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Yokozeki T, Hama Y, Fujita K, Igarashi T, Hirama M, Tsumuraya T. Evaluation of relative potency of calibrated ciguatoxin congeners by near-infrared fluorescent receptor binding and neuroblastoma cell-based assays. Toxicon 2023; 230:107161. [PMID: 37201801 DOI: 10.1016/j.toxicon.2023.107161] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2023] [Revised: 03/08/2023] [Accepted: 05/15/2023] [Indexed: 05/20/2023]
Abstract
Ciguatera fish poisoning (CFP) is a foodborne illness affecting > 50,000 people worldwide annually. It is caused by eating marine invertebrates and fish that have accumulated ciguatoxins (CTXs). Recently, the risk of CFP to human health, the local economy, and fishery resources have increased; therefore, detection methods are urgently needed. Functional assays for detecting ciguatoxins in fish include receptor binding (RBA) and neuroblastoma cell-based assay (N2a assay), which can detect all CTX congeners. In this study, we made these assays easier to use. For RBA, an assay was developed using a novel near-infrared fluorescent ligand, PREX710-BTX, to save valuable CTXs. In the N2a assay, a 1-day assay was developed with the same detection performance as the conventional 2-day assay. Additionally, in these assays, we used calibrated CTX standards from the Pacific determined by quantitative NMR for the first time to compare the relative potency of congeners, which differed significantly among previous studies. In the RBA, there was almost no difference in the binding affinity among congeners, showing that the differences in side chains, stereochemistry, and backbone structure of CTXs did not affect the binding affinity. However, this result did not correlate with the toxic equivalency factors (TEFs) based on acute toxicity in mice. In contrast, the N2a assay showed a good correlation with TEFs based on acute toxicity in mice, except for CTX3C. These findings, obtained with calibrated toxin standards, provide important insights into evaluating the total toxicity of CTXs using functional assays.
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Affiliation(s)
- Toshiaki Yokozeki
- Japan Food Research Laboratories, Osaka Saito Laboratory, 7-4-41 Saitoasagi, Ibaraki shi, Osaka, 567-0085, Japan; Osaka Prefecture University, Department of Biological Science, Graduate School of Science, 1-2 Gakuen-cho, Sakai-shi, Osaka, 599-8570, Japan; Osaka Metropolitan University, Department of Biological Chemistry, Graduate School of Science, 1-2 Gakuen-cho, Sakai-shi, Osaka, 599-8570, Japan
| | - Yuka Hama
- Osaka Prefecture University, Department of Biological Science, Graduate School of Science, 1-2 Gakuen-cho, Sakai-shi, Osaka, 599-8570, Japan
| | - Kazuhiro Fujita
- Japan Food Research Laboratories, Osaka Saito Laboratory, 7-4-41 Saitoasagi, Ibaraki shi, Osaka, 567-0085, Japan
| | - Tomoji Igarashi
- Japan Food Research Laboratories, Tama Laboratory, 6-11-10 Nagayama, Tama-shi, Tokyo, 206-0025, Japan
| | - Masahiro Hirama
- Osaka Prefecture University, Department of Biological Science, Graduate School of Science, 1-2 Gakuen-cho, Sakai-shi, Osaka, 599-8570, Japan; Osaka Metropolitan University, Department of Biological Chemistry, Graduate School of Science, 1-2 Gakuen-cho, Sakai-shi, Osaka, 599-8570, Japan
| | - Takeshi Tsumuraya
- Osaka Prefecture University, Department of Biological Science, Graduate School of Science, 1-2 Gakuen-cho, Sakai-shi, Osaka, 599-8570, Japan; Osaka Metropolitan University, Department of Biological Chemistry, Graduate School of Science, 1-2 Gakuen-cho, Sakai-shi, Osaka, 599-8570, Japan.
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2
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Sarkar D, Mishra S, Nisal R, Majhi S, Shrivas R, Singh Y, Anusree VS, Kalia J. Site-Specific Fluorescent Labeling of the Cysteine-Rich Toxin, DkTx, for TRPV1 Ion Channel Imaging and Membrane Binding Studies. Bioconjug Chem 2022; 33:1761-1770. [PMID: 36073164 DOI: 10.1021/acs.bioconjchem.2c00355] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Peptide toxins secreted by venomous animals bind to mammalian ion channel proteins and modulate their function. The high specificity of these toxins for their target ion channels enables them to serve as powerful tools for ion channel biology. Toxins labeled with fluorescent dyes are employed for the cellular imaging of channels and also for studying toxin-channel and toxin-membrane interactions. Several of these toxins are cysteine-rich, rendering the production of properly folded fluorescently labeled toxins technically challenging. Herein, we evaluate a variety of site-specific protein bioconjugation approaches for producing fluorescently labeled double-knot toxin (DkTx), a potent TRPV1 ion channel agonist that contains an uncommonly large number of cysteines (12 out of a total of 75 amino acids present in the protein). We find that popular cysteine-mediated bioconjugation approaches are unsuccessful as the introduction of a non-native cysteine residue for thiol modification leads to the formation of misfolded toxin species. Moreover, N-terminal aldehyde-mediated bioconjugation approaches are also not suitable as the resultant labeled toxin lacks activity. In contrast to these approaches, C-terminal bioconjugation of DkTx via the sortase bioconjugation technology yields functionally active fluorescently labeled DkTx. We employ this labeled toxin for imaging rat TRPV1 heterologously expressed in Xenopus laevis oocytes, as well as for performing membrane binding studies on giant unilamellar vesicles composed of different lipid compositions. Our studies set the stage for using fluorescent DkTx as a tool for TRPV1 biology and provide an informative blueprint for labeling cysteine-rich proteins.
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Affiliation(s)
- Debayan Sarkar
- Department of Biology, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Satyajit Mishra
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Rahul Nisal
- Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India
| | - Sumita Majhi
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Rohit Shrivas
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Yashaswi Singh
- Department of Biology, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - V S Anusree
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
| | - Jeet Kalia
- Department of Biology, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India.,Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India.,Department of Chemistry, Indian Institute of Science Education and Research (IISER) Pune, Dr. Homi Bhabha Road, Pashan, Pune, Maharashtra 411008, India.,Department of Chemistry, Indian Institute of Science Education and Research (IISER) Bhopal, Bhopal Bypass Road, Bhauri, Bhopal, Madhya Pradesh 462066, India
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3
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Darius HT, Revel T, Viallon J, Sibat M, Cruchet P, Longo S, Hardison DR, Holland WC, Tester PA, Litaker RW, McCall JR, Hess P, Chinain M. Comparative Study on the Performance of Three Detection Methods for the Quantification of Pacific Ciguatoxins in French Polynesian Strains of Gambierdiscus polynesiensis. Mar Drugs 2022; 20:md20060348. [PMID: 35736151 PMCID: PMC9229625 DOI: 10.3390/md20060348] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2022] [Revised: 05/14/2022] [Accepted: 05/19/2022] [Indexed: 02/04/2023] Open
Abstract
Gambierdiscus and Fukuyoa dinoflagellates produce a suite of secondary metabolites, including ciguatoxins (CTXs), which bioaccumulate and are further biotransformed in fish and marine invertebrates, causing ciguatera poisoning when consumed by humans. This study is the first to compare the performance of the fluorescent receptor binding assay (fRBA), neuroblastoma cell-based assay (CBA-N2a), and liquid chromatography tandem mass spectrometry (LC-MS/MS) for the quantitative estimation of CTX contents in 30 samples, obtained from four French Polynesian strains of Gambierdiscus polynesiensis. fRBA was applied to Gambierdiscus matrix for the first time, and several parameters of the fRBA protocol were refined. Following liquid/liquid partitioning to separate CTXs from other algal compounds, the variability of CTX contents was estimated using these three methods in three independent experiments. All three assays were significantly correlated with each other, with the highest correlation coefficient (r2 = 0.841) found between fRBA and LC-MS/MS. The CBA-N2a was more sensitive than LC-MS/MS and fRBA, with all assays showing good repeatability. The combined use of fRBA and/or CBA-N2a for screening purposes and LC-MS/MS for confirmation purposes allows for efficient CTX evaluation in Gambierdiscus. These findings, which support future collaborative studies for the inter-laboratory validation of CTX detection methods, will help improve ciguatera risk assessment and management.
