The effect of the nematode peptides SDPNFLRFamide (PF1) and SADPNFLRFamide (PF2) on synaptic transmission in the parasitic nematode Ascaris suum

Parasitology ◽  
1995 ◽  
Vol 110 (4) ◽  
pp. 449-455 ◽  
Author(s):  
L. Holden-Dye ◽  
C. J. Franks ◽  
R. G. Williams ◽  
R. J. Walker
Keyword(s):  
Synaptic Transmission ◽  
Parasitic Nematode ◽  
Ascaris Suum ◽  
Somatic Muscle ◽  
Free Living ◽  
Panagrellus Redivivus ◽  
Site Of Action ◽  
Free Living Nematode ◽  
Excitatory Junction Potentials ◽  
Input Conductance

SUMMARYThe action of two peptides isolated from the nematode Panagrellus redivivus, PF1 (SDPNFLRFamide) and PF2 (SADPNFLRFamide) have been studied on synaptic transmission in the motornervous system of the parasitic nematode Ascaris suum. Intracellular recordings were made from Ascaris somatic muscle cells and excitatory junction potentials (EJPs) elicited by stimulation of the ventral nerve cord. The EJPs were cholinergic as they were blocked by the Ascaris nicotinic receptor antagonist, benzoquinonium. PF1 caused a slow hyperpolarization, similar to the action of this peptide first reported by Bowman, Geary & Thompson (1990) and further characterized by Franks et al. (1994). The hyper-polarization was accompanied by a marked decrease in the amplitude of the EJPs with an EC50 of 311 ± 30 nM (n = 5). This inhibition is unlikely to be due to a post-synaptic site of action of the peptide as the muscle cell input conductance was not significantly altered by PF1 and furthermore the response to bath-applied acetylcholine was not inhibited by PF1 at concentrations up to 10μM (n = 6). PF2 also inhibited the EJPs in a similar manner to PF1. These studies indicate that both of the peptides isolated from the free-living nematode Panagrellus redivivus have biological activity in the parasitic nematode Ascaris suum. PF1 and PF2 have inhibitory actions in contrast to the predominantly excitatory actions of the Ascaris endogenous peptides AF1 (KNEFIRFamide) and AF2 (KHEYLRFamide). The potent actions of the Panagrellus neuropeptides PF1 and PF2 in Ascaris suggest that peptides with a similar or identical sequence may also occur in Ascarisand have an inhibitory role in the motornervous system.

Nitric oxide mediates the inhibitory effects of SDPNFLRFamide, a nematode FMRFamide-related neuropeptide, in Ascaris suum

1995 ◽  
Vol 74 (5) ◽  
pp. 1880-1888 ◽  
Author(s):  
J. W. Bowman ◽  
C. A. Winterrowd ◽  
A. R. Friedman ◽  
D. P. Thompson ◽  
R. D. Klein ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Specific Binding ◽  
Ascaris Suum ◽  
No Synthase ◽  
Muscle Membrane ◽  
Inhibitory Effects ◽  
Somatic Muscle ◽  
Free Living ◽  
Panagrellus Redivivus ◽  
Free Living Nematode

1. The physiological effects of two Phe-Met-Arg-Phe-NH2 (FMRFamide)-related neuropeptides isolated from the free-living nematode Panagrellus redivivus, SDPNFLRFamide (PF1) and SADPNFLRFamide (PF2), were examined using neuromuscular preparations from the parasitic nematode Ascaris suum. 2. PF1 and PF2 hyperpolarized muscle membrane and induced sustained flaccid paralysis, independent of external Cl-, in both innervated and denervated preparations. 3. PF1 reversed spastic contractions induced by the cholinomimetic levamisole, elevated K+, or the excitatory nematode FMRFamide-related neuropeptides KNEFIRFamide or KHEYLRFamide. 4. PF1 reversal of levamisole contraction was blocked by pretreatment with agents that interfere with nitric oxide (NO) synthesis (e.g., N-nitro-L-arginine), whereas sodium nitroprusside, which releases NO in solution, mimicked PF1 and PF2. 5. NO synthase activity, monitored by the conversion of [3H]arginine to [3H]citrulline, was twice as abundant in A. suum hypodermis as in muscle, but was not present in reproductive tissue. The relative abundance of NO synthase activity in these tissues was similar to the observed specific binding of [3H]PF1. 6. These results suggest that the inhibitory effects of PF1 and PF2 on nematode somatic muscle are mediated by NO, and that the hypodermis may serve a role in this process analogous to that of the endothelium in vertebrate vasculature.

