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Jobson J, Tsegay PS, Beltran MT, Taher EA, Rein SR, Liu Y, Rein KS. Brevetoxin induces a shift in the redox state of the proteome and unfolded protein response in human lymphoblast cells that can be alleviated with the acrolein scavenger MESNA. ENVIRONMENTAL TOXICOLOGY AND PHARMACOLOGY 2023; 100:104137. [PMID: 37127110 DOI: 10.1016/j.etap.2023.104137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2022] [Revised: 04/24/2023] [Accepted: 04/29/2023] [Indexed: 05/03/2023]
Abstract
Human lymphoblast cells were treated with the marine algal toxin, brevetoxin-2 (PbTx-2), and its effects on the proteome were assessed by redox proteomics using cysteine reactive tandem mass tags (TMT). Additionally, cells were simultaneously treated with PbTx-2 and the antioxidant and acrolein scavenger sodium 2-mercaptoethylsulfonate (MESNA) to determine if MESNA could prevent the proteomic effects of brevetoxin-2. A massive shift in the redox state of the proteome of brevetoxin-2 treated cells was observed. The main pathway affected was genetic information processing. Significantly oxidized proteins included Trx-1, peroxyredoxins (Prxs), ribosomal proteins, and the eukaryotic initiation factor 2 β subunit (eIF2β). Proteins that were overexpressed in brevetoxin-treated cells included four folding chaperones. These effects were diminished in the presence of MESNA indicating that MESNA may act through its antioxidant properties or as a brevetoxin scavenger. These studies provide novel insights into new prophylactics for brevetoxicosis in humans and wildlife.
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Affiliation(s)
- Jordan Jobson
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Pawlos S Tsegay
- Biochemistry Ph.D. Program, Florida International University, Miami, FL 33199, USA
| | - Mayra Tabares Beltran
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Eman A Taher
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA
| | - Samuel R Rein
- The School District of Philadelphia, Philadelphia, PA 19130, USA
| | - Yuan Liu
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Biochemistry Ph.D. Program, Florida International University, Miami, FL 33199, USA; Biomolecular Sciences Institute, Florida International University, Miami, FL 33199, USA
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, Miami, FL 33199, USA; Current address: The Water School, Department of Marine and Earth Science and Department of Chemistry and Physics, Florida Gulf Coast University, Fort Myers, FL 33965.
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2
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Tuladhar A, Hondal RJ, Colon R, Hernandez EL, Rein KS. Effectors of thioredoxin reductase: Brevetoxins and manumycin-A. Comp Biochem Physiol C Toxicol Pharmacol 2019; 217:76-86. [PMID: 30476593 PMCID: PMC7485175 DOI: 10.1016/j.cbpc.2018.11.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/20/2018] [Accepted: 11/21/2018] [Indexed: 02/03/2023]
Abstract
The activities of two effectors, brevetoxin (PbTx) and manumycin-A (Man-A), of thioredoxin reductase (TrxR) have been evaluated against a series of fourteen TrxR orthologs originating from mammals, insects and protists and several mutants. Man-A, a molecule with numerous electrophilic sites, forms a covalent adduct with most selenocystine (Sec)-containing TrxR enzymes. The evidence also demonstrates that Man-A can form covalent adducts with some non-Sec-containing enzymes. The activities of TrxR enzymes towards various substrates are moderated by Man-A either positively or negatively depending on the enzyme. In general, the reduction of substrates by Sec-containing TrxR is inhibited and NADPH oxidase activity is activated. For non-Sec-containing TrxR the effect of Man-A on the reduction of substrates is variable, but NADPH oxidase activity can be activated even in the absence of covalent modification of TrxR. The effect of PbTx is less pronounced. A smaller subset of enzymes is affected by PbTx. With a single exception, the activities of most of this subset are activated. Although both PbTx variants can react with selenocysteine, a stable covalent adduct is not formed with any of the TrxR enzymes. The key findings from this work are (i) the identification of an alternate mechanism of toxicity for the algal toxin brevetoxin (ii) the demonstration that covalent modification of TrxR is not a prerequisite for the activation of NADPH oxidase activity of TrxR and (iii) the identification of an inhibitor which can discriminate between cytosolic and mitochondrial TrxR.
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Affiliation(s)
- Anupama Tuladhar
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Robert J Hondal
- Department of Biochemistry, 89 Beaumont Ave, Given Building Room 413B, Burlington, VT 05405, United States
| | - Ricardo Colon
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Elyssa L Hernandez
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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Chen W, Tuladhar A, Rolle S, Lai Y, Rodriguez Del Rey F, Zavala CE, Liu Y, Rein KS. Brevetoxin-2, is a unique inhibitor of the C-terminal redox center of mammalian thioredoxin reductase-1. Toxicol Appl Pharmacol 2017; 329:58-66. [PMID: 28551108 DOI: 10.1016/j.taap.2017.05.027] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/15/2017] [Accepted: 05/22/2017] [Indexed: 11/15/2022]
Abstract
Karenia brevis, the Florida red tide dinoflagellate produces a suite of neurotoxins known as the brevetoxins. The most abundant of the brevetoxins PbTx-2, was found to inhibit the thioredoxin-thioredoxin reductase system, whereas the PbTx-3 has no effect on this system. On the other hand, PbTx-2 activates the reduction of small disulfides such as 5,5'-dithio-bis-(2-nitrobenzoic acid) by thioredoxin reductase. PbTx-2 has an α, β-unsaturated aldehyde moiety which functions as an efficient electrophile and selenocysteine conjugates are readily formed. PbTx-2 blocks the inhibition of TrxR by the inhibitor curcumin, whereas curcumin blocks PbTx-2 activation of TrxR. It is proposed that the mechanism of inhibition of thioredoxin reduction is via the formation of a Michael adduct between selenocysteine and the α, β-unsaturated aldehyde moiety of PbTx-2. PbTx-2 had no effect on the rates of reactions catalyzed by related enzymes such as glutathione reductase, glutathione peroxidase or glutaredoxin.
