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Guo Q, Fu J, Yuan L, Liao Y, Li M, Li X, Yi B, Zhang J, Gao B. Diversity analysis of sea anemone peptide toxins in different tissues of Heteractis crispa based on transcriptomics. Sci Rep 2024; 14:7684. [PMID: 38561372 PMCID: PMC10985097 DOI: 10.1038/s41598-024-58402-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2023] [Accepted: 03/28/2024] [Indexed: 04/04/2024] Open
Abstract
Peptide toxins found in sea anemones venom have diverse properties that make them important research subjects in the fields of pharmacology, neuroscience and biotechnology. This study used high-throughput sequencing technology to systematically analyze the venom components of the tentacles, column, and mesenterial filaments of sea anemone Heteractis crispa, revealing the diversity and complexity of sea anemone toxins in different tissues. A total of 1049 transcripts were identified and categorized into 60 families, of which 91.0% were proteins and 9.0% were peptides. Of those 1049 transcripts, 416, 291, and 307 putative proteins and peptide precursors were identified from tentacles, column, and mesenterial filaments respectively, while 428 were identified when the datasets were combined. Of these putative toxin sequences, 42 were detected in all three tissues, including 33 proteins and 9 peptides, with the majority of peptides being ShKT domain, β-defensin, and Kunitz-type. In addition, this study applied bioinformatics approaches to predict the family classification, 3D structures, and functional annotation of these representative peptides, as well as the evolutionary relationships between peptides, laying the foundation for the next step of peptide pharmacological activity research.
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Affiliation(s)
- Qiqi Guo
- Engineering Research Center of Tropical Medicine Innovation and Transformation, Ministry of Education, International Joint Research Center of Human-machine Intelligent Collaborative for Tumor Precision Diagnosis and Treatment of Hainan Province, School of Pharmacy, Hainan Medical University, Haikou, China
| | - Jinxing Fu
- Engineering Research Center of Tropical Medicine Innovation and Transformation, Ministry of Education, International Joint Research Center of Human-machine Intelligent Collaborative for Tumor Precision Diagnosis and Treatment of Hainan Province, School of Pharmacy, Hainan Medical University, Haikou, China
| | - Lin Yuan
- Engineering Research Center of Tropical Medicine Innovation and Transformation, Ministry of Education, International Joint Research Center of Human-machine Intelligent Collaborative for Tumor Precision Diagnosis and Treatment of Hainan Province, School of Pharmacy, Hainan Medical University, Haikou, China
- Department of Pharmacy, 928th Hospital of PLA Joint Logistics Support Force, Haikou, China
| | - Yanling Liao
- Engineering Research Center of Tropical Medicine Innovation and Transformation, Ministry of Education, International Joint Research Center of Human-machine Intelligent Collaborative for Tumor Precision Diagnosis and Treatment of Hainan Province, School of Pharmacy, Hainan Medical University, Haikou, China
| | - Ming Li
- Engineering Research Center of Tropical Medicine Innovation and Transformation, Ministry of Education, International Joint Research Center of Human-machine Intelligent Collaborative for Tumor Precision Diagnosis and Treatment of Hainan Province, School of Pharmacy, Hainan Medical University, Haikou, China
| | - Xinzhong Li
- School of Health and Life Sciences, Teesside University, Middlesbrough, UK
| | - Bo Yi
- Department of Pharmacy, 928th Hospital of PLA Joint Logistics Support Force, Haikou, China
| | - Junqing Zhang
- Engineering Research Center of Tropical Medicine Innovation and Transformation, Ministry of Education, International Joint Research Center of Human-machine Intelligent Collaborative for Tumor Precision Diagnosis and Treatment of Hainan Province, School of Pharmacy, Hainan Medical University, Haikou, China.
| | - Bingmiao Gao
- Engineering Research Center of Tropical Medicine Innovation and Transformation, Ministry of Education, International Joint Research Center of Human-machine Intelligent Collaborative for Tumor Precision Diagnosis and Treatment of Hainan Province, School of Pharmacy, Hainan Medical University, Haikou, China.
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Smith HL, Prentis PJ, Bryan SE, Norton RS, Broszczak DA. Acontia, a Specialised Defensive Structure, Has Low Venom Complexity in Calliactis polypus. Toxins (Basel) 2023; 15:218. [PMID: 36977109 PMCID: PMC10051995 DOI: 10.3390/toxins15030218] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2023] [Revised: 03/08/2023] [Accepted: 03/10/2023] [Indexed: 03/14/2023] Open
Abstract
Phylum Cnidaria represents a unique group among venomous taxa, with its delivery system organised as individual organelles, known as nematocysts, heterogeneously distributed across morphological structures rather than packaged as a specialised organ. Acontia are packed with large nematocysts that are expelled from sea anemones during aggressive encounters with predatory species and are found in a limited number of species in the superfamily Metridioidea. Little is known about this specialised structure other than the commonly accepted hypothesis of its role in defence and a rudimentary understanding of its toxin content and activity. This study utilised previously published transcriptomic data and new proteomic analyses to expand this knowledge by identifying the venom profile of acontia in Calliactis polypus. Using mass spectrometry, we found limited toxin diversity in the proteome of acontia, with an abundance of a sodium channel toxin type I, and a novel toxin with two ShK-like domains. Additionally, genomic evidence suggests that the proposed novel toxin is ubiquitous across sea anemone lineages. Overall, the venom profile of acontia in Calliactis polypus and the novel toxin identified here provide the basis for future research to define the function of acontial toxins in sea anemones.
