The Experts below are selected from a list of 1647 Experts worldwide ranked by ideXlab platform
Ruthann Nichols - One of the best experts on this subject based on the ideXlab platform.
-
FMRFamide related peptides and serotonin regulate drosophila melanogaster heart rate mechanisms and structure requirements
Peptides, 2006Co-Authors: Ruthann NicholsAbstract:Drosophila melanogaster FMRFamide-related peptides (FaRPs) include SDNFMRFamide, PDNFMRFamide, and TDVDHVFLRFamide (dromyosuppressin, DMS); each peptide contains a C-terminal FMRFamide but a different N-terminal extension. FaRPs and serotonin (5-HT) each affect the frequency of D. melanogaster heart contractions in vivo. We examined the cellular expression of FaRPs and 5-HT, and the activities of FMRFamide, SDNFMRFamide, PDNFMRFamide, or DMS and 5-HT on heart rate. FaRPs and 5-HT were not co-localized; FaRP-and 5-HT-immunoreactive fibers extended from different brain cells and innervated the anterior D. melanogaster dorsal vessel. However, no neuron expressed both a FaRP and 5-HT. The effect of FMRFamide and 5-HT was not different from the effect of 5-HT alone on heart rate. The effect of PDNFMRFamide and 5-HT showed an additive effect on heart rate. SDNFMRFamide and 5-HT or DMS and 5-HT resulted in non-additive effects on heart rate. Our data provide evidence for the complexity of FaRP and 5-HT interactions to regulate frequency of heart contractions in vivo. Our results also confirm the biological importance of FaRP N-terminal amino acid extensions.
-
signaling pathways and physiological functions of drosophila melanogaster FMRFamide related peptides
Annual Review of Entomology, 2003Co-Authors: Ruthann NicholsAbstract:▪ Abstract FMRFamide-related peptides (FaRPs) contain a C-terminal RFamide but unique N-terminal extensions. They are expressed throughout the animal kingdom and affect numerous biological activities. Like other animal species, Drosophila melanogaster contains multiple genes that encode different FaRPs. The ease of genetic manipulations, the availability of genomic sequence data, the existence of established bioassays, and its short lifespan make D. melanogaster a versatile experimental organism in which to investigate peptide processing, functions, and signal transduction pathways. Here, the structures, precursor organizations, distributions, and activities of FaRPs encoded by D. melanogaster FMRFamide (dFMRFamide), myosuppressin (Dms), and sulfakinin (Dsk) genes are reviewed, and predictions are made on their signaling pathways and biological functions.
-
the structure of the FMRFamide receptor and activity of the cardioexcitatory neuropeptide are conserved in mosquito
Neuropeptides, 2003Co-Authors: Amanda Duttlinger, Melissa Mispelon, Ruthann NicholsAbstract:Abstract Numerous peptides are structurally related to the cardioexcitatory tetrapeptide FMRFamide. One subgroup of FMRFamide-related peptides (FaRPs) contains an FMRFamide C terminus. Searches of the Drosophila melanogaster genome database identified the first invertebrate FMRFamide G-protein coupled receptor (GPCR), DrmFMRFa-R ( Cazzamali and Grimmelikhuijzen, 2002 ; Meeusen et al., 2002 ). In order to explore molecular mechanisms involved in FMRFamide signal transduction we identified a receptor from the malaria mosquito Anopheles gambiae genome ( Holt et al., 2002 ), AngFMRFa-R, and compared its structure to DrmFMRFa-R. The cytoplasmic loops, extracellular loops, and transmembrane regions are highly conserved between these two FMRFamide receptors. Another subgroup of FaRPs is the sulfakinins which are represented by the consensus structure –XDYGHMRFamide, where X is D or E ( Nichols, 2003 ). We compared AngFMRFa-R and DrmFMRFa-R to the A. gambiae sulfakinin receptors, ASK-R1 and ASK-R2 ( Duttlinger et al., 2003 ), and the D. melanogaster sulfakinin receptors, DSK-R1 and DSK-R2 ( Brody and Cravchik, 2000 ; Hewes and Taghert, 2001 ). The cytoplasmic loops, extracellular loops, and the transmembrane regions are not highly conserved between the FMRFamide and sulfakinin receptors. In order to explore the role of FMRFamide in mosquito biology we measured the effect of the tetrapeptide on in vivo heart rate. The tetrapeptide increased the frequency of spontaneous contractions of the larval mosquito heart and, thus, increased heart rate. These data support the conclusion that the structure of the FMRFamide receptor and activity of the cardioexcitatory FMRFamide neuropeptide are conserved in mosquito.