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Affiliation(s)
- Wei Chen
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Anupama Tuladhar
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Shantelle Rolle
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Yanhao Lai
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Freddy Rodriguez Del Rey
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Cristian E Zavala
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Yuan Liu
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States; Biomolecular Sciences Institute, School of Integrated Sciences and Humanity, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States
| | - Kathleen S Rein
- Department of Chemistry and Biochemistry, Florida International University, 11200 SW 8th Street, Miami, FL 33199, United States.
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Benson JM, Wolf ML, Kajon A, Tibbetts BM, Bourdelais AJ, Baden DG, March TH. Brevetoxin inhalation alters the pulmonary response to influenza A in the male F344 rat. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:313-324. [PMID: 21240731 PMCID: PMC3444170 DOI: 10.1080/15287394.2010.519316] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Epidemiological studies demonstrated that the number of emergency-room visits for respiratory indications increases during periods of Florida Red Tides. The purpose of this study was to examine whether or not repeated brevetoxin inhalation, as may occur during a Florida Red Tide, affects pulmonary responses to influenza A. Male F344 rats were divided into four groups: (1) sham aerosol/no influenza; (2) sham aerosol/influenza; (3) brevetoxin/no influenza; and (4) brevetoxin/influenza. Animals were exposed by nose-only inhalation to vehicle or 50 μg brevetoxin-3/m3, 2 h/d for 12 d. On d 6 of aerosol exposure, groups 2 and 4 were administered 10,000 plaque-forming units of influenza A, strain HKX-31 (H3N2), by intratracheal instillation. Subgroups were euthanized at 2, 4, and 7 d post influenza treatment. Lungs were evaluated for viral load, cytokine content, and histopathologic changes. Influenza virus was cleared from the lungs over the 7-d period; however, there was significantly more virus remaining in the group 4 lungs compared to group 2. Influenza virus significantly increased interleukins-1α and -6 and monocyte chemotactic protein-1 in lung; brevetoxin exposure significantly enhanced the influenza-induced response. At 7 d, the severity of perivascular and peribronchiolar inflammatory cell infiltrates was greatest in group 4. Bronchiolitis persisted, with low incidence and severity, only in group 4 at d 7. These results suggest that repeated inhalation exposure to brevetoxin may delay virus particle clearance and recovery from influenza A infection in the rat lung.
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Affiliation(s)
- Janet M. Benson
- Lovelace Respiratory Research Institute, 2425 Ridgecrest Dr. SE, Albuquerque, NM 87108
| | - Molly L. Wolf
- Lovelace Respiratory Research Institute, 2425 Ridgecrest Dr. SE, Albuquerque, NM 87108
| | - Adriana Kajon
- Lovelace Respiratory Research Institute, 2425 Ridgecrest Dr. SE, Albuquerque, NM 87108
| | - Brad M. Tibbetts
- Lovelace Respiratory Research Institute, 2425 Ridgecrest Dr. SE, Albuquerque, NM 87108
| | - Andrea J. Bourdelais
- Center for Marine Science Research, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, NC 28409
| | - Daniel G. Baden
- Center for Marine Science Research, University of North Carolina at Wilmington, 5600 Marvin K. Moss Lane, Wilmington, NC 28409
| | - Thomas H. March
- Lovelace Respiratory Research Institute, 2425 Ridgecrest Dr. SE, Albuquerque, NM 87108
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Naar JP, Flewelling LJ, Lenzi A, Abbott JP, Granholm A, Jacocks HM, Gannon D, Henry M, Pierce R, Baden DG, Wolny J, Landsberg JH. Brevetoxins, like ciguatoxins, are potent ichthyotoxic neurotoxins that accumulate in fish. Toxicon 2007; 50:707-23. [PMID: 17675204 PMCID: PMC2652748 DOI: 10.1016/j.toxicon.2007.06.005] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2007] [Revised: 06/04/2007] [Accepted: 06/05/2007] [Indexed: 11/15/2022]
Abstract
Brevetoxins and ciguatoxins are closely related potent marine neurotoxins. Although ciguatoxins accumulate in fish to levels that are dangerous for human consumption, live fish have not been considered as potential sources of brevetoxin exposure in humans. Here we show that, analogous to ciguatoxins, brevetoxins can accumulate in live fish by dietary transfer. We experimentally identify two pathways leading to brevetoxin-contaminated omnivorous and planktivorous fish. Fish fed with toxic shellfish and Karenia brevis cultures remained healthy and accumulated high brevetoxin levels in their tissues (up to 2675 ng g(-1) in viscera and 1540 ng g(-1) in muscle). Repeated collections of fish from St. Joseph Bay in the Florida panhandle reveal that accumulation of brevetoxins in healthy fish occurs in the wild. We observed that levels of brevetoxins in the muscle of fish at all trophic levels rise significantly, but not to dangerous levels, during a K. brevis bloom. Concentrations were highest in fish liver and stomach contents, and increased during and immediately following the bloom. The persistence of brevetoxins in the fish food web was followed for 1 year after the K. brevis bloom.
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Affiliation(s)
- Jerome P Naar
- Center for Marine Science, University of North Carolina at Wilmington, NC 28409, USA.
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Bourdelais AJ, Jacocks HM, Wright JLC, Bigwarfe PM, Baden DG. A new polyether ladder compound produced by the dinoflagellate Karenia brevis. JOURNAL OF NATURAL PRODUCTS 2005; 68:2-6. [PMID: 15679307 PMCID: PMC2659471 DOI: 10.1021/np049797o] [Citation(s) in RCA: 93] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
A new ladder-frame polyether compound containing five fused ether rings was isolated from laboratory cultures of the marine dinoflagellate Karenia brevis. This compound, named brevenal, and its dimethyl acetal derivative both competitively displace brevetoxin from its binding site in rat brain synaptosomes. Significantly, these compounds are also nontoxic to fish and antagonize the toxic effects of brevetoxins in fish. The structure and biological activity of brevenal, as well as the dimethyl acetal derivative, are described in this paper.
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Affiliation(s)
- Andrea J Bourdelais
- Wilmington Center for Marine Science, University of North Carolina, 5600 Marvin K. Moss Lane, Wilmington, North Carolina 28409, USA.
