was observed only in frozen sections, appeared only with W. bancrofti-filariasis and onchocerciasis sera. T. spiralis larvae antigen exhibited only cuticular fluorescence in the frozen section, but in the case, however, against all reference sera. Trichinellosis patients' serum reacted on the other hand only with T. spiralis antigen. Uterine microfilaria from B. malayi, L. carinii, O. volvulus and D. viteae could differenciate species specifically between reference sera.

Adult↗
PubMed1994

KSAYMRFamide: a novel FMRFamide-related heptapeptide from the free-living nematode, Panagrellus redivivus, which is myoactive in the parasitic nematode, Ascaris suum.

In nematodes, FMRFamide-related peptides (FaRPs) have been structurally characterised from the parasite, Ascaris suum, and from two free-living species, Panagrellus redivivus and Caenorhabditis elegans. While both FaRPs isolated from P. redivivus (PF1 and PF2) have been identified in C. elegans, the two heptapeptides isolated from A. suum (AF1 and AF2) have until recently been considered unique to this parasitic species. We have recently isolated AF2 from P. redivivus and, during this study, an additional novel heptapeptide amide, Lys-Ser-Ala-Tyr-Met-Arg-Phe amide (KSAYMRFamide), was structurally characterised. A synthetic replicate of this peptide induced a rapid concentration-dependent muscle tension increase in an isolated. A. suum somatic muscle preparation, with a threshold of approximately 0.1 microM. These data suggest that the complement of FaRPs in parasitic and free-living nematodes may not be as radically different as preliminary studies would suggest, and that the absence of AF1, AF2 and KSAYMRFamide on the C.elegans FMRFamide-related peptide gene (flp-1) may imply the presence of at least two different FaRP genes in nematodes.

Amino Acid Sequence↗
PubMed2001

Nematode chitin synthases: gene structure, expression and function in Caenorhabditis elegans and the plant parasitic nematode Meloidogyne artiellia.

Although the presence of chitin in nematodes is well documented little is known about its synthesis in this phyletic group. The recently completed genome sequence of Caenorhabditis elegans predicts two sequences with homology to chitin synthases (chitin-UDP acetyl-glucosaminyl transferase; EC 2.4.1.16). We show that these genes are differentially expressed in a pattern that may reflect different functional roles. One gene is expressed predominantly in the adult hermaphrodite (the main egg-producing stage in the nematode) and later larval stages, which is consistent with a role in production of chitin for the eggshell. The other gene, however, is expressed in the cells that form the pharynx, and only in the period directly preceding a moult. These data suggest that the product of this gene is involved in synthesis of the feeding apparatus, which is replaced during each moult. We have also isolated a full-length genomic sequence of a chitin synthase orthologue from the plant parasitic nematode Meloidogyne artiellia. The single gene present in M. artiellia shows an expression pattern that is consistent with a role for the protein in production of the eggshell.

Animals↗
PubMed1993

Nematode-trapping fungi against parasitic cattle nematodes.

Interactions between larvae of bovine gastrointestinal nematode parasites and nematode-trapping fungi, such as Arthrobotrys and Duddingtonia species and strains have been studied in Denmark. In this article Jørn Grønvold, Jens Wolstrup, Peter Nansen and Svend Aage Henriksen discuss how these fungi are able to grow, trap and kill parasitic nematode larvae, both on agar in the laboratory and in cattle faeces in the field.

Journal Article↗
PubMed1994

Plant-cyst nematode and plant-root-knot nematode interactions.

Root-knot nematodes and cyst nematodes are obligate plant parasites that cause extensive damage to the agriculture of both temperate and tropical countries. In this review, Andreas Niebel, Godelieve Gheysen and Marc Van Montagu describe how, in the past decade, the use of molecular techniques has provided new insights in the complex interactions between these sedentary plant-parasitic nematodes and their infected host plants. They give an account of the progress in our understanding of both the parasite and the host during compatible and incompatible interactions. They also outline the importance of a new model host system. Arabidopsis thaliana.

Journal Article↗
PubMed1998

The soybean cyst nematode, Heterodera glycines: a genetic model system for the study of plant-parasitic nematodes.

Despite advances in understanding plant responses to nematode infection, little information exists regarding parasitic mechanisms. Recently, it has become possible to perform genetic analysis of soybean cyst nematode. Integration of classic and reverse genetics and genomic approaches for the parasite, with host genetics and genomics will expand our knowledge of nematode parasitism.

Animals↗
PubMed2003

Efficacy of the nematode-trapping fungus Duddingtonia flagrans against three species of gastro-intestinal nematodes in laboratory faecal cultures from sheep and goats.

