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Chen PW, Wu WL, Hwang DF. The complete mitochondrial genome of Conus quercinus (Neogastropoda: Conidae). MITOCHONDRIAL DNA PART B-RESOURCES 2018; 3:933-934. [PMID: 33490546 PMCID: PMC7800317 DOI: 10.1080/23802359.2018.1501314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The complete mitochondrial genome sequence of cone snail Conus quercinus a kind of worm-hunting sea snails, was performed by next-generation sequencing. The mitogenome is 16,439 bp in length, including 13 protein-coding genes, 22 tRNA genes, two ribosomal RNA genes (12S and 16S rRNA), and one control region. It has overall base composition of A (28.1%), T (38.2%), C (14.7%), and G (18.6%). It shows 75.9% identity with C. capitaneus, which also belongs to worm-hunting sea snail. The phylogenetic analysis was conducted with 22 closely related species to assess their phylogenetic relationship. The complete mitogenome of the C. quercinus provides important DNA molecular data for further phylogeography.
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Affiliation(s)
- Po-Wei Chen
- Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan
| | - Wen-Lung Wu
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Deng-Fwu Hwang
- Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan
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2
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Chen PW, Hsiao ST, Chen KS, Tseng CT, Wu WL, Hwang DF. The complete mitochondrial genome of Conus capitaneus (Neogastropoda: Conidae). MITOCHONDRIAL DNA PART B-RESOURCES 2016; 1:520-521. [PMID: 33473541 PMCID: PMC7800245 DOI: 10.1080/23802359.2016.1197060] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/02/2022]
Abstract
The complete mitochondrial genome sequence of cone snail Conus capitaneus, a kind of worm-hunting sea snails, was performed by next-generation sequencing. The mitogenome is 15,829 bp in length, including 13 protein-coding genes, 22 tRNA genes, 2 ribosomal RNA genes (12S and 16S rRNA) and 1 control region. It has an overall base composition of A (25.6%), T (36.6%), C (16.3%) and G (21.5%). It shows 79.8% identity with C. tribblei, which also belongs to worm-hunting sea snail. The phylogenetic analysis was conducted with 21 closely related species to assess their phylogenetic relationship. The complete mitogenome of the C. capitaneus provides important DNA molecular data for further phylogeography.
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Affiliation(s)
- Po-Wei Chen
- Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan
| | - Sheng-Tai Hsiao
- Marine Fisheries Division, Fisheries Research Institute, Keelung, Taiwan
| | - Kao-Sung Chen
- Planning and Information Division, Fisheries Research Institute, Keelung, Taiwan
| | - Chen-Te Tseng
- Planning and Information Division, Fisheries Research Institute, Keelung, Taiwan
| | - Wen-Lung Wu
- Academia Sinica, Biodiversity Research Center, Taipei, Taiwan
| | - Deng-Fwu Hwang
- Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan
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3
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Chen PW, Hsiao ST, Chen KS, Tseng CT, Wu WL, Hwang DF. The complete mitochondrial genome of Conus striatus (Neogastropoda: Conidae). MITOCHONDRIAL DNA PART B-RESOURCES 2016; 1:493-494. [PMID: 33490403 PMCID: PMC7800990 DOI: 10.1080/23802359.2016.1192502] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Conus striatus is a kind of piscivorous cone snail. We have sequenced it by next generation sequencing method. We used de novo assembly and reference mapping methods to assemble mitogenome. The mitochondrial genome is 15,738 bp, containing 13 protein coding genes, 22 transfer RNAs and 2 ribosomal RNAs genes. The overall base composition of C. striatus is 25.9% for A, 16.3% for C, 20.8% for G and 38.6% for T. The phylogenetic analysis was conducted with 18 related species and confirmed the classification status. The complete mitogenome of the C. striatus provides an essential and important DNA molecular data for further phylogeography and evolutionary analysis for cone snail phylogeny.