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Fujiwara K, Murai A. Recent Advances in the Synthesis oftrans-Fused Polycyclic Ethers by Hydroxy-Epoxide-Cyclization and Ether-Ring-Expansion Reactions. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 2004. [DOI: 10.1246/bcsj.77.2129] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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8
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Benson J, Hahn F, March T, McDonald J, Sopori M, Seagrave J, Gomez A, Bourdelais A, Naar J, Zaias J, Bossart G, Baden D. Inhalation toxicity of brevetoxin 3 in rats exposed for 5 days. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2004; 67:1443-56. [PMID: 15371231 PMCID: PMC2846653 DOI: 10.1080/15287390490483809] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Brevetoxins are potent neurotoxins produced by the marine dinoflagellate Karenia brevis. Exposure to brevetoxins may occur during a K. brevis red tide when the compounds become aerosolized by wind and surf. This study assesses possible adverse health effects associated with short-term inhalation exposure to brevetoxin 3. Male F344/Crl/Br rats were exposed to 500 microg brevetoxin 3/m3 by nose-only inhalation for 0.5 or 2 h/d for 5 consecutive days. Control rats were sham exposed for 2 h to vehicle. Calculated deposited brevetoxin doses were 8.3 and 33 microg/kg/d for the low- and high-dose groups, respectively. At the termination of exposures, only body weights of the high-dose group (Group B) were significantly below control values. By immunohistochemistry (IHC), small numbers of splenic and peribronchiolar lymphoid tissue macrophages stained positive for brevetoxin, while nasal mucosa, liver, and brain were IHC negative for brevetoxin. No gross or microscopic lesions were observed in any tissue examined. There was no biochemical evidence of cytotoxicity or inflammation in bronchoalveolar lavage fluid. Alveolar macrophages showed some evidence of activation following brevetoxin exposure. Humoral-mediated immunity was suppressed in brevetoxin-exposed rats as indicated by a >70% reduction in splenic plaque-forming cells in brevetoxin-exposed animals compared to controls. Results suggest that the immune system may be a target of toxicity following brevetoxin inhalation. Future studies will focus on identification of a no-effect level and mechanisms underlying brevetoxin-induced immune suppression.
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Affiliation(s)
- Janet Benson
- Lovelace Respiratory Research Institute, Albuquerque, New Mexico 87108, USA.
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9
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Abstract
Citation of a published work is one of the parameters considered in the analysis of relevance and importance of scientific contributions. In 2002, for the first time the Impact Factor of Toxicon has risen above 2.0, placing it at the 17th position among 76 journals in the 'toxicology' field. The aim of this article was to identify the most cited articles in Toxicon, that have contributed to the steady increase of its Impact Factor. The number of citations, complete reference and type of all documents appearing in Toxicon in the period 1963-2003 were retrieved from the ISI Web-of-Science homepage. The documents retrieved were sorted by the number of citations received. A 'citation index', defined as the number of citations divided by the number of years since publication, was calculated for each document. It was clearly seen that reviews in Toxicon received 4.4-fold more citations than articles. Unexpectedly, it was found that recent papers were proportionally more cited than old ones. A decrease in the proportion of papers dealing on 'snake*' through out the period and the broadened range of subjects of the most cited papers recently published in Toxicon reflects an increased 'visibility' in other fields of toxinology. Research on plant toxins gained its own space in Toxicon with newer publications showing high citation indexes. It can be postulated that these facts helped to increase Toxicon's Impact Factor from 1.248 in 1999 to 2.003 in 2002. With the increased number of issues in Toxicon as well as publications of subject-dedicated volumes containing mostly reviews, the Impact Factor of Toxicon is expected to keep rising in the near future.
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Affiliation(s)
- Jorge A Guimarães
- Center of Biotechnology, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, Prédio 43.421, CEP 91501970 Porto Alegre, RS, Brazil
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10
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Walsh PJ, Bookman RJ, Zaias J, Mayer GD, Abraham W, Bourdelais AJ, Baden DG. Toxicogenomic effects of marine brevetoxins in liver and brain of mouse. Comp Biochem Physiol B Biochem Mol Biol 2003; 136:173-82. [PMID: 14529743 PMCID: PMC2663909 DOI: 10.1016/s1096-4959(03)00223-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although the polyether brevetoxins (PbTx's) produced by Karenia brevis (the organism responsible for blooms of the Florida red tide) are known to exert their acute toxic effects through ion-channel mediated pathways in neural tissue, prior studies have also demonstrated that at least one form of the toxin (PbTx-6) is bound avidly by the aryl hydrocarbon receptor (AhR). Since AhR binding of a prototypical ligand such as dioxin is the first step in a cascade pathway producing major changes in gene expression, we reasoned that PbTx-6 might produce similar genomic-wide changes in expression. Mice were injected i.p. with sub-lethal doses of PbTx's (either 1.5 or 3 mg/g body weight of PbTx-6; or 0.15 mg/g body weight of PbTx-2, a toxin not avidly bound by the AhR), and liver and brain tissues were sampled at 8, 24 and 72 h and RNA was isolated. Changes in gene-specific RNA levels were assessed using commercially available mouse cDNA arrays (Incyte) containing >9600 array elements, including many elements from AhR-mediated genes. Histopathology of the two organs was also assessed. We observed minor histopathological effects and a total of only 29 significant (>2.0-fold) changes in gene expression, most of which occurred in the liver, and most of which could be attributable to an 'acute phase' inflammatory response. These results argue against the hypothesis that PbTx-6 acts via a classic AhR-mediated mechanism to evoke gene expression changes. However, given the avidity with which PbTx-6 binds to the AhR, these findings have important implications for how PbTx's may act in concert with other toxicants that are sensed by the AhR.
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Affiliation(s)
- Patrick J Walsh
- NIEHS Marine and Freshwater Biomedical Sciences Center, Rosenstiel School of Marine and Atmospheric Science, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149, USA.
