1
|
Preza M, Van Bael S, Temmerman L, Guarnaschelli I, Castillo E, Koziol U. Global analysis of neuropeptides in cestodes identifies Attachin, a SIFamide homolog, as a stimulant of parasite motility and attachment. J Neurochem 2022; 162:467-482. [PMID: 35689626 DOI: 10.1111/jnc.15654] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 06/07/2022] [Accepted: 06/08/2022] [Indexed: 11/28/2022]
Abstract
Many anthelmintics target the neuromuscular system, in particular by interfering with signaling mediated by classical neurotransmitters. Although peptidergic signaling has been proposed as a novel target for anthelmintics, current knowledge of the neuropeptide complement of many helminth groups is still limited, especially for parasitic flatworms (cestodes, trematodes, and monogeneans). In this work, we have characterized the neuropeptide complement of the model cestode Hymenolepis microstoma. Peptidomic characterization of adults of H. microstoma validated many of the neuropeptide precursor (npp) genes previously predicted in silico, and identified novel neuropeptides that are conserved in parasitic flatworms. Most neuropeptides from parasitic flatworms lack significant similarity to those from other animals, confirming the uniqueness of their peptidergic signaling. Analysis of gene expression of ten npp genes by in situ hybridization confirmed that all of them are expressed in the nervous system and identified cryptic features, including the first evidence of dorsoventral asymmetry, as well as a new population of peripheral peptidergic cells that appears to be conserved in the trematode Schistosoma mansoni. Finally, we characterized in greater detail Attachin, an SIFamide homolog. Although its expression is largely restricted to the longitudinal nerve cords and cerebral commissure in H. microstoma, it shows widespread localization in the larval nervous system of Echinococcus multilocularis and Mesocestoides corti. Exogenous addition of a peptide corresponding to the highly conserved C-terminus of Attachin stimulated motility and attachment of M. corti larvae. Altogether, this work provides a robust experimental foothold for the characterization of peptidergic signaling in parasitic flatworms.
Collapse
Affiliation(s)
- Matías Preza
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Sven Van Bael
- Animal Physiology and Neurobiology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Liesbet Temmerman
- Animal Physiology and Neurobiology, University of Leuven (KU Leuven), Leuven, Belgium
| | - Inés Guarnaschelli
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Estela Castillo
- Laboratorio de Biología Parasitaria, Instituto de Higiene, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Uriel Koziol
- Sección Biología Celular, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| |
Collapse
|
2
|
McKay FM, McCoy CJ, Crooks B, Marks NJ, Maule AG, Atkinson LE, Mousley A. In silico analyses of neuropeptide-like protein (NLP) profiles in parasitic nematodes. Int J Parasitol 2022; 52:77-85. [PMID: 34450132 PMCID: PMC8764417 DOI: 10.1016/j.ijpara.2021.07.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2021] [Revised: 07/01/2021] [Accepted: 07/05/2021] [Indexed: 01/06/2023]
Abstract
Nematode parasite infections cause disease in humans and animals and threaten global food security by reducing productivity in livestock and crop farming. The escalation of anthelmintic resistance in economically important nematode parasites underscores the need for the identification of novel drug targets in these worms. Nematode neuropeptide signalling is an attractive system for chemotherapeutic exploitation, with neuropeptide G-protein coupled receptors (NP-GPCRs) representing the lead targets. In order to successfully validate NP-GPCRs for parasite control it is necessary to characterise their function and importance to nematode biology. This can be aided through identification of receptor activating ligand(s) via deorphanisation. Such efforts require the identification of all neuropeptide ligands within parasites. Here we mined the genomes of nine therapeutically relevant pathogenic nematodes to characterise the neuropeptide-like protein complements and demonstrate that: (i) parasitic nematodes possess a reduced complement of neuropeptide-like protein-encoding genes relative to Caenorhabditis elegans; (ii) parasite neuropeptide-like protein profiles are broadly conserved between nematode clades; (iii) five Ce-nlps are completely conserved across the nematode species examined; (iv) the extent and position of neuropeptide-like protein-motif conservation is variable; (v) novel RPamide-encoding genes are present in parasitic nematodes; (vi) novel Allatostatin-C-like peptide encoding genes are present in both C. elegans and parasitic nematodes; (vii) novel neuropeptide-like protein families are absent in C. elegans; and (viii) highly conserved nematode neuropeptide-like proteins are bioactive. These data highlight the complexity of nematode neuropeptide-like proteins and reveal the need for nomenclature revision in this diverse neuropeptide family. The identification of neuropeptide-like protein ligands, and characterisation of those with functional relevance, advance our understanding of neuropeptide signalling to support exploitation of the neuropeptidergic system as an anthelmintic target.
Collapse
Affiliation(s)
- Fiona M McKay
- Microbes & Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, United Kingdom
| | - Ciaran J McCoy
- Microbes & Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, United Kingdom
| | - Bethany Crooks
- Microbes & Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, United Kingdom
| | - Nikki J Marks
- Microbes & Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, United Kingdom
| | - Aaron G Maule
- Microbes & Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, United Kingdom
| | - Louise E Atkinson
- Microbes & Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, United Kingdom
| | - Angela Mousley
- Microbes & Pathogen Biology, The Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, 19 Chlorine Gardens, Belfast BT9 5DL, United Kingdom.
| |
Collapse
|
3
|
Kreshchenko ND. A Study of the Mechanisms of Action of FMRF-Like Peptides in Inducing Muscle Contraction in Planarians (Platyhelminthes). Biophysics (Nagoya-shi) 2021. [DOI: 10.1134/s000635092103009x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
|
4
|
Mair GR, Halton DW, Maule AG. The neuromuscular system of the sheep tapeworm Moniezia expansa. INVERTEBRATE NEUROSCIENCE 2020; 20:17. [PMID: 32978688 DOI: 10.1007/s10158-020-00246-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 08/05/2020] [Indexed: 01/06/2023]
Abstract
Cestodes are common gastrointestinal parasites of humans and livestock. They attach to the host gut and, without a mouth or intestinal system, absorb nutrients through their epidermis. Here we show that despite this simplified anatomy and sessile lifestyle, they maintain a complex neuromuscular system. We used fluorescently labelled phalloidin as a specific probe for filamentous actin to define the overall organisation of several distinct muscle systems in the cyclophyllidean Moniezia expansa. Like all flatworms, the body wall musculature below the neodermis of this intestinal parasite of sheep is characterised by outer circular and inner longitudinal muscle fibres. Diagonal fibres, typically found in free-living and trematode platyhelminths, on the other hand, are notably absent. Prominent longitudinal sheaths dominate the parenchyma and provide retractor muscles to the four acetabula in the scolex; they attach at the bottom of each cup-shaped holdfast. Within sexually mature proglottids, circular fibres dominate the duct walls of the male and female reproductive systems. Nerve cells and fibres that express serotonin or neuropeptide F supply well-developed innervation to several of the described muscle systems: emanating from the central nervous system, fibres in the periphery develop pervasive nerve nets that anastomose within body wall musculature as well as the parenchymal longitudinal and oblique muscle fibres, and innervate the sexual organs and gonopore in mature proglottids. Using homology searches, we provide evidence for 20 neuropeptide precursors together with four prepropeptide processing enzymes as well as several 5-HT signalling components to be represented in the Moniezia transcriptome.
Collapse
Affiliation(s)
- Gunnar R Mair
- Biomedical Sciences, Iowa State University, 1800 Christensen Drive, 2008 Vet Med, Ames, IA, 50011-1134, USA.
| | - David W Halton
- School of Biological Sciences, Queen's University of Belfast, Belfast, BT9 5DL, UK
| | - Aaron G Maule
- School of Biological Sciences, Queen's University of Belfast, Belfast, BT9 5DL, UK
| |
Collapse
|
5
|
Serotonin and Neuropeptide FMRFamide in the Attachment Organs of Trematodes. Helminthologia 2018; 55:185-194. [PMID: 31662646 PMCID: PMC6662011 DOI: 10.2478/helm-2018-0022] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 06/05/2018] [Indexed: 11/25/2022] Open
Abstract
The serotoninergic and FMRFamidergic nervous system of the attachment organs of trematodes were examined using immunocytochemical techniques and confocal scanning laser microscopy. Adult trematodes from eight families as well as cercariae and metacercariae from ten families were studied. TRITC-conjugated phalloidin was used to stain the muscle fibres. The serotonin- and FMRFamide-immunoreactive (IR) nerve cells and fibres were revealed to be near the muscle fibres of the oral and ventral suckers of the trematodes and their larvae. The results indicate the important role of neurotransmitters, serotonin and neuropeptide FMRFamide in the regulation of muscle activity in the attachment organs of trematodes and can be considered in perspective for the development of new anthelmintic drugs, which can interrupt the function of the attachment organs of the parasites.