-
identification in drosophila melanogaster of the invertebrate g protein coupled FMRFamide receptor
Proceedings of the National Academy of Sciences of the United States of America, 2002Co-Authors: Tom Meeusen, Arnold De Loof, Inge Mertens, Elke Clynen, Geert Baggerman, Ruthann Nichols, Ronald J Nachman, Roger Huybrechts, Liliane SchoofsAbstract:We here describe the cloning and characterization of the functionally active Drosophila melanogaster (Drm) FMRFamide receptor, which we designated as DrmFMRFa-R. The full-length ORF of a D. melanogaster orphan receptor, CG 2114 (Berkeley Drosophila Genome Project), was cloned from genomic DNA. This receptor is distantly related to mammalian thyroid-stimulating hormone-releasing hormone receptors and to a set of Caenorhabditis elegans orphan receptors. An extract of 5,000 central nervous systems from the related but bigger flesh fly, Neobellieria bullata (Neb), was used to screen cells expressing the orphan receptor. Successive purification steps, followed by MS, revealed the sequence of two previously uncharacterized endogenous peptides, APPQPSDNFIRFamide (Neb-FIRFamide) and pQPSQDFMRFamide (Neb-FMRFamide). These are reminiscent of other insect FMRFamide peptides, having neurohormonal as well as neurotransmitter functions. Nanomolar concentrations of the Drm FMRFamides (DPKQDFMRFamide, TPAEDFMRFamide, SDNFMRFamide, SPKQDFMRFamide, and PDNFMRFamide) activated the cognate receptor in a dose-dependent manner. To our knowledge, the cloned DrmFMRFa-R is the first functionally active FMRFamide G protein-coupled receptor described in invertebrates to date.
-
drosophila melanogaster FMRFamide containing peptides redundant or diverse functions
Peptides, 2002Co-Authors: Janna Merte, Ruthann NicholsAbstract:FMRFamide-related peptides (FaRPs) are expressed throughout the animal kingdom and regulate a multitude of physiological activities. FaRPs have an RFamide C-terminal consensus structure that is important for interaction with the receptor. The ease of genetic manipulation and availability of genomic sequences makes Drosophila melanogaster an important experimental organism. Multiple classes of FaRPs encoded by different genes have been identified within this species. Here, we review FMRFamide-containing peptides encoded by the D. melanogaster FMRFamide gene in order to review the data on the expression, regulation, and activity of these peptides as well as acknowledge further endeavors required to elucidate FaRP signaling.
G A Cottrell - One of the best experts on this subject based on the ideXlab platform.
-
location of a ligand recognition site of FMRFamide gated na channels
FEBS Letters, 2001Co-Authors: Michael C Jeziorski, G A Cottrell, Kevin A GreenAbstract:The second FMRFamide-gated Na+ channel (HtFaNaC), from Helisoma trivolvis, has been cloned. HtFaNaC has some different pharmacological properties to HaFaNaC, from Helix aspersa, which has enabled a rational approach to be made to start to identify the FMRFamide recognition site. Several chimeras were made by switching sections between the channels. The differences in sensitivity to FMRFamide, and amiloride, were assessed after expression in Xenopus oocytes. The data suggest that a recognition site for FMRFamide, and the potentiating action of amiloride, resides in a sequence of about 120 amino acids in the extracellular loop proximal to the first transmembrane segment.