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Monastyrnaya MM, Kalina RS, Kozlovskaya EP. The Sea Anemone Neurotoxins Modulating Sodium Channels: An Insight at Structure and Functional Activity after Four Decades of Investigation. Toxins (Basel) 2022; 15:toxins15010008. [PMID: 36668828 PMCID: PMC9863223 DOI: 10.3390/toxins15010008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Revised: 12/13/2022] [Accepted: 12/15/2022] [Indexed: 12/24/2022] Open
Abstract
Many human cardiovascular and neurological disorders (such as ischemia, epileptic seizures, traumatic brain injury, neuropathic pain, etc.) are associated with the abnormal functional activity of voltage-gated sodium channels (VGSCs/NaVs). Many natural toxins, including the sea anemone toxins (called neurotoxins), are an indispensable and promising tool in pharmacological researches. They have widely been carried out over the past three decades, in particular, in establishing different NaV subtypes functional properties and a specific role in various pathologies. Therefore, a large number of publications are currently dedicated to the search and study of the structure-functional relationships of new sea anemone natural neurotoxins-potential pharmacologically active compounds that specifically interact with various subtypes of voltage gated sodium channels as drug discovery targets. This review presents and summarizes some updated data on the structure-functional relationships of known sea anemone neurotoxins belonging to four structural types. The review also emphasizes the study of type 2 neurotoxins, produced by the tropical sea anemone Heteractis crispa, five structurally homologous and one unique double-stranded peptide that, due to the absence of a functionally significant Arg14 residue, loses toxicity but retains the ability to modulate several VGSCs subtypes.
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Menezes C, Thakur NL. Sea anemone venom: Ecological interactions and bioactive potential. Toxicon 2022; 208:31-46. [DOI: 10.1016/j.toxicon.2022.01.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Revised: 01/05/2022] [Accepted: 01/06/2022] [Indexed: 10/19/2022]
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Mackieh R, Abou-Nader R, Wehbe R, Mattei C, Legros C, Fajloun Z, Sabatier JM. Voltage-Gated Sodium Channels: A Prominent Target of Marine Toxins. Mar Drugs 2021; 19:562. [PMID: 34677461 DOI: 10.3390/md19100562] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/29/2021] [Accepted: 10/02/2021] [Indexed: 12/19/2022] Open
Abstract
Voltage-gated sodium channels (VGSCs) are considered to be one of the most important ion channels given their remarkable physiological role. VGSCs constitute a family of large transmembrane proteins that allow transmission, generation, and propagation of action potentials. This occurs by conducting Na+ ions through the membrane, supporting cell excitability and communication signals in various systems. As a result, a wide range of coordination and physiological functions, from locomotion to cognition, can be accomplished. Drugs that target and alter the molecular mechanism of VGSCs’ function have highly contributed to the discovery and perception of the function and the structure of this channel. Among those drugs are various marine toxins produced by harmful microorganisms or venomous animals. These toxins have played a key role in understanding the mode of action of VGSCs and in mapping their various allosteric binding sites. Furthermore, marine toxins appear to be an emerging source of therapeutic tools that can relieve pain or treat VGSC-related human channelopathies. Several studies documented the effect of marine toxins on VGSCs as well as their pharmaceutical applications, but none of them underlined the principal marine toxins and their effect on VGSCs. Therefore, this review aims to highlight the neurotoxins produced by marine animals such as pufferfish, shellfish, sea anemone, and cone snail that are active on VGSCs and discuss their pharmaceutical values.
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Abstract
Cnidarians have been known since ancient times for the painful stings they induce to humans. The effects of the stings range from skin irritation to cardiotoxicity and can result in death of human beings. The noxious effects of cnidarian venoms have stimulated the definition of their composition and their activity. Despite this interest, only a limited number of compounds extracted from cnidarian venoms have been identified and defined in detail. Venoms extracted from Anthozoa are likely the most studied, while venoms from Cubozoa attract research interests due to their lethal effects on humans. The investigation of cnidarian venoms has benefited in very recent times by the application of omics approaches. In this review, we propose an updated synopsis of the toxins identified in the venoms of the main classes of Cnidaria (Hydrozoa, Scyphozoa, Cubozoa, Staurozoa and Anthozoa). We have attempted to consider most of the available information, including a summary of the most recent results from omics and biotechnological studies, with the aim to define the state of the art in the field and provide a background for future research.