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11
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Singh JN, Das Gupta S, Gupta AK, Dube SN, Deshpande SB. Relative potency of synthetic analogs of Ptychodiscus brevis toxin in depressing synaptic transmission evoked in neonatal rat spinal cord in vitro. Toxicol Lett 2002; 128:177-83. [PMID: 11869828 DOI: 10.1016/s0378-4274(02)00011-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Effects of Ptychodiscus brevis toxin (PbTx) analogs on the spinal synaptic transmission in neonatal rats in vitro were evaluated. PbTx1/PbTx2 had aromatic groups and PbTx3/PbTx4 had aliphatic groups. All the analogs depressed monosynaptic reflex (MSR) and polysynaptic reflex (PSR) in a concentration-dependent manner. The maximal depression of MSR (75% from initial) and PSR (96%) was at 84 microM for PbTx1. Concentration to produce 25% inhibition from initial (IC25) by PbTx1 for MSR and PSR was < or =2.8 microM. The maximal depression of MSR (80%) was at 96 microM and PSR (100%) was at 32 microM by PbTx2. IC25 for MSR and PSR were 5.5 microM and <3.2 microM, respectively. PbTx3 decreased MSR by 25% maximally (=IC25) at 36 microM. The depression of PSR fluctuated and was maximal (75%) at 108 microM and IC25 was 6.2 microM. PbTx4 depressed MSR and PSR at the maximum of 35% at 32 microM and IC25 for MSR was 8.3 microM and for PSR was 35 microM. Rank order of potency of toxins for depressing MSR was PbTx1>PbTx2>>PbTx4>PbTx3; and for PSR it was PbTx2>PbTx1>PbTx3>>PbTx4. Results indicate that the toxins having aromatic groups exhibited greater neurotoxicity.
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Affiliation(s)
- J N Singh
- Department of Physiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi 221005, India
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12
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Rundle NT, Xu L, Andersen RJ, Roberge M. G2 DNA damage checkpoint inhibition and antimitotic activity of 13-hydroxy-15-oxozoapatlin. J Biol Chem 2001; 276:48231-6. [PMID: 11572854 DOI: 10.1074/jbc.m103990200] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Checkpoints activated in response to DNA damage cause arrest in the G(1) and G(2) phases of the cell cycle. Inhibitors of the G(2) checkpoint may be used as tools to study this response and also to increase the effectiveness of DNA-damaging therapies against cancers lacking p53 function. Using a cell-based assay for G(2) checkpoint inhibitors, we have screened extracts from the NCI National Institutes of Health Natural Products Repository and have identified 13-hydroxy-15-oxozoapatlin (OZ) from the African tree Parinari curatellifolia. Flow cytometry with a mitosis-specific antibody showed that checkpoint inhibition by OZ was maximal at 10 microm, which released 20% of irradiated MCF-7 cells expressing defective p53 and 30% of irradiated HCT116p53(-/-) cells from G(2) arrest. OZ additively increased the response to the checkpoint inhibitors isogranulatimide and debromohymenialdisine, but it did not augment the effects of UCN-01 or caffeine. Unlike other checkpoint inhibitors, OZ did not inhibit ataxia-telangiectasia mutated (ATM), ATM and Rad3-related (ATR), Chk1, Chk2, Plk1, or Ser/Thr protein phosphatases in vitro. Treatment with OZ also caused G(2)-arrested and cycling cells to arrest in mitosis in a state resembling prometaphase. In these cells, the chromosomes were condensed and scattered over disordered mitotic spindles. The results demonstrate that OZ is both a G(2) checkpoint inhibitor and an antimitotic agent.
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Affiliation(s)
- N T Rundle
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
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13
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Abstract
Maitotoxin (MTX), a putative Ca(2+) channel activator produced by the dinoflagellate Gambierdiscus toxicus showed extremely potent hemolytic and ichthyotoxic activities. Hemolysis of 1% mouse blood cell suspension in saline occurred at 15 nM of MTX. The activity was enhanced six-fold in the presence of 10 microM of Ca(2+) and completely blocked by EDTA2Na, indicating its dependency on external Ca(2+). The MTX-induced hemolysis was little affected by L-type Ca(2+) channel blockers (diltiazem, nifedipine, verapamil) but was strongly inhibited by calmodulin blockers (prenylamine and chlorpromazine) or a phospholipase A2 inhibitor (quinacrine). MTX was mimicked by a calcium ionophore, calcimycin. Based on these results, a series of cellular events triggered by MTX were presumed to occur in the following sequence: increased Ca(2+) entry in cells, activation of calmodulin, promotion of phospholipase A2 activity, and finally destruction of cell membrane resulting from hydrolysis of membrane lipids. The sensitivity of blood cells to MTX varied significantly, dependent on the animal sources. Nucleated blood cells of carps and chickens were 100 times more resistant than those of mammals. LC(50) of MTX to freshwater fish Tanichthys albonubes in Ca(2+) free media (pH 8) was 5 nM but was markedly lowered to 3 pM by raising pH to 8 and increasing Ca(2+) concentration to 2 mM. In a marine environment MTX was 2000 times more toxic to fish than 42-di-hydrobrevetoxin-B (PbTx-3), one of the best known ichthyotoxins of red-tide origins.
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Affiliation(s)
- T Igarashi
- Department of Applied Biochemistry, Graduate school of Agriculture, Tohoku University, Sendai, Japan.
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Igarashi T, Satake M, Yasumoto T. Structures and Partial Stereochemical Assignments for Prymnesin-1 and Prymnesin-2: Potent Hemolytic and Ichthyotoxic Glycosides Isolated from the Red Tide Alga Prymnesium parvum. J Am Chem Soc 1999. [DOI: 10.1021/ja991740e] [Citation(s) in RCA: 101] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Tomoji Igarashi
- Contribution from the Department of Applied Biochemistry, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Masayuki Satake
- Contribution from the Department of Applied Biochemistry, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
| | - Takeshi Yasumoto
- Contribution from the Department of Applied Biochemistry, Graduate School of Agricultural Science, Tohoku University, Sendai, Japan
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15
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Koley J, Sinha S, Basak AK, Das M, Dube SN, Majumder PK, Gupta AK, Dasgupta S, Koley B. Cardiovascular and respiratory changes following exposure to a synthetic toxin of Ptychodiscus brevis. Eur J Pharmacol 1995; 293:483-6. [PMID: 8748702 DOI: 10.1016/0926-6917(95)90069-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The present study demonstrated cardiorespiratory effects of a synthetic phosphorus-containing ichthyotoxic metabolite elaborated by the marine dinoflagellate Ptychodiscus brevis in anaesthetised cats. The metabolite at a dose of 0.25-1.5 mg/kg i.v., resulted in a dose-dependent fall in blood pressure and such vasodepressor effect was associated with bradycardia. There is initial respiratory apnoea followed by increased rate and depth of respiration (hyperapnoea) following the administration of the toxin. The hypotensive response was accompanied by a decrease in aortic baroreceptor activity. The ECG showed atrioventricular conduction block, arrhythmia and depression of S-T segment and T wave which indicated coronary insufficiency. Vasodepressive property of the toxin is presumably muscarinic in nature as atropine counteracted the vasodepression.
