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Vaasjo LO, Miller MW. A conserved gastropod withdrawal circuit in Biomphalaria glabrata, an intermediate host for schistosomiasis. J Neurophysiol 2024; 131:903-913. [PMID: 38478883 PMCID: PMC11383391 DOI: 10.1152/jn.00390.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2023] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 05/18/2024] Open
Abstract
Neuronal signals mediated by the biogenic amine serotonin (5-HT) underlie critical survival strategies across the animal kingdom. This investigation examined serotonin-like immunoreactive neurons in the cerebral ganglion of the panpulmonate snail Biomphalaria glabrata, a major intermediate host for the trematode parasite Schistosoma mansoni. Five neurons comprising the cerebral serotonergic F (CeSF) cluster of B. glabrata shared morphological characteristics with neurons that contribute to withdrawal behaviors in numerous heterobranch species. The largest member of this group, designated CeSF-1, projected an axon to the tentacle, a major site of threat detection. Intracellular recordings demonstrated repetitive activity and electrical coupling between the bilateral CeSF-1 cells. In semi-intact preparations, the CeSF-1 cells were not responsive to cutaneous stimuli but did respond to photic stimuli. A large FMRF-NH2-like immunoreactive neuron, termed C2, was also located on the dorsal surface of each cerebral hemiganglion near the origin of the tentacular nerve. C2 and CeSF-1 received coincident bouts of inhibitory synaptic input. Moreover, in the presence of 5-HT they both fired rhythmically and in phase. As the CeSF and C2 cells of Biomphalaria share fundamental properties with neurons that participate in withdrawal responses in Nudipleura and Euopisthobranchia, our observations support the proposal that features of this circuit are conserved in the Panpulmonata.NEW & NOTEWORTHY Neuronal signals mediated by the biogenic amine serotonin underlie critical survival strategies across the animal kingdom. This investigation identified a group of serotonergic cells in the panpulmonate snail Biomphalaria glabrata that appear to be homologous to neurons that mediate withdrawal responses in other gastropod taxa. It is proposed that an ancient withdrawal circuit has been highly conserved in three major gastropod lineages.
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Affiliation(s)
- Lee O Vaasjo
- Institute of Neurobiology and Department of Anatomy & Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
| | - Mark W Miller
- Institute of Neurobiology and Department of Anatomy & Neurobiology, University of Puerto Rico Medical Sciences Campus, San Juan, Puerto Rico
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2
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Wood EA, Stopka SA, Zhang L, Mattson S, Maasz G, Pirger Z, Vertes A. Neuropeptide Localization in Lymnaea stagnalis: From the Central Nervous System to Subcellular Compartments. Front Mol Neurosci 2021; 14:670303. [PMID: 34093125 PMCID: PMC8172996 DOI: 10.3389/fnmol.2021.670303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Accepted: 04/09/2021] [Indexed: 12/02/2022] Open
Abstract
Due to the relatively small number of neurons (few tens of thousands), the well-established multipurpose model organism Lymnaea stagnalis, great pond snail, has been extensively used to study the functioning of the nervous system. Unlike the more complex brains of higher organisms, L. stagnalis has a relatively simple central nervous system (CNS) with well-defined circuits (e.g., feeding, locomotion, learning, and memory) and identified individual neurons (e.g., cerebral giant cell, CGC), which generate behavioral patterns. Accumulating information from electrophysiological experiments maps the network of neuronal connections and the neuronal circuits responsible for basic life functions. Chemical signaling between synaptic-coupled neurons is underpinned by neurotransmitters and neuropeptides. This review looks at the rapidly expanding contributions of mass spectrometry (MS) to neuropeptide discovery and identification at different granularity of CNS organization. Abundances and distributions of neuropeptides in the whole CNS, eleven interconnected ganglia, neuronal clusters, single neurons, and subcellular compartments are captured by MS imaging and single cell analysis techniques. Combining neuropeptide expression and electrophysiological data, and aided by genomic and transcriptomic information, the molecular basis of CNS-controlled biological functions is increasingly revealed.
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Affiliation(s)
- Ellen A. Wood
- Department of Chemistry, The George Washington University, Washington, DC, United States
| | - Sylwia A. Stopka
- Department of Neurosurgery, Brigham and Women’s Hospital, Harvard Medical School, Boston, MA, United States
| | - Linwen Zhang
- Department of Chemistry, The George Washington University, Washington, DC, United States
| | - Sara Mattson
- Department of Chemistry, The George Washington University, Washington, DC, United States
| | - Gabor Maasz
- Balaton Limnological Research Institute, Eötvös Loránd Research Network (ELKH), Tihany, Hungary
- Soós Ernő Research and Development Center, University of Pannonia, Nagykanizsa, Hungary
| | - Zsolt Pirger
- Balaton Limnological Research Institute, Eötvös Loránd Research Network (ELKH), Tihany, Hungary
| | - Akos Vertes
- Department of Chemistry, The George Washington University, Washington, DC, United States
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3
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Watson WH, Nash A, Lee C, Patz MD, Newcomb JM. The Distribution and Possible Roles of Small Cardioactive Peptide in the Nudibranch Melibe leonina. Integr Org Biol 2020; 2:obaa016. [PMID: 33791559 PMCID: PMC7671164 DOI: 10.1093/iob/obaa016] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
The neuropeptide small cardioactive peptide (SCP) plays an integrative role in exciting various motor programs involved in feeding and locomotion in a number of gastropod species. In this study, immunohistochemistry, using monoclonal antibodies against SCPB, was used to localize SCPB-like-immunoreactive neurons in the central nervous system, and map their connections to various tissues, in the nudibranch, Melibe leonina. Approximately 28-36 SCPB-like-immunoreactive neurons were identified in the M. leonina brain, as well as one large neuron in each of the buccal ganglia. The neuropil of the pedal ganglia contained the most SCPB-like-immunoreactive varicosities, although only a small portion of these were due to SCPB-like-immunoreactive neurons in the same ganglion. This suggests that much of the SCPB-like immunoreactivity in the neuropil of the pedal ganglia was from neurons in other ganglia that projected through the pedal-pedal connectives or the connectives from the cerebral and pleural ganglia. We also observed extensive SCPB innervation along the length of the esophagus. Therefore, we investigated the impact of SCPB on locomotion in intact animals, as well as peristaltic contractions of the isolated esophagus. Injection of intact animals with SCPB at night led to a significant increase in crawling and swimming, compared to control animals injected with saline. Furthermore, perfusion of isolated brains with SCPB initiated expression of the swim motor program. Application of SCPB to the isolated quiescent esophagus initiated rhythmic peristaltic contractions, and this occurred in preparations both with and without the buccal ganglia being attached. All these data, taken together, suggest that SCPB could be released at night to arouse animals and enhance the expression of both feeding and swimming motor programs in M. leonina.