The ability of the nematode-killing fungus Duddingtonia flagrans to reduce number of infective larvae of three species of gastro-intestinal parasitic nematodes developing in dung was investigated in both goats and sheep. Groups of lambs and kids (12-20 weeks old) were given mono-specific infections of Haemonchus contortus, Ostertagia (Teladorsagia) circumcincta or Trichostrongylus colubriformis. Following patency of the infections (t1) faecal samples were collected for determination of faecal nematode egg count (FEC) and culture of parasite larvae. Groups of animals were then dosed on 2 consecutive days with one of the two dose rates of the fungus (250,000 or 500,000 spores/kg liveweight). One (t2) and 5 (t3) days after the second dose of fungus samples were again collected for FEC and culture. The number of larvae recovered from the faecal cultures at t1 and t3 were used as controls to assess the efficacy of the experimental treatment at t2. Average efficacy was 78% with group means ranging from 40 to 93%. Dose rate of fungus appeared to influence efficacy against O. circumcincta but not against H. contortus or T. colubriformis. Overall, there were no differences in the efficacy of the fungus against any of the parasite species or in either host animal. The results of this trial indicate the potential use of this fungus as a broad spectrum anti-parasite agent for use in both goats and sheep.

Animals↗
PubMed2006

Evolutionary loss of parasitism by nematodes? Discovery of a free-living filaroid nematode.

A cattle-drinking pool in nature reserve "Zwin" on the Belgian coast contained free-living third-stage infective filaroid juveniles. These juveniles clearly differ morphologically from all known nematodes. Morphological and molecular analyses indicate a position within the Filaroidea. The aberrant biology of this nematode, namely, a free-living stage in an aquatic environment, is unknown within this superfamily, and the evolution of the parasitic phenotype to a free-living state is generally thought to be unlikely. However, the obtained placement in the small subunit molecular phylogenetic tree suggests that this free-living stage is most likely a secondary adaptation. It is reasonable to assert that nematodes with complex life cycles still have the genetic potential for a reversion from parasitism to a (partial) free-living stage.

Animals↗
PubMed2006

Substitution of benzimidazole-resistant nematodes for susceptible nematodes in grazing lambs.

Multi-drug-resistant gastrointestinal nematode parasite populations are becoming more and more prevalent. Since anthelmintic treatments are of limited effectiveness, one solution could be to replace the anthelmintic-resistant population by a susceptible population, in order to re-establish the possibility of drug-based anthelmintic control. We investigated this substitution strategy in 4 paddocks of 0.7 ha, each of which was seeded with a benzimidazole-resistant Teladorsagia circumcincta population. The proportion of benzimidazole-resistant worms in these paddocks ranged from 20% to 89%. A 2-step replacement was performed: first, the paddocks were not grazed for 6 months (from December to July), and then the grass was cut to eliminate any residual infective larvae, before contaminating each of the paddocks with 10 seeder lambs experimentally infected with a benzimidazole-susceptible strain of T. circumcincta (from July to November). At the end of the experiment, all the populations on the 4 paddocks were phenotypically benzimidazole-susceptible, but genotyping indicated that 2 populations harboured 1% and 3% resistant worms respectively. This study demonstrates that nematode replacement is feasible in temperate areas, using semi-intensive stock management, even when the initial levels of benzimidazole-resistance are very high. Further research should next assess replacing the whole community to cope with the species diversity observed under field conditions.

Animals↗
PubMed2005

Cecropin P1 and novel nematode cecropins: a bacteria-inducible antimicrobial peptide family in the nematode Ascaris suum.

Cecropin P1 was first identified as a mammalian antimicrobial peptide isolated from the pig intestine. Much research aimed at characterizing this peptide has been reported. Recently, the workers who discovered the peptide corrected their original conclusion, and confirmed that this peptide originates in fact from the pig intestinal parasitic nematode, Ascaris suum. In the present study, we carried out a semi-exhaustive search for bacteria-inducible transcripts in A. suum by the cDNA subtraction method. The transcripts encoding cecropin P1 and novel Ascaris cecropins, designated cecropins P2, P3 and P4, were found to be positively induced factors. Chemically synthesized Ascaris cecropins were bactericidal against a wide range of microbes, i.e. Gram-positive (Staphylococcus aureus, Bacillus subtilis and Micrococcus luteus) and Gram-negative (Pseudomonas aeruginosa, Salmonella typhimurium, Serratia marcescens and Esherichia coli) bacteria, and were weakly but detectably active against yeasts (Saccharomyces cerevisiae and Candida albicans). Cecropin P1-like sequences were also detected at least in two other species (Ascaris lumbricoides and Toxocara canis) of the Ascarididae. All Ascaris cecropin precursors contain an acidic pro-region connected by a tetra-basic cleavage site at the C-terminus. Such an acidic pro-region is also reported to be present in the tunicate cecropin-type antimicrobial peptide styelin. On the basis of the evolutionary position of nematodes and tunicates, the ancestral cecropin may have contained the acidic pro-region at the C-terminus.

Amino Acid Sequence↗
PubMed2000

Susceptibility of Pseudaletia unipuncta (Lepidoptera: Noctuidae) to entomopathogenic nematodes (Rhabditida: Steinernematidae and Heterorhabditidae) isolated in the Azores: effect of nematode strain and host age.