The Pharmacology of Cholinoceptors on the Somatic Muscle Cells of the Parasitic Nematode Ascaris Suum

1991 ◽  
Vol 158 (1) ◽  
pp. 509-530
Author(s):  
L. COLQUHOUN ◽  
L. HOLDEN-DYE ◽  
R. J. WALKER
Keyword(s):  
Nicotinic Receptor ◽  
Nicotinic Receptors ◽  
Parasitic Nematode ◽  
Ascaris Suum ◽  
Muscle Cells ◽  
The Other ◽  
Pharmacological Properties ◽  
Somatic Muscle ◽  
Input Conductance ◽  
Muscarinic Agents

1. Acetylcholine (ACh) elicited depolarization and an increase in input conductance of the somatic muscle cells of the parasitic nematode Ascaris suum. 2. The relative potency of nicotinic and muscarinic agents was studied in this preparation. The order of potency of these compounds was metahydroxyphenylpropyltrimethylammonium (HPPT)> 1,1 dimethyl-4-phenylpiperazinium>(DMPP)> ACh> carbachol> nicotine> tetramethylammonium (TMA+)> muscarone> furtrethonium> arecoline. Decamethonium was also a weak agonist. McN-A-343 elicited a very weak depolarization at concentrations above 1 mmoll−1. Bethanechol and methacholine were without effect up to 1 mmoll−1. Pilocarpine and muscarine elicited a slight hyperpolarization of up to 3 mV with a threshold for the response of around 500 μmoll−1. Oxotremorine (1 mmoll−1) was without effect. 3. The nitromethylene insecticide 2(nitromethylene)tetrahydro 1,3-thiazine (NMTHT), an agonist at insect nicotinic receptors, was without effect on Ascaris muscle cells up to 1 mmoll−1. 4. Mecamylamine and benzoquinonium were the most potent antagonists of the acetylcholine response. The order of potency of the other antagonists was tetraphenylphosphonium (TPP) > quinacrine > pancuronium, curare> trimethaphan> atropine chlorisondamine, decamethonium > hexamethonium > dihydro-/3-ery throidine. 5. The agonist profile of the Ascaris muscle cell ACh receptor clearly indicates that it is nicotinic. The potency of ganglionic and neuromuscular nicotinic receptor antagonists in Ascaris does not enable a further subclassification of this nicotinic receptor. The Ascaris nicotinic receptor seems to possess some of the pharmacological properties of each type of vertebrate nicotinic receptor. The pharmacology of the Ascaris nicotinic receptor is discussed in relation to that of nicotinic receptors in other invertebrate preparations and in vertebrate preparations. Note: To whom reprint requests should be addressed.

The FMRFamide-like neuropeptide AF2 (Ascaris suum) is present in the free-living nematode,Panagrellus redivivus(Nematoda, Rhabditida)

Parasitology ◽  
1994 ◽  
Vol 109 (3) ◽  
pp. 351-356 ◽  
Author(s):  
A. G. Maule ◽  
C. Shaw ◽  
J. W. Bowman ◽  
D. W. Halton ◽  
D. P. Thompson ◽  
...  
Keyword(s):  
Structural Information ◽  
Ascaris Suum ◽  
Alcoholic Extract ◽  
Reverse Phase Hplc ◽  
Free Living ◽  
Panagrellus Redivivus ◽  
Unequivocal Identification ◽  
Free Living Nematode ◽  
Living Species ◽  
Wet Weight