Collapse
|
6
|
Reasons to Be Nervous about Flukicide Discovery. Trends Parasitol 2017; 34:184-196. [PMID: 29269027 DOI: 10.1016/j.pt.2017.11.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 11/26/2017] [Accepted: 11/28/2017] [Indexed: 01/21/2023]
Abstract
The majority of anthelmintics dysregulate neuromuscular function, a fact most prominent for drugs against nematode parasites. In contrast to the strong knowledge base for nematode neurobiology, resource and tool deficits have prevented similar advances in flatworm parasites since those driven by bioimaging, immunocytochemistry, and neuropeptide biochemistry 20-30 years ago. However, recent developments are encouraging a renaissance in liver fluke neurobiology that can now support flukicide discovery. Emerging data promote neuromuscular signalling components, and especially G protein-coupled receptors (GPCRs), as next-generation targets. Here, we summarise these data and expose some of the new opportunities to accelerate progress towards GPCR-targeted flukicides for Fasciola hepatica.
Collapse
|
7
|
Quiroga SY, Carolina Bonilla E, Marcela Bolaños D, Carbayo F, Litvaitis MK, Brown FD. Evolution of flatworm central nervous systems: Insights from polyclads. Genet Mol Biol 2015; 38:233-48. [PMID: 26500427 PMCID: PMC4612602 DOI: 10.1590/s1415-475738320150013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Accepted: 04/19/2015] [Indexed: 01/15/2023] Open
Abstract
The nervous systems of flatworms have diversified extensively as a consequence of the broad range of adaptations in the group. Here we examined the central nervous system (CNS) of 12 species of polyclad flatworms belonging to 11 different families by morphological and histological studies. These comparisons revealed that the overall organization and architecture of polyclad central nervous systems can be classified into three categories (I, II, and III) based on the presence of globuli cell masses -ganglion cells of granular appearance-, the cross-sectional shape of the main nerve cords, and the tissue type surrounding the nerve cords. In addition, four different cell types were identified in polyclad brains based on location and size. We also characterize the serotonergic and FMRFamidergic nervous systems in the cotylean Boninia divae by immunocytochemistry. Although both neurotransmitters were broadly expressed, expression of serotonin was particularly strong in the sucker, whereas FMRFamide was particularly strong in the pharynx. Finally, we test some of the major hypothesized trends during the evolution of the CNS in the phylum by a character state reconstruction based on current understanding of the nervous system across different species of Platyhelminthes and on up-to-date molecular phylogenies.
Collapse
Affiliation(s)
- Sigmer Y. Quiroga
- Programa de Biología, Facultad de Ciencias Básicas, Universidad del Magdalena, Santa Marta, Colombia
| | - E. Carolina Bonilla
- Laboratorio de Biología del Desarrollo, Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
| | - D. Marcela Bolaños
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA
- Laboratorio de Biología del Desarrollo, Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
| | - Fernando Carbayo
- Laboratório de Ecologia e Evolução, Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, São Paulo, SP, Brazil
- Programa de Pós-Graduação em Zoologia, Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
| | - Marian K. Litvaitis
- Department of Natural Resources and the Environment, University of New Hampshire, Durham, NH, USA
| | - Federico D. Brown
- Laboratorio de Biología del Desarrollo, Departamento de Ciencias Biológicas, Universidad de los Andes, Bogotá, Colombia
- Programa de Pós-Graduação em Zoologia, Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, SP, Brazil
- Departamento de Zoologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, Brazil
- Centro de Biologia Marinha, Universidade de São Paulo, São Sebastião, Brazil
| |
Collapse
|
8
|
McVeigh P, Atkinson L, Marks NJ, Mousley A, Dalzell JJ, Sluder A, Hammerland L, Maule AG. Parasite neuropeptide biology: Seeding rational drug target selection? Int J Parasitol Drugs Drug Resist 2012; 2:76-91. [PMID: 24533265 PMCID: PMC3862435 DOI: 10.1016/j.ijpddr.2011.10.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2011] [Revised: 10/25/2011] [Accepted: 10/28/2011] [Indexed: 01/16/2023]
Abstract
The rationale for identifying drug targets within helminth neuromuscular signalling systems is based on the premise that adequate nerve and muscle function is essential for many of the key behavioural determinants of helminth parasitism, including sensory perception/host location, invasion, locomotion/orientation, attachment, feeding and reproduction. This premise is validated by the tendency of current anthelmintics to act on classical neurotransmitter-gated ion channels present on helminth nerve and/or muscle, yielding therapeutic endpoints associated with paralysis and/or death. Supplementary to classical neurotransmitters, helminth nervous systems are peptide-rich and encompass associated biosynthetic and signal transduction components - putative drug targets that remain to be exploited by anthelmintic chemotherapy. At this time, no neuropeptide system-targeting lead compounds have been reported, and given that our basic knowledge of neuropeptide biology in parasitic helminths remains inadequate, the short-term prospects for such drugs remain poor. Here, we review current knowledge of neuropeptide signalling in Nematoda and Platyhelminthes, and highlight a suite of 19 protein families that yield deleterious phenotypes in helminth reverse genetics screens. We suggest that orthologues of some of these peptidergic signalling components represent appealing therapeutic targets in parasitic helminths.
Collapse
Affiliation(s)
- Paul McVeigh
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Louise Atkinson
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Nikki J. Marks
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Angela Mousley
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Johnathan J. Dalzell
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| | - Ann Sluder
- Scynexis Inc., P.O. Box 12878, Research Triangle Park, NC 27709-2878, USA
| | | | - Aaron G. Maule
- Molecular Biosciences–Parasitology, Institute of Agri-Food and Land Use, School of Biological Sciences, Queen’s University Belfast, Belfast BT9 7BL, UK
| |
Collapse
|
9
|
McVeigh P, Mair GR, Novozhilova E, Day A, Zamanian M, Marks NJ, Kimber MJ, Day TA, Maule AG. Schistosome I/Lamides--a new family of bioactive helminth neuropeptides. Int J Parasitol 2011; 41:905-13. [PMID: 21554884 PMCID: PMC3118037 DOI: 10.1016/j.ijpara.2011.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2011] [Revised: 03/30/2011] [Accepted: 03/31/2011] [Indexed: 11/19/2022]
Abstract
Here we report the identification of a new family of helminth neuropeptides with members in both nematodes and flatworms, and include preliminary cell biological and functional characterisation of one of the peptides from the trematode parasite of humans, Schistosoma mansoni. Bioinformatics and Rapid Amplification of cDNA Ends (RACE)-PCR were used to identify the complete S. mansoni neuropeptide precursor gene Sm-npp-1, which encodes three pentapeptides bearing the motif (A/G)FVR(I/L).NH(2). Similar peptides were identified in three other flatworm species and in 15 nematode species. Quantitative PCR (qPCR) and immunocytochemical (ICC) analyses showed that Sm-npp-1 is constitutively expressed in larval and adult worms. ICC and confocal microscopy were employed to localise one of the schistosome NPP-1 peptides (GFVRIamide) in adult worms and schistosomules; antibodies labelled a pair of neurones in the cerebral ganglia that extend posteriorly along the main nerve cords. GFVRIamide displayed no detectable co-localisation with FMRFamide-like peptides (FLPs), nor was it detectable in muscle innervation. Exogenously applied peptide had a significant inhibitory effect on the mobility of whole adult worm pairs at 10(-5)M (n = 9). Finally, we explored Sm-npp-1 function in schistosomules using RNA interference (RNAi); we successfully achieved specific knockdown of the Sm-npp-1 transcript (54.46 ± 10.41% knockdown, n = 3), but did not detect any clear, aberrant mobility or morphological phenotypes. NPP-1-like peptides are a new family of helminth peptides with a cell-specific expression pattern distinct from FLPs and a modulatory effect on schistosome muscular activity.