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Affiliation(s)
- W H Watson
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - A Nash
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - C Lee
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - M D Patz
- Department of Biological Sciences, University of New Hampshire, Durham, NH 03824, USA
| | - J M Newcomb
- Department of Biology and Health Science, New England College, Henniker, NH 03242, USA
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4
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Cropper EC, Jing J, Vilim FS, Barry MA, Weiss KR. Multifaceted Expression of Peptidergic Modulation in the Feeding System of Aplysia. ACS Chem Neurosci 2018; 9:1917-1927. [PMID: 29309115 DOI: 10.1021/acschemneuro.7b00447] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Neuropeptides are present in species throughout the animal kingdom and generally exert actions that are distinct from those of small molecule transmitters. It has, therefore, been of interest to define the unique behavioral role of this class of substances. Progress in this regard has been made in experimentally advantageous invertebrate preparations. We focus on one such system, the feeding circuit in the mollusc Aplysia. We review research conducted over several decades that played an important role in establishing that peptide cotransmitters are released under behaviorally relevant conditions. We describe how this was accomplished. For example, we describe techniques developed to purify novel peptides, localize them to identified neurons, and detect endogenous peptide release. We also describe physiological experiments that demonstrated that peptides are bioactive under behaviorally relevant conditions. The feeding system is like others in that peptides exert effects that are both convergent and divergent. Work in the feeding system clearly illustrates how this creates potential for behavioral flexibility. Finally, we discuss experiments that determined physiological consequences of one of the hallmark features of peptidergic modulation, its persistence. Research in the feeding system demonstrated that this persistence can change network state and play an important role in determining network output.
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Affiliation(s)
- Elizabeth C. Cropper
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York 10029, United States
| | - Jian Jing
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York 10029, United States
- State Key Laboratory of Pharmaceutical Biotechnology, Advanced Institute for Life Sciences, School of Life Sciences, Nanjing University, Nanjing, Jiangsu 210093, China
| | - Ferdinand S. Vilim
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York 10029, United States
| | - Michael A. Barry
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York 10029, United States
| | - Klaudiusz R. Weiss
- Department of Neuroscience and Friedman Brain Institute, Icahn School of Medicine at Mount Sinai, One Gustave L. Levy Place, New York, New York 10029, United States
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5
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Adamson KJ, Wang T, Rotgans BA, Kruangkum T, Kuballa AV, Storey KB, Cummins SF. Genes and associated peptides involved with aestivation in a land snail. Gen Comp Endocrinol 2017; 246:88-98. [PMID: 26497253 DOI: 10.1016/j.ygcen.2015.10.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Revised: 10/14/2015] [Accepted: 10/19/2015] [Indexed: 01/01/2023]
Abstract
Some animals can undergo a remarkable transition from active normal life to a dormant state called aestivation; entry into this hypometabolic state ensures that life continues even during long periods of environmental hardship. In this study, we aimed to identify those central nervous system (CNS) peptides that may regulate metabolic suppression leading to aestivation in land snails. Mass spectral-based neuropeptidome analysis of the CNS comparing active and aestivating states, revealed 19 differentially produced peptides; 2 were upregulated in active animals and 17 were upregulated in aestivated animals. Of those, the buccalin neuropeptide was further investigated since there is existing evidence in molluscs that buccalin modulates physiology by muscle contraction. The Theba pisana CNS contains two buccalin transcripts that encode precursor proteins that are capable of releasing numerous buccalin peptides. Of these, Tpi-buccalin-2 is most highly expressed within our CNS transcriptome derived from multiple metabolic states. No significant difference was observed at the level of gene expression levels for Tpi-buccalin-2 between active and aestivated animals, suggesting that regulation may reside at the level of post-translational control of peptide abundance. Spatial gene and peptide expression analysis of aestivated snail CNS demonstrated that buccalin-2 has widespread distribution within regions that control several physiological roles. In conclusion, we provide the first detailed molecular analysis of the peptides and associated genes that are related to hypometabolism in a gastropod snail known to undergo extended periods of aestivation.
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Affiliation(s)
- K J Adamson
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia
| | - T Wang
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia
| | - B A Rotgans
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia
| | - T Kruangkum
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia
| | - A V Kuballa
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia
| | - K B Storey
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
| | - S F Cummins
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia.
