Neuropeptide-like protein diversity in phylum Nematoda

This study reports the identification of nematode neuropeptide-like protein (nlp) sequelogs from the GenBank expressed sequence tag (EST) database, using BLAST (Basic Local Alignment Search Tool) search methodology. Search strings derived from peptides encoded by the 45 known Caenorhabatitis elegans nlp genes were used to identify more than 1000 ESTs encoding a total of 26 multi-species nlp sequelogs. The remaining 18 nlps (nlp-4, -16, -24 through -36, -39, -41 and -45) were identified only in C elegans, while the sole EST representative of nlp-23 was from Caenorhabditis remanei. Several ESTs encoding putative antibacterial peptides similar to those encoded by the C elegans genes nlp-24-33 were observed in several parasite species. A novel gene (nlp-46) was identified, encoding a single, amidated dodecapeptide (NIA[I/T]GR[G/A]DG[F/L]RPG) in eight species. Secretory signal peptides were identified in at least one species representing each nlp sequelog, confirming that all 46 nematode nlp genes encode secretory peptides. A random sub-set of C elegans NLPs was tested physiologically in Ascaris suum ovijector and body wall muscle bioassays. None of the peptides tested were able to modulate ovijector activity, while only three displayed measurable myoactivity on somatic body wall muscle. AFAAGWNRamide (from nlp-23) and AVNPFLDSIamide (nlp-3) both produced a relaxation of body wall muscle, while AIPFNGGMYamide (nlp-10) induced a transient contraction. Numerical analyses of nip-encoding ESTs demonstrate that nlp-3, -13, -14, -15 and -18 are amongst the most highly represented transcripts in the dataset. Using available bioinformatics resources, this study delineates the nlp complement of phylum Nematoda, providing a rich source of neuropeptide ligands for deorphanisation of nematode neuropeptide receptors. (C) 2008 Australian Society for Parasitology Inc. Published by Elsevier Ltd. All rights reserved.

POPULATION BIOLOGY OF HELIGMOSOMOIDES-POLYGYRUS (NEMATODA) IN THE WOOD MOUSE

1. This paper examines the interaction between the wood mouse, Apodemus sylvaticus L., and the intestinal nematode, Heligmosomoides polygyrus Dujardin, using data collected at Tollymore Park Forest, Co. Down, Northern Ireland, between November 1978 and July 1981.

Cellular and subcellular localization of SALMFamide (S1)-like immunoreactivity within the central nervous system of the nematode Ascaris suum (Nematoda, Ascaroidea)

The localization and distribution of SALMFamide (S1)-like immunoreactivity (IR), was determined at both the cellular and subcellular level in the central nervous system (CNS) of the nematode roundworm Ascaris suum. The techniques of indirect immunofluorescence in conjunction with confocal scanning laser microscopy and post-embedding, IgG-conjugated colloidal gold immunostaining were used, respectively. Immunostaining was widespread in the CNS of adult A. suum, with immunoreactivity (IR) being localized in nerve cells and fibres in the ganglia associated with the anterior nerve ring and in the main nerve cords and their commissures. At the subcellular level, gold labeling of peptide was localized exclusively over dense-cored vesicles within nerve cell bodies, nerve axons and nerve terminals of the neuropile of the anterior nerve ring, main ganglia and nerve cords in the CNS. Double-labeling demonstrated an apparent co-localization of S1- and FMRFamide-IR-together IR-together with S1- and pancreatic polypeptide (PP)-IR in the same dense-cored vesicles. Antigen preabsorption experiments indicated little cross-reactivity, if any, between the three antisera; indeed, neither FMRFamide nor PP antigens abolished S1 immunostaining.

ULTRASTRUCTURAL-LOCALIZATION OF PANCREATIC POLYPEPTIDE AND FMRFAMIDE IMMUNOREACTIVITIES WITHIN THE CENTRAL-NERVOUS-SYSTEM OF THE NEMATODE, ASCARIS-SUUM (NEMATODA, ASCAROIDEA)

A post-embedding immunogold technique has been used to examine the subcellular distribution of immunoreactivities to vertebrate pancreatic polypeptide (PP) and to the invertebrate peptide, FMRFamide within the central nervous system (CNS) of the nematode, Ascaris suum. Gold labelling of peptide was localized exclusively over dense-cored vesicles within nerve cell bodies, nerve axons and nerve terminals of the main ganglia and nerve cords in the CNS. Double-labelling of peptides demonstrated an apparent co-localization of PP and FMRFamide immunoreactivities in the same dense-cored vesicles, although populations of dense-cored vesicles that labelled solely for FMRFamide were also evident. Antigen preabsorption studies indicated little or no cross-reactivity between the two antisera.