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Affiliation(s)
- Isabella D’Ambra
- Integrative Marine Ecology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy
| | - Chiara Lauritano
- Marine Biotechnology Department, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Napoli, Italy;
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Gusmão LC, Rodríguez E, Daly M. Description of Calliactis tigris sp. nov.: reconciling taxonomy and phylogeny in hermit-crab symbiotic anemones (Cnidaria: Actiniaria: Hormathiidae). ORG DIVERS EVOL 2019. [DOI: 10.1007/s13127-019-00414-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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Abstract
Sea anemones produce venoms of exceptional molecular diversity, with at least 17 different molecular scaffolds reported to date. These venom components have traditionally been classified according to pharmacological activity and amino acid sequence. However, this classification system suffers from vulnerabilities due to functional convergence and functional promiscuity. Furthermore, for most known sea anemone toxins, the exact receptors they target are either unknown, or at best incomplete. In this review, we first provide an overview of the sea anemone venom system and then focus on the venom components. We have organised the venom components by distinguishing firstly between proteins and non-proteinaceous compounds, secondly between enzymes and other proteins without enzymatic activity, then according to the structural scaffold, and finally according to molecular target.
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Affiliation(s)
- Bruno Madio
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4072, Australia.
| | - Glenn F King
- Institute for Molecular Bioscience, The University of Queensland, St Lucia, QLD, 4072, Australia.
| | - Eivind A B Undheim
- Centre for Advanced Imaging, The University of Queensland, St. Lucia, QLD 4072, Australia.
- Centre for Ecology and Evolutionary Synthesis, Department of Biosciences, University of Oslo, 0316 Oslo, Norway.
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Abstract
Venomous animals including cone snails, spiders, scorpions, anemones, and snakes have evolved a myriad of components in their venoms that target the opening and/or closing of voltage-gated sodium channels to cause devastating effects on the neuromuscular systems of predators and prey. These venom peptides, through design and serendipity, have not only contributed significantly to our understanding of sodium channel pharmacology and structure, but they also represent some of the most phyla- and isoform-selective molecules that are useful as valuable tool compounds and drug leads. Here, we review our understanding of the basic function of mammalian voltage-gated sodium channel isoforms as well as the pharmacology of venom peptides that act at these key transmembrane proteins.
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Affiliation(s)
- Mathilde R Israel
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Bryan Tay
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia
| | - Jennifer R Deuis
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia.
| | - Irina Vetter
- Centre for Pain Research, Institute for Molecular Bioscience, The University of Queensland, Brisbane, QLD, Australia; School of Pharmacy, The University of Queensland, Brisbane, QLD, Australia.
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Jouiaei M, Yanagihara AA, Madio B, Nevalainen TJ, Alewood PF, Fry BG. Ancient Venom Systems: A Review on Cnidaria Toxins. Toxins (Basel) 2015; 7:2251-71. [PMID: 26094698 PMCID: PMC4488701 DOI: 10.3390/toxins7062251] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Revised: 06/09/2015] [Accepted: 06/10/2015] [Indexed: 01/22/2023] Open
Abstract
Cnidarians are the oldest extant lineage of venomous animals. Despite their simple anatomy, they are capable of subduing or repelling prey and predator species that are far more complex and recently evolved. Utilizing specialized penetrating nematocysts, cnidarians inject the nematocyst content or "venom" that initiates toxic and immunological reactions in the envenomated organism. These venoms contain enzymes, potent pore forming toxins, and neurotoxins. Enzymes include lipolytic and proteolytic proteins that catabolize prey tissues. Cnidarian pore forming toxins self-assemble to form robust membrane pores that can cause cell death via osmotic lysis. Neurotoxins exhibit rapid ion channel specific activities. In addition, certain cnidarian venoms contain or induce the release of host vasodilatory biogenic amines such as serotonin, histamine, bunodosine and caissarone accelerating the pathogenic effects of other venom enzymes and porins. The cnidarian attacking/defending mechanism is fast and efficient, and massive envenomation of humans may result in death, in some cases within a few minutes to an hour after sting. The complexity of venom components represents a unique therapeutic challenge and probably reflects the ancient evolutionary history of the cnidarian venom system. Thus, they are invaluable as a therapeutic target for sting treatment or as lead compounds for drug design.
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Affiliation(s)
- Mahdokht Jouiaei
- Venom Evolution Lab, School of Biological Sciences, the University of Queensland, St. Lucia 4072, QLD, Australia.