Collapse
Affiliation(s)
- Paul McVeigh
- School of Biological Sciences, Queen's University Belfast, Belfast, UK.
| | | | | | | | | | | | | | | | | |
Collapse
|
10
|
Mousley A, Novozhilova E, Kimber MJ, Day TA. Neuropeptide physiology in helminths. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 692:78-97. [PMID: 21189675 DOI: 10.1007/978-1-4419-6902-6_5] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
Parasitic worms come from two distinct, distant phyla, Nematoda (roundworms) and Platyhelminthes (flatworms). The nervous systems of worms from both phyla are replete with neuropeptides and there is ample physiological evidence that these neuropeptides control vital aspects of worm biology. In each phyla, the physiological evidence for critical roles for helminth neuropeptides is derived from both parasitic and free-living members. In the nematodes, the intestinal parasite Ascaris suum and the free-living Caenorhabditis elegans have yielded most of the data; in the platyhelminths, the most physiological data has come from the blood fluke Schistosoma mansoni. FMRFamide-like peptides (FLPs) have many varied effects (excitation, relaxation, or a combination) on somatic musculature, reproductive musculature, the pharynx and motor neurons in nematodes. Insulin-like peptides (INSs) play an essential role in nematode dauer formation and other developmental processes. There is also some evidence for a role in somatic muscle control for the somewhat heterogeneous grouping ofpeptides known as neuropeptide-like proteins (NLPs). In platyhelminths, as in nematodes, FLPs have a central role in somatic muscle function. Reports of FLP physiological action in platyhelminths are limited to a potent excitation of the somatic musculature. Platyhelminths are also abundantly endowed with neuropeptide Fs (NPFs), which appear absent from nematodes. There is not yet any data linking platyhelminth NPF to any particular physiological outcome, but this neuropeptide does potently and specifically inhibit cAMP accumulation in schistosomes. In nematodes and platyhelminths, there is an abundance of physiological evidence demonstrating that neuropeptides play critical roles in the biology of both free-living and parasitic helminths. While it is certainly true that there remains a great deal to learn about the biology of neuropeptides in both phyla, physiological evidence presently available points to neuropeptidergic signaling as a very promising field from which to harvest future drug targets.
Collapse
Affiliation(s)
- Angela Mousley
- Department of Biomedical Sciences, 2008 Veterinary Medicine Building, Iowa State University, Ames, Iowa 50011-1250, USA
| | | | | | | |
Collapse
|
11
|
Pierson L, Mousley A, Devine L, Marks NJ, Day TA, Maule AG. RNA interference in a cestode reveals specific silencing of selected highly expressed gene transcripts. Int J Parasitol 2010; 40:605-15. [DOI: 10.1016/j.ijpara.2009.10.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2009] [Revised: 10/23/2009] [Accepted: 10/26/2009] [Indexed: 01/31/2023]
|
12
|
Abstract
SUMMARYAs the most primitive metazoan phylum, the Platyhelminthes occupies a unique position in nervous system evolution. Centrally, their nervous system consists of an archaic brain from which emanate one or more pairs of longitudinal nerve cords connected by commissures; peripherally, a diverse arrangement of nerve plexuses of varying complexity innervate the subsurface epithelial and muscle layers, and in the parasitic taxa they are most prominent in the musculature of the attachment organs and egg-forming apparatus. There is a range of neuronal-cell types, the majority being multi- and bipolar. The flatworm neuron is highly secretory and contains a heterogeneity of vesicular inclusions, dominated by densecored vesicles, whose contents may be released synaptically or by paracrine secretion for presumed delivery to target cells via the extracellular matrix. A wide range of sense organ types is present in flatworms, irrespective of life-styles. The repertoire of neuronal substances identified cytochemically includes all of the major candidate transmitters known in vertebrates. Two groups of native flatworm neuropeptides have been sequenced, neuropeptide F and FMRFamide-related peptides (FaRPs), and immunoreactivities for these have been localised in dense-cored neuronal vesicles in representatives of all major fiatworm groups. There is evidence of co-localisation of peptidergic and cholinergic elements; serotoninergic components generally occupy a separate set of neurons. The actions of neuronal substances in flatworms are largely undetermined, but FaRPs and 5-HT are known to be myoactive in all of the major groups, and there is immuno-cytochemical evidence that they have a role in the mechanism of egg assembly.
Collapse
|
13
|
Kreshchenko ND, Sedelnikov Z, Sheiman IM, Reuter M, Maule AG, Gustafsson MKS. Effects of neuropeptide F on regeneration in Girardia tigrina (Platyhelminthes). Cell Tissue Res 2007; 331:739-50. [PMID: 18095002 DOI: 10.1007/s00441-007-0519-y] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2007] [Accepted: 09/13/2007] [Indexed: 11/25/2022]
Abstract
The effects of neuropeptide F (NPF; from Moniezia expansa) on the regeneration of Girardia tigrina were studied. The animals were decapitated and incubated in water (control) or NPF. The dynamics of the proliferation of the neoblasts in the developing tissue were studied during the course of regeneration by monitoring the mitotic index (MI). The effects of incubation in FMRFamide and GYIRFamide on the MI were also tested. The course of cephalic regeneration was followed with in vivo computer-assisted morphometry for up to 7 days. The development of the regenerating nervous system and the musculature was visualised by immunostaining with a primary antiserum to the C-terminal decapeptide of NPF (YFAIIGRPRFa) and tetramethylrhodamine-isothiocyanate-conjugated phalloidin, which stains F-actin in muscle filaments. The study showed that NPF had a stimulatory effect on the mitotic activity of the neoblasts. FMRFamide and GYIRFamide did not have this effect. NPF also stimulated the growth of the regenerating head and the growing nervous system and musculature. NPF is postulated to have a morphogenetic action in the regenerating animals.
Collapse
|
14
|
Mousley A, Maule AG, Halton DW, Marks NJ. Inter-phyla studies on neuropeptides: the potential for broad-spectrum anthelmintic and/or endectocide discovery. Parasitology 2007; 131 Suppl:S143-67. [PMID: 16569287 DOI: 10.1017/s0031182005008553] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Flatworm, nematode and arthropod parasites have proven their ability to develop resistance to currently available chemotherapeutics. The heavy reliance on chemotherapy and the ability of target species to develop resistance has prompted the search for novel drug targets. In view of its importance to parasite/pest survival, the neuromusculature of parasitic helminths and pest arthropod species remains an attractive target for the discovery of novel endectocide targets. Exploitation of the neuropeptidergic system in helminths and arthropods has been hampered by a limited understanding of the functional roles of individual peptides and the structure of endogenous targets, such as receptors. Basic research into these systems has the potential to facilitate target characterization and its offshoots (screen development and drug identification). Of particular interest to parasitologists is the fact that selected neuropeptide families are common to metazoan pest species (nematodes, platyhelminths and arthropods) and fulfil specific roles in the modulation of muscle function in each of the three phyla. This article reviews the inter-phyla activity of two peptide families, the FMRFamide-like peptides and allatostatins, on motor function in helminths and arthropods and discusses the potential of neuropeptide signalling as a target system that could uncover novel endectocidal agents.
Collapse
Affiliation(s)
- A Mousley
- Parasitology Research Group, School of Biology and Biochemistry, Queen's University Belfast, 97 Lisburn Road, Belfast BT9 7BL, Northern Ireland, UK.
| | | | | | | |
Collapse
|
15
|
Abstract
Two distinct families of neuropeptides are known to endow platyhelminth nervous systems - the FMRFamide-like peptides (FLPs) and the neuropeptide Fs (NPFs). Flatworm FLPs are structurally simple, each 4-6 amino acids in length with a carboxy terminal aromatic-hydrophobic-Arg-Phe-amide motif. Thus far, four distinct flatworm FLPs have been characterized, with only one of these from a parasite. They have a widespread distribution within the central and peripheral nervous system of every flatworm examined, including neurones serving the attachment organs, the somatic musculature and the reproductive system. The only physiological role that has been identified for flatworm FLPs is myoexcitation. Flatworm NPFs are believed to be invertebrate homologues of the vertebrate neuropeptide Y (NPY) family of peptides. Flatworm NPFs are 36-39 amino acids in length and are characterized by a caboxy terminal GRPRFamide signature and conserved tyrosine residues at positions 10 and 17 from the carboxy terminal. Like FLPs, NPF occurs throughout flatworm nervous systems, although less is known about its biological role. While there is some evidence for a myoexcitatory action in cestodes and flukes, more compelling physiological data indicate that flatworm NPF inhibits cAMP levels in a manner that is characteristic of NPY action in vertebrates. The widespread expression of these neuropeptides in flatworm parasites highlights the potential of these signalling systems to yield new targets for novel anthelmintics. Although platyhelminth FLP and NPF receptors await identification, other molecules that play pivotal roles in neuropeptide signalling have been uncovered. These enzymes, involved in the biosynthesis and processing of flatworm neuropeptides, have recently been described and offer other distinct and attractive targets for therapeutic interference.