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Affiliation(s)
- Hélène Taiana Darius
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
- Correspondence: ; Tel.: +689-40-416-484
| | - Taina Revel
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
| | - Jérôme Viallon
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
| | - Manoëlla Sibat
- IFREMER, PHYTOX, Laboratoire METALG, F-44000 Nantes, France; (M.S.); (P.H.)
| | - Philippe Cruchet
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
| | - Sébastien Longo
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
| | - Donnie Ransom Hardison
- National Oceanic and Atmospheric Administration, Center for Coastal Fisheries and Habitat Research, Beaufort, NC 28516, USA; (D.R.H.); (W.C.H.)
| | - William C. Holland
- National Oceanic and Atmospheric Administration, Center for Coastal Fisheries and Habitat Research, Beaufort, NC 28516, USA; (D.R.H.); (W.C.H.)
| | | | - R. Wayne Litaker
- CSS, Inc. Under Contract to National Oceanic and Atmospheric Administration, National Centers for Coastal Ocean Science, National Ocean Service, Beaufort, NC 28516, USA;
| | - Jennifer R. McCall
- Center for Marine Science, University of North Carolina Wilmington, 601 South College Road, Wilmington, NC 28403, USA;
| | - Philipp Hess
- IFREMER, PHYTOX, Laboratoire METALG, F-44000 Nantes, France; (M.S.); (P.H.)
| | - Mireille Chinain
- Institut Louis Malardé (ILM), Laboratory of Marine Biotoxins, UMR 241-EIO (IFREMER, ILM, IRD, Université de Polynésie Française), P.O. Box 30, Papeete 98713, French Polynesia; (T.R.); (J.V.); (P.C.); (S.L.); (M.C.)
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Abstract
This review deals with the synthesis of naturally occurring alkaloids containing partially or completely saturated pyrimidine nuclei. The interest in these compounds is associated with their structural diversity, high biological activity and toxicity. The review is divided into four parts, each of which describes a number of synthetic methodologies toward structurally different naturally occurring alkaloids containing saturated cyclic six-membered amidine, guanidine, aminal and urea (thiourea) moieties, respectively. The development of various synthetic strategies for the preparation of these compounds has remarkably increased during the past few decades. This is primarily due to the fact that some of these compounds are isolated only in limited quantities, which makes it practically impossible to study their full structural characteristics and biological activity.
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5
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Nuclease-assisted target recycling signal amplification strategy for graphene quantum dot-based fluorescent detection of marine biotoxins. Mikrochim Acta 2021; 188:118. [PMID: 33687572 DOI: 10.1007/s00604-020-04684-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2020] [Accepted: 12/07/2020] [Indexed: 10/22/2022]
Abstract
Saxitoxin (STX) is a major marine toxin from shellfish, and it is responsible for paralytic shellfish poisoning (PSP). In this study, a highly sensitive and rapid aptamer assay was developed for STX detection by combining fluorescence resonance energy transfer (FRET) and nuclease-assisted target recycling signal amplification. The aptamer STX-41 conjugated with graphene quantum dots (GQDs) was adsorbed on magnetic reduced graphene oxide (MRGO) to establish a fluorescence quenching system. Then, the binding between STX and aptamer induced the desorption of GQD-aptamer from MRGO and the restoring of fluorescence for the fluorescent determination of STX. The digestion of the target bound aptamer by DNase I could release the target for recycling thus achieving signal amplification. Under the optimized conditions, the aptamer assay showed a wide detection range (0.1-100 ng·mL-1), low detection limit (LOD of 0.035 ng·mL-1), high specificity, good recovery (86.75-94.08% in STX-spiked clam samples) and repeatability (RSD of 4.27-7.34%). Combined with fluorescent detection technology, signal amplification technology, and magnetic separation technology, the proposed method can be used to detect STX in seafood products successfully.
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Smith ML, Westerman DC, Putnam SP, Richardson SD, Ferry JL. Emerging Lyngbya wollei toxins: A new high resolution mass spectrometry method to elucidate a potential environmental threat. HARMFUL ALGAE 2019; 90:101700. [PMID: 31806161 PMCID: PMC6905196 DOI: 10.1016/j.hal.2019.101700] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Revised: 10/16/2019] [Accepted: 10/25/2019] [Indexed: 05/22/2023]
Abstract
Mass spectrometric methods for the quantitative and qualitative analyses of algal biotoxins are often complicated by co-eluting compounds that present analytically as interferences. This issue is particularly critical for organic polyamines, where co-eluting materials can suppress the formation of cations during electrospray ionization. Here we present an extraction procedure designed specifically to overcome matrix-derived ion suppression of algal toxins in samples of Lyngbya wollei, a filamentous benthic algae known to produce several saxitoxin analogues. Lyngbya wollei samples were collected from a large, persistent harmful algal bloom in Lake Wateree, SC. Six known Lyngbya wollei-specific toxins (LWT1-6) were successfully resolved and quantified against saxitoxin using hydrophilic interaction liquid chromatography coupled with triple quadrupole and quadrupole time-of-flight mass spectrometry. The parent ions [M2+ - H+]+ were observed for LWTs 1-6 and the [M]2+ ion was observed for LWT5. High resolution mass spectra and unique fragmentation ions were obtained for LWTs 1-6. A dilution factor of 50 resulted in a linear calibration of saxitoxin in the algae matrix. Ion suppression was resolved by sample dilution, which led to linear, positive correlations between peak area and mass of the extracted sample (R2 > 0.96). Optimized sample extraction method and instrument parameters are presented.
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Affiliation(s)
- Meagan L Smith
- University of South Carolina, Department of Chemistry and Biochemistry, 631 Sumter Street Columbia, SC 29208, United States; University of South Carolina, Center for Interactions of Climate Change on Oceans and Human Health, 921 Assembly St Suit 401, Columbia, SC 29208, United States
| | - Danielle C Westerman
- University of South Carolina, Department of Chemistry and Biochemistry, 631 Sumter Street Columbia, SC 29208, United States; University of South Carolina, Center for Interactions of Climate Change on Oceans and Human Health, 921 Assembly St Suit 401, Columbia, SC 29208, United States
| | - Samuel P Putnam
- University of South Carolina, Department of Chemistry and Biochemistry, 631 Sumter Street Columbia, SC 29208, United States; University of South Carolina, Center for Interactions of Climate Change on Oceans and Human Health, 921 Assembly St Suit 401, Columbia, SC 29208, United States
| | - Susan D Richardson
- University of South Carolina, Department of Chemistry and Biochemistry, 631 Sumter Street Columbia, SC 29208, United States; University of South Carolina, Center for Interactions of Climate Change on Oceans and Human Health, 921 Assembly St Suit 401, Columbia, SC 29208, United States
| | - John L Ferry
- University of South Carolina, Department of Chemistry and Biochemistry, 631 Sumter Street Columbia, SC 29208, United States; University of South Carolina, Center for Interactions of Climate Change on Oceans and Human Health, 921 Assembly St Suit 401, Columbia, SC 29208, United States.