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia 4072, QLD, Australia.
| | - Angel A Yanagihara
- Pacific Cnidaria Research Lab, Department of Tropical Medicine, University of Hawaii, Honolulu, HI 96822, USA.
| | - Bruno Madio
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia 4072, QLD, Australia.
| | - Timo J Nevalainen
- Department of Pathology, University of Turku, Turku FIN-20520, Finland.
| | - Paul F Alewood
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia 4072, QLD, Australia.
| | - Bryan G Fry
- Venom Evolution Lab, School of Biological Sciences, the University of Queensland, St. Lucia 4072, QLD, Australia.
- Institute for Molecular Bioscience, the University of Queensland, St. Lucia 4072, QLD, Australia.
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Oliveira JS, Fuentes-Silva D, King GF. Development of a rational nomenclature for naming peptide and protein toxins from sea anemones. Toxicon 2012; 60:539-50. [DOI: 10.1016/j.toxicon.2012.05.020] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2012] [Revised: 05/21/2012] [Accepted: 05/24/2012] [Indexed: 01/30/2023]
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Frazão B, Vasconcelos V, Antunes A. Sea anemone (Cnidaria, Anthozoa, Actiniaria) toxins: an overview. Mar Drugs 2012; 10:1812-1851. [PMID: 23015776 PMCID: PMC3447340 DOI: 10.3390/md10081812] [Citation(s) in RCA: 138] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2012] [Revised: 07/09/2012] [Accepted: 07/25/2012] [Indexed: 01/20/2023] Open
Abstract
The Cnidaria phylum includes organisms that are among the most venomous animals. The Anthozoa class includes sea anemones, hard corals, soft corals and sea pens. The composition of cnidarian venoms is not known in detail, but they appear to contain a variety of compounds. Currently around 250 of those compounds have been identified (peptides, proteins, enzymes and proteinase inhibitors) and non-proteinaceous substances (purines, quaternary ammonium compounds, biogenic amines and betaines), but very few genes encoding toxins were described and only a few related protein three-dimensional structures are available. Toxins are used for prey acquisition, but also to deter potential predators (with neurotoxicity and cardiotoxicity effects) and even to fight territorial disputes. Cnidaria toxins have been identified on the nematocysts located on the tentacles, acrorhagi and acontia, and in the mucous coat that covers the animal body. Sea anemone toxins comprise mainly proteins and peptides that are cytolytic or neurotoxic with its potency varying with the structure and site of action and are efficient in targeting different animals, such as insects, crustaceans and vertebrates. Sea anemones toxins include voltage-gated Na⁺ and K⁺ channels toxins, acid-sensing ion channel toxins, Cytolysins, toxins with Kunitz-type protease inhibitors activity and toxins with Phospholipase A2 activity. In this review we assessed the phylogentic relationships of sea anemone toxins, characterized such toxins, the genes encoding them and the toxins three-dimensional structures, further providing a state-of-the-art description of the procedures involved in the isolation and purification of bioactive toxins.
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Affiliation(s)
- Bárbara Frazão
- CIMAR/CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas 177, 4050-123 Porto, Portugal; (B.F.); (V.V.)
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
| | - Vitor Vasconcelos
- CIMAR/CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas 177, 4050-123 Porto, Portugal; (B.F.); (V.V.)
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
| | - Agostinho Antunes
- CIMAR/CIIMAR, Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Rua dos Bragas 177, 4050-123 Porto, Portugal; (B.F.); (V.V.)
- Departamento de Biologia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, 4169-007 Porto, Portugal
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Maeda M, Honma T, Shiomi K. Isolation and cDNA cloning of type 2 sodium channel peptide toxins from three species of sea anemones (Cryptodendrum adhaesivum, Heterodactyla hemprichii and Thalassianthus aster) belonging to the family Thalassianthidae. Comp Biochem Physiol B Biochem Mol Biol 2010; 157:389-93. [PMID: 20817118 DOI: 10.1016/j.cbpb.2010.08.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Revised: 08/29/2010] [Accepted: 08/29/2010] [Indexed: 10/19/2022]
Abstract
The crude extracts from three species of sea anemones (Cryptodendrum adhaesivum, Heterodactyla hemprichii and Thalassianthus aster) belonging to the family Thalassianthidae exhibited potent lethality to freshwater crabs (Potamon dehaani). Regardless of the species, high and low molecular weight toxins were found in gel filtration of the crude extract. Following reverse-phase HPLC of the low molecular weight toxin fractions, one toxin (δ-TLTX-Ca1a), two toxins (δ-TLTX-Hh1a and c) and one toxin (δ-TLTX-Ta1a) were isolated from C. adhaesivum, H. hemprichii and T. aster, respectively. Based on the determined N-terminal amino acid sequences, the cDNAs encoding δ-TLTX-Ca1a, δ-TLTX-Hh1x (not assignable to either δ-TLTX-Hh1a or δ-TLTX-Hh1c) and δ-TLTX-Ta1a were successfully cloned by both 3' and 5' RACE methods. In common with the three toxins, the precursor is composed of a signal peptide (19 amino acid residues), propart (16 residues) and mature portion (49 residues), similar to those of many sea anemone peptide toxins. The deduced amino acid sequences showed that the three toxins are closely similar to one another, being all new members of the type 2 sea anemone sodium channel peptide toxin family.
