The peptide FMRFamide activates a divalent cation‐conducting channel in heart muscle cells of the snail Lymnaea stagnalis.

Brezden, B.L.; Benjamin, Paul R.; Gardner, D.R.

doi:10.1113/jphysiol.1991.sp018860

Cited by 35 publications

(24 citation statements)

References 15 publications

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“…FaRPs have long been known to have a wide range of functions in adult molluscs, playing important roles including control of cardiac output (Smith and Hill, 1987;Kanda et al, 1989;Brezden et al, 1991), reproductive endocrinology (Fisher et al, 1993;De Lange et al, 1998), and sensory processing (Sweatt et al, 1989;Endo et al, 1995). To date, the best studied role in larval gastropods involves the control of the velar retractor muscle (Braubach et al, 2006), although further research is likely to demonstrate as wide a diversity of functions in developing molluscs as is already known in mature animals.…”

Section: Discussionmentioning

confidence: 98%

Molecular analysis of two FMRFamide‐encoding transcripts expressed during the development of the tropical abalone haliotis asinina

Cummins

Tollenaere

Degnan

et al. 2011

J of Comparative Neurology

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FMRFamide-related peptides (FaRPs) are involved in numerous neural functions across the animal kingdom and serve as important models for understanding the evolution of neuropeptides. Gastropod molluscs have proved to be particularly useful foci for such studies, but the developmental expression of FaRPs and the evolution of specific transcripts for different peptides are unclear within the molluscs. Here we show that FaRPs are encoded by two transcripts that appear to be splice variants of a single gene in the abalone, Haliotis asinina, which represents the basal vetigastropods. Has-FMRF1 comprises 1,438 nucleotides and encodes a precursor protein of 329 amino acids that can potentially produce two copies of FLRFamide, one copy each of TLAGDSFLRFamide, QFYRIamide, SDPDLDDVIRASLLAYSLDDSPNN, and SVATAPVEAKAVEAGNKDIE, and 13 copies of FMRFamide. The second 1,241-nucleotide transcript, Has-FMRF2, encodes a 206-amino acid precursor protein with single copies of FLRFamide and FMRFamide along with such extended forms as NFGEPFLRFamide, FDSYEDKALRFamide, and NGWLHFamide, in addition to SDPGEDMLKSILLRGAPSNNGLQY and DTUDETTUNDNAHSRQ. Both transcripts are present early in life and are expressed in different but overlapping patterns within the developing larval nervous system. Mass spectrometry and immunocytochemistry demonstrate that FaRPs are cleaved from larger precursors and localize to the developing nervous system. Our results confirm previous evidence that FaRPs are expressed early and potentially play many roles during molluscan development and suggest that the last common ancestor to living gastropods used alternative splicing of an FMRFamide gene to generate a diversity of FaRPs in spatially restricted patterns in the nervous system.

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Section: Discussionmentioning

confidence: 98%

Molecular analysis of two FMRFamide‐encoding transcripts expressed during the development of the tropical abalone haliotis asinina

Cummins

Tollenaere

Degnan

et al. 2011

J of Comparative Neurology

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“…1990b). These peptides, derived from protein precursor 1 of the FMRFamide gene, modulate the frequency and amplitude of the heartbeat (Buckett e f al., 1990a, b;Brezden et al, 1991;Santama et a/., 1993Santama et a/., , 1995b. The Ehe receive weak synaptic inputs from the VWI (Buckett e f al., 1990~).…”

Section: Distribution Of the Acidic Peptide In The Cns Of Lymnaeamentioning

confidence: 98%

Post‐translational Processing of the Alternative Neuropeptide Precursor Encoded by the FMRFamide Gene in the Pulmonate Snail Lymnaea stagnalis