The armyworm, Pseudaletia unipuncta (Haworth), is a serious pest to the Azores's pastures. In laboratory bioassays we tested the susceptibility of this insect to entomopathogenic nematodes isolated in Azores: Steinernema carpocapsae Az20, Az150, and A48 strains, S. glaseri Az26 strain and Heterorhabditis bacteriophora Az33 strain. The A48, Az20, and Az150 strains caused parasitism rates of 96.6, 90, and 53.3%, and mortality rates of 63.3, 46.6, and 23.3%, respectively, to sixth instar. The Az33 strain caused a parasitism rate of 73.3% and a mortality rate of 40%; whereas, the Az26 strain caused a parasitism rate of 40% and no mortality. A linear response dose-parasitism with a positive regression (r2 = 0.993) was observed in insects exposed to S. carpocapsae Az150 strain. Positive regressions were also observed between mortality and dose rate for S. carpocapsae A48 (r2 = 0.980), Az20 (r2 = 0.956), and Az150 (r2 = 0.963) strains, and H. bacteriophora Az33 strain (r2 = 0.999). Fourth instars were the most susceptible to the A48 strain, followed by the fifth instars, while the sixth instars were the less susceptible, with LD50 values of 26.2, 62.8, and 320.7 infective juveniles, respectively. The lethal time for each of the tested instars was 32.3, 35.5, and 49.2 h, respectively. The invasion rate was 33.5, 28.2, and 40.8 nematodes per treated larvae in the fourth, fifth, and sixth instars, respectively.

Animals↗
PubMed1978

Redescription of the nematode Philometra obturans (Prenant, 1886) with a key to the philometrid nematodes parasitic in European freshwater fishes.

A redescription of the nematode Ph. obturans (Prenant, 1886), based on specimens from pike (Esox lucius L.) from the R. Elbe basin in Czechoslovakia, is presented. In addition to gravid, subgravid and mature females from the blood system also the male and mature female, found for the first time in the host's eye, are described. The paper is supplemented by a key for the identification of the philometrid nematodes parasitizing freshwater fishes of Europe.

Animals↗
PubMed1993

IgE antibody responses induced by transplantation of the nematode Nippostrongylus brasiliensis in rats: a possible role of nematode excretory-secretory product in IgE production.

In order to examine the effective site of sensitization for IgE responses, we transplanted 2000 adult-stage worms of the nematode Nippostrongylus brasiliensis into the duodenum or the peritoneal cavity of naive rats. Total serum IgE began to increase 1 week after the nematode inoculations and reached a peak at week 2. Living worms inoculated into the duodenum induced the highest serum IgE, this being 800 times the level in control animals. Intraperitoneal inoculations of living and dead worms resulted in increases of the serum IgE levels to 120 and 13 times the control level, respectively. The intraduodenal inoculation of living adult worms also induced a significant increase in specific IgE against the excretory-secretory (ES) product of adult N. brasiliensis 1 week later than the rise in total IgE, whereas intraperitoneal inoculations did not induce such an increase. These results suggest that sensitization through the intestinal mucosa with adult N. brasiliensis might be important for the effective induction of both specific and non-specific IgE responses. Since these findings also indicated that factors secreted by living worms play an important role in the induction of total IgE response, the ES product was injected to naive rats for 6 consecutive days (total 2.7-4.4 mg). Intraperitoneal injection of the ES product alone induced a 14.7-fold increase in total IgE without any specific IgE response. This indicates that some constituents of the ES product have the potential to trigger a non-specific IgE response.

Allergens↗
PubMed2006

Texel sheep are more resistant to natural nematode challenge than Suffolk sheep based on faecal egg count and nematode burden.

Limited information is available on differences between sheep breeds with respect to helminth resistance under temperate conditions. The present study was designed to confirm and extend preliminary findings on observed breed differences in resistance to naturally acquired gastrointestinal nematodes in Suffolk and Texel sheep. Three trials were carried out. In trial 1 (1999-2003) lambs co-grazed from birth were faecal sampled at various time points up to 17 weeks of age. Worm burden was assessed at 17 weeks of age from a minimum of six lambs per breed in each of the 3 years. In trial 2, faecal egg count (FEC) was determined on six farms with co-grazed Suffolk and Texel purebred lambs. In trial 3 (2001-2003), ewes were faecal sampled at winter housing. In all three trials, an influence of breed on resistance to naturally acquired trichostrongyle infection was demonstrated. In trial 1, significantly higher FEC and worm burden was observed in Suffolk compared with Texel lambs following natural challenge. In trial 2, FEC recorded in lambs from six farms confirmed the breed differences previously observed. A breed difference in resistance to GI parasites was also observed in older ewes. In both breeds, an age effect on the FEC was observed with younger ewes having greater FEC than older ewes.

Age Factors↗