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Affiliation(s)
- Mikiko Maeda
- Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Tokyo, Japan
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Xiang H, Wang L, Cui J, Du J, Wang K, Xu A. Effects of recombinant neurotoxins on single Na(+) channels in isolated rat hippocampal neurons. J Biochem Mol Toxicol 2009; 23:244-55. [PMID: 19705351 DOI: 10.1002/jbt.20285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Four recombinant neurotoxins Hk2a, Hk7a, Hk8a, Hk16a, originally from a sea anemone species Anthopleura sp., were obtained by fusion expression of their genes in Escherichia coli. These neurotoxins were composed of 47 amino acid residues, among which the differences were found at positions 14, 22, 25, and 37, respectively. The effects of the four neurotoxins on single-channel current of sodium in rat hippocampal neurons were studied by cell-attached patch clamp. Each neurotoxin 2 microM could modulate the sodium channel by prolonging the opening dwell time and increasing the open probability, but did not change the amplitude of sodium channel currents. Based on the studies of the structure-function relationship, we found that Hk7a displayed the biggest increase of the open probability because His14 (from Arg14) makes its structure seem more compact in comparison with the other three toxins and Ap-A. Phe25 (Hk8a, Hk16a), which varied from Ala25 (Hk2a, Hk7a), showed that phenyl group might interfere with other key amino acid residue to decrease the activity of toxins. Arg37 (from His37) in Hk8a contributed to decrease of open probability. In our work, it was shown that these important amino acid sites might provide a reliable proof for the future pharmaceutical design.
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Affiliation(s)
- Hui Xiang
- Department of Biological Science and Technology, Sun Yat-sen, Zhongshan University, Guangzhou, Guangdong Province, People's Republic of China.
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Abstract
Sea anemones produce a variety of toxic peptides and proteins, including many ion channel blockers and modulators, as well as potent cytolysins. This review describes the structures that have been determined to date for the major classes of peptide and protein toxins. In addition, established and emerging methods for structure determination are summarized and the prospects for modelling newly described toxins are evaluated. In common with most other classes of proteins, toxins display conformational flexibility which may play a role in receptor binding and function. The prospects for obtaining atomic resolution structures of toxins bound to their receptors are also discussed.
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Abstract
The venom of sea anemones is rich in low molecular weight proteinaceous neurotoxins that vary greatly in structure, site of action, and phyletic (insect, crustacean or vertebrate) preference. This toxic versatility likely contributes to the ability of these sessile animals to inhabit marine environments co-habited by a variety of mobile predators. Among these toxins, those that show prominent activity at voltage-gated sodium channels and are critical in predation and defense, have been extensively studied for more than three decades. These studies initially focused on the discovery of new toxins, determination of their covalent and folded structures, understanding of their mechanisms of action on different sodium channels, and identification of the primary sites of interaction of the toxins with their channel receptors. The channel binding site for Type I and the structurally unrelated Type III sea anemone toxins was identified as neurotoxin receptor site 3, a site previously shown to be targeted by scorpion alpha-toxins. The bioactive surfaces of toxin representatives from these two sea anemone types have been characterized by mutagenesis. These analyses pointed to heterogeneity of receptor site 3 at various sodium channels. A turning point in evolutionary studies of sea anemone toxins was the recent release of the genome sequence of Nematostella vectensis, which enabled analysis of the genomic organization of the corresponding genes. This analysis demonstrated that Type I toxins in Nematostella and other species are encoded by gene families and suggested that these genes developed by concerted evolution. The current review provides a brief historical description of the discovery and characterization of sea anemone toxins that affect voltage-gated sodium channels and delineates recent advances in the study of their structure-activity relationship and evolution.
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Affiliation(s)
- Yehu Moran
- Department of Plant Sciences, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel.
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Abstract
Sea anemone toxins, whose biological function is the capture of marine prey, are invaluable tools for studying the structure and function of mammalian voltage-gated sodium channels. Their high degree of specificity and selectivity have allowed for detailed analysis of inactivation gating and assignment of molecular entities responsible for this process. Because of their ability to discriminate among channel isoforms, and their high degree of structural conservation, these toxins could serve as important lead compounds for future pharmaceutical design.