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7
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Aballay-González A, Gallardo-Rodriguez JJ, Silva-Higuera M, Rivera A, Ulloa V, Delgado-Rivera L, Rivera-Belmar A, Astuya A. Neuro-2a cell-based assay for toxicity equivalency factor - proposal and evaluation in Chilean contaminated shellfish samples. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2019; 37:162-173. [DOI: 10.1080/19440049.2019.1676919] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Ambbar Aballay-González
- Laboratorio de Biotoxinas UdeC, Departamento de Oceanografía, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
- Centro de Investigación Oceanográfica COPAS Sur-Austral, Universidad de Concepción, Concepción, Chile
| | | | - Macarena Silva-Higuera
- Laboratorio de Biotoxinas UdeC, Departamento de Oceanografía, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
- Centro de Investigación Oceanográfica COPAS Sur-Austral, Universidad de Concepción, Concepción, Chile
| | - Alejandra Rivera
- Laboratorio de Biotoxinas UdeC, Departamento de Oceanografía, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
- Centro de Investigación Oceanográfica COPAS Sur-Austral, Universidad de Concepción, Concepción, Chile
| | - Viviana Ulloa
- Laboratorio de Biotoxinas UdeC, Departamento de Oceanografía, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
| | - Lorena Delgado-Rivera
- Laboratorio de Toxinas Marinas y Micotoxinas, Sección de Química de Alimentos, Departamento de Salud Ambiental, Instituto de Salud Pública de Chile, Ñuñoa, Chile
| | - Andrea Rivera-Belmar
- Departamento de Alimentación y Nutrición, División de Salud y Política Pública, Subsecretaría de Salud Pública, Ministerio de Salud, Santiago, Chile
| | - Allisson Astuya
- Laboratorio de Biotoxinas UdeC, Departamento de Oceanografía, Facultad de Ciencias Naturales y Oceanográficas, Universidad de Concepción, Concepción, Chile
- Centro de Investigación Oceanográfica COPAS Sur-Austral, Universidad de Concepción, Concepción, Chile
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Zhang D, Tang J, Zhang J, Zhang DL, Hu CX. Responses of pro- and anti-inflammatory cytokines in zebrafish liver exposed to sublethal doses of Aphanizomenon flosaquae DC-1 aphantoxins. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2019; 215:105269. [PMID: 31408752 DOI: 10.1016/j.aquatox.2019.105269] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2019] [Revised: 07/31/2019] [Accepted: 08/01/2019] [Indexed: 06/10/2023]
Abstract
Blooms of the dominant cyanobacterium Aphanizomenon flosaquae are frequently encountered in natural waters, and their secretion of neurotoxic paralytic shellfish toxins called aphantoxins threatens environmental safety and human health worldwide. The liver is the primary detoxification organ in animals, and its pro- and anti-inflammatory responses are important functions in the detoxification of toxins. Therefore, we investigated the response of these inflammatory factors to aphantoxins in the liver of zebrafish (Danio rerio). A. flosaquae DC-1 was sampled during blooms in Dianchi Lake, China and cultured, and the toxin was extracted and analyzed using high performance liquid chromatography. The primary constituents were gonyautoxins 1 (34.04%) and 5 (21.28%) and neosaxitoxin (12.77%). Zebrafish were injected intraperitoneally with 5.3 μg (low dose) or 7.61 μg (high dose) of saxitoxin equivalents [equivalents (eq.)]/kg body weight of A. flosaquae DC-1 aphantoxins. Hyperemia, the hepatosomatic index (HSI), and physiological and molecular responses of pro- and anti-inflammatory cytokines in the zebrafish liver were investigated at different time points 1-24 h post-exposure. Aphantoxins significantly enhanced hepatic hyperemia and altered the HSI 3-24 h post-exposure, suggesting that inflammation caused morphological changes. Subsequent investigations using the enzyme-linked immunosorbent assay showed that the pro-inflammatory cytokines tumor necrosis factor-α, interleukin-1β (IL-1β), IL-6, and IL-8 and anti-inflammatory cytokines IL-10 and transforming growth factor β were higher in the liver of zebrafish exposed to aphantoxins, which indicated physiological inflammatory responses. Further analysis by real-time fluorescence quantitative polymerase chain reaction demonstrated upregulated mRNA expression of these cytokines, suggesting molecular inflammatory responses in the zebrafish liver. These changes showed dose- and time-dependent patterns. These results indicated that aphantoxins induced hyperemia and altered the HSI, and subsequently increased the levels of proinflammatory cytokines TNF-α, IL-1β, IL-6 and IL-8 to induce physiological inflammatory responses. These changes activated the anti-inflammatory cytokines IL-10 and TGF-β to suppress inflammatory damage. The induced changes were the result of upregulated mRNA expression of these inflammatory cytokines caused by aphantoxins. Aphantoxins resulted in hepatic immunotoxicity and response by inducing pro-inflammatory cytokines. Zebrafish liver in turn suppressed the inflammatory damage by upregulating the activities of anti-inflammatory cytokines. In the future, these pro- and anti-inflammatory cytokines in the zebrafish liver may be prove to be useful biomarkers of aphantoxins and blooms in nature.
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Affiliation(s)
- Di Zhang
- Department of Bioscience and Technology, College of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, PR China
| | - Jing Tang
- Department of Rehabilitation Medicine, People's Hospital of Dongxihu District, Wuhan, 430040, PR China
| | - Jing Zhang
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA
| | - De Lu Zhang
- Department of Bioscience and Technology, College of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, PR China.
| | - Chun Xiang Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China.
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9
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Lukowski AL, Denomme N, Hinze ME, Hall S, Isom LL, Narayan ARH. Biocatalytic Detoxification of Paralytic Shellfish Toxins. ACS Chem Biol 2019; 14:941-948. [PMID: 30983320 PMCID: PMC6528162 DOI: 10.1021/acschembio.9b00123] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
![]()
Small molecules that bind to voltage-gated
sodium channels (VGSCs)
are promising leads in the treatment of numerous neurodegenerative
diseases and pain. Nature is a highly skilled medicinal chemist in
this regard, designing potent VGSC ligands capable of binding to and
blocking the channel, thereby offering compounds of potential therapeutic
interest. Paralytic shellfish toxins (PSTs), produced by cyanobacteria
and marine dinoflagellates, are examples of these naturally occurring
small molecule VGSC blockers that can potentially be leveraged to
solve human health concerns. Unfortunately, the remarkable potency
of these natural products results in equally exceptional toxicity,
presenting a significant challenge for the therapeutic application
of these compounds. Identifying less potent analogs and convenient
methods for accessing them therefore provides an attractive approach
to developing molecules with enhanced therapeutic potential. Fortunately,
Nature has evolved tools to modulate the toxicity of PSTs through
selective hydroxylation, sulfation, and desulfation of the core scaffold.
Here, we demonstrate the function of enzymes encoded in cyanobacterial
PST biosynthetic gene clusters that have evolved specifically for
the sulfation of highly functionalized PSTs, the substrate scope of
these enzymes, and elucidate the biosynthetic route from saxitoxin
to monosulfated gonyautoxins and disulfated C-toxins. Finally, the
binding affinities of the nonsulfated, monosulfated, and disulfated
products of these enzymatic reactions have been evaluated for VGSC
binding affinity using mouse whole brain membrane preparations to
provide an assessment of relative toxicity. These data demonstrate
the unique detoxification effect of sulfotransferases in PST biosynthesis,
providing a potential mechanism for the development of more attractive
PST-derived therapeutic analogs.
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Affiliation(s)
| | | | | | - Sherwood Hall
- United States Food and Drug Administration, College Park, Maryland 20740, United States
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10
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Lukowski AL, Narayan ARH. Natural Voltage-Gated Sodium Channel Ligands: Biosynthesis and Biology. Chembiochem 2019; 20:1231-1241. [PMID: 30605564 PMCID: PMC6579537 DOI: 10.1002/cbic.201800754] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2018] [Indexed: 12/18/2022]
Abstract
Natural product biosynthetic pathways are composed of enzymes that use powerful chemistry to assemble complex molecules. Small molecule neurotoxins are examples of natural products with intricate scaffolds which often have high affinities for their biological targets. The focus of this Minireview is small molecule neurotoxins targeting voltage-gated sodium channels (VGSCs) and the state of knowledge on their associated biosynthetic pathways. There are three small molecule neurotoxin receptor sites on VGSCs associated with three different classes of molecules: guanidinium toxins, alkaloid toxins, and ladder polyethers. Each of these types of toxins have unique structural features which are assembled by biosynthetic enzymes and the extent of information known about these enzymes varies among each class. The biosynthetic enzymes involved in the formation of these toxins have the potential to become useful tools in the efficient synthesis of VGSC probes.