Collapse
Affiliation(s)
- P McVeigh
- Parasitology Research Group, Queen's University Belfast, Belfast BT9 7BL, Northern Ireland, UK
| | | | | | | |
Collapse
|
16
|
Omar HH, Humphries JE, Larsen MJ, Kubiak TM, Geary TG, Maule AG, Kimber MJ, Day TA. Identification of a platyhelminth neuropeptide receptor. Int J Parasitol 2007; 37:725-33. [PMID: 17362965 DOI: 10.1016/j.ijpara.2006.12.019] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2006] [Revised: 12/15/2006] [Accepted: 12/17/2006] [Indexed: 11/17/2022]
Abstract
We report the characterisation of the first neuropeptide receptor from the phylum Platyhelminthes, an early-diverging phylum which includes a number of important human and veterinary parasites. The G protein-coupled receptor (GPCR) was identified from the model flatworm Girardia tigrina (Tricladida: Dugesiidae) based on the presence of motifs widely conserved amongst GPCRs. In two different assays utilising heterologous expression in Chinese hamster ovary cells, the Girardia GPCR was most potently activated by neuropeptides from the FMRFamide-like peptide class. The most potent platyhelminth neuropeptide in both assays was GYIRFamide, a FMRFamide-like peptide known to be present in G. tigrina. There was no activation by neuropeptide Fs, another class of flatworm neuropeptides. Also active were FMRFamide-like peptides derived from other phyla but not known to be present in any platyhelminth. Most potent among these were nematode neuropeptides encoded by the Caenorhabditis elegans flp-1 gene which share a PNFLRFamide carboxy terminal motif. The ability of nematode peptides to stimulate a platyhelminth receptor demonstrates a degree of structural conservation between FMRFamide-like peptide receptors from these two distinct, distant phyla which contain parasitic worms.
Collapse
Affiliation(s)
- Hanan H Omar
- Department of Biomedical Sciences and Neuroscience Program, Iowa State University, Ames IA 50011, USA
| | | | | | | | | | | | | | | |
Collapse
|
17
|
Sebelová S, Stewart MT, Mousley A, Fried B, Marks NJ, Halton DW. The musculature and associated innervation of adult and intramolluscan stages of Echinostoma caproni (Trematoda) visualised by confocal microscopy. Parasitol Res 2004; 93:196-206. [PMID: 15133660 DOI: 10.1007/s00436-004-1120-x] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Gross anatomy of muscle and sensory/motor innervation of adult and intramolluscan developmental stages of Echinostoma caproni have been investigated to ascertain the organisation and the functional correlates of any stage-specific patterns of staining. Using indirect immunocytochemistry to demonstrate neuroactive substances and the phalloidin-fluorescence technique for staining myofibril F-actin, the muscle systems and aminergic and peptidergic innervation of daughter rediae, cercariae, metacercariae, and pre- and post-ovigerous adults were examined and compared using confocal scanning laser microscopy. A complex arrangement of specific muscle fibre systems occurs within the body wall (composed of circular, longitudinal and diagonal fibres), suckers (radial, equatorial, meridional), pharynx (radial, circular), gut caeca (mainly circular), cercarial tail (circular, pseudo-striated longitudinal), and ducts of the reproductive system (circular, longitudinal), presumed to serve locomotor, adhesive, alimentary and reproductive functions. Immunostaining for serotonin (5-HT) and FMRFamide-related peptides (FaRPs) was evident throughout the central (CNS) and peripheral (PNS) nervous systems of all stages, and use of dual-labelling techniques demonstrated separate neuronal pathways for 5-HT and FaRP in both CNS and PNS. FaRP expression in the innervation of the ootype wall was demonstrated only in post-ovigerous worms and not in pre-ovigerous worms, suggesting an involvement of FaRP neuropeptides in the process of egg assembly. Comparison of the present findings with those recorded for other digeneans suggests that muscle organisation and innervation patterns in trematodes are highly conserved.
Collapse
Affiliation(s)
- Sárka Sebelová
- Parasitology Research Group, School of Biology and Biochemistry, Medical Biology Centre, Queen's University Belfast, Belfast, BT9 7BL, UK
| | | | | | | | | | | |
Collapse
|
18
|
Mousley A, Marks NJ, Halton DW, Geary TG, Thompson DP, Maule AG. Arthropod FMRFamide-related peptides modulate muscle activity in helminths. Int J Parasitol 2004; 34:755-68. [PMID: 15111097 DOI: 10.1016/j.ijpara.2004.02.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2004] [Revised: 02/25/2004] [Accepted: 02/25/2004] [Indexed: 11/29/2022]
Abstract
FMRFamide-related peptides are common to a wide variety of invertebrate species, including helminths and arthropods. In arthropods, five distinct FMRFamide-related peptide subfamilies are recognised: the myosuppressins, extended-FLRFamides, -FMRFamides, -RFamides, and sulfakinins, members of which induce potent and diverse myotropic effects. Whilst >80 FMRFamide-related peptides have been identified in nematodes, only four FMRFamide-related peptides have been characterised from flatworms. The Ascaris suum ovijector/body wall bioassay and the Procerodes littoralis muscle fibre bioassay have proved both reliable and sensitive systems for assessing the functional activities of FMRFamide-related peptides in vitro, and data describing the effects of native FMRFamide-related peptides in these systems are rapidly accumulating. This is the first study to determine the cross-phyla activities of non-native FMRFamide-related peptides in both nematode and flatworm species. In the present study, the effects of 10 arthropod FMRFamide-related peptides (leucomyosuppressin [pQDVDHVFLRFamide], schistoFLRFamide [PDVDHVFLRFamide] and truncated analogues [HVFLRFamide and VFLRFamide], lobster peptide I [TNRNFLRFamide], lobster peptide II [SDRNFLRFamide], manducaFLRFamide II [GNSFLRFamide], manducaFLRFamide III [DPSFLRFamide], calliFMRFamide 4 [KPNQDFMRFamide] and perisulfakinin [EQFDDY(SO(3)H)GHMRFamide]), representing the five subfamilies, were examined on the body wall and ovijector of the parasitic porcine nematode, A. suum and dispersed muscle fibres from the free-living turbellarian, P. littoralis. The muscle activity of the ovijector was found to be modulated significantly by each of the arthropod FMRFamide-related peptides tested; the effects were concentration-dependent, reversible and repeatable. All but one (perisulfakinin) of the 10 arthropod FMRFamide-related peptides examined modulated significantly the activity of A. suum body wall muscle. In addition, all of the arthropod FMRFamide-related peptides examined induced potent concentration-dependent contractions of P. littoralis muscle fibres. These results reveal similarities in the ligand requirement(s) between FMRFamide-related peptide receptors within the Phyla Arthropoda, Nematoda and Platyhelminthes, and indicate significant receptor promiscuity, which highlights the potential of FMRFamide-related peptide receptors as legitimate targets for novel endectocidal agents.