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Affiliation(s)
- Jaime J Smith
- Department of Biochemistry, School of Medicine and Biomedical Sciences, State University of New York, 3435 Main St. Buffalo, NY 14214, USA
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Abstract
Sea anemones are a rich source of two classes of peptide toxins, sodium channel toxins and potassium channel toxins, which have been or will be useful tools for studying the structure and function of specific ion channels. Most of the known sodium channel toxins delay channel inactivation by binding to the receptor site 3 and most of the known potassium channel toxins selectively inhibit Kv1 channels. The following peptide toxins are functionally unique among the known sodium or potassium channel toxins: APETx2, which inhibits acid-sensing ion channels in sensory neurons; BDS-I and II, which show selectivity for Kv3.4 channels and APETx1, which inhibits human ether-a-go-go-related gene potassium channels. In addition, structurally novel peptide toxins, such as an epidermal growth factor (EGF)-like toxin (gigantoxin I), have also been isolated from some sea anemones although their functions remain to be clarified.
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Affiliation(s)
- Tomohiro Honma
- Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Konan-4, Minato-ku, Tokyo, 108-8477 Japan
| | - Kazuo Shiomi
- Department of Food Science and Technology, Tokyo University of Marine Science and Technology, Konan-4, Minato-ku, Tokyo, 108-8477 Japan
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Cunha RB, Santana ANC, Amaral PC, Carvalho MDF, Carvalho DMF, Cavalheiro EA, Maigret B, Ricart CAO, Cardi BA, Sousa MV, Carvalho KM. Primary structure, behavioral and electroencephalographic effects of an epileptogenic peptide from the sea anemone Bunodosoma cangicum. Toxicon 2005; 45:207-17. [PMID: 15626370 DOI: 10.1016/j.toxicon.2004.10.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2004] [Revised: 10/11/2004] [Accepted: 10/13/2004] [Indexed: 10/26/2022]
Abstract
The primary structure of cangitoxin (CGX), a 4958 Da peptide from the sea anemone Bunodosoma cangicum, was determined: GVACRCDSDGPTVRGNSLSGTLWLTGGCPSGWHNCRGSGPFIGYCCKK. CGX contains all the 11 residues that are conserved and the 5 that are conservatively substituted within or between the type 1 and type 2 sequences of sea anemone peptides with specific action on voltage-sensitive sodium channels. Furthermore, it also has 6 identities (Asp9, Arg14, Asn16, Leu18, Trp33 and Lys48) and 1 homology (Arg36) in the 8 residues of the pharmacophore of the sea anemone ApB which are essential for interaction with mammalian sodium channels. The intrahippocampal injection of CGX induces several sequential behavioral alterations--episodes of akinesia alternating with facial automatisms and head tremor, salivation, rearing, jumping, barrel-rolling, wet dog shakes and forelimb clonic movements--and the electroencephalography analysis shows that they were followed by important seizure periods that gradually evolved to status epilepticus that lasted 8-12 h, similar to that observed in the acute phase of the pilocarpine model of epilepsy. These results suggest that CGX may be an important tool to develop a new experimental model of status epilepticus which may contribute to understanding the etiology of epilepsy and to test the effects of new antiepileptic drugs.
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Affiliation(s)
- Ricardo B Cunha
- Centro Brasileiro de Serviços e Pesquisas em Proteínas, Departamento de Biologia Celular, Universidade de Brasília, CEP 70.910-900 Brasília, DF, Brazil
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Béress L. Biologically Active Polypeptides ofAnemonia sulcata—and of Other Sea Anemones—Tools in the Study of Exitable Membranes. ACTA ACUST UNITED AC 2004. [DOI: 10.1081/txr-200038380] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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23
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Santana AN, Leite AB, França MS, França L, Vale OC, Cunha RB, Ricart CA, Sousa MV, Carvalho KM. Partial sequence and toxic effects of granulitoxin, a neurotoxic peptide from the sea anemone Bundosoma granulifera. Braz J Med Biol Res 1998; 31:1335-8. [PMID: 9876306 DOI: 10.1590/s0100-879x1998001000015] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A neurotoxic peptide, granulitoxin (GRX), was isolated from the sea anemone Bunodosoma granulifera. The N-terminal amino acid sequence of GRX is AKTGILDSDGPTVAGNSLSGT and its molecular mass is 4958 Da by electrospray mass spectrometry. This sequence presents a partial degree of homology with other toxins from sea anemones such as Bunodosoma caissarum, Anthopleura fuscoviridis and Anemonia sulcata. However, important differences were found: the first six amino acids of the sequence are different, Arg-14 was replaced by Ala and no cysteine residues were present in the partial sequence, while two cysteine residues were present in the first 21 amino acids of the other toxins described above. Purified GRX injected i.p. (800 micrograms/kg) into mice produced severe neurotoxic effects such as circular movements, aggressive behavior, dyspnea, tonic-clonic convulsion and death. The 2-h LD50 of GRX was 400 +/- 83 micrograms/kg.