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Affiliation(s)
- April L Lukowski
- Program in Chemical Biology, University of Michigan, 210 Washtenaw Ave., Ann Arbor, MI, 48109, USA
| | - Alison R H Narayan
- Life Sciences Institute, University of Michigan, 210 Washtenaw Ave., Ann Arbor, MI, 48109, USA
- Department of Chemistry, University of Michigan, 930 N University Ave., Ann Arbor, MI, 48109, USA
- Program in Chemical Biology, University of Michigan, 210 Washtenaw Ave., Ann Arbor, MI, 48109, USA
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Turner AD, Hatfield RG, Maskrey BH, Algoet M, Lawrence JF. Evaluation of the new European Union reference method for paralytic shellfish toxins in shellfish: A review of twelve years regulatory monitoring using pre-column oxidation LC-FLD. Trends Analyt Chem 2019. [DOI: 10.1016/j.trac.2019.02.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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12
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Díaz-Asencio L, Clausing RJ, Rañada ML, Alonso-Hernández CM, Dechraoui Bottein MY. A radioligand receptor binding assay for ciguatoxin monitoring in environmental samples: Method development and determination of quality control criteria. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2018; 192:289-294. [PMID: 30015314 DOI: 10.1016/j.jenvrad.2018.06.019] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Revised: 06/26/2018] [Accepted: 06/26/2018] [Indexed: 06/08/2023]
Abstract
Ciguatoxins are algal toxins responsible for tens of thousands of human intoxications yearly, both in tropical and subtropical endemic regions as well as worldwide through fish exportation. Previously developed methods for biotoxin surveillance in the environment and seafood include analytical methods and in vivo and in vitro bioassays. The radioligand receptor binding assay (r-RBA) is among the in vitro methodologies currently used for the detection and quantification of marine biotoxins. For the ciguatoxin group, the r-RBA has been widely used as a means to characterize the mode of action and as detection method in various biological matrices. Yet, screening methods have not been standardized, and the details of the ciguatoxin-specific r-RBA are not well-documented, which limit interlaboratory comparison and progress toward method validation. This work presents the development of an optimized r-RBA for ciguatoxins and provides guidance on its use and quality control checks for analysis of environmental samples. We focus on the analysis of critical parameters involved in determining assay acceptability. Calculation of toxin concentrations in fish samples is illustrated with four examples. Thus, this paper provides the detailed information required for a full validation of the r-RBA, a necessary step toward the development and implementation of a regulatory monitoring programme for ciguatoxins in seafood products using the r-RBA.
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Affiliation(s)
- Lisbet Díaz-Asencio
- Centro de Estudios Ambientales de Cienfuegos (CEAC), Carretera a Castillo de Jagua Km 1 ½, Ciudad Nuclear AP, 59350, Cienfuegos, Cuba
| | - Rachel J Clausing
- Environment Laboratories, Department of Nuclear Science and Application, International Atomic Energy Agency, 98000, Monaco
| | - Ma Llorina Rañada
- IAEA Collaborating Center on Harmful Algal Bloom (HAB) Studies, Chemistry Research Section, Philippine Nuclear Research Institute - Department of Science and Technology (DOST-PNRI), Diliman, Quezon City, 1101, Philippines
| | - Carlos M Alonso-Hernández
- Centro de Estudios Ambientales de Cienfuegos (CEAC), Carretera a Castillo de Jagua Km 1 ½, Ciudad Nuclear AP, 59350, Cienfuegos, Cuba
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13
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Lukowski AL, Ellinwood DC, Hinze ME, DeLuca RJ, Du Bois J, Hall S, Narayan ARH. C-H Hydroxylation in Paralytic Shellfish Toxin Biosynthesis. J Am Chem Soc 2018; 140:11863-11869. [PMID: 30192526 PMCID: PMC6558983 DOI: 10.1021/jacs.8b08901] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The remarkable degree of synthetic selectivity found in Nature is exemplified by the biosynthesis of paralytic shellfish toxins such as saxitoxin. The polycyclic core shared by saxitoxin and its relatives is assembled and subsequently elaborated through the installation of hydroxyl groups with exquisite precision that is not possible to replicate with traditional synthetic methods. Here, we report the identification of the enzymes that carry out a subset of C-H functionalizations involved in paralytic shellfish toxin biosynthesis. We have shown that three Rieske oxygenases mediate hydroxylation reactions with perfect site- and stereoselectivity. Specifically, the Rieske oxygenase SxtT is responsible for selective hydroxylation of a tricyclic precursor to the famous natural product saxitoxin, and a second Rieske oxygenase, GxtA, selectively hydroxylates saxitoxin to access the oxidation pattern present in gonyautoxin natural products. Unexpectedly, a third Rieske oxygenase, SxtH, does not hydroxylate tricyclic intermediates, but rather a linear substrate prior to tricycle formation, rewriting the biosynthetic route to paralytic shellfish toxins. Characterization of SxtT, SxtH, and GxtA is the first demonstration of enzymes carrying out C-H hydroxylation reactions in paralytic shellfish toxin biosynthesis. Additionally, the reactions of these oxygenases with a suite of saxitoxin-related molecules are reported, highlighting the substrate promiscuity of these catalysts and the potential for their application in the synthesis of natural and unnatural saxitoxin congeners.
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Affiliation(s)
- April L. Lukowski
- Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan 48109
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109
| | - Duncan C. Ellinwood
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
| | - Meagan E. Hinze
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109
| | - Ryan J. DeLuca
- Department of Chemistry, Stanford University, Stanford, California 94305
| | - J. Du Bois
- Department of Chemistry, Stanford University, Stanford, California 94305
| | - Sherwood Hall
- United States Food and Drug Administration, College Park, Maryland 20740
| | - Alison R. H. Narayan
- Program in Chemical Biology, University of Michigan, Ann Arbor, Michigan 48109
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109
- Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109
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Use of the receptor binding assay for determination of paralytic shellfish poisoning toxins in bivalve molluscs from Great Britain and the assessment of method performance in oysters. Toxicon 2018; 148:155-164. [PMID: 29705148 DOI: 10.1016/j.toxicon.2018.04.025] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 04/20/2018] [Accepted: 04/25/2018] [Indexed: 11/20/2022]
Abstract
A receptor binding assay (RBA) for the determination of paralytic shellfish poisoning toxicity is formally validated through collaborative study and approved for regulatory monitoring use in the US for mussels and clams. However, to date, the method has not been tested on bivalve molluscs originating from European waters and no validation studies have been conducted for oysters, a shellfish species of great importance globally. This study firstly reports the work conducted to assess the performance of the assay in comparison with a regulatory chemical detection method for a range of shellfish species originating from Great Britain. Data obtained showed a complete absence of false negative RBA results, with a tendency to over-estimate PSP toxicity for some shellfish species in comparison with liquid chromatography with fluorescence detection. Secondly, the performance of the RBA was assessed for oysters, with the analysis of a dilution series of oyster matrix certified reference materials. Method trueness, sensitivity and precision were found to compare well with results reported previously for other species. In addition, the RBA analysis of untreated and demetallated oyster extracts, provided good evidence that the RBA is not suppressed in the presence of high concentrations of zinc as reported previously for the mouse bioassay. Consequently, there is strong evidence from this study, that the RBA would be suitable for determination of PSP toxicity in bivalve molluscs from GB, with acceptable method performance in oysters. Further validation studies would be required for other shellfish species of interest before the method can be considered suitable for implementation in Europe.