SummaryAvailable primary structural information suggests that the FMRFamide-related peptides (FaRPs) from parasitic and free-living nematodes are different, and that free-living forms may not represent appropriate models for the study of the neurochemistry of parasitic forms in the laboratory. However, here we report the isolation and unequivocal identification of AF2 (originally isolated from the parasite,Ascaris suum) from acidified alcoholic extracts of the free-living species,Panagrellus redivivus. While reverse-phase HPLC analysis of extracts revealed FMRFamide-immunoreactivity to be highly heterogeneous, AF2 was the predominant FMRFamide-immunoreactive peptide present (at least 26 pmol/g wet weight of worms). This peptide was also the major immunoreactant identified by an antiserum raised to the conserved C- terminal hexapeptide amide of mammalian pancreatic polypeptide (PP), which has been used previously to isolate neuropeptide F (NPF). These observations were confirmed by radioimmunoassay and chromatographic fractionation of an acidified alcoholic extract ofA. suumheads. The FMRFamide-related peptides present in a nematode extract may be highly dependent on the extraction medium employed, and these data would suggest that this complement of neuropeptides may not be as different between parasitic and free-living nematodes as initial studies have suggested. Finally, all of the evidence suggests that NPF is not present in nematodes and that the PP-immunoreactant previously demonstrated immunochemically is probably AF2.

scholarly journals Acanthocytes of Stropharia rugosoannulata Function as a Nematode-Attacking Device

2006 ◽  
Vol 72 (4) ◽  
pp. 2982-2987 ◽  
Author(s):  
Hong Luo ◽  
Xuan Li ◽  
Guohong Li ◽  
Yanbo Pan ◽  
Keqin Zhang
Keyword(s):  
Bursaphelenchus Xylophilus ◽  
Mechanical Force ◽  
Free Living ◽  
Pine Wilt ◽  
Panagrellus Redivivus ◽  
Free Living Nematode

ABSTRACT Efficient killing of nematodes by Stropharia rugosoannulata Farlow ex Murrill cultures was observed. This fungus showed the ability to immobilize the free-living nematode Panagrellus redivivus Goodey within minutes and to immobilize the pine wilt nematode Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle within hours on agar plates. Moreover, P. redivivus worms were completely degraded by the fungus within 24 to 48 h. The cultures of S. rugosoannulata studied shared the characteristic of abundantly producing cells with finger-like projections called acanthocytes. We showed that the nematode-attacking activity of this fungus is carried out by these spiny acanthocytes and that mechanical force is an important factor in the process. Furthermore, the growth and nematode-attacking activity of the fungus in soil were also determined, and our results suggest that acanthocytes are functional in soil.

An ion-sensitive microelectrode study on the effect of a high concentration of ivermectin on chloride balance in the somatic muscle bag cells of Ascaris suum

Parasitology ◽  
1993 ◽  
Vol 106 (4) ◽  
pp. 421-427 ◽  
Author(s):  
H. R. Parri ◽  
M. B. A. Djamgoz ◽  
L. Holden-Dye ◽  
R. J. Walker
Keyword(s):  
Receptor Antagonist ◽  
Chloride Channel ◽  
Gaba Receptor ◽  
Parasitic Nematode ◽  
Ascaris Suum ◽  
Muscle Cells ◽  
High Concentration ◽  
Somatic Muscle ◽  
Ion Sensitive Microelectrodes ◽  
Bag Cells

SUMMARYIvermectin has been shown to increase chloride conductances of invertebrate cells. On the muscle cells of the parasitic nematode Ascaris, ivermectin acts as both a GABA receptor antagonist and a chloride channel opener. In this study, ion-sensitive microelectrodes were used to investigate the effect of ivermectin on intracellular C1− concentration of the somatic muscle bag cells of Ascaris suum. Incubation of muscle cells with ivermectin (10 μM in 1% dimethyl sulphoxide vehicle for 60 min) increased intracellular C1− by 2·9 mM or 15% compared to controls (P > 0·01, n = 6).

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