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6
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Adamson KJ, Wang T, Rotgans BA, Kuballa AV, Storey KB, Cummins SF. Differential peptide expression in the central nervous system of the land snail Theba pisana, between active and aestivated. Peptides 2016; 80:61-71. [PMID: 26303007 DOI: 10.1016/j.peptides.2015.08.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/14/2015] [Revised: 08/16/2015] [Accepted: 08/17/2015] [Indexed: 12/25/2022]
Abstract
Hypometabolism is a physiological state of dormancy entered by many animals in times of environmental stress. There are gaps in our understanding of the molecular components used by animals to achieve this metabolic state. The availability of genomic and transcriptome data can be useful to study the process of hypometabolism at the molecular level. In this study, we use the land snail Theba pisana to identify peptides that may be involved in the hypometabolic state known as aestivation. We found a total of 22 neuropeptides in the central nervous system (CNS) that were differentially produced during activity and aestivation based on mass spectral-based neuropeptidome analysis. Of these, 4 were upregulated in active animals and 18 were upregulated in aestivation. A neuropeptide known to regulate muscle contractions in a variety of molluscs, the small cardioactive peptide A (sCAPA), and a peptide of yet unknown function (termed Aestivation Associated Peptide 12) were chosen for further investigation using temporal and spatial expression analysis of the precursor gene and peptide. Both peptides share expression within regions of the CNS cerebral ganglia and suboesophageal ganglia. Relative transcript abundance suggests that regulation of peptide synthesis and secretion is post-transcriptional. In summary, we provide new insights into the molecular basis of the regulation of aestivation in land snails through CNS peptide control.
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Affiliation(s)
- K J Adamson
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia
| | - T Wang
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia
| | - B A Rotgans
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia
| | - A V Kuballa
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia
| | - K B Storey
- Institute of Biochemistry & Department of Biology, Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6, Canada
| | - S F Cummins
- Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore DC, Queensland 4558, Australia.
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7
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Stewart MJ, Wang T, Koene JM, Storey KB, Cummins SF. A "Love" Dart Allohormone Identified in the Mucous Glands of Hermaphroditic Land Snails. J Biol Chem 2016; 291:7938-50. [PMID: 26817846 DOI: 10.1074/jbc.m115.704395] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2015] [Indexed: 11/06/2022] Open
Abstract
Animals have evolved many ways to enhance their own reproductive success. One bizarre sexual ritual is the "love" dart shooting of helicid snails, which has courted many theories regarding its precise function. Acting as a hypodermic needle, the dart transfers an allohormone that increases paternity success. Its precise physiological mechanism of action within the recipient snail is to close off the entrance to the sperm digestion organ via a contraction of the copulatory canal, thereby delaying the digestion of most donated sperm. In this study, we used the common garden snailCornu aspersumto identify the allohormone that is responsible for this physiological change in the female system of this simultaneous hermaphrodite. The love dart allohormone (LDA) was isolated from extracts derived from mucous glands that coat the dart before it is stabbed through the partner's body wall. We isolated LDA from extracts using bioassay-guided contractility measurement of the copulatory canal. LDA is encoded within a 235-amino acid precursor protein containing multiple cleavage sites that, when cleaved, releases multiple bioactive peptides. Synthetic LDA also stimulated copulatory canal contractility. Combined with our finding that the protein amino acid sequence resembles previously described molluscan buccalin precursors, this indicates that LDA is partially conserved in helicid snails and less in other molluscan species. In summary, our study provides the full identification of an allohormone that is hypodermically injected via a love dart. More importantly, our findings have important consequences for understanding reproductive biology and the evolution of alternative reproductive strategies.
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Affiliation(s)
- Michael J Stewart
- From the Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland 4558, Australia
| | - Tianfang Wang
- From the Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland 4558, Australia
| | - Joris M Koene
- the Department of Ecological Science, Faculty of Earth and Life Sciences, Vrije Universiteit, 1081HV Amsterdam, The Netherlands, and
| | - Kenneth B Storey
- the Institute of Biochemistry and Department of Biology, Carleton University, Ottawa, Ontario K1S 5B6, Canada
| | - Scott F Cummins
- From the Genecology Research Centre, Faculty of Science, Health, Education and Engineering, University of the Sunshine Coast, Maroochydore, Queensland 4558, Australia,
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8
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Kanda A, Minakata H. Isolation and characterization of a novel small cardioactive peptide-related peptide from the brain of Octopus vulgaris. Peptides 2006; 27:1755-61. [PMID: 16443307 DOI: 10.1016/j.peptides.2005.12.006] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/29/2005] [Revised: 12/12/2005] [Accepted: 12/14/2005] [Indexed: 11/28/2022]
Abstract
A novel small cardioactive peptide (SCP)-related peptide (oct-SCPRP: Ser-Asn-Gly-Tyr-Leu-Ala-Leu-Pro-Arg-Gln-NH2) was isolated from the brain of the octopus (Octopus vulgaris). cDNA encoding this precursor protein was cloned. Oct-SCPRP was shown to evoke contraction in the radula protractor muscle, and the precursor protein was highly homologous to the SCP family in the Mollusk but did not encode a related peptide, SCPB. The expression of oct-SCPRP mRNA was present not only in the peripheral nervous system (PNS) which is a motor center for the control of feeding, but also in the central nervous system (CNS) which is capable of complex analysis, learning, and controls behaviors.
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Affiliation(s)
- Atsuhiro Kanda
- Suntory Institute for Bioorganic Research, 1-1-1 Wakayamadai, Shimamoto, Mishima, Osaka 618-8503, Japan
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9
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Sheeley SA, Rubakhin SS, Sweedler JV. The detection of nitrated tyrosine in neuropeptides: a MALDI matrix-dependent response. Anal Bioanal Chem 2005; 382:22-7. [PMID: 15900447 DOI: 10.1007/s00216-005-3145-0] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2004] [Revised: 01/28/2005] [Accepted: 02/02/2005] [Indexed: 11/29/2022]
Abstract
Neuropeptides are a diverse class of signaling molecules that typically have one or more posttranslational modifications. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) is an effective tool for identification and characterization of neuropeptides from samples as small as individual neurons. However, the detection of one particular posttranslational modification-nitrotyrosine-has been problematic because of the lability of the nitro group of nitrotyrosine under MALDI-MS conditions. The detection of nitrated tyrosine in peptide standards was dependent on the MALDI matrix used for the analysis. Specifically, sinapinic acid was the optimum matrix tested to observe this modification while it was not consistently detected with matrices such as 2,5-dihydroxybenzoic acid. Using the optimized procedures, several identified nitric-oxide-synthase positive neurons from Lymnaea stagnalis were tested to determine if the neuropeptides present were nitrated. In all cases, the nitrated form of the neuropeptide was not observed. The dependence on the sample-preparation procedures of observing this particular chemical modification demonstrates the need for careful selection of sample-preparation methods with MALDI or the use of other ionization methods.