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Affiliation(s)
- Po-Wei Chen
- Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan
| | - Sheng-Tai Hsiao
- Marine Fisheries Division, Fisheries Research Institute, Keelung, Taiwan
| | - Kao-Sung Chen
- Planning and Information Division, Fisheries Research Institute, Keelung, Taiwan
| | - Chen-Te Tseng
- Planning and Information Division, Fisheries Research Institute, Keelung, Taiwan
| | - Wen-Lung Wu
- Biodiversity Research Center, Academia Sinica, Taipei, Taiwan
| | - Deng-Fwu Hwang
- Department of Food Science, National Taiwan Ocean University, Keelung, Taiwan
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4
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Fedosov AÉ, Moshkovskiĭ SA, Kuznetsova KG, Olivera BM. [Conotoxins: from the biodiversity of gastropods to new drugs]. BIOMEDIT︠S︡INSKAI︠A︡ KHIMII︠A︡ 2013; 59:267-94. [PMID: 23987066 DOI: 10.18097/pbmc20135903267] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A review describes general trends in research of conotoxins that are peptide toxins isolated from sea gastropods of the Conus genus, since the toxins were discovered in 1970th. There are disclosed a conotoxin classification, their structure diversity and different ways of action to their molecular targets, mainly, ion channels. In the applied aspect of conotoxin research, drug discovery and development is discussed, the drugs being based on conotoxin structure. A first exemplary drug is a ziconotide, which is an analgesic of new generation.
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5
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Jiang L, Liu C, Duan Z, Deng M, Tang X, Liang S. Transcriptome analysis of venom glands from a single fishing spider Dolomedes mizhoanus. Toxicon 2013; 73:23-32. [PMID: 23851222 DOI: 10.1016/j.toxicon.2013.07.005] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 06/19/2013] [Accepted: 07/03/2013] [Indexed: 11/15/2022]
Abstract
The spider venom is a large pharmacological repertoire composed of different types of bioactive peptide toxins. Despite the importance of spider toxins in capturing terrestrial prey and defending themselves against predators, we know little about the venom components from the spider acting on the fish. Here we constructed a cDNA library of a pair of venomous glands from a single fish-hunting spider Dolomedes mizhoanus. A total of 356 high-quality expressed sequence tags (ESTs) were obtained from the venom gland cDNA library and analyzed. These transcripts were further classified into 45 clusters (19 contigs and 26 singletons), most of which encoded cystine knot toxins (CKTs) and non-CKTs. The ESTs coding for 53 novel CKT precursors were abundant transcripts in the venom glands of the spider D. mizhoanus, accounting for 76% of the total ESTs, the precursors of which were grouped into six families based on the sequence identity and the phylogenetic analysis. In addition, the non-CKTs deduced from 21% of the total ESTs were annotated by Gene Ontology terms and eukaryotic orthologous groups. Fifty-five CKT precursors deduced from 273 ESTs are the largest dataset for a single spider specimen to date. The results may contribute to discovering novel potential drug leads from spider venoms and a better understanding of the evolutionary relationship of the spider toxin.
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Affiliation(s)
- Liping Jiang
- Department of Parasitology, Xiangya School of Medicine, Central South University, Changsha, Hunan 410013, PR China
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6
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Glycosylation of conotoxins. Mar Drugs 2013; 11:623-42. [PMID: 23455513 PMCID: PMC3705362 DOI: 10.3390/md11030623] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 01/25/2013] [Accepted: 02/06/2013] [Indexed: 01/02/2023] Open
Abstract
Conotoxins are small peptides present in the venom of cone snails. The snail uses this venom to paralyze and capture prey. The constituent conopeptides display a high level of chemical diversity and are of particular interest for scientists as tools employed in neurological studies and for drug development, because they target with exquisite specificity membrane receptors, transporters, and various ion channels in the nervous system. However, these peptides are known to contain a high frequency and variability of post-translational modifications-including sometimes O-glycosylation-which are of importance for biological activity. The potential application of specific conotoxins as neuropharmalogical agents and chemical probes requires a full characterization of the relevant peptides, including the structure of the carbohydrate part. In this review, the currently existing knowledge of O-glycosylation of conotoxins is described.
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7
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Abstract
Venoms and toxins are of significant interest due to their ability to cause a wide range of pathophysiological conditions that can potentially result in death. Despite their wide distribution among plants and animals, the biochemical pathways associated with these pathogenic agents remain largely unexplored. Impoverished and underdeveloped regions appear especially susceptible to increased incidence and severity due to poor socioeconomic conditions and lack of appropriate medical treatment infrastructure. To facilitate better management and treatment of envenomation victims, it is essential that the biochemical mechanisms of their action be elucidated. This review aims to characterize downstream envenomation mechanisms by addressing the major neuro-, cardio-, and hemotoxins as well as ion-channel toxins. Because of their use in folk and traditional medicine, the biochemistry behind venom therapy and possible implications on conventional medicine will also be addressed.