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Affiliation(s)
- J Koley
- Department of Physiology, University College of Science and Technology, Calcutta, India
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16
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Melinek R, Rein KS, Schultz DR, Baden DG. Brevetoxin PbTx-2 immunology: differential epitope recognition by antibodies from two goats. Toxicon 1994; 32:883-90. [PMID: 7527163 DOI: 10.1016/0041-0101(94)90367-0] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
The epitopic regions of the brevetoxin PbTx-3 molecule, produced by the marine dinoflagellate Ptychodiscus brevis, have been identified by structural modification at three distinct regions of the toxin. These are: the A-ring lactone region of the molecule, the K-ring side-chain and the H-ring. The modified PbTx-3 derivatives were tested for their ability to bind brevetoxin goat antisera directed against the PbTx-3 molecule, by radioimmunoassay. The results showed that at least two major epitopes and one minor epitope are recognized: the A-ring lactone region of the molecule and the K-ring side-chain, and the H-ring. The results illustrate the variety of antibodies which may be produced, even within a species, and suggests that epitope characterization is important in the development of assays which are to be employed in seafood safety issues.
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Affiliation(s)
- R Melinek
- Marine and Freshwater Biomedical Sciences Center, University of Miami, FL 33149
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17
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Hokama Y. Recent methods for detection of seafood toxins: recent immunological methods for ciguatoxin and related polyethers. FOOD ADDITIVES AND CONTAMINANTS 1993; 10:71-82. [PMID: 8504876 DOI: 10.1080/02652039309374131] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A brief summation of the methods for detection of each of the marine toxins is presented in this report. The toxins are brevetoxin (PbTx), palytoxin (PTX), okadaic acid (OA), paralytic shellfish toxins (PSP) and ciguatoxin (CTX). The immunological and biotechnical procedures developed for each of these toxins are reviewed. Details of the recent methodology (solid-phase immunobead assay) for detection of ciguatoxin and related polyethers with monoclonal antibodies and receptors are presented. The capabilities of immunological technology for assessment of toxins in seafood products are promising and will probably be widely used in the future for seafood monitoring.
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Affiliation(s)
- Y Hokama
- Department of Pathology, John A. Burns School of Medicine, University of Hawaii, Honolulu 96822
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18
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Edwards RA, Trainer VL, Baden DG. Brevetoxins bind to multiple classes of sites in rat brain synaptosomes. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 1992; 14:64-70. [PMID: 1323018 DOI: 10.1016/0169-328x(92)90011-y] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
The brevetoxins (PbTx series), neurotoxins produced by the marine dinoflagellate Ptychodiscus brevis, cause dose-dependent activation of the voltage-sensitive sodium channel (VSSC). Saturation binding studies employing adult rat brain synaptosomes suggest the existence of a high affinity/low capacity (HA/LC) and a second, lower affinity/higher capacity (LA/HC) class of binding site. LIGAND analysis of saxitoxin and brevetoxin saturation binding data yields a statistically identical Bmax for the brevetoxin high affinity/low capacity (HA/LC) site (1.9 +/- 0.98 pmol/mg protein) and for saxitoxin (1.72 +/- 0.78 pmol/mg protein; P less than 0.001). The stoichiometry of HA/LC brevetoxin binding and saxitoxin binding approaches 1:1. Covalent modification of synaptosomes with a brevetoxin photoaffinity probe preferentially blocks the HA/LC binding site. Hill plots of saturation binding data yield a coefficient of 1.0 +/- 0.02, demonstrating a lack of cooperativity between brevetoxin binding site classes. Kd and Bmax for toxin binding are independent of membrane polarity, intimating that the observed low affinity/high capacity (LA/HC) binding characteristics are not due to modification of the HA/LC site, and strongly argue for the presence of multiple brevetoxin binding site classes. Half-maximal binding at the LA/HC site, and strongly argue for the presence of multiple brevetoxin binding site classes. Half-maximal binding at the LA/HC site occurs at concentration ranges for which the brevetoxins allosterically modulate binding of other natural toxins to their specific sites.
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Affiliation(s)
- R A Edwards
- University of Miami, Rosenstiel School of Marine and Atmospheric Science, NIEHS Marine and Freshwater Biomedical Sciences Center, FL 33149
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19
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Abstract
1. The effects of brevetoxin-B, a red tide toxin, on motor nerve terminal activity were assessed on mouse triangularis sterni nerve-muscle preparations. The perineural waveforms were recorded with extracellular electrodes placed in the perineural sheaths of motor nerves. 2. At 0.11 microM, brevetoxin-B increased the components of waveforms associated with sodium and potassium currents while it decreased the calcium activated potassium current and the slow calcium current of the nerve terminal. The fast calcium current and slow potassium current were not affected. 3. At 1.11 microM, brevetoxin-B decreased all of the components of waveforms associated with sodium, potassium and calcium currents. 4. It is concluded that brevetoxin-B affects sodium, potassium as well as calcium currents in the nerve terminal. The effects may contribute to its pharmacological actions on synaptic transmission.