-
cloning and expression of a FMRFamide gated na channel from helisoma trivolvis and comparison with the native neuronal channel
The Journal of Physiology, 2000Co-Authors: Michael C Jeziorski, Kevin A Green, John Sommerville, G A CottrellAbstract:We have cloned a cDNA encoding a Phe-Met-Arg-Phe-NH2 (FMRFamide)-gated Na+ channel from nervous tissue of the pond snail Helisoma trivolvis (HtFaNaC) and expressed the channel in Xenopus oocytes. The deduced amino acid sequence of the protein expressed by HtFaNaC is 65 % identical to that of the FMRFamide-gated channel cloned from Helix aspersa (HaFaNaC). HtFaNaC expressed in oocytes was less sensitive to FMRFamide (EC50 = 70 μM) than HaFaNaC (EC50 = 2 μM). The two had a similar selectivity for Na+. The amplitude of the FMRFamide response of HtFaNaC was increased by reducing the extracellular concentration of divalent cations. The conductance of the two channels was similar, but the mean open time of unitary events was shorter for expressed HtFaNaC compared to expressed HaFaNaC. Each channel was susceptible to peptide block by high agonist concentrations. In marked contrast to HaFaNaC and other amiloride-sensitive Na+ channels, amiloride, and the related drugs benzamil and 5-(N-ethyl-N-isopropyl)-amiloride (EIPA), enhanced the FMRFamide response in oocytes expressing HtFaNaC cRNA. The potentiating effects of EIPA and benzamil were greater than those of amiloride. Unitary current analysis showed that with such drugs, there was channel blockade as well as an increased probability of channel opening. The similar permeability of the oocyte-expressed HtFaNaC and the Helisoma neuronal channel, and the susceptibility of both to agonist blockade and blockade by divalent cations, suggest that the channels are the same. However, neuronal channels were less susceptible to enhancement by amiloride analogues and in some patches were more sensitive to FMRFamide than expressed HtFaNaC. The fast depolarization activated by the neuropeptide FMRFamide in Helixaspersa (subsequently referred to here as Helix) neurones is mediated by a ligand-gated ion channel. This response is notable not only because it is uniquely gated by a peptide, but also because the channel is selective for Na+ and blocked by amiloride (Cottrell et al. 1990; Green et al. 1994). The cDNA of a channel with similar properties (FaNaC) was cloned from Helix neurones and expressed in Xenopus oocytes (Lingueglia et al. 1995). FaNaC (subsequently referred to here as HaFaNaC) is similar in structure to the amiloride-sensitive epithelial Na+ channel (ENaC) and the degenerins of Caenorhabditiselegans (see North, 1996). Available data suggest that the functional FMRFamide-gated channel is a homotetramer (Coscoy et al. 1998). More recently, similar amiloride-sensitive channels have been cloned from mammalian nervous tissue, some of which can be activated by H+ (see Waldmann & Lazdunski, 1998; Chen et al. 1998). To help define functional domains in this new class of ligand-gated ion channel, we have cloned the cDNA encoding a FMRFamide-gated channel subunit (HtFaNaC) from the pond snail Helisomatrivolvis (subsequently referred to here as Helisoma) and expressed the protein in Xenopus oocytes. The deduced amino acid sequence of the Helisoma channel shows many similarities to that of HaFaNaC but there are differences in agonist sensitivity. The properties of the expressed HtFaNaC clone are similar to those of the neuronal FMRFamide-gated channel of the giant dopamine neurone (GDN) and the large serotonin neurone (LSN), which are located in the pedal ganglia of Helisoma (Harris & Cottrell, 1995). During the course of the work we observed that amiloride, benzamil and ethylisopropylamiloride (EIPA), which are known to block epithelial Na+ channels and related channels (see e.g. Benos et al. 1997), had an unusual potentiating effect on FMRFamide-activated currents of HtFaNaC expressed in Xenopus oocytes. This led to studies designed to compare the effects of amiloride and EIPA in more detail at the whole-cell and unitary current level on expressed HtFaNaC and also on Helisoma neurones, the results of which are included here.