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Affiliation(s)
- A N Santana
- Departamento de Fisiologia e Farmacologia, Faculdade de Medicina, Universidade Federal do Ceará, Fortaleza, CE, Brasil
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Shiomi K, Qian WH, Lin XY, Shimakura K, Nagashima Y, Ishida M. Novel polypeptide toxins with crab lethality from the sea anemone Anemonia erythraea. Biochim Biophys Acta 1997; 1335:191-8. [PMID: 9133656 DOI: 10.1016/s0304-4165(96)00137-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The sea anemone Anemonia erythraea was found to contain polypeptide toxins with crab lethality as well as hemolysins. Three polypeptide toxins (AETX I, II and III) were isolated by gel filtration on Sephadex G-50 and reverse-phase HPLC on TSKgel ODS-120T. A geographic variation in toxin composition was suggested. The LD50 against crabs of AETX I, II and III were estimated to be 2.2, 0.53 and 0.28 microg/kg, respectively, but none of the toxins showed lethality in mice. The amino acid sequences of the three toxins were deduced from sequencings of the whole molecules and their enzymatic fragments. Amino acid analyses and molecular mass determinations supported the accuracy of the deduced sequences. AETX I, comprising 47 amino acid residues including 6 half-Cys residues, is an analog of sea anemone type I toxins. On the other hand, AETX II and III, which are highly homologous with each other, are quite distinct from the known sea anemone polypeptide toxins in that they are composed of 59 residues including 10 half-Cys residues. Interestingly, both toxins have sequence similarities with neurotoxins isolated from the Brazilian 'armed' spider Phoneutria nigriventer.
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Affiliation(s)
- K Shiomi
- Department of Food Science and Technology, Tokyo University of Fisheries, Minato-ku, Japan
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25
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Conlon JM, Sower SA. Isolation of a peptide structurally related to mammalian corticostatins from the lamprey Petromyzon marinus. Comp Biochem Physiol B Biochem Mol Biol 1996; 114:133-7. [PMID: 8759287 DOI: 10.1016/0305-0491(95)02132-9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Peptides in an extract of skin from the agnathan Petromyzon marinus (sea lamprey) were purified by reversed-phase high-performance liquid chromatography and characterized by Edman degradation. The primary structure of a cysteine- and arginine-rich peptide (termed lamprey corticostatin-related peptide [LCRP]) was established as Cys-Pro-Cys-Gly-Arg-Arg-Arg-Cys-Cys-Val-Arg-Gly-Leu-Asn-Val-Tyr-Cys-Cys- Phe. Mass spectrometry indicated that all cysteine residues are intramolecularly linked. This amino acid sequence shows structural similarity to rat corticostatin R4 and rabbit corticostatin R1. In particular, LCRP contains the polyarginine sequence at the N-terminus of the peptide that is believed to mediate both the inhibition of ACTH stimulated steroidogenesis and the antimicrobial (defensin-like) actions of the corricostatins.
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Affiliation(s)
- J M Conlon
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE 68178, USA
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26
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Lin XY, Ishida M, Nagashima Y, Shiomi K. A polypeptide toxin in the sea anemone Actinia equina homologous with other sea anemone sodium channel toxins: isolation and amino acid sequence. Toxicon 1996; 34:57-65. [PMID: 8835334 DOI: 10.1016/0041-0101(95)00121-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The sea anemone (Actinia equina) was newly established to contain a polypeptide toxin (named Ae I) having lethal activity to crabs, besides the well-known cytolytic toxins (equinatoxins) of proteinic nature. Ae I, with a minimum lethal dose against crabs of 25 micrograms/kg, was easily isolated by gel filtration on Sephadex G-50 and reverse-phase HPLC on Nucleosil 300-7C18. Its amino acid composition is characterized by the abundance of Gly, the absence of Ala and the presence of Met. The complete amino acid sequence of Ae I was determined. Ae I has high sequence homology with type 1 sea anemone neurotoxins. Interestingly, the polypeptide chain of Ae I comprises 54 amino acid residues, being 5-8 residues longer than the known type 1 toxins having 46-49 residues.
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Affiliation(s)
- X Y Lin
- Department of Food Science and Technology, Tokyo University of Fisheries, Japan
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27
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Abstract
Chemical modification studies have been carried out on the sea anemone polypeptide anthopleurin-A in order to clarify the role of Arg-14 in its cardiac stimulatory activity. Reaction with 1,2-cyclohexanedione at 37 degrees C produced a range of protein products, including some with amino group modifications. These side-reactions were eliminated by prior citraconylation of the amino groups, which, following reaction with cyclohexanedione, could be reversed under conditions which preserved the cyclohexanedione adduct. Citraconylation of the three amino groups, one from the N-terminus and two from Lys-37 and Lys-48, destroyed the cardiac stimulatory activity of the molecule, but this was fully recoverable upon reversal of this reaction. It appears that one or more of the amino groups is essential for activity. Anthopleurin-A contains only one arginine residue, and this was confirmed as the site of modification by cyclohexanedione by showing that the product was refractory to proteolysis by trypsin, which normally cleaves the molecule at this residue. The positive inotropic activity of the cyclohexanedione adduct on isolated guinea-pig atria was identical to that of unmodified anthopleurin-A, indicating that the side-chain of Arg-14 is not required for cardiotonic activity.