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Affiliation(s)
- Sarah A Sheeley
- Department of Chemistry and the Beckman Institute, University of Illinois at Urbana-Champaign, 600 S. Mathews Ave 63-5, Urbana, IL 61801, USA
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10
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CROLL ROGERP, DICKINSON AMANDAJ. Form and function of the larval nervous system in molluscs. INVERTEBR REPROD DEV 2004. [DOI: 10.1080/07924259.2004.9652620] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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11
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Britz FC, Hirth IC, Deitmer JW. Second messenger cascade of glial responses evoked by interneuron activity and by a myomodulin peptide in the leech central nervous system. Eur J Neurosci 2004; 19:983-92. [PMID: 15009146 DOI: 10.1111/j.0953-816x.2004.03192.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
The giant glial cell in the neuropil of segmental ganglia of the leech Hirudo medicinalis responds to the activity of the Leydig interneuron and to a peptide of the myomodulin family, the presumed transmitter mediating the Leydig neuron-to-giant glial cell transmission, with a membrane hyperpolarization due to an increased membrane K+ conductance [Britz et al. (2002) Glia, 38, 215-227]. We have now studied the second messenger cascade initiated by Leydig neuron stimulation and by the endogenous myomodulin (MMHir) in the voltage-clamped giant glial cell. Glial responses to both stimuli are mediated by a G-protein-coupled receptor linked to adenylyl cyclase by the following criteria: (i) injection of GDP-beta-S, but not GDP, resulted in an irreversible decrease of the glial responses to both stimuli; (ii) the responses to both stimuli were reversibly inhibited by the adenylyl cyclase inhibitor SQ22,536; and (3) bath-applied di-butyryl-cyclic AMP, but not di-butyryl-cyclic GMP, elicited an outward current, which reduced the responses elicited by neuronal stimulation or myomodulin. A cocktail of protein kinase (PK) inhibitors (H-8, KT5720), the PKA antagonist Rp-cAMPS, or presumed inhibitors of cyclic nucleotide channels, LY83583 and l-cis-diltiazem, had no effect on the glial responses. Our results suggest that Leydig neuron stimulation and MMHir activate a cAMP-mediated K+ conductance in the glial cell, which appeared neither to be due to the activation of PKA nor of known cyclic nucleotide-gated channels directly.
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Affiliation(s)
- Frank C Britz
- Abteilung für Allgemeine Zoologie, FB Biologie, Universität Kaiserslautern, Postfach 3049, D-67653 Kaiserslautern, Germany
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12
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Dickinson AJG, Croll RP. Development of the larval nervous system of the gastropod Ilyanassa obsoleta. J Comp Neurol 2003; 466:197-218. [PMID: 14528448 DOI: 10.1002/cne.10863] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Gastropods have been well studied in terms of early cell cleavage patterns and the neural basis of adult behaviors; however, much less is known about neural development in this taxon. Here we reveal a relatively sophisticated larval nervous system in a well-studied gastropod, Ilyanassa obsoleta. The present study employed immunocytochemical and histofluorescent techniques combined with confocal microscopy to examine the development of cells containing monoamines (serotonin and catecholamine), neuropeptides (FMRFamide and leu-enkephalin related peptides), and a substance(s) reactive to antibodies raised against dopamine beta-hydroxylase. Neurons were first observed in the apical organ and posterior regions during the embryonic trochophore stage. During later embryonic development neurons appeared in peripheral regions such as the foot, velum, and mantle and in the developing ganglia destined to become the adult central nervous system. In subsequent free-swimming veliger stages the larval nervous system became increasingly elaborate and by late larval stages there existed approximately 26-28 apical cells, 80-100 neurons in the central ganglia, and 200-300 peripherally located neurons. During metamorphosis some populations of neurons in the apical organ and in the periphery disappeared, while others were incorporated into the juvenile nervous system. Comparisons of neural elements in other molluscan larvae reveal several similarities such as comparable arrangements of cells in the apical organ and patterns of peripheral cells. This investigation reveals the most extensive larval nervous system described in any mollusc to date and information from this study will be useful for future experimental studies determining the role of larval neurons and investigations of the cellular and molecular mechanisms governing neural development in this taxon.
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Affiliation(s)
- Amanda J G Dickinson
- Department of Physiology and Biophysics, Faculty of Medicine, Dalhousie University, Halifax, B3H 4H7 Nova Scotia, Canada.
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13
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Abstract
A myomodulin peptide has been suggested to mediate the response of the giant glial cells to stimulation of the Leydig interneuron in the central nervous system of the leech Hirudo medicinalis [Eur. J. Neurosci. 11 (1999) 3125]. We have now studied the glial response to the endogenous leech MM peptide (GMGALRL-NH(2), MMHir). The peptide evokes a membrane outward current (EC(50) approximately 2 microM), which neither desensitizes nor shows any sign of run-down, and elicits a K(+) conductance increase of the glial cell membrane. The peptidase inhibitor phenylmethylsulfonyl fluoride (PMSF) enhances the glial current response, suggesting the presence of endogenous extracellular peptidases.