Collapse
Affiliation(s)
- Angela Mousley
- Parasitology Research Group, School of Biology and Biochemistry, Queen's University Belfast, Belfast BT9 7BL, UK.
| | | | | | | | | | | |
Collapse
|
19
|
Abstract
Platyhelminthes occupy a unique position in nerve–muscle evolution, being the most primitive of metazoan phyla. Essentially, their nervous system consists of an archaic brain and associated pairs of longitudinal nerve cords cross-linked as an orthogon by transverse commissures. Confocal imaging reveals that these central nervous system elements are in continuity with an array of peripheral nerve plexuses which innervate a well-differentiated grid work of somatic muscle as well as a complexity of myofibres associated with organs of attachment, feeding, and reproduction. Electrophysiological studies of flatworm muscles have exposed a diversity of voltage-activated ion channels that influence muscle contractile events. Neuronal cell types are mainly multi- and bi-polar and highly secretory in nature, producing a heterogeneity of vesicular inclusions whose contents have been identified cytochemically to include all three major types of cholinergic, aminergic, and peptidergic messenger molecules. A landmark discovery in flatworm neuro biology was the biochemical isolation and amino acid sequencing of two groups of native neuropeptides: neuro peptide F and FMRFamide-related peptides (FaRPs). Both families of neuropeptide are abundant and broadly distributed in platyhelminths, occurring in neuronal vesicles in representatives of all major flatworm taxa. Dual localization studies have revealed that peptidergic and cholinergic substances occupy neuronal sets separate from those of serotoninergic components. The physiological actions of neuronal messengers in flatworms are beginning to be established, and where examined, FaRPs and 5-HT are myoexcitatory, while cholinomimetic substances are generally inhibitory. There is immunocytochemical evidence that FaRPs and 5-HT have a regulatory role in the mechanism of egg assembly. Use of muscle strips and (or) muscle fibres from free-living and parasitic flatworms has provided baseline information to indicate that muscle responses to FaRPs are mediated by a G-protein-coupled receptor, and that the signal transduction pathway for contraction involves the second messengers cAMP and protein kinase C.
Collapse
|
20
|
Hrckova G, Velebný S, Halton DW, Day TA, Maule AG. Pharmacological characterisation of neuropeptide F (NPF)-induced effects on the motility of Mesocestoides corti (syn. Mesocestoides vogae) larvae. Int J Parasitol 2004; 34:83-93. [PMID: 14711593 DOI: 10.1016/j.ijpara.2003.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Neuropeptide F is the most abundant neuropeptide in parasitic flatworms and is analogous to vertebrate neuropeptide Y. This paper examines the effects of neuropeptide F on tetrathyridia of the cestode Mesocestoides vogae and provides preliminary data on the signalling mechanisms employed. Neuropeptide F (>/=10 microM) had profound excitatory effects on larval motility in vitro. The effects were insensitive to high concentrations (1 mM) of the anaesthetic procaine hydrochloride suggesting extraneuronal sites of action. Neuropeptide F activity was not significantly blocked by a FMRFamide-related peptide analog (GNFFRdFamide) that was found to inhibit GNFFRFamide-induced excitation indicating the occurrence of distinct neuropeptide F and FMRFamide-related peptide receptors. Larval treatment with guanosine 5'-O-(2-thiodiphosphate) trilithium salt prior to the addition of neuropeptide F completely abolished the excitatory effects indicating the involvement of G-proteins and a G-protein coupled receptor in neuropeptide F activity. Addition of guanosine 5'-O-(2-thiodiphosphate) following neuropeptide F had limited inhibitory effects consistent with the activation of a signalling cascade by the neuropeptide. With respect to Ca(2+) involvement in neuropeptide F-induced excitation of M. vogae larvae, the L-type Ca(2+)-channel blockers verapamil and nifedipine both abolished neuropeptide F activity as did high Mg(+) concentrations and drugs which blocked sarcoplasmic reticulum Ca(2+)-activated Ca(2+)-channels (ryanodine) and sarcoplasmic reticulum Ca(2+) pumps (cyclopiazonic acid). Therefore, both extracellular and intracellular Ca(2+) is important for neuropeptide F excitation in M. vogae. With respect to second messengers, the protein kinase C inhibitor chelerythrine chloride and the adenylate cyclase inhibitor MDL-2330A both abolished neuropeptide F-induced excitation. The involvement of a signalling pathway that involves protein kinase C was further supported by the fact that phorbol-12-myristate-13-acetate, known to directly activate protein kinase C, had direct excitatory effects on larval motility. Although neuropeptide F is structurally analogous to neuropeptide Y, its mode-of-action in flatworms appears quite distinct from the common signalling mechanism seen in vertebrates.
Collapse
Affiliation(s)
- Gabriela Hrckova
- Parasitological Institute of the Slovak Academy of Sciences, Hlinkova 3, 040 01 Kosice, Slovak Republic.
| | | | | | | | | |
Collapse
|
21
|
Stewart MT, Mousley A, Koubková B, Sebelová S, Marks NJ, Halton DW. Development in vitro of the neuromusculature of two strigeid trematodes, Apatemon cobitidis proterorhini and Cotylurus erraticus. Int J Parasitol 2003; 33:413-24. [PMID: 12705934 DOI: 10.1016/s0020-7519(03)00011-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Confocal microscopy interfaced with cytochemical procedures has been used to monitor development of the major muscle systems and associated serotoninergic (5-HT, 5-hydroxytryptamine) and peptidergic (FaRP, FMRFamide-related peptide) innervation of the strigeid trematodes, Apatemon cobitidis proterorhini and Cotylurus erraticus during cultivation in vitro. Sexually undifferentiated metacercariae were successfully grown to ovigerous adults using tissue culture medium NCTC 135, chicken serum and egg albumen. Eggs were produced after 5 days in culture but had abnormal shells and failed to embryonate. 5-HT and FaRP (the flatworm FaRP, GYIRFamide) were localised immunocytochemically in both central and peripheral nervous systems of developing worms. During cultivation, the central serotoninergic and FaRPergic neuronal pathways of the forebody became more extensive, but retained the same basic orthogonal arrangement as found in the excysted metacercaria. Longitudinal extensor and flexor muscles of the hindbody provide support for the developing reproductive complex. The male reproductive tracts were established in advance (day 3) of those of the female system (day 4); completion of the latter was marked by the appearance of the ootype/egg chamber. The inner longitudinal muscle fibres of the female tract appeared prior to the outer and more densely arranged circular muscles. Circular fibres dominate the muscle complement of both alimentary and reproductive tracts. 5-HT- and GYIRFamide-immunoreactivities were demonstrable in the central nervous system (CNS) and subtegumental parasympathetic nervous system (PNS) throughout the culture period, but innervation of the developing reproductive structures was reactive just for 5-HT. Only at the onset of egg production was FaRP-IR observed in the reproductive system and was expressed only in the innervation of the ootype, a finding consistent with the view that FaRPs may regulate egg assembly in platyhelminths.
Collapse
Affiliation(s)
- Michael T Stewart
- Parasitology Research Group, School of Biology and Biochemistry, Medical Biology Centre, Queen's University Belfast, UK
| | | | | | | | | | | |
Collapse
|
22
|
Thompson DP, Davis JP, Larsen MJ, Coscarelli EM, Zinser EW, Bowman JW, Alexander-Bowman SJ, Marks NJ, Geary TG. Effects of KHEYLRFamide and KNEFIRFamide on cyclic adenosine monophosphate levels in Ascaris suum somatic muscle. Int J Parasitol 2003; 33:199-208. [PMID: 12633657 DOI: 10.1016/s0020-7519(02)00259-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
KHEYLRF-NH(2) (AF2) is a FMRFamide-related peptide (FaRP) present in parasitic and free-living nematodes. At concentrations as low as 10 pM, AF2 induces a biphasic tension response, consisting of a transient relaxation followed by profound excitation, in neuromuscular strips prepared from Ascaris suum. In the present study, the effects of AF2 on cyclic adenosine monophosphate (cAMP), cyclic guanosine monophosphate (cGMP) and inositol-1,4,5-triphosphate (IP(3)) levels were measured following muscle tension recordings from 2 cm neuromuscular strips prepared from adult A. suum. AF2 induced a concentration- and time-dependent increase in cAMP, beginning at 1 nM; cAMP levels increased by 84-fold following 1 h exposure to 1 microM AF2. cGMP and IP(3) levels were unaffected by AF2 at concentrations </=1 microM. AF2-induced stimulation of cAMP was unaffected by removal of the dorsal or ventral nerve cord, even though this form of denervation abolished the excitatory phase of the tension response. The effects of 0.1 and 1 microM AF2 on cAMP were also unaffected by 10 microM SDPNFLRF-NH(2) (PF1, an inhibitory FaRP) and 10 microM PF1022A (an inhibitory cyclodepsipeptide), even though each of these peptides abolished the excitatory phase of the tension response induced by AF2. Within an alanine-scan series of AF2 analogues, only KHAYLRF-NH(2) stimulated cAMP production with equipotency to AF2; the effects of this peptide on muscle tension also mimicked AF2. Another excitatory FaRP present in nematodes, KNEFIRF-NH(2) (AF1), also stimulated cAMP production, but was 100-fold less potent than AF2. The stimulatory effects of AF1 on tension and cAMP levels were blocked by an alanine-substituted analogue of this peptide (Ala(6)-AF1, KNEFIAF-NH(2)), while the stimulatory effects of AF2 on tension and cAMP were not affected by this analogue. AF2 and AF1 increase A. suum somatic muscle cAMP by targeting different receptors. Increases in cAMP stimulated by AF2 can be decoupled from the excitatory response caused by this peptide, and it is not possible to establish a causal linkage between the contractile response elicited by this peptide and its effects on cAMP accumulation.