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Affiliation(s)
- M C Tsai
- Pharmacological Institute, College of Medicine, National Taiwan University, Taipei
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20
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Mehta M, Kemppainen BW, Stafford RG. In vitro penetration of tritium-labelled water (THO) and [3H]PbTx-3 (a red tide toxin) through monkey buccal mucosa and skin. Toxicol Lett 1991; 55:185-94. [PMID: 1998206 DOI: 10.1016/0378-4274(91)90133-q] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The permeability coefficients (Kp) for tritium-labelled water (THO) were determined in human and monkey skin, and monkey buccal mucosa. Kp of human skin (0.47 x 10(-3) cm/h) correlated favorably with previous reports. Kp of hydrated monkey skin for THO (0.77 x 10(-3) cm/h) was not significantly different (P greater than 0.05) from Kp of hydrated human skin (0.88 x 10(-3) cm/h). Kp of monkey buccal mucosa for THO (6.15 x 10(-3) cm/h) was significantly greater than that for monkey skin. Penetration and disposition of [3H]PbTx-3 into layers of monkey buccal mucosa and skin was determined. [3H]PbTx-3 (5-7 microCi) dissolved in 2 ml of water was applied to epithelial/epidermal surface (2.8 cm2) at zero time. The relative percent dose recovered from the upper layers of buccal mucosa (epithelium) and skin (epidermis) varied, but at each time interval was less than 2.5% of the dose. At most of the time intervals (2-24 h), a larger percent of the dose was recovered from the inner layer of the buccal mucosa (lamina propria) than from the inner layer of skin (dermis). After 24 h, as much as 34 or 13% of the dose was recovered from lamina propria or dermis, respectively. At each time interval studied, less than 2% of dose of [3H]PbTx-3 penetrated into the receptor fluid which bathed the inner surfaces of the lamina propria or dermis. The results of this study demonstrate that monkey buccal mucosa is more permeable than skin to THO and PbTx-3.
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Affiliation(s)
- M Mehta
- Department of Physiology and Pharmacology, College of Veterinary Medicine, Auburn University, AL
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21
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Abstract
A non-competitive solid-phase enzyme immunoassay for detection of brevetoxins in various matrices has been developed. The assay utilizes antibodies raised in a goat against brevetoxin PbTx-3-keyhole limpet hemocyanin conjugates with specific purification of brevetoxin antibodies through protein G and brevetoxin affinity columns, and rabbit anti-goat antibodies covalently linked to horseradish peroxidase. The assay was used specifically to detect brevetoxins in both cell culture and contaminated tissues. Sensitivity of the assay is 0.04 picomolar, and toxin can be quantified from 0.04 pM to 0.4 pM brevetoxin per well in microtiter plates by comparison with standard curves.
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Affiliation(s)
- V L Trainer
- University of Miami School of Medicine, Department of Biochemistry and Molecular Biology, FL 33101
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22
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Richards IS, Kulkarni AP, Brooks SM, Pierce R. Florida red-tide toxins (brevetoxins) produce depolarization of airway smooth muscle. Toxicon 1990; 28:1105-11. [PMID: 2260108 DOI: 10.1016/0041-0101(90)90149-2] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Crude preparations of brevetoxin (PBTX) produce airway contraction; however, it is not known if this toxin-induced mechanical response is coupled to changes in airway smooth muscle membrane potential. Membrane potentials and contractility of in vitro canine trachealis smooth muscle preparations were simultaneously measured with a microelectrode and microforce transducer before and during exposure to either the crude toxin (0.01-1.2 micrograms/ml), or the purified fractions PBTX-2 or PBTX-3 (0.01-0.07 micrograms/ml). Membrane potentials in cultured airway smooth muscle-reaggregate preparations were similarly studied. Toxins produced concentration-dependent depolarizations and contractions in in vitro preparations. These responses were not obtained in the presence of either the muscarinic blocking agent atropine, the sodium channel blocker tetrodotoxin (TTX), 0 mM extracellular Ca2+, or the Ca2+ channel blocker verapamil. The toxins were without effect in cultured cells, whereas acetylcholine produced depolarizations which were blocked in the presence of atropine, but not TTX. This suggested the presence of functional cholinergic receptors in cultured cells, and the PBTX-induced release of endogenous acetylcholine from peripheral nerve endings in the in vitro airway smooth muscle response.
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Affiliation(s)
- I S Richards
- College of Public Health, University of South Florida, Tampa 33612
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23
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Hokama Y, Smith S. Review: Immunological assessment of marine toxins. FOOD AGR IMMUNOL 1990. [DOI: 10.1080/09540109009354708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
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24
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Baden DG, Mende TJ, Szmant AM, Trainer VL, Edwards RA, Roszell LE. Brevetoxin binding: molecular pharmacology versus immunoassay. Toxicon 1988; 26:97-103. [PMID: 3347935 DOI: 10.1016/0041-0101(88)90141-9] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Brevetoxin PbTx-3 isolated from Florida's red tide dinoflagellate Ptychodiscus brevis has been produced recently in tritiated form by reductive tritiation of brevetoxin PbTx-2. Tritiated PbTx-3 has been used as a specific probe in competitive radioimmunoassays developed to detect brevetoxins in food sources, and this probe has also been utilized to characterize the brevetoxin binding component in rat brain synaptosomes. Brevetoxins PbTx-2 and PbTx-3, possessing the same structural backbone (type-1) as the tritiated probe, and PbTx-1 and PbTx-7, possessing a second structural backbone (type-2), have been compared quantitatively in their individual abilities to competitively displace tritiated PbTx-3 from its specific binding site in each assay. Type-1 toxins displaced labeled probe with ED50 values of 20-22 nM and 12-17 nM in radioimmunoassay and synaptosomes, respectively. Type-2 toxins displaced labeled probe with ED50 values of 92-93 nM and 3.5-4.1 nM in RIA and synaptosomes, respectively. Synaptosome assays reflect potency of each toxin examined, while radioimmunoassay reflects structural similarities to the immunizing toxin PbTx-3.
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Affiliation(s)
- D G Baden
- University of Miami, Rosenstiel School of Marine and Atmospheric Science, Division of Biology and Living Resources, Florida 33149
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25
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Abstract
Extracts from six clones of Ptychodiscus brevis (formerly known as Gymnodinium breve) were analyzed by high performance liquid chromatography for the presence of brevetoxins PbTx-1, PbTx-2, and PbTx-3. Analyses indicated a wide clonal variability of the three toxin fractions in logarithmic phase cultures when normalized on a per cell basis. It appears that a much wider variability exists in toxin content for different P. brevis clones than exists in replicate extraction of multiple cultures of the diploid clone originally isolated by Wilson.