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Affiliation(s)
- Frank C Britz
- Abteilung für Allgemeine Zoologie, FB Biologie, Universität Kaiserslautern, Postfach 3049, D-67653 Kaiserslautern, Germany
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Masino MA, Calabrese RL. Period differences between segmental oscillators produce intersegmental phase differences in the leech heartbeat timing network. J Neurophysiol 2002; 87:1603-15. [PMID: 11877529 DOI: 10.1152/jn.00338.2001] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Considerable experimental and theoretical effort has been exerted to understand how constant intersegmental phase relationships are produced between oscillators in segmentally organized pattern generating networks. The phase relationship between the segmental oscillators in the isolated timing network of the leech heartbeat central pattern generator is quite regular within individual preparations. However, it varies considerably among different preparations. Our goal is to determine how the phase relationships in this network are established. Here we assess whether inherent period differences, as suggested by the excitability-gradient hypothesis, play a role in establishing the phase relationships between the two coupled segmental oscillators of the leech heartbeat timing network. To do this we developed methods for reversibly uncoupling the segmental oscillators (sucrose knife) and pharmacological manipulation of the individual oscillators (split bath). Differences in inherent cycle periods between the third and fourth segmental oscillators (G3 and G4) were present in most (20 of 26) preparations. These period differences correlated with the phase differences observed between the segmental oscillators in the recoupled timing network, such that the oscillator with the faster cycle period, regardless of the segment in which it was located, led in phase in proportion to its period difference with the other oscillator. The phase differences between the original (coupled) and recoupled states of individual preparations were similar. Thus application and removal of the sucrose knife did not alter the period difference between the segmental oscillators in the timing network. Pharmacological manipulation of the uncoupled oscillators to alter the period difference between the oscillators led to similar correlated phase differences in the recoupled timing network. Across all experiments the uncoupled segmental oscillator with the faster cycle period established the cycle period of the timing network when recoupled. In conclusion, our findings indicate that an excitability-gradient plays a role in establishing the phase relationship between the segmental oscillators of the leech heartbeat central pattern generator since inherent period differences present between the oscillators are correlated to the phase relationships of the coupled/recoupled timing network.
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Affiliation(s)
- Mark A Masino
- Biology Department, Emory University, 1510 Clifton Road, Atlanta, GA 30322, USA
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15
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de Lange RP, Moorer-van Delft CM, de Boer PA, van Minnen J, de Jong-Brink M. Target-dependent differentiation and development of molluscan neurons and neuroendocrine cells: use of parasitisation as a tool. Neuroscience 2001; 103:289-99. [PMID: 11311809 DOI: 10.1016/s0306-4522(00)00556-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Specimens of the freshwater snail Lymnaea stagnalis infected with the schistosome parasite Trichobilharzia ocellata show a strongly inhibited development of their reproductive tract. We hypothesised that the effects of the underdevelopment of targets are reflected at the level of the neuronal development of (i) the motor neurons innervating the male copulation organ and (ii) neuroendocrine cells regulating the gonad. We determined the state of neuronal development by measuring cell number, cell size and neuropeptide gene expression. Our results show that the neuronal development of both copulation controlling anterior lobe motor neurons of the right cerebral ganglion and neuroendocrine caudodorsal cells, which produce neuropeptides regulating ovulation, egg laying and accompanying behaviour, are affected in parasitised animals in which their respective target organs were not developed. The cell bodies were smaller and fewer cells were found to express neuropeptide genes compared to those in non-parasitised animals. These effects were not observed in the appropriate controls. Backfills and lesions of the penis nerve have shown that the inhibited development of central motor neurons in parasitised snails is target dependent; neighbouring neurons that have no connection with the male copulation organ are not affected. Our data suggest that this effect is established by target-derived neurotrophic factors that need this connection for being transported to the innervating motor neurons. We propose that the effect on the neuroendocrine caudodorsal cells is mediated by a humoral factor, since they have no known connection with their target. We have shown that the size and gene expression of motor neurons controlling copulation behaviour in the pond snail Lymnaea stagnalis are related to the size of their target, the copulation organ, and depend on the connection with this target.
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Affiliation(s)
- R P de Lange
- Graduate School Neurosciences Amsterdam, Research Institute Neurosciences Vrije Universiteit, Faculty of Biology, Department of Organismal Neurobiology, De Boelelaan 1087, 1081 HV Amsterdam, The Netherlands
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16
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17
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Li C, Nelson LS, Kim K, Nathoo A, Hart AC. Neuropeptide gene families in the nematode Caenorhabditis elegans. Ann N Y Acad Sci 2000; 897:239-52. [PMID: 10676452 DOI: 10.1111/j.1749-6632.1999.tb07895.x] [Citation(s) in RCA: 129] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Neuropeptides have diverse roles in the function and development of the nervous system. With the completion of the sequencing of the C. elegans genome, rapid identification of nematode neuropeptide genes is possible. To date, 41 C. elegans neuropeptide genes have been identified. Of these genes, 20 genes, named flp (FMRFamide-like peptide) genes, encode FMRFamide-related proteins (FaRPs). Deletion of one of the flp genes, flp-1, results in several behavioral defects, suggesting that at least one flp gene is not functionally redundant with other flp genes. Twenty-one genes, named neuropeptide-like protein (nlp) genes, encode peptides distinct from the FaRP family. The predicted nlp-1 and nlp-2 neuropeptides have modest similarity to buccalin and myomodulin, respectively. Cellular expression patterns and genetic analysis of flp and nlp genes suggest that neuropeptides in nematodes also have widespread and varied roles in nervous system function.
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Affiliation(s)
- C Li
- Department of Biology, Boston University, Massachusetts 02215, USA.