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8
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Saggiomo SLA, Seymour JE. Cardiotoxic effects of venom fractions from the Australian box jellyfish Chironex fleckeri on human myocardiocytes. Toxicon 2012; 60:391-5. [PMID: 22560886 DOI: 10.1016/j.toxicon.2012.03.025] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2012] [Revised: 03/08/2012] [Accepted: 03/29/2012] [Indexed: 11/18/2022]
Abstract
An investigation into the cardiotoxic effects in human cardiomyocytes of different fractions (as produced from an FPLC) of the venom from Chironex fleckeri showed that whole venom caused cardiac cell death in minutes, measured as cell detachment using xCELLigence technology. However, only one fraction of the venom was responsible for this effect. When all extracted venoms were recombined a similar result was seen for the toxic fraction, however these effects were slower than unfractionated venom alone even though the concentrations were similar. The difference in the results between fractioned and unfractionated venom may have been caused by compounds remaining in the FPLC column, which may interact with the toxic fraction to cause rapid cell detachment or death.
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Affiliation(s)
- Silvia L A Saggiomo
- School of Marine and Tropical Biology, James Cook University, PO Box 6811, Cairns, QLD 4870, Australia
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Safavi-Hemami H, Siero WA, Kuang Z, Williamson NA, Karas JA, Page LR, MacMillan D, Callaghan B, Kompella SN, Adams DJ, Norton RS, Purcell AW. Embryonic toxin expression in the cone snail Conus victoriae: primed to kill or divergent function? J Biol Chem 2011; 286:22546-57. [PMID: 21504902 DOI: 10.1074/jbc.m110.217703] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Predatory marine cone snails (genus Conus) utilize complex venoms mainly composed of small peptide toxins that target voltage- and ligand-gated ion channels in their prey. Although the venoms of a number of cone snail species have been intensively profiled and functionally characterized, nothing is known about the initiation of venom expression at an early developmental stage. Here, we report on the expression of venom mRNA in embryos of Conus victoriae and the identification of novel α- and O-conotoxin sequences. Embryonic toxin mRNA expression is initiated well before differentiation of the venom gland, the organ of venom biosynthesis. Structural and functional studies revealed that the embryonic α-conotoxins exhibit the same basic three-dimensional structure as the most abundant adult toxin but significantly differ in their neurological targets. Based on these findings, we postulate that the venom repertoire of cone snails undergoes ontogenetic changes most likely reflecting differences in the biotic interactions of these animals with their prey, predators, or competitors. To our knowledge, this is the first study to show toxin mRNA transcripts in embryos, a finding that extends our understanding of the early onset of venom expression in animals and may suggest alternative functions of peptide toxins during development.
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Affiliation(s)
- Helena Safavi-Hemami
- Department of Biochemistry and Molecular Biology, University of Melbourne, 3010 Victoria, Australia
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Safavi-Hemami H, Young ND, Williamson NA, Purcell AW. Proteomic Interrogation of Venom Delivery in Marine Cone Snails: Novel Insights into the Role of the Venom Bulb. J Proteome Res 2010; 9:5610-9. [DOI: 10.1021/pr100431x] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Helena Safavi-Hemami
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular Science and Biotechnology Institute, and Department of Veterinary Science, University of Melbourne, Victoria, Australia
| | - Neil D. Young
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular Science and Biotechnology Institute, and Department of Veterinary Science, University of Melbourne, Victoria, Australia
| | - Nicholas A. Williamson
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular Science and Biotechnology Institute, and Department of Veterinary Science, University of Melbourne, Victoria, Australia
| | - Anthony W. Purcell
- Department of Biochemistry and Molecular Biology, The Bio21 Molecular Science and Biotechnology Institute, and Department of Veterinary Science, University of Melbourne, Victoria, Australia
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11
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Safavi-Hemami H, Bulaj G, Olivera BM, Williamson NA, Purcell AW. Identification of Conus peptidylprolyl cis-trans isomerases (PPIases) and assessment of their role in the oxidative folding of conotoxins. J Biol Chem 2010; 285:12735-46. [PMID: 20147296 PMCID: PMC2857115 DOI: 10.1074/jbc.m109.078691] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2009] [Revised: 02/09/2010] [Indexed: 11/06/2022] Open
Abstract
Peptidylprolyl cis-trans isomerases (PPIases) are ubiquitous proteins that catalyze the cis-trans isomerization of prolines. A number of proteins, such as Drosophila rhodopsin and the human immunodeficiency viral protein HIV-1 Gag, have been identified as endogenous substrates for PPIases. However, very little is known about the interaction of PPIases with small, disulfide-rich peptides. Marine cone snails synthesize a wide array of cysteine-rich peptides, called conotoxins, many of which contain one or more prolines or hydroxyprolines. To identify whether PPIase-associated cis-trans isomerization of these residues affects the oxidative folding of conotoxins, we identified, sequenced, and expressed three functionally active isoforms of PPIase from the venom gland of Conus novaehollandiae, and we characterized their ability to facilitate oxidative folding of conotoxins in vitro. Three conotoxins, namely mu-GIIIA, mu-SIIIA, and omega-MVIIC, derived from two distinct toxin gene families were assayed. Conus PPIase significantly increased the rate of appearance of the native form of mu-GIIIA, a peptide containing three hydroxyprolines. In contrast, the presence of PPIase had no effect on the folding of mu-SIIIA and omega-MVIIC, peptides containing no or one proline residue, respectively. We further showed that an endoplasmic reticulum-resident PPIase isoform facilitated folding of mu-GIIIA more efficiently than two cytosolic isoforms. This is the first study to demonstrate PPIase-assisted folding of conotoxins, small disulfide-rich peptides with unique structural properties.