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Affiliation(s)
- D G Baden
- Division of Biology and Living Resources, Rosenstiel School of Marine and Atmospheric Science, University of Miami, FL 33149
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26
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Marine Metabolites Which Inhibit Development of Echinoderm Embryos. BIOORGANIC MARINE CHEMISTRY 1987. [DOI: 10.1007/978-3-642-72726-9_3] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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27
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Atchison WD, Luke VS, Narahashi T, Vogel SM. Nerve membrane sodium channels as the target site of brevetoxins at neuromuscular junctions. Br J Pharmacol 1986; 89:731-8. [PMID: 2434175 PMCID: PMC1917225 DOI: 10.1111/j.1476-5381.1986.tb11177.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Actions of two structurally related toxins, T-17 and brevetoxin-B, isolated from the red-tide dinoflagellate, Ptychodiscus brevis, were studied on the giant axon of the squid and the neuromuscular junctions of the frog and rat. T-17 toxin caused a large increase in the frequency of miniature endplate potentials at nanomolar concentrations. In one typical case with a frog endplate, the frequency increased from 1.9 s-1 before application of 3.5 nM T-17 to 69.3 s-1 within 5 min after application. In the rat muscle, the mean frequency increased from 1.39 s-1 in control to 11.93 s-1 after application of 23.2 nM T-17. The increase in miniature endplate potential frequency was reversed by the addition of 1 microM tetrodotoxin, and was not observed in a solution containing elevated Mg2+ and reduced Ca2+ concentrations. External or internal application of T-17 toxin (2-5 microM) or brevetoxin-B (10-30 microM) to intact or internally perfused squid axons caused a depolarization of the membrane. This depolarization was abolished by the removal of external Na+ or by addition of tetrodotoxin to the external solution. In voltage clamped squid giant axons, exposure to T-17 toxin or brevetoxin-B increased the non-inactivating component of the tetrodotoxin-sensitive sodium current. The sodium current was activated at potentials 15 to 40 mV more negative than control. It is proposed that these toxins modify a fraction of the sodium channels to a form which opens at potentials more negative than normal and which inactivates to a lesser extent. This mechanism would predict a depolarization of the nerve membrane at the neuromuscular junction, thus explaining the increased discharge of transmitter.
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28
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Whitefleet-Smith J, Boyer GL, Schnoes HK. Isolation and spectral characteristics of four toxins from the dinoflagellate Ptychodiscus brevis. Toxicon 1986; 24:1075-90. [PMID: 3564059 DOI: 10.1016/0041-0101(86)90134-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Four ichthyotoxins were isolated from crude toxic extracts of Ptychodiscus brevis using a combination of solvent partitioning, thin layer chromatography and reversed phase high pressure liquid chromatography. The toxins were analyzed by mass, infrared, 1H- and 13C-NMR spectroscopy and were found to constitute two structural families of two toxins each: brevetoxins 1 and 2 and brevetoxins 3 and 4. Comparison with literature data indicates that brevetoxins 1 and 2 are identical to the previously described and characterized 11-ring polyether toxins brevetoxins C and B, respectively. The other two compounds (brevetoxins 3 and 4) also represent a structural pair (with chloroacetone and alpha-methylene-propanal side chains, respectively) which has a different, but related, basic ring-structure.
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29
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Abstract
Advances in knowledge concerning red tide toxin aerosols (airborne) of the Florida red tide organism, Ptychodiscus brevis, have not kept pace with information about waterborne toxins. This review provides a summary of current knowledge regarding the characterization, effect and production of red tide toxin aerosols. Insight into the chemical characterization and toxic effects of aerosolized toxins is provided from investigations of toxins extracted from natural blooms, as well as from laboratory cultures, of P. brevis. This information is used in conjunction with the few studies that have been performed on toxin aerosols to consider toxic effects. The production of aerosolized toxins is considered through studies of jet drop aerosol formation from bursting bubbles. Existing information suggests that aerosolized red tide toxins may be the same chemicals as those extracted from laboratory cultures, with one of the toxins having a greater respiratory effect than others.
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30
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Wu CH, Huang JM, Vogel SM, Luke VS, Atchison WD, Narahashi T. Actions of Ptychodiscus brevis toxins on nerve and muscle membranes. Toxicon 1985; 23:481-7. [PMID: 2411016 DOI: 10.1016/0041-0101(85)90032-7] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Pharmacological actions of two brevetoxins isolated from Ptychodiscus brevis, T17 and T34, on nerve and muscle membranes were studied using vertebrate and invertebrate preparations. T17 (10 ng/ml) caused an increase in the frequency of miniature endplate potentials (MEPPs) in rat and frog neuromuscular junctions. Application of tetrodotoxin (TTX) completely abolished the increase in MEPP frequency. The results suggest that T17 depolarizes the nerve terminal through opening of the sodium channel. Application of either T17 or T34 to the crayfish and squid giant axons caused a dose-dependent depolarization of the axon membranes with a maximum depolarization of about 30 mV. The depolarizing action was antagonized by sodium-free external saline solution or TTX. Voltage clamp experiments demonstrated that the primary action of the toxins is to cause the sodium channels to open at the normal resting potential. The binding of toxin to a channel site could be prevented by procaine, but not by TTX. The binding site for T17 is presumably separate from the TTX receptor, but related or identical to the binding site for procaine. The brevetoxin-induced depolarization of the nerve terminal membrane with the subsequent enhanced transmitter release is the underlying mechanism for a number of pharmacological actions on various neuro-effector systems.
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31
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Abstract
The structure of the unique 'red tide' dinoflagellate neurotoxin, brevetoxin-B is presented and the experimental data supporting the chemical structure is discussed. A brief account of the other brevetoxins and their structural relationships is also presented. A biosynthetic scheme for the natural formation of the brevetoxin skeleton is proposed. Studies of the most toxic of the three pure brevetoxins, brevetoxin-A, indicate a skeleton differing from that of brevetoxin-B.