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18
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Wang Y, Strong JA, Sahley CL. Modulatory effects of myomodulin on the excitability and membrane currents in Retzius cells of the leech. J Neurophysiol 1999; 82:216-25. [PMID: 10400950 DOI: 10.1152/jn.1999.82.1.216] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ion channel modulation by the peptide myomodulin (MM) has been demonstrated in a wide variety of organisms including Aplysia, Lymnaea, and Pleurobranchaea. This neural and muscular modulation has been shown to be important for shaping and modifying behavior. In this paper, we report that MM modulates several distinct ionic channels in another species, the medicinal leech Hirudo medicinalis. Experiments have focused on the Retzius cell (R) because the R cell is a multifunction neuron that has been implicated in a number of behaviors including feeding, swimming, secretion, thermal sensing, and the touch elicited shortening reflex and its plasticity. Previous work had identified a MM-like peptide in the leech and demonstrated that this peptide modulated the excitability of the R cell. Using combined current- and voltage-clamp techniques to examine the effects of MM on the R cell, we found that in response to a step pulse, MM increased the excitability of the R cell such that the cell fires more action potentials with a shorter latency to the first action potential. We found that this effect was mediated by the activation of a Na+-mediated inward current near the cell resting membrane potential. Second, we found that MM differentially modulated the potassium currents IA and IK. No effect of MM was found on IA, whereas MM significantly reduced both the peak and steady-state amplitudes of IK by 49 +/- 2.9% and 43 +/- 7.2%, respectively (means +/- SE). Finally we found that MM reduced the amplitude of the Ca2+ current by approximately 20%. The ionic currents modulated by MM are consistent with the overall effect of MM on the cellular activity of the R cell. An understanding of the cellular mechanisms by which MM modulates the activity of the R cell should help us to better understand the roles of both MM and the R cell in a variety of behaviors in the leech.
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Affiliation(s)
- Y Wang
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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19
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Perry SJ, Dobbins AC, Schofield MG, Piper MR, Benjamin PR. Small cardioactive peptide gene: structure, expression and mass spectrometric analysis reveals a complex pattern of co-transmitters in a snail feeding neuron. Eur J Neurosci 1999; 11:655-62. [PMID: 10051766 DOI: 10.1046/j.1460-9568.1999.00472.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The small cardioactive peptides (SCPs) are an important group of neural cotransmitters in molluscs where they are known to play both central and peripheral modulatory roles in the control of feeding behaviour. Here we show that in the snail Lymnaea the SCP gene exists in one interrupted copy that produces a single species of transcript which encodes a prepropeptide containing two structurally related SCPs SGYLAFPRMamide (SCP(A)) and pQNYLAFPRMamide (SCP(B)). In situ hybridization was used to localize expression specifically to the soma of several types of motoneurons in the feeding system of Lymnaea, including the giant B2 foregut motoneurons. The peptide content of individual B2 cell bodies was analysed by matrix-assisted laser desorption/ionization mass spectrometry and the structures of the SCPs predicted from the cloned gene were confirmed in these cells by post-source decay fragmentation analysis. Identical stimulatory activity for the two SCP peptides was demonstrated by their application to the isolated foregut, suggesting that their co-release from the B2 cells may play an important part in the co-modulation of gut motility, together with acetylcholine and the myomodulin family of peptides.
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Affiliation(s)
- S J Perry
- Sussex Centre for Neuroscience, School of Biological Sciences, University of Sussex, Brighton, East Sussex, UK
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20
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de Lange R, de Boer P, ter Maat A, Tensen C, van Minnen J. Transmitter identification in neurons involved in male copulation behavior inLymnaea stagnalis. J Comp Neurol 1998. [DOI: 10.1002/(sici)1096-9861(19980615)395:4<440::aid-cne2>3.0.co;2-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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21
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Perry SJ, Straub VA, Kemenes G, Santama N, Worster BM, Burke JF, Benjamin PR. Neural modulation of gut motility by myomodulin peptides and acetylcholine in the snail Lymnaea. J Neurophysiol 1998; 79:2460-74. [PMID: 9582220 DOI: 10.1152/jn.1998.79.5.2460] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Families of peptide neuromodulators are believed to play important roles in neural networks that control behaviors. Here, we investigate the expression and role of one such group of modulators, the myomodulins, in the feeding system of Lymnaea stagnalis. Using a combination of in situ hybridization and antibody staining, expression of the myomodulin gene was confirmed in a number of identified behaviorally significant neuronal types, including the paired B2 motor neurons. The B2 cells were shown to project axons to the proesophagus, where they modulate foregut contractile activity. The presence of the five myomodulin peptide structures was confirmed in the B2 cells, the proesophagus, and the intervening nerve by mass spectrometry. Using a sensitive cell culture assay, evidence that the B2 cells are cholinergic also is presented. Application of four of the five myomodulin peptides to the isolated foregut increased both contraction frequency and tonus, whereas the main effect of acetylcholine (ACh) application was a large tonal contraction. The fifth myomodulin peptide (pQIPMLRLamide) appeared to have little or no effect on gut motility. Coapplication of all five myomodulin peptides gave a greater increase in tonus than that produced by the peptides applied individually, suggesting that corelease of the peptides onto the gut would produce an enhanced response. The combined effects that the myomodulin peptides and ACh have on foregut motility can mimic the main actions of B2 cell stimulation.
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Affiliation(s)
- S J Perry
- Sussex Centre for Neuroscience, University of Sussex, Falmer, Brighton BN1 9QG, United Kingdom
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22
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23
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Abstract
A novel myomodulin-like peptide, GMGALRLamide, has been purified and sequenced from extracts of 1000 medicinal leech nerve cords. Synthetic leech myomodulin-like peptide blocked the specific staining pattern of leech ganglia by the antiserum against Aplysia myomodulin A PMGMLRLamide. Moreover, the synthetic leech myomodulin-like peptide GMGALRLamide showed identical neuronal modulation effect on the giant leech Retzius cell compare to that by the synthetic Aplysia myomodulin A PMGMLRLamide.