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Affiliation(s)
- A R Gould
- School of Biochemistry, University of New South Wales, Kensington, Australia
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Spagnuolo A, Zanetti L, Cariello L, Piccoli R. Isolation and characterization of two genes encoding calitoxins, neurotoxic peptides from Calliactis parasitica (Cnidaria). Gene 1994; 138:187-91. [PMID: 7510258 DOI: 10.1016/0378-1119(94)90805-2] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Among sea anemone neurotoxins, calitoxin, recently isolated from Calliactis parasitica, is a highly toxic peptide of 46 amino acids (aa), whose sequence differs greatly from that of all sea anemone toxins isolated so far. In this study, two genes (clx-1 and clx-2) coding for two highly homologous calitoxins were isolated and characterized from a C. parasitica genomic library. The clx-1 gene encodes the already known calitoxin sequence, named CLX-I, whereas a single bp substitution in the coding region of clx-2 is responsible for a single Glu6-->Lys replacement in a new peptide named CLX-II. The structural organization of the two genes is very similar: two introns and three exons, whose sequences are highly homologous for clx-1 and clx-2 (95% identity). The open reading frame (ORF) of both clx-1 and clx-2 codes for a precursor peptide of 79 aa, whose N-terminus has the feature of a single peptide, while the C-terminus corresponds to the sequences of mature CLX-I and CLX-II. The finding that a pair of basic aa is located upstream from the sequence of both mature toxins strongly suggests that proteolytic events, at specific cleavage sites, are responsible for the release of neurotoxins from their respective precursor molecules.
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Affiliation(s)
- A Spagnuolo
- Molecular Biology and Biochemistry Laboratory, Stazione Zoologica, A. Dohrn, Naples, Italy
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Khera P, Blumenthal K. Role of the cationic residues arginine 14 and lysine 48 in the function of the cardiotonic polypeptide anthopleurin B. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(17)42199-5] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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Abstract
The membrane actions of three recently isolated polypeptide neurotoxins from the sea anemones Stichodactyla helianthus (toxin ShI), Condylactis gigantea (toxin CgII) and Calliactis parasitica (toxin CpI) were investigated on action potentials and voltage-clamp membrane currents of the giant axon of the crayfish Procambarus clarkii. The first two toxins were also tested on the cockroach (Periplaneta americana) giant axon. All three toxins were particularly lethal to crustaceans, moderately toxic to an insect (cockroach), and essentially non-toxic to a mammal (mouse). ShI and CgII were 50- to 100-fold more potent on crayfish than on cockroach axons; this difference in activity was correlated with the relative reversibility of their effects on these arthropod axons. The crustacean selectivity of these toxins is therefore due largely to their greater affinity for crustacean sodium channels. All three toxins prolonged crayfish giant axon action potentials by selectively slowing Na channel inactivation without greatly affecting activation. Before toxin treatment, inactivation was nearly exponential, with a time constant less than 1 msec. After treatment, the inactivation time course could be described as the sum of two exponentially decaying components, plus a large steady-state component. The major component possessed the slower (10-20 msec) time constant. The steady-state component increased with depolarization, causing the sodium channel steady-state inactivation curve to reach a minimum between -60 and -20 mV and then increase at more positive potentials. All three toxins shifted the peak sodium current-voltage relation to the left. This voltage shift was greater at 20 degrees C than at 10 degrees C. Maintained membrane depolarization during toxin wash-in delayed the appearance of modified Na channels. Also, prolonged depolarization of toxin-treated axons converted modified sodium channels back to normal ones. The toxins did not affect potassium and leakage currents. Our results indicate that the three crustacean-active sea anemone toxins share a common electrophysiological action on arthropod sodium channels, at least at the macroscopic level.
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Affiliation(s)
- V L Salgado
- Rohm and Haas Company, Spring House, PA 19477
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Abstract
Sea anemones produce a series of toxic polypeptides and proteins with molecular weights in the range 3000-5000 that act by binding to specific receptor sites on the voltage-gated sodium channel of excitable tissue. This article reviews our current knowledge of the molecular basis for activity of these molecules, with particular emphasis on recent results on their receptor binding properties, the role of individual residues in activity and receptor binding, and their three-dimensional structures as determined by nuclear magnetic resonance spectroscopy. A region of these molecules that constitutes at least part of the receptor binding domain is proposed.
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Affiliation(s)
- R S Norton
- School of Biochemistry, University of New South Wales, Kensington, Australia
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Affiliation(s)
- A L Harvey
- Department of Physiology and Pharmacology, University of Strathclyde, Glasgow, Scotland
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