-
FMRFamide related peptides potentiate transmission at the squid giant synapse
Experimental Physiology, 1992Co-Authors: G A Cottrell, R Llinas, D A Price, M Sugimori, J W Lin, E F StanleyAbstract:The stellate ganglion of the squid Loligo pealli contains the neuropeptides Phe-Met-Arg-Phe-NH2 (FMRFamide), Phe-Leu-Arg-Phe-NH2 (FLRFamide) and at least one N-terminally extended FMRFamide-related peptide that is yet to be fully characterized. Both local application and arterial perfusion of FLRFamide potentiate transmission at the giant synapse. The N-terminally related peptide Ser-Asp-Pro-Phe-Leu-Arg-Phe-NH2 (SDPFLRFamide) produced a similar effect. The threshold for both the tetra- and the hepta-peptides was less than 10 microM. Potentiation could be detected as an increase in rate of rise of the EPSPs, as an increase in amplitude of the EPSP in the absence of spikes, or under voltage clamp as an increase in the EPSC. The effect was most pronounced when the synapse was fatigued by high frequency stimulation. Another molluscan peptide, eledoisin and also leucine enkephalin were without effect. In the absence of any detectable effects of FLRFamide on the resting membrane potential of either pre- or postsynaptic terminals or on the presynaptic spike, it is suggested that the peptide influences transmitter mobilization. However, the peptide could also exert small changes in preterminal calcium currents, which so far we have been unable to detect.
William G Bendena - One of the best experts on this subject based on the ideXlab platform.
-
FMRFamide related peptides a multifunctional family of structurally related neuropeptides in insects
Advances in Insect Physiology, 2001Co-Authors: Ian Orchard, Angela B Lange, William G BendenaAbstract:Publisher Summary This chapter reviews the information available on the extensive FMRFamide (Phe-Met-Arg-Pheamide)-related peptides (FaRPs) family in insects. The chapter examines the principles behind peptide discovery and the way information can be used as a tool for further investigation. In addition, it puts into perspective the FaRP family from gene to behavior, examining the molecular biology, distribution, receptor activation through to biological activity, and integrative actions on behavior. FMRFamide is regarded as the primary member of an extensive family of peptides with diverse biological activities. The FaRP family may itself be divided into subfamilies, including the extended FMRFamides, FLRFamides, HMRFamides and related peptides. Several molecular biological techniques have been applied to isolate either new members of the FaRP gene family or the homologous gene from a different species using available FaRP-encoding genomic DNA or cDNA as a probe. The most common method is screening of libraries of DNA sequences under conditions of reduced stringency. However, more research is needed on this family of neuropeptides before a clear picture emerges as to their true physiological relevance.
-
characterization of the gene for leucomyosuppressin and its expression in the brain of the cockroach diploptera punctata
Insect Biochemistry and Molecular Biology, 1996Co-Authors: Cameron B Donly, Ian Orchard, M Fuse, Stephen S Tobe, William G BendenaAbstract:Abstract Using HPLC separation, radioimmunoassay, and subsequent bioassay, we have detected the presence of an active peptide, which co-elutes with the insect myoinhibitory peptide leucomyosuppressin, in the brain of the cockroach Diploptera punctata . We have isolated a cDNA encoding the precursor for this peptide from cDNA libraries representing D. punctata brain RNA. The cDNA sequence contains an open reading frame that upon translation would result in a prepropolypeptide of 96 amino acids. Proteolytic cleavage of the predicted precursor could result in several peptides, including a 10 amino acid C-terminal peptide that would, upon modification of the NH 2 and COOH-terminal amino acids, be identical to the insect FLRFamide, leucomyosuppressin. No other RFamide products are predicted to be processed from the precursor. Southern blot analysis indicates that the gene is present in the D. punctata genome in a single copy. Northern blot analysis shows that the gene is predominantly expressed as a 3.8 kb mRNA in cockroach brain. Study of the expression of the leucomyosuppressin gene in D. punctata brain, using in situ hybridization, indicates that expression occurs primarily in the pars intercerebralis of the protocerebrum, a region showing abundant FMRFamide-like immunoreactive neurosecretory cells. Immunohistochemistry and HPLC coupled to radioimmunoassay indicates that leucomyosuppressin represents a significant proportion of FMRFamide-related peptide production in the brain. However, HPLC analysis also indicates the presence of significant levels of other related peptides, demonstrating the presence of more than one FMRFamide-related gene in this insect.