IMMUNOCYTOCHEMICAL DEMONSTRATION OF PEPTIDERGIC AND SEROTONINERGIC COMPONENTS IN THE ENTERIC NERVOUS-SYSTEM OF THE ROUNDWORM, ASCARIS-SUUM (NEMATODA, ASCAROIDEA)

The localization and distribution of neuropeptides and an indoleamine (serotonin or 5-hydroxytryptamine) in the enteric nervous system (ENS) of the pig roundworm, Ascaris suum, have been determined by the application of an indirect immunofluorescence technique in conjunction with confocal scanning laser microscopy. Whole-mount preparations of pharyngeal, intestinal and rectal regions were screened with antisera to 23 vertebrate peptides, 2 invertebrate peptides and serotonin(= 5-HT). Positive immunoreactivity (IR) was obtained with antisera to pancreatic polypeptide (PP), peptide YY (PYY), FMRFamide, gastrin and serotonin. The only IR observed in the ENS was that evident in the nerve supply to the pharynx and rectal region; no IR was associated with any region of the intestine. The most extensive patterns of IR occurred with antisera to PW, FMRFamide and serotonin. In the pharyngeal component of the ENS, IR was evident in the lateral and dorsal longitudinal pharyngeal nerves, pharyngeal commissures, nerve plexus, and associated nerve cells and fibres. In contrast, the distribution of IR to the PP and gastrin antisera was more restricted and displayed a lower intensity of immunostaining. The other component of the ENS, the rectal enteric system, only yielded immunostaining to FMRFamide. The possible role of neuropeptides and serotonin in the nutritional biology of nematodes is discussed.

IMMUNOCYTOCHEMICAL DEMONSTRATION OF NEUROPEPTIDES IN THE PERIPHERAL NERVOUS-SYSTEM OF THE ROUNDWORM ASCARIS-SUUM (NEMATODA, ASCAROIDEA)

The localisation and distribution of neuropeptides in the peripheral nervous system of the pig roundworm Ascaris suum have been determined by an indirect immunofluorescence technique in conjunction with confocal microscopy. Of the 31 antisera tested, immunostaining was obtained only with antisera to peptide YY (PYY), pancreatic polypeptide (PP) and FMRFamide. Immunostaining for PYY and FMRFamide was evident in the amphidial and papillary ganglia associated with the anterior nerve ring and in the nerves from these ganglia that terminated in sensory receptors within the buccal lips of the parasite. The only peptide immunoreactivity (IR) observed in the reproductive system of either sex was that evident in the nerve supply to the distal region of the vagina in the female worm. It took the form of a well-developed plexus of parallel nerve fibres, cross-connectives and looped commissures. The nerve net diminished in the more proximal region of the vagina. PP-IR was less intense than that for PYY and FMRFamide and was more restricted in distribution, being confined to a small number of nerve fibres in the nerve supply to the vagina; it did not occur in the nerves supplying the anterior sensory receptors. The possible roles of neuropeptides in the sensory and reproductive biology of nematodes are discussed.

IMMUNOCYTOCHEMICAL DEMONSTRATION OF NEUROPEPTIDES IN THE CENTRAL-NERVOUS-SYSTEM OF THE ROUNDWORM, ASCARIS-SUUM (NEMATODA, ASCAROIDEA)

The localization and distribution of neuropeptides in the central nervous system of the pig roundworm, Ascaris suum, have been determined by an indirect immunofluorescence technique in conjunction with confocal microscopy. Antisera to 25 vertebrate peptides and two invertebrate peptides were used to screen the worm for immunoreactivity (IR). Immunostaining was obtained with antisera to pancreatic polypeptide (PP), peptide YY (PYY), neuropeptide Y (NPY), gastrin, cholecystokinin (CCK), substance P (SP), atrial natriuretic peptide (ANP), salmon gonadotropin-releasing hormone (SGnRH), mammalian gonadotropin-releasing hormone (MGnRH), chromogranin A (CGA) and FMRFamide. The most extensive patterns of IR occurred with antisera to PYY, FMRFamide and gastrin. IR was evident in nerve cells and fibres in the ganglia associated with the anterior nerve ring and in the main nerve cords and their commissures; IR to FMRFamide also occurred in the posterior nerve ring. Immunostaining for the other peptides was confined to the nerve cords, with the number of immunoreactive nerve fibres varying from peptide to peptide.

THE FMRFAMIDE-LIKE NEUROPEPTIDE AF2 (ASCARIS-SUUM) IS PRESENT IN THE FREE-LIVING NEMATODE, PANAGRELLUS-REDIVIVUS (NEMATODA, RHABDITIDA)

Available 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 of A. suum heads. 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.