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15
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Durán-Riveroll LM, Cembella AD. Guanidinium Toxins and Their Interactions with Voltage-Gated Sodium Ion Channels. Mar Drugs 2017; 15:E303. [PMID: 29027912 PMCID: PMC5666411 DOI: 10.3390/md15100303] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Revised: 09/14/2017] [Accepted: 09/27/2017] [Indexed: 12/19/2022] Open
Abstract
Guanidinium toxins, such as saxitoxin (STX), tetrodotoxin (TTX) and their analogs, are naturally occurring alkaloids with divergent evolutionary origins and biogeographical distribution, but which share the common chemical feature of guanidinium moieties. These guanidinium groups confer high biological activity with high affinity and ion flux blockage capacity for voltage-gated sodium channels (NaV). Members of the STX group, known collectively as paralytic shellfish toxins (PSTs), are produced among three genera of marine dinoflagellates and about a dozen genera of primarily freshwater or brackish water cyanobacteria. In contrast, toxins of the TTX group occur mainly in macrozoa, particularly among puffer fish, several species of marine invertebrates and a few terrestrial amphibians. In the case of TTX and analogs, most evidence suggests that symbiotic bacteria are the origin of the toxins, although endogenous biosynthesis independent from bacteria has not been excluded. The evolutionary origin of the biosynthetic genes for STX and analogs in dinoflagellates and cyanobacteria remains elusive. These highly potent molecules have been the subject of intensive research since the latter half of the past century; first to study the mode of action of their toxigenicity, and later as tools to characterize the role and structure of NaV channels, and finally as therapeutics. Their pharmacological activities have provided encouragement for their use as therapeutants for ion channel-related pathologies, such as pain control. The functional role in aquatic and terrestrial ecosystems for both groups of toxins is unproven, although plausible mechanisms of ion channel regulation and chemical defense are often invoked. Molecular approaches and the development of improved detection methods will yield deeper understanding of their physiological and ecological roles. This knowledge will facilitate their further biotechnological exploitation and point the way towards development of pharmaceuticals and therapeutic applications.
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Affiliation(s)
- Lorena M Durán-Riveroll
- CONACYT-Instituto de Ciencias del Mary Limnología, Universidad Nacional Autónoma de México, Mexico 04510, Mexico.
| | - Allan D Cembella
- Alfred-Wegener-Institut, Helmholtz Zentrum für Polar-und Meeresforschung, 27570 Bremerhaven, Germany.
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16
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Ruberu SR, Langlois GW, Masuda M, Kittredge C, Perera SK, Kudela RM. Receptor binding assay for the detection of paralytic shellfish poisoning toxins: comparison to the mouse bioassay and applicability under regulatory use. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2017; 35:144-158. [PMID: 28820049 DOI: 10.1080/19440049.2017.1369584] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The receptor-binding assay (RBA) method for the detection of paralytic shellfish poisoning (PSP) toxins was evaluated for its overall performance in comparison with the mouse bioassay (MBA). An initial study to evaluate the effects of filtering shellfish extracts prior to running the RBA indicated no significant difference between filtered and unfiltered extracts on the determined saxitoxin (STX) concentrations. Next, we tested the RBA assay on 295 naturally contaminated mussel tissue samples, ranging in concentrations from 320 µg STX equiv. kg-1 to 13,000 µg STX equiv. kg-1 by MBA. An overall trend was observed with the RBA giving higher results (256 µg STX equiv. kg-1 on average) than the MBA; however, at low concentrations (< 500 µg STX equiv. kg-1) the RBA results were marginally lower. A third study was conducted using spiked mussel tissue analysed by three independent laboratories, two of which performed the RBA and one the MBA. This multi-laboratory study again showed the RBA to give higher results than the MBA; however, it also revealed that STX determination was accurate by the RBA, unlike the MBA. To optimise the assay for efficient usage under regulatory practice, three suggestions have been made: the use of an initial screening plate to separate those samples that exceed the alert level; use of rapid PSP test kits in the field and in the laboratory for screening negative samples and for early detection of toxicity; and use of an alternate commercially available porcine membrane in place of the laboratory-prepared rat membrane homogenate. The large number of samples analysed and the diversity of the tests conducted in this study further support the RBA as an affordable rapid method for STX detection that is also free of the routine sacrifice of live animals.
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Affiliation(s)
- Shiyamalie R Ruberu
- a Drinking Water and Radiation Laboratory Branch and Environmental Management Branch , California Department of Public Health , Richmond , CA , USA
| | - Gregg W Langlois
- a Drinking Water and Radiation Laboratory Branch and Environmental Management Branch , California Department of Public Health , Richmond , CA , USA
| | - Melisa Masuda
- a Drinking Water and Radiation Laboratory Branch and Environmental Management Branch , California Department of Public Health , Richmond , CA , USA
| | - Clive Kittredge
- a Drinking Water and Radiation Laboratory Branch and Environmental Management Branch , California Department of Public Health , Richmond , CA , USA
| | - S Kusum Perera
- a Drinking Water and Radiation Laboratory Branch and Environmental Management Branch , California Department of Public Health , Richmond , CA , USA
| | - Raphael M Kudela
- b Ocean Sciences Department , University of California Santa Cruz , Santa Cruz , CA , USA
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17
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Botana LM, Hess P, Munday R, Nathalie A, DeGrasse SL, Feeley M, Suzuki T, van den Berg M, Fattori V, Garrido Gamarro E, Tritscher A, Nakagawa R, Karunasagar I. Derivation of toxicity equivalency factors for marine biotoxins associated with Bivalve Molluscs. Trends Food Sci Technol 2017. [DOI: 10.1016/j.tifs.2016.09.015] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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18
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Dechraoui Bottein MY, Clausing RJ. Receptor-Binding Assay for the Analysis of Marine Toxins. RECENT ADVANCES IN THE ANALYSIS OF MARINE TOXINS 2017. [DOI: 10.1016/bs.coac.2017.08.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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19
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Application of rapid test kits for the determination of paralytic shellfish poisoning (PSP) toxins in bivalve molluscs from Great Britain. Toxicon 2016; 119:352-61. [DOI: 10.1016/j.toxicon.2016.06.019] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Accepted: 06/28/2016] [Indexed: 11/20/2022]
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20
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Wang C, Oki M, Nishikawa T, Harada D, Yotsu-Yamashita M, Nagasawa K. Total Synthesis of 11-Saxitoxinethanoic Acid and Evaluation of its Inhibitory Activity on Voltage-Gated Sodium Channels. Angew Chem Int Ed Engl 2016. [DOI: 10.1002/ange.201604155] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Chao Wang
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
| | - Mana Oki
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
| | - Toru Nishikawa
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
| | - Daisuke Harada
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
| | - Mari Yotsu-Yamashita
- Graduate School of Agricultural Science; Tohoku University; 1-1 Tsutsumidori-Amamiya Aoba-ku Sendai 981-8555 Japan
| | - Kazuo Nagasawa
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
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21
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Wang C, Oki M, Nishikawa T, Harada D, Yotsu-Yamashita M, Nagasawa K. Total Synthesis of 11-Saxitoxinethanoic Acid and Evaluation of its Inhibitory Activity on Voltage-Gated Sodium Channels. Angew Chem Int Ed Engl 2016; 55:11600-3. [DOI: 10.1002/anie.201604155] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2016] [Revised: 06/17/2016] [Indexed: 11/05/2022]
Affiliation(s)
- Chao Wang
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
| | - Mana Oki
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
| | - Toru Nishikawa
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
| | - Daisuke Harada
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
| | - Mari Yotsu-Yamashita
- Graduate School of Agricultural Science; Tohoku University; 1-1 Tsutsumidori-Amamiya Aoba-ku Sendai 981-8555 Japan
| | - Kazuo Nagasawa
- Department of Biotechnology and Life Science, Faculty of Technology; Tokyo University of Agriculture and Technology; 2-24-16 Nakamachi, Koganei Tokyo 184-8588 Japan