Grazia Tagliafierro - One of the best experts on this subject based on the ideXlab platform.
-
three dimensional computer aided reconstruction of FMRFamide immunopositive neuron distribution in the ventral ganglion of the barnacle balanus amphitrite cirripedia crustacea
European Journal of Histochemistry, 2009Co-Authors: Lorenzo Gallus, Alberto Diaspro, Francesco Beltrame, Marco Fato, Grazia TagliafierroAbstract:We have implemented a simple program to solve three of the problems related to 3D reconstruction (3D-Rec) of soft tissues: alignment of sections, distortions, and estimation of the spatial position of elements of interest inside the tissues. As a model, we chose the distribution of FMRFamide-like immunopositive neurons in the ventral ganglion of the barnacle Balanus amphitrite collected during different seasonal periods. Images of immunostained sections were acquired by means of a CCDcamera- equipped microscope and a PC and the reference points were taken inside the sections. The FMRFamide-like immunopositive neurons detected in the barnacle ventral ganglion were grouped into four different classes according to size, shape and staining intensity. More numerous FMRFamide- like immunopositive neurons were detected in the autumn-collected barnacle than in the summer counterpart. The two 3D reconstructions obtained from transverse and longitudinal ventral ganglion sections were efficaciously compared after 90° rotation of one of them. Comparison of these two 3D-Rec suggests the presence of at least two groups of FMRFamide-like immunopositive neurons that are seasonally-related and probably involved in reproduction.
-
distribution of FMRFamide like immunoreactivity in the alimentary tract and hindgut ganglia of the barnacle balanus amphitrite cirripedia crustacea
Microscopy Research and Technique, 2006Co-Authors: Lorenzo Gallus, Paola Ramoino, Sara Ferrando, Massimiliano Bottaro, Laura Girosi, Grazia TagliafierroAbstract:In this study, the presence and distribution of FMRFamide-like immunoreactivity in the alimentary tract of barnacle Balanus amphitrite were investigated. A net of nerve fibers strongly immunoreactive to FMRFamide-like molecules was localized in the posterior midgut and hindgut. Positive varicose nerve terminals were also localized close to the circular muscle cells and, in the hindgut, close to the radial muscular fibers. Besides this nerve fibers network, one pair of contralateral ganglia was localized in the hindgut, each of them constituted by two strongly FMRFamide-labeled neurons and one nonlabeled neuron. Their immunoreactive axons directed toward the hindgut and posterior midgut suggest an involvement of FMRFamide-like substances in adult B. amphitrite gut motility. The hindgut associated ganglia of barnacles seem to correspond to the terminal abdominal ganglia of the other crustaceans. Since they are the only residual gut ganglia in the barnacle's reduced nervous system, we can hypothesize that gut motility needs a nervous system regulation partially independent of the central nervous system.
Reinhard Predel - One of the best experts on this subject based on the ideXlab platform.