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Affiliation(s)
- Y Wang
- Department of Biological Sciences, Purdue University, West Lafayette, IN 47907, USA
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24
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Direct mass spectrometric peptide profiling and sequencing of nervous tissues to identify peptides involved in male copulatory behavior in Lymnaea stagnalis. ACTA ACUST UNITED AC 1997. [DOI: 10.1016/s0168-1176(97)00220-6] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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25
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Abstract
The myomodulin family of neuropeptides is an important group of neural cotransmitters in molluscs and is known to be present in the neural network that controls feeding behavior in the snail Lymnaea. Here we show that a single gene encodes five structurally similar forms of myomodulin: GLQMLRLamide, QIPMLRLamide, SMSMLRLamide, SLSMLRLamide, and PMSMLRLamide, the latter being present in nine copies. Analysis of the organization of the gene indicates that it is transcribed as a single spliced transcript from an upstream promoter region that contains multiple cAMP-responsive elements, as well as putative elements with homology to tissue-specific promoter-binding sites. The presence in nervous tissue of two of the peptides, GLQMLRLamide and PMSMLRLamide, is confirmed by mass spectrometry. In situ hybridization analysis indicates that the gene is expressed in specific cells in all ganglia of the CNS of Lymnaea, which will allow physiological analysis of the function of myomodulins at the level of single identified neurons.
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26
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DE BOER PA, JANSEN RF, MAAT ATER. Copulation in the hermaphroditic snailLymnaea stagnalis:a review. INVERTEBR REPROD DEV 1996. [DOI: 10.1080/07924259.1996.9672542] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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27
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Abstract
The distribution of myomodulinlike immunoreactivity in the leech CNS was determined using an antiserum raised against Aplysia myomodulin. Segmental ganglia contained approximately 60 immunoreactive neurons. In addition, numerous fibers containing immunoreactive varicosities were found throughout the neuropil. Using a combination of Lucifer Yellow injections and immunocytochemistry, we identified neurons including the anterior Pagodas (AP), annulus erector (AE), motor neurons, Leydig, longitudinal muscle motoneurons (L), S cells, and coupling interneurons, all of which are active during the touch-elicited shortening reflex. FMRF-amide-like immunoreactivity in three of these cells (L, AP, and AE) was previously demonstrated. Specific staining for myomodulin was abolished by preadsorption of the antiserum with synthetic myomodulin, but not with FMRF-amide. These results suggest a potential role for myomodulin in both intrinsic and extrinsic modulation of the leech touch-elicited shortening reflex. Further, it is possible that several neurons mediating this reflex contain multiple neuromodulatory peptides.
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Affiliation(s)
- H H Keating
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana 47907, USA
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28
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Santama N, Li KW, Geraerts WP, Benjamin PR, Burke JF. Post-translational processing of the alternative neuropeptide precursor encoded by the FMRFamide gene in the pulmonate snail Lymnaea stagnalis. Eur J Neurosci 1996; 8:968-77. [PMID: 8743745 DOI: 10.1111/j.1460-9568.1996.tb01584.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
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, III-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 spectrometry- the 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. Immunoreactive neurons included the single identifiable visceral white interneuron (VWI or VD4), a key cell of the cardiorespiratory network.
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Affiliation(s)
- N Santama
- Sussex Centre for Neuroscience, School of Biological Sciences, University of Sussex, Brighton BN1 9QG, UK
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29
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Santama N, Wheeler CH, Skingsley DR, Yeoman MS, Bright K, Kaye I, Burke JF, Benjamin PR. Identification, distribution and physiological activity of three novel neuropeptides of Lymnaea: EFLRlamide and pQFYRlamide encoded by the FMRFamide gene, and a related peptide. Eur J Neurosci 1995; 7:234-46. [PMID: 7757260 DOI: 10.1111/j.1460-9568.1995.tb01059.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We are interested in analysing the detailed modulation of defined neuronal systems by multiple neuropeptides encoded in the FMRFamide locus of the snail Lymnaea. Cloning of the FMRFamide gene has predicted the existence of two novel peptides previously unknown from biochemical analysis, the pentapeptides EFLRlamide and QFYRlamide. These peptides may form part of a new family of peptides sharing the sequence motif -FXRlamide. In this paper we adopt a novel approach to first identify and characterize -FXRlamide-like peptides in extracts from the central nervous system of Lymnaea. By a combination of high-performance liquid chromatography (HPLC) and continuous-flow fast atom bombardment mass spectrometry, we identify three novel peptides: EFLRlamide, pQFYRlamide and pQFLRlamide. The first two are those predicted in exon II of the FMRFamide locus whereas the last is, interestingly, a product which cannot be derived from post-translational modification of the predicted peptides but must be encoded by as yet unidentified nucleotide sequences. A specific antibody raised to EFLRlamide, and immunoreactive to all three peptides, revealed EFLRlamide-like expression throughout the central nervous system in the same cells where exon II is transcribed and the peptide SEEPLY (a post-translational product of exon II) was localized. Additional cells, however, were also identified. Immunoreactivity was mapped in a number of identified neurons in the central nervous system, including two heart cardioexcitatory motoneurons, the Ehe cells (E heart excitors of the visceral ganglion) and penial motoneurons in the right cerebral ganglion. The peripheral tissues (heart and penial complex) that these respective classes of neurons innervate also exhibited EFLRlamide immunoreactivity. The central and peripheral localization of EFLRlamide-like immunoreactivity suggested that EFLRlamide/pQFYRlamide may have an important physiological role in both these peripheral systems as well as in the central nervous system. This was confirmed by physiological experiments that showed that EFLRlamide and pQFYRlamide inhibited many central neurons and in particular the Bgp neurons in the right parietal ganglion. EFLRlamide had complex biphasic effects on the frequency of heart-beat: an initial inhibitory response was followed by a long-lasting increase in the rate of beating. Taken together with earlier work, this study now completes the analysis and localization of the full set of post-translational products of the FMRFamide precursor in Lymnaea and supplies further evidence towards the characterization of the physiological systems which such peptides may modulate in concert.