Collapse
Affiliation(s)
- D P Thompson
- Pharmacia Animal Health, 7923-25-410, 7000 Portage Road, Kalamazoo, MI 49001-0199, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
23
|
Dougan PM, Mair GR, Halton DW, Curry WJ, Day TA, Maule AG. Gene organization and expression of a neuropeptide Y homolog from the land planarian Arthurdendyus triangulatus. J Comp Neurol 2002; 454:58-64. [PMID: 12410618 DOI: 10.1002/cne.10440] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Neuropeptide Y is one of the most widespread regulatory peptides within the vertebrate nervous system and shares the C-terminal motif [FY]-x(3)-[LIVM]-x(2)-Y-x(3)-[LIVMFY]-x-R-x-R-[YF] with pancreatic polypeptide, peptide YY, and fish pancreatic peptide Y. All four peptides are believed to have arisen from a single ancestral gene through successive gene duplication events in vertebrates. The origin of this peptide family may date back further still; similarly sized peptide transmitters with an identical C-terminal motif have been identified in molluscs and flatworms and designated neuropeptide F (NPF). Cloning of the npf gene from the parasitic flatworm Moniezia expansa identified some unusual features within the peptide precursor organization but, at the same time, provided support for an evolutionary relationship of npf and npy genes through the presence of a single intron at a conserved position. To extend the analysis of the evolutionary relationships between invertebrate NPF and vertebrate NPY family peptides, the NPF precursor from the turbellarian Arthurdendyus triangulatus was characterized. Sequence analysis revealed the npf transcript to be 362 base pairs in length encoding a single open reading frame of 81 amino acids. The precursor comprises a signal peptide followed by the mature peptide of 36 amino acids in length, terminating in the typical invertebrate GRPRF motif, followed by a carboxyterminal glycyl extension. The NPF precursor of A. triangulatus shows significant similarities to the vertebrate NPY peptides. Indeed, the N-terminus of A. triangulatus prepro-NPF corresponds more closely to that of the vertebrate peptide homologs than to that of other invertebrate NPFs isolated to date. Immunocytochemical localization studies have demonstrated NPF immunoreactivity throughout the nervous system of A. triangulatus, particularly in association with muscular structures. The data support an early evolutionary origin for this peptide transmitter family within the nervous system of basal bilaterians.
Collapse
Affiliation(s)
- Paula M Dougan
- Parasitology Research Group, School of Biology and Biochemistry, Queen's University Belfast, Medical Biology Centre, Belfast BT9 7BL, United Kingdom
| | | | | | | | | | | |
Collapse
|
24
|
Abstract
The use of well-characterized antibodies raised to neuronal signal substances and their application through immunocytochemistry and confocal scanning laser microscopy has revolutionized studies of the flatworm nervous system (NS). Data about flatworm neuropeptides and the spatial relationship between neuropeptides and other neuronal signal substances and muscle fibers are presented. Neuropeptides form a large part of the flatworm NS. Neuropeptides are especially important as myoexcitatory transmitters or modulators, controlling the musculature of the attachment organs, the stomatogastric and the reproductive systems.
Collapse
Affiliation(s)
- M K S Gustafsson
- Department of Biology, Abo Akademi University, Artillerigatan 6, Finland.
| | | | | | | | | | | | | |
Collapse
|
25
|
Zurawski TH, Mousley A, Mair GR, Brennan GP, Maule AG, Gelnar M, Halton DW. Immunomicroscopical observations on the nervous system of adult Eudiplozoon nipponicum (Monogenea: Diplozoidae). Int J Parasitol 2001; 31:783-92. [PMID: 11403769 DOI: 10.1016/s0020-7519(01)00192-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Neuronal pathways have been examined in adult Eudiplozoon nipponicum (Monogenea: Diplozoidae), using cytochemistry interfaced with confocal scanning laser microscopy, in an attempt to ascertain the status of the nervous system. Peptidergic and serotoninergic innervation was demonstrated by indirect immunocytochemistry and cholinergic components by enzyme cytochemical methodology; post-embedding electron microscopical immunogold labelling revealed neuropeptide immunoreactivity at the subcellular level. All three classes of neuronal mediators were identified throughout both central and peripheral elements of a well-differentiated orthogonal nervous system. There was considerable overlap in the staining patterns for cholinergic and peptidergic components, while dual immunostaining revealed serotonin immunoreactivity to be largely confined to a separate set of neurons. The subcellular distribution of immunoreactivity to the flatworm neuropeptide, GYIRFamide, confirmed neuropeptide localisation in dense-cored vesicles in the majority of the axons and terminal varicosities of both central and peripheral nervous systems. Results reveal an extensive and chemically diverse nervous system and suggest that pairing of individuals involves fusion of central nerve elements; it is likely also that there is continuity between the peripheral nervous systems of the two partner worms.
Collapse
Affiliation(s)
- T H Zurawski
- Department of Zoology and Ecology, Masaryk University, 611 37 Brno, Czech Republic
| | | | | | | | | | | | | |
Collapse
|
26
|
Gustafsson MK, Terenina NB, Kreshchenko ND, Reuter M, Maule AG, Halton DW. Comparative study of the spatial relationship between nicotinamide adenine dinucleotide phosphate-diaphorase activity, serotonin immunoreactivity, and GYIRFamide immunoreactivity and the musculature of the adult liver fluke, Fasciola hepatica (Digenea, fasciolidae). J Comp Neurol 2001; 429:71-9. [PMID: 11086290 DOI: 10.1002/1096-9861(20000101)429:1<71::aid-cne6>3.0.co;2-m] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
This is the first detailed description of the nitrergic nervous system in a fluke. In this study, the authors analysed the distribution of the nicotinamide adenine dinucleotide phosphate-diaphorase (NADPH-d) reactivity in neuronal and nonneuronal tissues of the adult fluke Fasciola hepatica and compared this with the distribution of the musculature using tetramethylrhodamine isothiocyanate-phalloidin. To assess the correlation between the number of muscle cells in different parts of the fluke and the NADPH-d-stained cells, the nuclei were stained with Hoechst 333 42, which is specific for chromatin. The spatial relation between the NADPH-d-positive nerves and the 5-hydroxytryptamine (serotonin; 5-HT)-immunoreactive (-IR) and GYIRFamide-IR nervous elements was also examined. The methods complement each other. NADPH-d-positive staining occurs in both in neuronal tissue and nonneuronal tissue. Large, NADPH-d-stained neurones were localised in the nervous system. The oral and ventral suckers are innervated with many large NADPH-d-stained neurones. In addition, the NADPH-d staining reaction follows closely the muscle fibres in both the suckers, in the body, and in the ducts of the reproductive organs. The presence of NADPH-d activity along muscle fibres in F. hepatica and in other flatworms supports a possible myoinhibitory role for nitric oxide. Neuronal nitric oxide synthase in flatworms may form a novel drug target, which would facilitate the development of a novel anthelminthic.