Santama

Li²,

Geraerts³

et al. 1996

Eur J of Neuroscience

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The neuropeptide gene encoding FMRFamide-like peptides in the pulmonate mollusc Lymnaea is subject to alternative splicing that generates cell-specific expression of distinct sets of peptides in the CNS. In this paper, we analyse the post-translational processing of the alternative protein precursor encoded by the exon I, Ill-V transcript (type 2 transcript). We raised anti-peptide antisera specific to distinct segments of the precursor in order to address the pattern of endoproteolytic cleavages, specifically around the tetrabasic site RRKR. We first showed that not all peptides predicted by the precursor structure are generated as final steady-state products. We then identified a novel peptide by biochemical purification, amino acid sequencing and mass spectromettythe 35 amino acid SDPFFRFGKQQVATDDSGELDDEILSRVSDDDKNI, which we termed the acidic peptide, previously not predicted on the basis of the precursor structure. This novel peptide, abundant in the snail brain (0.7 pmol per central nervous system), includes the N-terminal sequence SDPFFRF, which was previously considered to be a variant of the known heptapeptide SDPFLRFamide, also encoded within the same protein precursor. We showed by in situ hybridization and immunocytochemistry that the acidic peptide is produced in all cells that transcribe type 2 FMRFamide mRNA. We mapped the expression of this novel peptide in the CNS and localized it mainly in three identifiable neuronal clusters-the E, F and B groups of cells-and some additional neurons, all situated in three of the eleven central ganglia. lmmunoreactive neurons included the single identifiable visceral white interneuron (VWI or VD4), a key cell of the cardiorespiratory network.

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“…Interestingly, all three channels are activated by the cardioexcitatory peptide FMRFa, and LG and SG channels also by the related peptide FLRFa. The signal transduction route has not been identified but is probably not membrane delimited as application outside the patch stimulates the cell attached recorded activity (Brezden et al, 1991). Ventricular cells from Mercenaria generate a mixed Na + and Ca 2+ dependent action potential, where interestingly the spike is Ca 2+ dependent and the plateau Na + dependent (Devlin, 1993a).…”

Section: Calcium Channels In Molluscs 15mentioning

confidence: 99%

Voltage gated calcium channels in molluscs: classification, Ca2+ dependent inactivation, modulation and functional roles

Kits

Mansvelder

1996

Invertebrate Neuroscience

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Molluscan neurons and muscle cells express transient (T-type like) and sustained LVA calcium channels, as well as transient and sustained HVA channels. In addition weakly voltage sensitive calcium channels are observed. In a number of cases toxin or dihydropyridine sensitivity justifies classification of the HVA currents in L, N or P-type categories. In many cases, however, pharmacological characterization is still preliminary. Characterization of novel toxins from molluscivorous Conus snails may facilitate classification of molluscan calcium channels. Molluscan preparations have been very useful to study calcium dependent inactivation of calcium channels. Proposed mechanisms explain calcium dependent inactivation through direct interaction of Ca2+ with the channel, through dephosphorylation by calcium dependent phosphatases or through calcium dependent disruption of connections with the cytoskeleton. Transmitter modulation operating through various second messenger mediated pathways is well documented. In general, phosphorylation through PKA, cGMP dependent PK or PKC facilitates the calcium channels, while putative direct G-protein action inhibits the channels. Ca2+ and cGMP may inhibit the channels through activation of phosphodiesterases or phosphatases. Detailed evidence has been provided on the role of sustained LVA channels in pacemaking and the generation of firing patterns, and on the role of HVA channels in the dynamic changes in action potentials during spiking, the regulation of the release of transmitters and hormones, and the regulation of growth cone behavior and neurite outgrowth. The accessibility of molluscan preparations (e.g. the squid giant synapse for excitation release studies, Helisoma B5 neuron for neurite and synapse formation) and the large body of knowledge on electrophysiological properties and functional connections of identified molluscan neurons (e.g. sensory neurons, R15, egg laying hormone producing cells, etc.) creates valuable opportunities to increase the insight into the functional roles of calcium channels.

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The peptide FMRFamide activates a divalent cation‐conducting channel in heart muscle cells of the snail Lymnaea stagnalis.

Cited by 35 publications

References 15 publications

Molecular analysis of two FMRFamide‐encoding transcripts expressed during the development of the tropical abalone haliotis asinina

Molecular analysis of two FMRFamide‐encoding transcripts expressed during the development of the tropical abalone haliotis asinina

Post‐translational Processing of the Alternative Neuropeptide Precursor Encoded by the FMRFamide Gene in the Pulmonate Snail Lymnaea stagnalis

Voltage gated calcium channels in molluscs: classification, Ca2+ dependent inactivation, modulation and functional roles

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