AMGSEFLamide, a member of a broadly conserved peptide family, modulates multiple neural networks inHomarus americanus

Abstract

Recent genomic/transcriptomic studies have identified a novel peptide family whose members share the carboxyl terminal sequence-GSEFLamide. However, the presence/identity of the predicted isoforms of this peptide group have yet to be confirmed biochemically, and no physiological function has yet been ascribed to any member of this peptide family. To determine the extent to which GSEFLamides are conserved within the Arthropoda, we searched publicly accessible databases for genomic/transcriptomic evidence of their presence. GSEFLamides appear to be highly conserved within the Arthropoda, with the possible exception of the Insecta, in which sequence evidence was limited to the more basal orders. One crustacean in which GSEFLamides have been predicted using transcriptomics is the lobster, Homarus americanus. Expression of the previously published transcriptome-derived sequences was confirmed by reverse transcription (RT)-PCR of brain and eyestalk ganglia cDNAs; mass spectral analyses confirmed the presence of all six of the predicted GSEFLamide isoforms-IGSEFLamide, MGSEFLamide, AMGSEFLamide, VMGSEFLamide, ALGSEFLamide and AVGSEFLamidein H. americanus brain extracts. AMGSEFLamide, of which there are multiple copies in the cloned transcripts, was the most abundant isoform detected in the brain. Because the GSEFLamides are present in the lobster nervous system, we hypothesized that they might function as neuromodulators, as is common for neuropeptides. We thus asked whether AMGSEFLamide modulates the rhythmic outputs of the cardiac ganglion and the stomatogastric ganglion. Physiological recordings showed that AMGSEFLamide potently modulates the motor patterns produced by both ganglia, suggesting that the GSEFLamides may serve as important and conserved modulators of rhythmic motor activity in arthropods.

Differential neuropeptide modulation of premotor and motor neurons in the lobster cardiac ganglion

“…Here, we assessed the effects of myosuppressin on the two neuron types in the lobster CG. In both this and a previous study (Stevens et al 2009), myosuppressin exerted clear effects on the isolated and intact CG at concentrations of 10 Ϫ6 to 10 Ϫ8 M. The upper ranges of the concentrations reported by Stevens et al (2009), however, are typically associated with local rather than hormonal release (Dickinson et al 2015(Dickinson et al , 2019aMessinger et al 2005). For example, when FMRFamide-like peptides were measured using a radioimmunoassay based on a FMRF-amide antibody in lobster, concentrations from 10 Ϫ11 to 10 Ϫ10 M were reported in circulating hemolymph (Kobierski et al 1987).…”

“…In this study, we investigated whether myosuppressin was capable of independently modulating the premotor and motor neurons of the CG, and if so, how such modulation might underlie the role of these neurons in the coordinated motor pattern. Because many of the effects of myosuppressin recorded previously and in the present study are evident only at concentrations that are consistent with local rather than hormonal release (i.e., 10 Ϫ6 M rather than 10 Ϫ7 to 10 Ϫ9 M; Dickinson et al 2015Dickinson et al , 2019aMessinger et al 2005), we asked whether myosuppressin is likely to be present within the neurons of the CG. In support of this, we found putative myosuppressin-encoding transcripts expressed in the neurons of the CG.…”

“…Flexibility in neuronal output underlies the ability of pattern-generating networks to elicit a wide array of rhythmic movements (e.g., breathing, locomotion); such flexibility is frequently achieved by the action of neuromodulators ( Delcomyn 1980 ; Marder and Calabrese 1996 ). Both circulating hormones and locally released neuromodulators have been shown to act on neural networks to elicit the physiological changes that lead to changes in behavioral output, although they generally do so at different concentrations ( Dickinson et al 2015 , 2019a ; Messinger et al 2005 ). While a wide range of molecules can serve as neuromodulators, peptides comprise the largest and most diverse group ( Brezina 2010 ; Briggman and Kristan 2008 ; Christie et al 2010a ).…”

Identification of Neuropeptides and Their Receptors in the Ectoparasitoid, Habrobracon hebetor

“…In insects, neuropeptides and their receptors also play significant roles in controlling myriad physiological processes, including development, reproduction, feeding, homeostasis, courtship, circadian rhythm, olfaction, movement, water, and ion homeostasis, among others (Schoofs et al, 2017 ; Dickinson et al, 2019 ; Pandit et al, 2019 ). Due to their specificity and high activity at low concentrations, neuropeptides have also been investigated as potential leads for developing new environmentally-friendly pest control agents (Xiong et al, 2019 ).…”

Cloning of the first cDNA encoding a putative CCRFamide precursor: identification of the brain, eyestalk ganglia, and cardiac ganglion as sites of CCRFamide expression in the American lobster, Homarus americanus

“…In silico analyses of these assemblies have provided evidence supporting the existence of a number of previously unknown peptide families (e.g., Christie, 2014;Conzelmann et al, 2013;Dircksen et al, 2011;Veenstra et al, 2012). While the presence of some of these groups has been confirmed via molecular cloning, mass spectrometry, and/or biochemical isolation and sequencing (e.g., Bao et al, 2015;Dickinson et al, 2019), others remain in silico discoveries only.…”