Collapse
Affiliation(s)
- M K Gustafsson
- Department of Biology, Abo Akademi University, FIN-20520 Abo, Finland.
| | | | | | | | | | | |
Collapse
|
27
|
Geary TG, Marks NJ, Maule AG, Bowman JW, Alexander-Bowman SJ, Day TA, Larsen MJ, Kubiak TM, Davis JP, Thompson DP. Pharmacology of FMRFamide-related peptides in helminths. Ann N Y Acad Sci 2000; 897:212-27. [PMID: 10676450 DOI: 10.1111/j.1749-6632.1999.tb07893.x] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Nervous systems of helminths are highly peptidergic. Species in the phylum Nematoda (roundworms) possess at least 50 FMRFamide-related peptides (FaRPs), with more yet to be identified. To date, few non-FaRP neuropeptides have been identified in these organisms, though evidence suggests that other families are present. FaRPergic systems have important functions in nematode neuromuscular control. In contrast, species in the phylum Platyhelminthes (flatworms) apparently utilize fewer FaRPs than do nematodes; those species examined possess one or two FaRPs. Other neuropeptides, such as neuropeptide F (NPF), play key roles in flatworm physiology. Although progress has been made in the characterization of FaRP pharmacology in helminths, much remains to be learned. Most studies on nematodes have been done with Ascaris suum because of its large size. However, thanks to the Caenorhabditis elegans genome project, we know most about the FaRP complement of this free-living animal. That essentially all C. elegans FaRPs are active on at least one A. suum neuromuscular system argues for conservation of ligand-receptor recognition features among the Nematoda. Structure-activity studies on nematode FaRPs have revealed that structure-activity relationship (SAR) "rules" differ considerably among the FaRPs. Second messenger studies, along with experiments on ionic dependence and anatomical requirements for activity, reveal that FaRPs act through many different mechanisms. Platyhelminth FaRPs are myoexcitatory, and no evidence exists of multiple FaRP receptors in flatworms. Interestingly, there are examples of cross-phylum activity, with some nematode FaRPs being active on flatworm muscle. The extent to which other invertebrate FaRPs show cross-phylum activity remains to be determined. How FaRPergic nerves contribute to the control of behavior in helminths, and are integrated with non-neuropeptidergic systems, also remains to be elucidated.
Collapse
Affiliation(s)
- T G Geary
- Animal Health Discovery Research, Pharmacia & Upjohn, Kalamazoo, Michigan 49007-4940, USA.
| | | | | | | | | | | | | | | | | | | |
Collapse
|
28
|
Marks NJ, Maule AG, Li C, Nelson LS, Thompson DP, Alexander-Bowman S, Geary TG, Halton DW, Verhaert P, Shaw C. Isolation, pharmacology and gene organization of KPSFVRFamide: a neuropeptide from Caenorhabditis elegans. Biochem Biophys Res Commun 1999; 254:222-30. [PMID: 9920762 DOI: 10.1006/bbrc.1998.9920] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
To date, 53 peptides with C-terminal RFamides have been identified by the genome sequencing project in the nematode, Caenorhabditis elegans. In this study the FMRFamide-related peptide (FaRP) KPSFVRFamide (879.90 Da [MH]+) was structurally characterized from extracts of the nematode, Caenorhabditis elegans. Two copies of KPSFVRFamide are encoded by a gene designated flp-9. RT-PCR identified a single cDNA product which was confirmed as flp-9 by sequence determination. Flp-9 cDNA was isolated from larval stages of C. elegans but was not detected in adult worms, indicating that its expression is may be developmentally regulated. KPSFVRFamide displays sequence homology to the nematode peptide, KPNFIRFamide (PF4). The physiological effects of KPSFVRFamide, PF4 and the chimeras, KPNFVRFamide and KPSFIRFamide, were measured on body wall muscle and the vagina vera of the parasitic nematode, Ascaris suum. KPNFVRFamide and KPNFIRFamide had Cl--dependent inhibitory activity on innervated and denervated muscle-preparations, whereas KPSFVRFamide and KPSFIRFamide did not elicit a detectable physiological effect. Although all 4 peptides had inhibitory effects on the vagina vera, KPSFVRFamide and KPSFIRFamide (threshold, >/=0.1 microM) were less potent than KPNFVRFamide and KPNFIRFamide (threshold, >/=10 nM).
Collapse
Affiliation(s)
- N J Marks
- Comparative Neuroendocrinology Research Group, Queen's University of Belfast, Belfast, BT9 7BL, Northern
| | | | | | | | | | | | | | | | | | | |
Collapse
|
29
|
Abstract
Parasitic worms come from two very different phyla-Platyhelminthes (flatworms) and Nematoda (roundworms). Although both phyla possess nervous systems with highly developed peptidergic components, there are key differences in the structure and action of native neuropeptides in the two groups. For example, the most abundant neuropeptide known in platyhelminths is the pancreatic polypeptide-like neuropeptide F, whereas the most prevalent neuropeptides in nematodes are FMRFamide-related peptides (FaRPs), which are also present in platyhelminths. With respect to neuropeptide diversity, platyhelminth species possess only one or two distinct FaRPs, whereas nematodes have upwards of 50 unique FaRPs. FaRP bioactivity in platyhelminths appears to be restricted to myoexcitation, whereas both excitatory and inhibitory effects have been reported in nematodes. Recently interest has focused on the peptidergic signaling systems of both phyla because elucidation of these systems will do much to clarify the basic biology of the worms and because the peptidergic systems hold the promise of yielding novel targets for a new generation of antiparasitic drugs.
Collapse
Affiliation(s)
- T A Day
- Department of Pharmacology and Toxicology, Michigan State University, East Lansing 48824, USA.
| | | |
Collapse
|
30
|
Halton DW, Maule AG, Mair GR, Shaw C. Monogenean neuromusculature: some structural and functional correlates. Int J Parasitol 1998; 28:1609-23. [PMID: 9801919 DOI: 10.1016/s0020-7519(98)00063-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Monogenean neuromuscular systems are structurally and functionally well-differentiated, as evidenced by research on the fish-gill parasite, Diclidophora merlangi. The nervous system in the worm exhibits a raft of putative intercellular signalling molecules, localised in neuronal vesicles. There is cytochemical evidence of co-localisation of neuropeptides and cholinergic substances, with aminergic components generally occupying separate neurons. The phalloidin-fluorescence technique for F-actin has enabled the demonstration of muscle organisation in the worm. Body wall musculature comprises circular, longitudinal and diagonal arrays of myofibres whose contractions are believed to be largely myogenic; circular fibres predominate in the walls of the reproductive tracts. The major somatic muscles are longitudinal muscle bundles that traverse the mesenchyme, the most extensive of which extend from the pharynx to the clamps of the haptor. Experiments have shown that some of these muscles may serve in a withdrawal reflex in the worm, which can be evoked by water turbulence. These and the muscles of the suckers, pharynx, clamps, male copulatory organ and ootype are provided with extensive synaptic innervation that is strongly immunoreactive for FMRFamide-related peptides (FaRPs), suggesting contractions may be neurogenic. Examination of the physiological effects of known flatworm FMRFamide-related peptides on muscle contractility in vitro has shown those FMRFamide-related peptides isolated from turbellarians to be the most excitatory. Results are discussed with respect to neuromuscular function in adhesion, alimentation, and reproduction in the worm.
Collapse
Affiliation(s)
- D W Halton
- Comparative Neuroendocrinology Research Group, Queen's University of Belfast, Northern Ireland, U.K.
| | | | | | | |
Collapse
|
31
|
Abstract
The musculature of parasitic platyhelminths (monogeneans, digeneans and cestodes) presents an attractive target for chemotherapeutic intervention in that it is central to locomotory movement and attachment and serves an essential role in alimentation (feeding, translocation of food and digestive waste) and reproduction (insemination, egg formation and oviposition). Here, Gunnar Mair, Aaron Maule, Chris Shaw and David Halton review muscle organization in flatworm parasites, and outline some of the recent physiological and molecular advances that have been made in flatworm muscle research.
Collapse
|
32
|
Humphries JE, Halton DW, Johnston RN, Maule AG, Johnston CF, Shaw C. Cholinergic, serotoninergic and peptidergic components of the nervous system of Haematoloechus medioplexus (Trematoda, Digenea), characterised by cytochemistry. Int J Parasitol 1997; 27:517-25. [PMID: 9193945 DOI: 10.1016/s0020-7519(97)00030-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Cholinergic, serotoninergic and peptidergic neuronal pathways have been demonstrated in whole-mount preparations of the frog-lung digenean trematode, Haematoloechus medioplexus, using enzyme cytochemical methodologies and indirect immunocytochemical techniques in conjunction with confocal scanning laser microscopy. All 3 classes of neuroactive substance were found throughout both central and peripheral elements of a well-developed orthogonal nervous system. Peptidergic immunoreactivity was particularly strong, using antisera directed to native flatworm neuropeptides, neuropeptide F, and FMRF amide-related peptides (FaRPs), and there was significant overlap in the staining with that for cholinergic components. The serotoninergic system appeared quite separate, with the staining localised to a different set of neurons.