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22
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Zhang D, Liu S, Zhang J, Zhang JK, Hu C, Liu Y. In vivo effects of Aphanizomenon flos-aquae DC-1 aphantoxins on gas exchange and ion equilibrium in the zebrafish gill. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 177:484-493. [PMID: 27424100 DOI: 10.1016/j.aquatox.2016.06.024] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 06/27/2016] [Accepted: 06/28/2016] [Indexed: 06/06/2023]
Abstract
Aphantoxins, neurotoxins or paralytic shellfish poisons (PSPs) generated by Aphanizomenon flos-aquae, are a threat to environmental safety and human health in eutrophic waters worldwide. The molecular mechanisms of neurotoxin function have been studied; however, the effects of these neurotoxins on oxidative stress, ion transport, gas exchange, and branchial ultrastructure in fish gills are not fully understood. Aphantoxins extracted from A. flos-aquae DC-1 were detected by high-performance liquid chromatography. The major ingredients were gonyautoxins 1 and 5 and neosaxitoxin, which comprised 34.04%, 21.28%, and 12.77% of the total, respectively. Zebrafish (Danio rerio) were administered A. flos-aquae DC-1 aphantoxins at 5.3 or 7.61μg saxitoxin equivalents (eq)/kg (low and high doses, respectively) by intraperitoneal injection. The activities of Na(+)-K(+)-ATPase (NKA), carbonic anhydrase (CA), and lactate dehydrogenase (LDH), ultrastructural alterations in chloride and epithelial cells, and reactive oxygen species (ROS) and total antioxidative capacity (T-AOC) were investigated in the gills during the first 24h after exposure. Aphantoxins significantly increased the level of ROS and decreased the T-AOC in zebrafish gills from 3 to 12h post-exposure, suggesting an induction of oxidative stress and inhibition of antioxidant capacity. Reduced activities of NKA and CA demonstrated abnormal ion transport and gas exchange in the gills of aphantoxin-treated fish. Toxin administration also resulted in increased LDH activity and ultrastructural alterations in chloride and epithelial cells, suggesting a disruption of function and structure in zebrafish gills. The observed abnormalities in zebrafish gills occurred in a time- and dose-dependent manner. These findings demonstrate that aphantoxins or PSPs may inhibit ion transport and gas exchange, increase LDH activity, and result in ultrastructural damage to the gills through elevations in oxidative stress and reduced antioxidant capacity. These effects of aphantoxins in the gills of zebrafish suggest an induction of respiratory toxicity. The parameters investigated in this study may be also considered as biomarkers for studying aphantoxin/PSP exposure and cyanobacterial blooms in nature.
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Affiliation(s)
- Delu Zhang
- Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China.
| | - Siyi Liu
- Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China
| | - Jing Zhang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Jian Kong Zhang
- Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China
| | - Chunxiang Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China.
| | - Yongding Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China
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23
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Zhang DL, Liu SY, Zhang J, Zhang JK, Hu CX, Liu YD. Respiratory toxicity of cyanobacterial aphantoxins from Aphanizomenon flos-aquae DC-1 in the zebrafish gill. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2016; 176:106-115. [PMID: 27130970 DOI: 10.1016/j.aquatox.2016.04.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2015] [Revised: 04/12/2016] [Accepted: 04/13/2016] [Indexed: 06/05/2023]
Abstract
Aphantoxins from Aphanizomenon flos-aquae are frequently identified in eutrophic waterbodies worldwide. These toxins severely endanger environmental safety and human health due to the production of paralytic shellfish poisons (PSPs). Although the molecular mechanisms of aphantoxin neurotoxicity have been studied, many questions remain to be resolved such as in vivo alterations in branchial histology and neurotransmitter inactivation induced by these neurotoxins. Aphantoxins extracted from a naturally isolated strain of A. flos-aquae DC-1 were determined by high performance liquid chromatography. The basic components of the isolated aphantoxins identified were gonyautoxin 1 (GTX1), gonyautoxin 5 (GTX5), and neosaxitoxin (neoSTX), which comprised 34.04, 21.28, and 12.77% of the total, respectively. Zebrafish (Danio rerio) was administrated 5.3 or 7.61mg STX equivalents (eq)/kg (low and high doses, respectively) of the A. flos-aquae DC-1 aphantoxins by intraperitoneal injection. Histological alterations and changes in neurotransmitter inactivation in the gills of zebrafish were investigated for 24h following exposure. Aphantoxin exposure significantly increased the activities of gill alanine aminotransferase (ALT) and aspartate aminotransferase (AST) and resulted in histological alterations in the gills during the first 12h of exposure, indicating the induction of functional and structural damage. Gill acetylcholinesterase (AChE) and monoamine oxidase (MAO) activities were inhibited significantly, suggesting an alteration of neurotransmitter inactivation in zebrafish gills. The observed alterations in gill structure and function followed a time- and dose-dependent pattern. The results demonstrate that aphantoxins or PSPs lead to structural damage and altered function in the gills of zebrafish, including changes in histological structure and increases in the activities of AST and ALT. The inhibition of the activities of AChE and MAO suggest that aphantoxins or PSPs could induce respiratory toxicity in the zebrafish gill. Furthermore, these parameters may be used as bioindicators for investigating aphantoxin exposure and cyanobacterial blooms in nature.
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Affiliation(s)
- De Lu Zhang
- Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China.
| | - Si Yi Liu
- Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China
| | - Jing Zhang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Jian Kun Zhang
- Department of Lifescience and Biotechnology, College of Chemistry, Chemical Engineering and Life Sciences, Wuhan University of Technology, Wuhan 430070, PR China
| | - Chun Xiang Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China.
| | - Yong Ding Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China
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24
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Hii KS, Lim PT, Kon NF, Takata Y, Usup G, Leaw CP. Physiological and transcriptional responses to inorganic nutrition in a tropical Pacific strain of Alexandrium minutum: Implications for the saxitoxin genes and toxin production. HARMFUL ALGAE 2016; 56:9-21. [PMID: 28073499 DOI: 10.1016/j.hal.2016.04.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Revised: 04/12/2016] [Accepted: 04/12/2016] [Indexed: 06/06/2023]
Abstract
Saxitoxins (STXs) constitute a family of potent sodium channel blocking toxins, causative agents of paralytic shellfish poisoning (PSP), and are produced by several species of marine dinoflagellates and cyanobacteria. Two STX-core genes, sxtA and sxtG, have been well elucidated in Alexandrium but the expression of these genes under various nutritional modes in tropical species remains unclear. This study investigates the physiological responses of a tropical Pacific strain of Alexandrium minutum growing with nitrate or ammonium, and with various nitrogen to phosphorus (N:P) supply ratios. The transcriptional responses of the sxt genes were observed. Likewise, a putative sxtI encoding O-carbamoyltransferase (herein designated as AmsxtI) was recovered from the transcriptomic data, and its expression was investigated. The results revealed that the cellular toxin quota (Qt) was higher in P-depleted, nitrate-grown cultures. With cultures at similar N:P (<16), cells grown with excess ammonium showed a higher Qt than those grown with nitrate. sxtA1 was not expressed under any culture conditions, suggesting that this gene might not be involved in STX biosynthesis by this strain. Conversely, sxtA4 and sxtG showed positive correlations with Qt, and were up-regulated in P-depleted, nitrate-grown cultures and with excess ambient ammonium. On the other hand, AmsxtI was expressed only when induced by P-depletion, suggesting that this gene may play an important role in P-recycling metabolism, while simultaneously enhancing toxin production.
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Affiliation(s)
- Kieng Soon Hii
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan 94300, Sarawak, Malaysia
| | - Po Teen Lim
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok 16310, Kelantan, Malaysia.
| | - Nyuk Fong Kon
- Institute of Biodiversity and Environmental Conservation, Universiti Malaysia Sarawak, Kota Samarahan 94300, Sarawak, Malaysia
| | - Yoshinobu Takata
- The University of Tokyo, Yayoi 1-1-1, Bunkyo-Ku, Tokyo 113-8657, Japan
| | - Gires Usup
- Faculty of Science and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia
| | - Chui Pin Leaw
- Bachok Marine Research Station, Institute of Ocean and Earth Sciences, University of Malaya, Bachok 16310, Kelantan, Malaysia.
