Identification of a Novel Amide Peptide, GLTPNMNSLFF‐NH₂, Involved in the Control of Vas Deferens Motility in Lymnaea stagnalis

Abstract

Peptide messengers are crucial for the execution of male copulatory processes in the snail Lymnaea stagnalis. In this study, we report the purification of a novel peptide from the penis complex of L. stagnalis. This peptide enhances the contraction frequency and contraction amplitude of the vas deferens. Amino acid sequencing and mass spectrometry indicate that the primary structure is GLTPNMNSLFF-NH,. We propose that this amide peptide modulates the transfer rate of semen in the vas deferens.Keywords. Myomodulatory peptide ; purification ; primary structure ; male behaviour Neuropeptides play a crucial role in the regulation of sexual activities of animals, and many unique characteristics of reproductive behaviours can be explained by the modulatory effects of the peptides in the central nervous system and in peripheral structures. In vertebrates, the role of neuropeptides and neuronal networks in the generation of behaviour is often difficult to study, because of the complexity of the brain and problems with the identification of neurons. By contrast, some invertebrates possess accessible brains that control simple behavioural systems that are advantageous for experiments on the role of peptides in behaviour [I, 21. Lymnaea stagnalis is a hermaphrodite snail, in which the neuronal circuits underlying both male behaviour (mating behaviour) and female behaviour (egg laying) are functionally present in each individual [l]. These behaviours are the subject of intense studies at various levels of organization (molecular, cellular, circuit, and behavioural levels). While egg laying is a stereotyped behaviour, male mating is a flexible (nonrhythmic) behaviour consisting of various stages of variable duration that are a prelude to actual copulation [3,4]. The neuronal network in the central nervous system that underlies copulation as a male consists of various clusters of peptidergic neurons that project into the penis nerve. This nerve innervates the male copulation structures, i.e. the penis complex (preputium with penis and retractor and protractor muscles) and the vas deferens, which runs from the prostate gland to the penis. During copulation, the preputium and penis are everted; during intromission, semen is subsequently ejaculated by peristaltic movements of the vas deferens. Finally, the preputium and penis are retracted by the retractor muscles.We are interested in the structure and actions of peptides involved in the control of male reproductive behaviour in Lymnaea. Previous studies suggest that many peptides may be involved [5], however, only a few of them have been characterized [5, 61. In this study, we report the purification, structural and functional characterization of a novel -FFamide peptide (GLTPNMNSLFF-NH,). This peptide does not share amino acid sequence identity with any other identified peptide. The peptide, which was isolated from the penis complex, has an excitatory MATERIALS AND METHODSAnimals. Mature L. stagnalis (22-30 mm) were used. They were cultured under standard laboratory condition...

Neuropeptides encoded by the genomes of the Akoya pearl oyster Pinctata fucata and Pacific oyster Crassostrea gigas: a bioinformatic and peptidomic survey

“…Full and partial-length P. fucata and C. gigas genes were also identified that encoded peptides with identity to allatostatin C (SHIRCLVNVIACY), buccalins (11 variants), CCAP (VFCNGFFGCSNamide, and LFCNTGGCFamide [although these were not verified by MS analysis]) cerebrin/PDF-like (NLGTVDSLYNLPDLLYRamide), FFamide/SIF-like peptides (GMNPNMNSLFFamide) similar in structure to the FFamides found in Lymnaea [ 53 ], FCAP, GGNamide (SKCKGPWANHMCFGGNamide), LASGLVamide (MMDPLASGLVa), LFRYa (SIKIPFRFa), luqin (APQWRPQGRFamide and VCVESNVPGLFKCY), two myomodulin variants (GMPMLRLamide, PFKMLRLamide GGLSMLRL, GLQMLRLamide, and AMPMLRLamide) and (xG/KFFRIamide), Pedal peptide, PKYMDT, sCAP (small Cardio Active Peptide)/pyrokinin-like peptides (APKYFYFPRMamide; SAFYFPRMamide); tachykinins (FGFAPMRamide, 824.01 Da; FRFTALRamide 909.09 Da), and the NdWFamide (Additional file 1 ). We also present for the first time the expression of opioid-like neuropeptides, considered to represent the protostome counterparts of enkephalins [ 2 ] (Additional file 1 ).…”

In silico prediction of neuropeptides from the neural ganglia of Pacific abalone Haliotis discus hannai (Mollusca: Gastropoda)

“…FFamide has been reported in some mollusks, including gastropods. It was first identified in L. stagnalis (Li et al 1995), L. gigantea (Veenstra 2010), Theba pisana (Adamson et al 2015), and the cephalopod S. officinalis (Zatylny-Gaudin et al 2016). This amide peptide is crucial for modulating the transfer rate of semen within the vas deferens.…”

Peptidergic modulation of male sexual behavior inLymnaea stagnalis: structural and functional characterization of –FVamide neuropeptides

“…It is evident that the structural organization of the Lymnaea precursor, of which GAPRFVamide constitutes the major gene product without any copy of FFamide, is very different from the Aplysia precursor. Nevertheless, bioactive FFamide peptide has previously been isolated and characterized in Lymnaea (Li et al . 1995a), suggesting that a distinct Lymnaea FFamide precursor must exist.…”

“…1992). (iii) A screen for bioactive peptides from the male copulatory system identified an –FFamide peptide with a specific role in the modulation of muscular contractions in the male copulatory organs (Li et al . 1995a).…”