Collapse
Affiliation(s)
- J E Humphries
- Comparative Neuroendocrinology Research Group, School of Clinical Medicine, Queen's University of Belfast, U.K
| | | | | | | | | | | |
Collapse
|
33
|
Day TA, Maule AG, Shaw C, Pax RA. Structure-activity relationships of FMRFamide-related peptides contracting Schistosoma mansoni muscle. Peptides 1997; 18:917-21. [PMID: 9357046 DOI: 10.1016/s0196-9781(97)00073-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
This study reports the potent myoactivity of flatworm FMRFamide-related peptides (FaRPs) on isolated muscle fibers of the human blood fluke, Schistosoma mansoni. The turbellarian peptides YIRFamide (EC50 4 eta M), GYIRFamide (EC50 1 eta M), and RYIRFamide (EC50 7 eta M), all induced muscle contraction more potently than the cestode FaRP GNFFRFamide (EC50 500 eta M). Using a series of synthetic analogs of the flatworm peptides YIRFamide, GYIRFamide and RYIRFamide, the structure-activity relationships of the muscle FaRP receptor were examined. With a few exceptions, each residue in YIRFamide is important in the maintenance of its myoactivity. Alanine scans resulted in peptides that were inactive (Ala1, Ala2, Ala3 and Ala4 YIRFamide; Ala4 and Ala5 RYIRFamide) or had much reduced potencies (Ala1, Ala2 and Ala3 RYIRFamide). Substitution of the N-terminal (Tyr1) residue of YIRFamide with the non-aromatic residues Thr or Arg produced analogs with greatly reduced potency. Replacement of the N-terminal Tyr with aromatic amino acids resulted in myoactive peptides (FIRFamide, EC50 100 eta M; WIRFamide, EC50 0.5 eta M). The activity of YIRFamide analogs which possessed a Leu2, Phe2 or Met2 residue (EC50's 10, 1 and 3 eta M, respectively) instead of Ile2 was not significantly altered, whereas, YVRFamide had a greatly reduced (EC50 200 eta M) activity. Replacement of the Phe4 with a Tyr4 (YIRYamide) also greatly lowered potency. Truncated analogs were either inactive (FRFamide, YRFamide, HRFamide, RFamide, Famide) or had very low potency (IRFamide and MRFamide), with the exception of nLRFamide (EC50 20 eta M). YIRF free acid was inactive. In summary, these data show the general structural requirements of this schistosome muscle FaRP receptor to be similar, but not identical, to those of previously characterized molluscan FaRP receptors.
Collapse
Affiliation(s)
- T A Day
- Department of Zoology, Michigan State University, East Lansing 48824, USA.
| | | | | | | |
Collapse
|
34
|
Johnston RN, Halton DW, Anderson PA, Johnston CF, Shaw C. The peptidergic nervous system of the triclad turbellarian, Bdelloura candida (Maricola, Bdellouridae): an immunocytochemical study using an antiserum raised to an endogenous neuropeptide, GYIRFamide. J Comp Neurol 1996; 376:214-22. [PMID: 8951638 DOI: 10.1002/(sici)1096-9861(19961209)376:2<214::aid-cne4>3.0.co;2-6] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The organisation of the nervous system of Bdelloura candida (Tricladida, Maricola, and Bdellouridae) was studied by immunocytochemistry, by using an antiserum raised to the authentic B. candida FMRFamide-related peptide (FaRP), GYIRFamide. Immunostaining was intense and abundant throughout both the central and peripheral nervous systems, being localised to the brain, the longitudinal nerve cords and their transverse and lateral connections, the pharyngeal plexus, the extensive sub-epidermal and sub-muscular plexuses, and elements of the reproductive apparatus. Compared to an earlier anatomical investigation of this species, and also to the neuroanatomy of other triclad turbellarians, the pattern of GYIRFamide-immunoreactivity reveals differences in the following aspects: the shape and structure of the brain, the distribution of longitudinal nerve cords and their relationships with the peripheral nervous system, the structure and distribution of the lateral nerves and the transverse connectives between the longitudinal nerve cords, organisation of the pharyngeal nervous system, and innervation of the eyespots and epidermal sensory structures. Although this study focuses on a descriptive account of the neuroanatomy of Bdelloura candida, by using anti-GYIRFamide as a neuronal marker, the possible functions of the native peptide are also discussed. The quality and reproducibility of the immunostaining obtained during this work highlights the effectiveness of the GYIRFamide antiserum in the neuroanatomical study of flatworms, and also the suitability of B. candida as a model species in studies of the turbellarian nervous system.
Collapse
Affiliation(s)
- R N Johnston
- Comparative Neuroendocrinology Research Group, Schools of Clinical Medicine and Biology/Biochemistry, Queen's University of Belfast, Northern Ireland
| | | | | | | | | |
Collapse
|
35
|
Maule AG, Bowman JW, Thompson DP, Marks NJ, Friedman AR, Geary TG. FMRFamide-related peptides (FaRPs) in nematodes: occurrence and neuromuscular physiology. Parasitology 1996; 113 Suppl:S119-35. [PMID: 9051931 DOI: 10.1017/s0031182000077933] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The occurrence of classical neurotransmitter molecules and numerous peptidic messenger molecules in nematode nervous systems indicate that although structurally simple, nematode nervous systems are chemically complex. Thus far, studies on one nematode neuropeptide family, namely the FMRFamide-related peptides (FaRPs), have revealed an unexpected variety of neuropeptide structures in both free-living and parasitic species. To date 23 nematode FaRPs have been structurally characterized including 12 from Ascaris suum, 8 from Caenorhabditis elegans, 5 from Panagrellus redivivus and 1 from Haemonchus contortus. Ten FaRP-encoding genes have been identified in Caenorhabditis elegans. However, the full complement of nematode neuronal messengers has yet to be described and unidentified nematode FaRPs await detection. Preliminary characterization of the actions of nematode neuropeptides on the somatic musculature and neurones of A, suum has revealed that these peptidic messengers have potent and complex effects. Identified complexities include the biphasic effects of KNEFIRFamide/KHEYLRFamide (AF1/2; relaxation of tone followed by oscillatory contractile activity) and KPNFIRFamide (PF4; rapid relaxation of tone followed by an increase in tone), the diverse actions of KSAYMRFamide (AF8 or PF3; relaxes dorsal muscles and contracts ventral muscles) and the apparent coupling of the relaxatory effects of SDPNFLRFamide/SADPNFLRFamide (PF1/PF2) to nitric oxide release. Indeed, all of the nematode FaRPs which have been tested on somatic muscle strips of A. suum have actions which are clearly physiologically distinguishable. Although we are a very long way from understanding how the actions of these peptides are co-ordinated, not only with those of each other but also with those of the classical transmitter molecules, to control nematode behaviour, their abundance coupled with their diversity of structure and function indicates a hitherto unidentified sophistication to nematode neuromuscular intergration.
Collapse
Affiliation(s)
- A G Maule
- Comparative Neuroendocrinology Research Group, School of Biology and Biochemistry and Clinical Medicine, Queen's University of Belfast, Northern Ireland
| | | | | | | | | | | |
Collapse
|
36
|
Pax RA, Day TA, Miller CL, Bennett JL. Neuromuscular physiology and pharmacology of parasitic flatworms. Parasitology 1996; 113 Suppl:S83-96. [PMID: 9051929 DOI: 10.1017/s003118200007791x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The trematode and cestode flatworms include numerous parasitic forms of major medical and economic importance. A better knowledge of the neuromuscular physiology of these animals could lead to development of new control measures against these parasites. Since these animals are near the stem from which all other animals have evolved, better knowledge of these animals could also yield valuable information about the early evolution of nerve and muscle systems in the animal kingdom. This review focuses on what is known about the characteristics of the somatic muscle in these animals. The anatomy of the muscles is described along with a review of current information about their electrophysiology, including descriptions of the ion channels present. Also included is a summary of recently acquired data concerning the nature of serotonin, peptide, acetylcholine and glutamate receptors on the membranes of the muscles.
Collapse
Affiliation(s)
- R A Pax
- Department of Zoology, Michigan State University, East Lansing 48824, USA
| | | | | | | |
Collapse
|