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25
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Zhang DL, Liu SY, Zhang J, Hu CX, Li DH, Liu YD. Antioxidative responses in zebrafish liver exposed to sublethal doses Aphanizomenon flos-aquae DC-1 aphantoxins. ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2015; 113:425-432. [PMID: 25544652 DOI: 10.1016/j.ecoenv.2014.12.029] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 12/15/2014] [Accepted: 12/16/2014] [Indexed: 06/04/2023]
Abstract
Aphanizomenon flos-aquae secretes paralytic shellfish poisons (PSPs), termed aphantoxins, and endangers environmental and human health via eutrophication of water worldwide. Although the molecular mechanism of neuronal PSP toxicity has been well studied, several issues remain unresolved, notably the in vivo hepatic antioxidative responses to this neurotoxin. Aphantoxins extracted from a natural isolate of A. flos-aquae DC-1 were resolved by high performance liquid chromatography. The primary components were gonyautoxins 1 and 5 and neosaxitoxin. Zebrafish (Danio rerio) were treated intraperitoneally with either 5.3 or 7.61 (low and high doses, respectively) μg saxitoxin (STX) equivalents (eq)/kg of A. flos-aquae DC-1 aphantoxins. Antioxidative responses in zebrafish liver were examined at different timepoints 1-24h post-exposure. Aphantoxin administration significantly enhanced hepatic malondialdehyde (MDA) content 1-12h post-exposure, indicative of oxidative stress and lipid peroxidation. By contrast, levels of reduced glutathione (GSH) in zebrafish liver declined significantly after 3-24h exposure, suggesting that GSH participates in MDA metabolism. A significant upregulation of the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) was observed, suggesting that aphantoxins induce lipid peroxidation in zebrafish liver and are likely to be hepatotoxic. Hepatic levels of MDA and GSH, and of the three enzymes (SOD, CAT, and GPx), therefore provide potential biomarkers for studying environmental exposure to aphantoxins/PSPs from cyanobacterial blooms.
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Affiliation(s)
- De Lu Zhang
- Department of Lifescience and Biotechnology, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, PR China.
| | - Si Yi Liu
- Department of Lifescience and Biotechnology, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, PR China
| | - Jing Zhang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Chun Xiang Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China.
| | - Dun Hai Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China
| | - Yong Ding Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China
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Zhang DL, Zhang J, Hu CX, Wang GH, Li DH, Liu YD. Morphological alterations and acetylcholinesterase and monoamine oxidase inhibition in liver of zebrafish exposed to Aphanizomenon flos-aquae DC-1 aphantoxins. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2014; 157:215-224. [PMID: 25456236 DOI: 10.1016/j.aquatox.2014.10.016] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/12/2014] [Revised: 10/18/2014] [Accepted: 10/21/2014] [Indexed: 06/04/2023]
Abstract
Aphanizomenon flos-aquae is a cyanobacterium that produces neurotoxins or paralytic shellfish poisons (PSPs) called aphantoxins, which present threats to environmental safety and human health via eutrophication of water bodies worldwide. Although the molecular mechanisms of this neurotoxin have been studied, many questions remain unsolved, including those relating to in vivo hepatic neurotransmitter inactivation, physiological detoxification and histological and ultrastructural alterations. Aphantoxins extracted from the natural strain of A. flos-aquae DC-1 were analyzed by high-performance liquid chromatography. The main components were gonyautoxins 1 and 5 (GTX1, GTX5) and neosaxitoxin (neoSTX), which comprised 34.04%, 21.28%, and 12.77% respectively. Zebrafish (Danio rerio) were exposed intraperitoneally to 5.3 or 7.61 μg STX equivalents (eq)/kg (low and high doses, respectively) of A. flos-aquae DC-1 aphantoxins. Morphological alterations and changes in neurotransmitter conduction functions of acetylcholinesterase (AChE) and monoamine oxidase (MAO) in zebrafish liver were detected at different time points 1-24h post-exposure. Aphantoxin significantly enhanced hepatic alanine aminotransferase (ALT) and aspartate aminotransferase (AST) activities and histological and ultrastructural damage in zebrafish liver at 3-12 h post-exposure. Toxin exposure increased the reactive oxygen species content and reduced total antioxidative capacity in zebrafish liver, suggesting oxidative stress. AChE and MAO activities were significantly inhibited, suggesting neurotransmitter inactivation/conduction function abnormalities in zebrafish liver. All alterations were dose- and time-dependent. Overall, the results indicate that aphantoxins/PSPs induce oxidative stress through inhibition of AChE and MAO activities, leading to neurotoxicity in zebrafish liver. The above parameters may be useful as bioindicators for investigating aphantoxins/PSPs and cyanobacterial blooms in nature.
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Affiliation(s)
- De Lu Zhang
- Department of Lifescience and Biotechnology, School of Chemistry, Chemical Engineering and Life Science, Wuhan University of Technology, Wuhan 430070, PR China.
| | - Jing Zhang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, PR China
| | - Chun Xiang Hu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China.
| | - Gao Hong Wang
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China
| | - Dun Hai Li
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China
| | - Yong Ding Liu
- Key Laboratory of Algal Biology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, PR China
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Nishikawa T, Wang C, Akimoto T, Koshino H, Nagasawa K. Synthesis of an Advanced Model of Zetekitoxin AB Focusing on theN-Acylisoxazolidine Amide Structure Corresponding to C13-C17. ASIAN J ORG CHEM 2014. [DOI: 10.1002/ajoc.201402206] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Acute toxicities of saxitoxin, neosaxitoxin, decarbamoyl saxitoxin and gonyautoxins 1&4 and 2&3 to mice by various routes of administration. Toxicon 2013; 76:77-83. [DOI: 10.1016/j.toxicon.2013.09.013] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2013] [Revised: 08/27/2013] [Accepted: 09/12/2013] [Indexed: 11/20/2022]
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Zhang DL, Hu CX, Li DH, Liu YD. Lipid peroxidation and antioxidant responses in zebrafish brain induced by Aphanizomenon flos-aquae DC-1 aphantoxins. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 144-145:250-256. [PMID: 24189433 DOI: 10.1016/j.aquatox.2013.10.011] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2013] [Revised: 10/04/2013] [Accepted: 10/08/2013] [Indexed: 06/02/2023]
Abstract
Aphanizomenon flos-aquae is a cyanobacterium that is frequently encountered in eutrophic waters worldwide. It is source of neurotoxins known as aphantoxins or paralytic shellfish poisons (PSPs), which present a major threat to the environment and human health. The molecular mechanism of PSP action is known, however the in vivo effects of this neurotoxin on oxidative stress, lipid peroxidation and the antioxidant defense responses in zebrafish brain remain to be understood. Aphantoxins purified from a natural isolate of A. flos-aquae DC-1 were analyzed using high performance liquid chromatography. The major components of the toxins were gonyautoxins 1 and 5 (GTX1 and GTX5, 34.04% and 21.28%, respectively) and neosaxitoxin (neoSTX, 12.77%). Zebrafish (Danio rerio) were injected intraperitoneally with 7.73 μg/kg (low dose) and 11.13 μg/kg (high dose) of A. flos-aquae DC-1 aphantoxins. Oxidative stress, lipid peroxidation and antioxidant defense responses in the zebrafish brain were investigated at various timepoints at 1-24h post-exposure. Aphantoxin exposure was associated with significantly increased (>1-2 times) reactive oxygen species (ROS) and malondialdehyde (MDA) in zebrafish brain compared with the controls at 1-12h postexposure, suggestive of oxidative stress and lipid peroxidation. In contrast, reduced glutathione (GSH) levels in the zebrafish brain exposed to high or low doses of aphantoxins decreased by 44.88% and 41.33%, respectively, after 1-12h compared with the controls, suggesting that GSH participated in detoxification to ROS and MDA. Further analysis showed a significant increase in the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) compared with the controls, suggesting elimination of oxidative stress by the antioxidant response in zebrafish brain. All these changes were dose and time dependent. These results suggested that aphantoxins or PSPs increased ROS and MDA and decreased GSH in zebrafish brain, and these changes induced oxidative stress. The increased activity of SOD, CAT and GPx demonstrated that these antioxidant enzymes could play important roles in eliminating excess ROS and MDA. These results also suggest that MDA, ROS, GSH and these three antioxidant enzymes in the brain of zebrafish may act as bioindicators for investigating A. flos-aquae DC-1 aphantoxins or PSPs and algal blooms in nature.