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Affiliation(s)
- N Santama
- Sussex Centre for Neuroscience, School of Biological Sciences, University of Sussex, Brighton, UK
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30
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Santama N, Benjamin PR, Burke JF. Alternative RNA splicing generates diversity of neuropeptide expression in the brain of the snail Lymnaea: in situ analysis of mutually exclusive transcripts of the FMRFamide gene. Eur J Neurosci 1995; 7:65-76. [PMID: 7711938 DOI: 10.1111/j.1460-9568.1995.tb01021.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In the CNS of the snail Lymnaea stagnalis, Phe-Met-Arg-Phe-amide (FMRFamide)-like and additional novel neuropeptides are encoded by a common, multi-exon gene. This complex locus, comprising at least five exons, is subject to post-transcriptional regulation at the level of alternative RNA splicing. Our aim was first to analyse the pattern by which exons of this neuropeptide locus combine during splicing of the primary RNA transcript, and second to investigate the functional significance of splicing by mapping the expression and neuronal localization in the CNS of the alternative mRNA transcripts, in the context of defined neuronal networks and single identified neurons. The approach was a combination of comparative in situ hybridization and immunocytochemistry, using a battery of exon-specific oligonucleotides and anti-peptide antisera. The analysis illustrated that exons III, IV and V were always coexpressed and colocalized whereas the expression of exon II was always differential and mutually exclusive. Both sets of exons were, however, coexpressed with exon I: the total number of exon I-expressing neurons was equal to the combined number of neurons expressing exon III/IV/V and neurons expressing exon II. In addition, it was revealed that the extreme 5' of exon II, encoding a potential hydrophobic leader signal, was not expressed in the CNS of Lymnaea but was apparently spliced out during RNA processing. Both mRNA transcripts of the FMRFamide locus, type 1 (exons I/II) and type 2 (exons I/III/IV/V), were translated in the CNS and the resulting protein precursors were also expressed in a mutually exclusive fashion, as were their respective transcripts. The expression of alternative transcripts within identified networks or neuronal clusters was heterogeneous, as exemplified by the cardiorespiratory network. On the basis of this work and a previous cDNA analysis, we put forward a revised model of differential splicing and expression of the FMRFamide gene in the CNS of Lymnaea.
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Affiliation(s)
- N Santama
- Sussex Centre for Neuroscience, School of Biological Sciences, University of Sussex, Falmer, Brighton, UK
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31
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Abstract
Substantial progress has been made in identifying the possible signals for initiating and terminating the appetitive aspects of feeding behavior in vertebrates. Strong evidence now implicates ATP (or an ATP-like molecule) and a fall in glucose in initiating feeding. In invertebrates, particular progress has been made in defining the nature and mechanisms of action of the neurotransmitters and peptide co-transmitters that regulate the consummatory aspects of feeding, and a number of new research tools for modelling the operation of simple feeding motor program networks have been developed.
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Affiliation(s)
- I Kupfermann
- Center for Neurobiology and Behavior College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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32
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Santama N, Brierley M, Burke JF, Benjamin PR. Neural network controlling feeding in Lymnaea stagnalis: immunocytochemical localization of myomodulin, small cardioactive peptide, buccalin, and FMRFamide-related peptides. J Comp Neurol 1994; 342:352-65. [PMID: 7912700 DOI: 10.1002/cne.903420304] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
This paper investigates the distribution of four classes of neuropeptides, myomodulin, small cardioactive peptide (SCP), buccalin, and FMRFamide, in central neurons forming the network that underlies feeding behavior in the snail Lymnaea stagnalis. Intracellular dye-marking and immunocytochemical analysis, using antisera to the different classes of peptides, were applied to identified neurons of all three levels of the hierarchy of the circuitry: modulatory interneurons (cerebral giant cells, CGC; slow oscillator, SO), central pattern generator (CPG) interneurons (N1, N2, N3), motoneurons (B1-B10), and their peripheral target organs. Myomodulin immunoreactivity was detected in the CGC interneurons, in the SO, and in ventral N2-type CPG interneurons. Several large buccal motoneurons, the paired B1, B2, B3, B7, and neurons located in the dorsal posterior area (putative B4 cluster types) were also myomodulin immunoreactive. Target organs of buccal motoneurons, the buccal mass, salivary glands, and oesophagus contained myomodulin-immunopositive fibers. SCP appeared in N2-type interneurons and was found colocalized with myomodulin in the B1 and B2 motoneurons. SCP-containing neurons in the B4 cluster area were also detected. The buccal mass and salivary glands exhibited SCP-immunoreactive fibers. Buccalin immunoreactivity was scarce in the buccal ganglia and was identified only in N1-type interneurons and three pairs of dorsal posterior neurons. In the periphery, immunoreactive fibers were localized in the oesophagus only. None of the buccal neuronal types examined revealed immunoreactivity to SEQPDVDDYLRDVVLQSEEPLY ("SEEPLY"), a peptide encoded in the FMRFamide precursor protein of Lymnaea. SEEPLY immunoreactivity was confined to a pair of novel ventral neurons with projections to the laterobuccal nerve innervating the buccal mass. Immunoreactive fibers were also traced in this organ.
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Affiliation(s)
- N Santama
- Sussex Centre for Neuroscience, School of Biological Sciences, University of Sussex, Brighton, United Kingdom
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