-
toward a single cell based analysis of neuropeptide expression in periplaneta americana antennal lobe neurons
The Journal of Comparative Neurology, 2012Co-Authors: Susanne Neupert, Joachim Schachtner, Debora Fusca, Peter Kloppenburg, Reinhard PredelAbstract:A multitude of potential neurotransmitters and neuromodulators, including peptides, have been detected in the antennal lobe (AL), the first synaptic relay of the central olfactory pathway in the insect brain. However, the functional role of neuropeptides in this system has yet to be revealed. An important prerequisite to understanding the role of neuropeptides is to match the functionally different cell types in the AL with their peptide profiles by using electrophysiological recordings combined with immunocytochemical studies and/or single-cell mass spectrometry. The olfactory system of Periplaneta americana is particularly well suited to accomplish this goal because several physiologically distinct neuron types can be unequivocally identified. With the aim to analyze the neuropeptide inventory of the P. americana AL, this study is an essential step in this direction. First, we systematically analyzed different parts of the AL by matrix-assisted laser desorption/ionization time of flight (MALDI-TOF) mass spectrometry to obtain the complete set of neuropeptides present. Altogether, 56 ion signals could be assigned to products of 10 neuropeptide genes (allatostatins A, B, C, SIFamide, allatotropin, FMRFamide-related peptides [myosuppressin, short neuropeptides F, extended FMRFamides], crustacean cardioactive peptide, tachykinin-related peptides). In a second step, a combination of immunocytochemistry and mass spectrometric profiling of defined AL compartments was used to reveal the spatial distribution of neuropeptide-containing cells. Finally, we demonstrated the feasibility of MALDI-TOF mass spectrometric profiling of single AL neurons, which is an important precondition for combining electrophysiology with peptide profiling at the single-cell level.
-
Examination of the role of FMRFamide-related peptides in the circadian clock of the cockroach Leucophaea maderae
Cell and Tissue Research, 2008Co-Authors: Sandra Soehler, Susanne Neupert, Reinhard Predel, Monika StenglAbstract:The accessory medulla, the circadian clock of the cockroach Leucophaea maderae , is abundant in neuropeptides. Among these neuropeptides are the FMRFamide-related peptides (FaRPs), which generally share the C-terminal RFamide. As a first step toward understanding the functional role of FaRPs in the circadian clock of the cockroach, immunocytochemistry with antisera against various FaRPs, MALDI-TOF mass spectrometry, and injections of two FaRPs combined with running-wheel assays were performed. Prominent FMRFamide-like immunoreactivity was found in maximally four soma clusters associated with the accessory medulla and in most neuropils of the protocerebrum. By MALDI-TOF mass spectrometry, various extended FMRFamides of the cockroach L. maderae were partially identified in thoracic perisympathetic organs, structures known to accumulate extended FMRFamides in insects. By mass match, several of these peptides were also detected in the accessory medulla. Injections of FMRFamide and Pea-FMRFa-7 (DRSDNFIRF-NH_2) into the vicinity of the accessory medulla caused time-dependent phase-shifts of locomotor activity rhythms at circadian times 8, 18, and 4. Thus, our data suggest a role for the different FaRPs in the control of circadian locomotor activity rhythms in L. maderae .
-
unique accumulation of neuropeptides in an insect FMRFamide related peptides in the cockroach periplaneta americana
European Journal of Neuroscience, 2004Co-Authors: Reinhard Predel, Susanne Neupert, D Wicher, M Gundel, Siegfried Roth, Christian DerstAbstract:FMRFamides belong to the most extensively studied neuropeptides in invertebrates and exhibit diverse physiological effects on different target organs, such as muscles, intestine and the nervous system. This study on the American cockroach confirms for the first time that extended FMRFamides occur in non-dipteran insects. By means of tandem mass spectrometry, these neuropeptides were structurally elucidated, and sequence information was used for subsequent cloning of the cockroach FMRFamide gene. This precursor gene encodes for 24 putative peptides and shows sufficient similarity with the Drosophila FMRFamide gene. Of the 24 peptides, 23 were detected by mass spectrometric methods; it is the highest number of neuropeptide forms shown to be expressed from a single precursor in any insect. The expression was traced back to single neurons in the thoracic ganglia. The unique accumulation of these FMRFamide-related peptides in thoracic perisympathetic organs provides the definite evidence for a tagma-specific distribution of peptidergic neurohormones in neurohaemal release sites of the insect CNS. Excitatory effects of the cockroach FMRFamides were observed on antenna-heart preparations. In addition, the newly described FMRFamides reduce the spike frequency of dorsal-unpaired median neurons and reduce the intracellular calcium concentration, which may affect the peripheral release of the biogenic amine octopamine.