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32
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Rodgers RL, Chou HN, Temma K, Akera T, Shimizu Y. Positive inotropic and toxic effects of brevetoxin-B on rat and guinea pig heart. Toxicol Appl Pharmacol 1984; 76:296-305. [PMID: 6093288 DOI: 10.1016/0041-008x(84)90011-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Brevetoxin-B (GbTX-B), a cyclic polyether purified from the marine dinoflagellate Gymnodinium breve, produced positive inotropic and arrhythmogenic effects on isolated rat and guinea pig cardiac preparations at concentrations between 1.25 X 10(-8) and 1.87 X 10(-7) M. The toxin (10(-7) M) transiently increased left ventricular +dP/dt, hydraulic work, and oxygen consumption of paced working rat hearts, then reduced these variables during continuous exposure. Brevetoxin-B exerted a much smaller positive inotropic effect on working guinea pig hearts, but produced a marked and sustained inotropic effect on guinea pig left atria. The toxin also produced arrhythmias in rat and guinea pig hearts, characterized by ventricular tachycardia and A-V blockade. Sympatholytic procedures (beta blockade or reserpine pretreatment) partially blocked the positive inotropic effects, and eliminated the ventricular tachycardia, but not the A-V blockade. Tetrodotoxin markedly inhibited the positive inotropic effect of GbTX-B. Brevetoxin-B did not inhibit guinea pig cardiac Na,K-ATPase activities. The results show that GbTX-B is a potent cardiotoxin and suggest that GbTX-B exerts positive inotropic and arrhythmogenic effects by increasing sarcolemmal sodium permeability, and by releasing catecholamines from sympathetic nerve endings.
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33
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Baden DG, Mende TJ, Walling J, Schultz DR. Specific antibodies directed against toxins of Ptychodiscus brevis (Florida's red tide dinoflagellate). Toxicon 1984; 22:783-9. [PMID: 6084345 DOI: 10.1016/0041-0101(84)90161-2] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Specific antibodies directed against Ptychodiscus brevis 'brevetoxins' have been produced in a goat. The haptenic toxin T34 was chemically reduced to toxin T17, covalently-linked to succinic acid via anhydride coupling, and coupled to bovine serum albumin using standard carbodiimide condensation procedures. The hapten coupling efficiency ranged from 10.4 to 13.5 moles of toxin bound per mole of protein. Antibody titers were directly related to the frequency of immunization, and weekly intervals appeared optimum for maintaining adequate titers. [3H]Brevetoxin T17 is displaced in a competitive manner from the antibody-antigen complexes by unlabeled toxin, but the antibodies do not distinguish between T17 and T34. The sensitivity achieved, using purified brevetoxins as competitive inhibitors of [3H]T17 binding, was 600 picograms. The assay linearity ranged from 1.5 to 48 ng.
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34
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Baden DG, Bikhazi G, Decker SJ, Foldes FF, Leung I. Neuromuscular blocking action of two brevetoxins from the Florida red tide organism Ptychodiscus brevis. Toxicon 1984; 22:75-84. [PMID: 6539006 DOI: 10.1016/0041-0101(84)90140-5] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
The action of Ptychodiscus brevis "brevetoxins" T17 and T34 on rat phrenic nerve-stimulated hemidiaphragm contraction is reported. The potency of T34 is greater than the potency of T17, but both cause a complete block of neuromuscular transmission in the nM to pM concentration ranges. Preparations exposed to low concentrations of T17 can recover in the presence of the toxin, whereas the effects of T34 are irreversible. The initial contracture produced by each is prevented by tetrodotoxin or curare. Neuromuscular block does not appear to be due to acetylcholine depletion, as determined by electron microscope examination of the neuromuscular junctions of blocked preparations. Persistent nerve depolarization is believed to be responsible for the neuromuscular block.
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35
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Hokama Y, Abad MA, Kimura LH. A rapid enzyme-immunoassay for the detection of ciguatoxin in contaminated fish tissues. Toxicon 1983; 21:817-24. [PMID: 6362075 DOI: 10.1016/0041-0101(83)90070-3] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
An enzyme-immunoassay procedure for the detection of ciguatoxin has been developed using the sheep anti-ciguatoxin serum described earlier in the radioimmunoassay method for ciguatoxin. In the enzyme-immunoassay procedure, the sheep anti-ciguatoxin was coupled to horseradish peroxidase. Analyses of fish tissues showed that the enzyme-immunoassay procedure distinguished between clinically documented toxic and nontoxic tissues (P less than 0.001). Comparisons of the enzyme-immunoassay method with the radioimmunoassay for ciguatoxin and with a mouse bioassay demonstrated significant associations (P less than 0.001 and P less than 0.01, respectively). Preliminary studies showed that purified ciguatoxin inhibited the binding of sheep anti-ciguatoxin horseradish peroxidase to toxic fish tissues. Results suggest that the enzyme-immunoassay procedure may be valuable for routine direct assessment of ciguatoxin in fish tissues because of its practicality, sensitivity and specificity.
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36
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37
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38
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39
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Abstract
T17, a toxin purified from laboratory cultures of Florida's redtide organism, Ptychodiscus brevis (formerly Gymnodinium breve), produces bronchoconstriction in anesthetized artificially-ventilated guinea pigs. Bronchoconstriction, measured as a resistance to mechanical pulmonary inflation, was antagonized by atropine, but not by interruption of vagal nerve stimulation or diaphragm dissection.
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40
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Baden DG, Mende TJ. Toxicity of two toxins from the Florida red tide marine dinoflagellate, Ptychodiscus brevis. Toxicon 1982; 20:457-61. [PMID: 6896247 DOI: 10.1016/0041-0101(82)90009-5] [Citation(s) in RCA: 80] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The purification and crystallization of T17, a toxin from Ptychodiscus brevis, is reported. The toxicity of this compound and a second toxin known as T34 are compared by i.v., i.p. and oral administration in mice. Both toxins produce symptoms characteristic of muscarnic stimulants; hypersalivation, rhinorrhea and excessive urination and defecation being the most commonly observed. T17, which is orally toxic, is believed to be the agent responsible for Neurotoxic Shellfish Poisoning.
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