title: Arthropod FMRFamide-related peptides modulate muscle activity in helminths.
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.
authors.affiliation: Parasitology Research Group, School of Biology and Biochemistry, Queen's University Belfast, Belfast BT9 7BL, UK. a.mousley@qub.ac.uk
authors.forename: Angela
authors.initials: A
authors.lastname: Mousley
authors.forename: Nikki J
authors.initials: NJ
authors.lastname: Marks
authors.forename: David W
authors.initials: DW
authors.lastname: Halton
authors.forename: Timothy G
authors.initials: TG
authors.lastname: Geary
authors.forename: David P
authors.initials: DP
authors.lastname: Thompson
authors.forename: Aaron G
authors.initials: AG
authors.lastname: Maule
mesh_terms: D000818:Animals; D017165:Ascaris suum / Q000502:physiology*; D019835:FMRFamide / Q000502:physiology; D007447:Invertebrate Hormones / Q000502:physiology*; D008024:Ligands; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D009479:Neuropeptides / Q000502:physiology*; D009842:Oligopeptides / Q000502:physiology*; D010446:Peptide Fragments / Q000502:physiology; D018010:Receptors, Invertebrate Peptide / Q000502:physiology; D014419:Turbellaria / Q000502:physiology*
chemical_list: C055209:FMRFamide receptor; C096424:HVFLRFamide; D007447:Invertebrate Hormones; D008024:Ligands; D009479:Neuropeptides; D009842:Oligopeptides; D010446:Peptide Fragments; D018010:Receptors, Invertebrate Peptide; C096425:VFLRFamide; C058650:leucomyosuppressin; C083410:SDRNFLRFamide; C070157:TNRNFLRFamide; C059573:SchistoFLRFamide; C062380:perisulfakinin; D019835:FMRFamide