The identification of, and studies on, a FMRF-NH2-related peptide from the nematode Haemonchus contortus
The identification of, and studies on, a FMRF-NH2-related peptide from the nematode Haemonchus contortus
Indirect immunocytochemistry was used to identify neurones in Haemonchus contortus that exhibited immunoreactivity to the polyclonal antisera KYSALMFamide (code: BL). It was possible to identify major neurones in the central and motor nervous system of H.contortus that showed BL-like immunoreactivity (SLI), and this pattern of immunoreactivity was also obtained in Ascaris suum. Preabsorption of BL(IV) using FMRFamide-related peptides (FaRPs) abolished SLI in H.contortus in the following decreasing order of potency; AF2>AF1=FLRFamide>FMRFamide. These studies provided evidence that the BL antisera was detecting FaRP-like epitopes in the nervous system of this parasite that had some structural homology to AF2.
BL antisera was used in a standard radioimmunoassay, and was found to cross react preferentially with FaRPs terminating in Leu-Arg-Phe-NH2. The antisera was subsequently used in a RIA to monitor purification of FaRPs from acid: methanol extracts of H.contortus using reverse phase high performance liquid chromatography. Six areas of SLI were resolved and one FaRP was isolated. It was unequivocally identified as AF2 (KHEYLRFamide). A second non-immunoreactive peptide, QPIEYTYIamide was also identified.
The role of AF2 in the nervous system of nematodes was investigated using A.suum as a model organism. It was found that AF2 potentiated the contractions elicited by acetylcholine (ACh) on Ascaris muscle strips by 140±22% and increased the Emax of a concentration-response curve to ACh to 114±6% of the control response. AF2 also increased the relaxation rate of ACh elicited contractions from 0.19±0.04 g. sec-1 in the absence of AF2 to 0.45±0.14 g. sec-1 in the presence of the peptide, an increase of 236%.
It is suggested that one action of AF2 is to increase the rate and strength of nematode muscular contractions by modulating the effect of an endogenous neurotransmitter, and that this modulation may be linked to the peptide inhibiting cAMP, or potentiating the protein kinase C pathways.
University of Southampton
Keating, Christopher David Irving
1996
Keating, Christopher David Irving
Keating, Christopher David Irving
(1996)
The identification of, and studies on, a FMRF-NH2-related peptide from the nematode Haemonchus contortus.
University of Southampton, Doctoral Thesis.
Record type:
Thesis
(Doctoral)
Abstract
Indirect immunocytochemistry was used to identify neurones in Haemonchus contortus that exhibited immunoreactivity to the polyclonal antisera KYSALMFamide (code: BL). It was possible to identify major neurones in the central and motor nervous system of H.contortus that showed BL-like immunoreactivity (SLI), and this pattern of immunoreactivity was also obtained in Ascaris suum. Preabsorption of BL(IV) using FMRFamide-related peptides (FaRPs) abolished SLI in H.contortus in the following decreasing order of potency; AF2>AF1=FLRFamide>FMRFamide. These studies provided evidence that the BL antisera was detecting FaRP-like epitopes in the nervous system of this parasite that had some structural homology to AF2.
BL antisera was used in a standard radioimmunoassay, and was found to cross react preferentially with FaRPs terminating in Leu-Arg-Phe-NH2. The antisera was subsequently used in a RIA to monitor purification of FaRPs from acid: methanol extracts of H.contortus using reverse phase high performance liquid chromatography. Six areas of SLI were resolved and one FaRP was isolated. It was unequivocally identified as AF2 (KHEYLRFamide). A second non-immunoreactive peptide, QPIEYTYIamide was also identified.
The role of AF2 in the nervous system of nematodes was investigated using A.suum as a model organism. It was found that AF2 potentiated the contractions elicited by acetylcholine (ACh) on Ascaris muscle strips by 140±22% and increased the Emax of a concentration-response curve to ACh to 114±6% of the control response. AF2 also increased the relaxation rate of ACh elicited contractions from 0.19±0.04 g. sec-1 in the absence of AF2 to 0.45±0.14 g. sec-1 in the presence of the peptide, an increase of 236%.
It is suggested that one action of AF2 is to increase the rate and strength of nematode muscular contractions by modulating the effect of an endogenous neurotransmitter, and that this modulation may be linked to the peptide inhibiting cAMP, or potentiating the protein kinase C pathways.
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Published date: 1996
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Local EPrints ID: 459379
URI: http://eprints.soton.ac.uk/id/eprint/459379
PURE UUID: d5dc35bb-93e5-4833-8eee-a68d48aca838
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Date deposited: 04 Jul 2022 17:09
Last modified: 04 Jul 2022 17:09
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Author:
Christopher David Irving Keating
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