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Affiliation(s)
- Helena Safavi-Hemami
- From the
Department of Biochemistry and Molecular Biology, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 3010 Victoria, Australia and
| | | | | | - Nicholas A. Williamson
- From the
Department of Biochemistry and Molecular Biology, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 3010 Victoria, Australia and
| | - Anthony W. Purcell
- From the
Department of Biochemistry and Molecular Biology, The Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, 3010 Victoria, Australia and
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12
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BINFORD GRETAJ. Differences in venom composition between orb-weaving and wandering Hawaiian Tetragnatha (Araneae). Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2001.tb01415.x] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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13
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Quinton L, Demeure K, Dobson R, Gilles N, Gabelica V, De Pauw E. New method for characterizing highly disulfide-bridged peptides in complex mixtures: application to toxin identification from crude venoms. J Proteome Res 2007; 6:3216-23. [PMID: 17580849 DOI: 10.1021/pr070142t] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Animal venoms are highly complex mixtures that can contain many disulfide-bridged toxins. This work presents an LC-MALDI approach allowing (1) a rapid classification of toxins according to their number of disulfide bonds and (2) a rapid top-down sequencing of the toxins using a new MALDI matrix enhancing in-source decay (ISD). The crude venom is separated twice by LC: the fractions of the first separation are spotted on the MALDI matrix alpha-cyano-4-hydroxycinnamic acid (CHCA) and the others using 1,5-diaminonaphthalene (1,5-DAN). CHCA spots are more convenient for obtaining a precise mass fingerprint of a large number of peptides; however, the analysis of 1,5-DAN spots allows the number of disulfide bridges to be counted owing to their partial in-plume reduction by this particular matrix. Subsequently, the disulfide bonds of all peptides present in the crude venom were reduced by an excess of tris(carboxyethyl)phosphine before the LC separation and were subjected to the same analysis in CHCA and 1,5-DAN. Toxins were sequenced using a TOF/TOF analysis of metastable fragments from CHCA spots and ISD fragmentation from 1,5-DAN spots. Novel conotoxin sequences were found using this approach. The use of 1,5-DAN for ISD top-down sequencing is also illustrated for higher molecular weight toxins such as snake cardiotoxins and neurotoxins (>6500 Da), where sequence coverage >70% is obtained from the c-ion series.
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Affiliation(s)
- Loïc Quinton
- Laboratoire de Spectrométrie de Masse, Centre d'Analyse des Résidus en Traces, Université de Liège, Liège B-4000, Belgium
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14
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Kelley WP, Schulz JR, Jakubowski JA, Gilly WF, Sweedler JV. Two toxins from Conus striatus that individually induce tetanic paralysis. Biochemistry 2006; 45:14212-22. [PMID: 17115716 PMCID: PMC2530915 DOI: 10.1021/bi061485s] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe structural properties and biological activities of two related O-glycosylated peptide toxins isolated from injected (milked) venom of Conus striatus, a piscivorous snail that captures prey by injecting a venom that induces a violent, spastic paralysis. One 30 amino acid toxin is identified as kappaA-SIVA (termed s4a here), and another 37 amino acid toxin, s4b, corresponds to a putative peptide encoded by a previously reported cDNA. We confirm the amino acid sequences and carry out structural analyses of both mature toxins using multiple mass spectrometric techniques. These include electrospray ionization ion-trap mass spectrometry and nanoelectrospray techniques for small volume samples, as well as matrix-assisted laser desorption/ionization time of flight mass spectrometric analysis as a complementary method to assist in the determination of posttranslational modifications, including O-linked glycosylation. Physiological experiments indicate that both s4a and s4b induce intense repetitive firing of the frog neuromuscular junction, leading to a tetanic contracture in muscle fiber. These effects apparently involve modification of voltage-gated sodium channels in motor axons. Notably, application of either s4a or s4b alone mimics the biological effects of the whole injected venom on fish prey.
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Affiliation(s)
| | | | | | | | - Jonathan V. Sweedler
- To whom correspondence should be addressed. E-mail: . Tel: (217) 244-7359. Fax: (217) 244-8068
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15
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Stewart J, Gilly WF. Piscivorous behavior of a temperate cone snail, Conus californicus. THE BIOLOGICAL BULLETIN 2005; 209:146-53. [PMID: 16260774 DOI: 10.2307/3593132] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Most of the more than 500 species of predatory marine snails in the genus Conus are tropical or semitropical, and nearly all are thought to be highly selective regarding type of prey. Conus californicus Hinds, 1844, is unusual in that it is endemic to the North American Pacific coast and preys on a large variety of benthic organisms, primarily worms and other molluscs, and also scavenges. We studied the feeding behavior of C. californicus in captivity and found that it regularly killed and consumed live prickleback fishes (Cebidichthys violaceus and Xiphister spp.). Predation involved two behavioral methods similar to those employed by strictly piscivorous relatives. One method utilized stings delivered by radular teeth; the other involved engulfing the prey without stinging. Both methods were commonly used in combination, and individual snails sometimes employed multiple stings to subdue a fish. During the course of the study, snails became aroused by the presence of live fish more quickly, as evidenced by more rapid initiation of hunting behavior. Despite this apparent adaptation, details of prey-capture techniques and effectiveness of stings remained similar over the same period.
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Affiliation(s)
- Julia Stewart
- Department of Ecology and Evolutionary Biology, University of California Los Angeles, 621 Charles E. Young Dr. South, Los Angeles, California 90095, USA
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16
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Barbier J, Lamthanh H, Le Gall F, Favreau P, Benoit E, Chen H, Gilles N, Ilan N, Heinemann SH, Gordon D, Ménez A, Molgó J. A δ-Conotoxin from Conus ermineus Venom Inhibits Inactivation in Vertebrate Neuronal Na+ Channels but Not in Skeletal and Cardiac Muscles. J Biol Chem 2004; 279:4680-5. [PMID: 14615484 DOI: 10.1074/jbc.m309576200] [Citation(s) in RCA: 52] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We have isolated delta-conotoxin EVIA (delta-EVIA), a conopeptide in Conus ermineus venom that contains 32 amino acid residues and a six-cysteine/four-loop framework similar to that of previously described omega-, delta-, microO-, and kappa-conotoxins. However, it displays low sequence homology with the latter conotoxins. delta-EVIA inhibits Na+ channel inactivation with unique tissue specificity upon binding to receptor site 6 of neuronal Na+ channels. Using amphibian myelinated axons and spinal neurons, we showed that delta-EVIA increases the duration of action potentials by inhibiting Na+ channel inactivation. delta-EVIA considerably enhanced nerve terminal excitability and synaptic efficacy at the frog neuromuscular junction but did not affect directly elicited muscle action potentials. The neuronally selective property of delta-EVIA was confirmed by showing that a fluorescent derivative of delta-EVIA labeled motor nerve endings but not skeletal muscle fibers. In a heterologous expression system, delta-EVIA inhibited inactivation of rat neuronal Na+ channel subtypes (rNaV1.2a, rNaV1.3, and rNaV1.6) but did not affect rat skeletal (rNaV1.4) and human cardiac muscle (hNaV1.5) Na+ channel subtypes. delta-EVIA, in the range of concentrations used, is the first conotoxin found to affect neuronal Na+ channels without acting on Na+ channels of skeletal and cardiac muscle. Therefore, it is a unique tool for discriminating voltage-sensitive Na+ channel subtypes and for studying the distribution and modulation mechanisms of neuronal Na+ channels, and it may serve as a lead to design new drugs adapted to treat diseases characterized by defective nerve conduction.
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Affiliation(s)
- Julien Barbier
- Laboratoire de Neurobiologie Cellulaire et Moléculaire, UPR 9040, CNRS, 91198 Gif-sur-Yvette cedex, France
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