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Affiliation(s)
- De Lu Zhang
- Department of Lifescience and Biotechnology, College of Science, Wuhan University of Technology, Wuhan 430070, PR China.
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Zhang DL, Hu CX, Li DH, Liu YD. Zebrafish locomotor capacity and brain acetylcholinesterase activity is altered by Aphanizomenon flos-aquae DC-1 aphantoxins. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2013; 138-139:139-149. [PMID: 23792258 DOI: 10.1016/j.aquatox.2013.04.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 04/20/2013] [Accepted: 04/22/2013] [Indexed: 06/02/2023]
Abstract
Aphanizomenon flos-aquae (A. flos-aquae) is a source of neurotoxins known as aphantoxins or paralytic shellfish poisons (PSPs) that present a major threat to the environment and to human health. Generally, altered neurological function is reflected in behavior. Although the molecular mechanism of action of PSPs is well known, its neurobehavioral effects on adult zebrafish and its relationship with altered neurological functions are poorly understood. Aphantoxins purified from a natural isolate of A. flos-aquae DC-1 were analyzed by HPLC. The major analogs found in the toxins were the gonyautoxins 1 and 5 (GTX1 and GTX5; 34.04% and 21.28%, respectively) and the neosaxitoxin (neoSTX, 12.77%). Zebrafish (Danio rerio) were intraperitoneally injected with 5.3 and 7.61 μg STXeq/kg (low and high dose, respectively) of A. flos-aquae DC-1 aphantoxins. The swimming activity was investigated by observation combined with video at 6 timepoints from 1 to 24 h post-exposure. Both aphantoxin doses were associated with delayed touch responses, reduced head-tail locomotory abilities, inflexible turning of head, and a tailward-shifted center of gravity. The normal S-pattern (or undulating) locomotor trajectory was replaced by a mechanical motor pattern of swinging the head after wagging the tail. Finally, these fish principally distributed at the top and/or bottom water of the aquarium, and showed a clear polarized distribution pattern at 12 h post-exposure. Further analysis of neurological function demonstrated that both aphantoxin doses inhibited brain acetylcholinesterase activity. All these changes were dose- and time-dependent. These results demonstrate that aphantoxins can alter locomotor capacity, touch responses and distribution patterns by damaging the cholinergic system of zebrafish, and suggest that zebrafish locomotor behavior and acetylcholinesterase can be used as indicators for investigating aphantoxins and blooms in nature.
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Affiliation(s)
- De Lu Zhang
- Department of Lifescience and Biotechnology, College of Science, Wuhan University of Technology, Wuhan 430070, PR China.
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Zhang D, Hu C, Wang G, Li D, Li G, Liu Y. Zebrafish neurotoxicity from aphantoxins--cyanobacterial paralytic shellfish poisons (PSPs) from Aphanizomenon flos-aquae DC-1. ENVIRONMENTAL TOXICOLOGY 2013; 28:239-254. [PMID: 21710505 DOI: 10.1002/tox.20714] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 02/20/2011] [Indexed: 05/31/2023]
Abstract
Aphanizomenon flos-aquae (A. flos-aquae), a cyanobacterium frequently encountered in water blooms worldwide, is source of neurotoxins known as PSPs or aphantoxins that present a major threat to the environment and to human health. Although the molecular mechanism of PSP action is well known, many unresolved questions remain concerning its mechanisms of toxicity. Aphantoxins purified from a natural isolate of A. flos-aquae DC-1 were analyzed by high-performance liquid chromatography (HPLC), the major component toxins were the gonyautoxins1 and 5 (GTX1 and GTX5, 34.04% and 21.28%, respectively) and the neosaxitoxin (neoSTX, 12.77%). The LD50 of the aphantoxin preparation was determined to be 11.33 μg/kg (7.75 μg saxitoxin equivalents (STXeq) per kg) following intraperitoneal injection of zebrafish (Danio rerio). To address the neurotoxicology of the aphantoxin preparation, zebrafish were injected with low and high sublethal doses of A. flos-aquae DC-1 toxins 7.73 and 9.28 μg /kg (5.3 and 6.4 μg STXeq/kg, respectively) and brain tissues were analyzed by electron microscopy and RT-PCR at different timepoints postinjection. Low-dose aphantoxin exposure was associated with chromatin condensation, cell-membrane blebbing, and the appearance of apoptotic bodies. High-dose exposure was associated with cytoplasmic vacuolization, mitochondrial swelling, and expansion of the endoplasmic reticulum. At early timepoints (3 h) many cells exhibited characteristic features of both apoptosis and necrosis. At later timepoints apoptosis appeared to predominate in the low-dose group, whereas necrosis predominated in the high-dose group. RT-PCR revealed that mRNA levels of the apoptosis-related genes encoding p53, Bax, caspase-3, and c-Jun were upregulated after aphantoxin exposure, but there was no evidence of DNA laddering; apoptosis could take place by pathways independent of DNA fragmentation. These results demonstrate that aphantoxin exposure can cause cell death in zebrafish brain tissue, with low doses inducing apoptosis and higher doses inducing necrosis.
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Affiliation(s)
- Delu Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, The Chinese Academy of Sciences, Wuhan 430072, People's Republic of China.
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An overview on the marine neurotoxin, saxitoxin: genetics, molecular targets, methods of detection and ecological functions. Mar Drugs 2013; 11:991-1018. [PMID: 23535394 PMCID: PMC3705384 DOI: 10.3390/md11040991] [Citation(s) in RCA: 169] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 02/17/2013] [Accepted: 02/19/2013] [Indexed: 11/17/2022] Open
Abstract
Marine neurotoxins are natural products produced by phytoplankton and select species of invertebrates and fish. These compounds interact with voltage-gated sodium, potassium and calcium channels and modulate the flux of these ions into various cell types. This review provides a summary of marine neurotoxins, including their structures, molecular targets and pharmacologies. Saxitoxin and its derivatives, collectively referred to as paralytic shellfish toxins (PSTs), are unique among neurotoxins in that they are found in both marine and freshwater environments by organisms inhabiting two kingdoms of life. Prokaryotic cyanobacteria are responsible for PST production in freshwater systems, while eukaryotic dinoflagellates are the main producers in marine waters. Bioaccumulation by filter-feeding bivalves and fish and subsequent transfer through the food web results in the potentially fatal human illnesses, paralytic shellfish poisoning and saxitoxin pufferfish poisoning. These illnesses are a result of saxitoxin’s ability to bind to the voltage-gated sodium channel, blocking the passage of nerve impulses and leading to death via respiratory paralysis. Recent advances in saxitoxin research are discussed, including the molecular biology of toxin synthesis, new protein targets, association with metal-binding motifs and methods of detection. The eco-evolutionary role(s) PSTs may serve for phytoplankton species that produce them are also discussed.
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Zhang X, Zhang Z. Capillary electrophoresis-based immunoassay with electrochemical detection as rapid method for determination of saxitoxin and decarbamoylsaxitoxin in shellfish samples. J Food Compost Anal 2012. [DOI: 10.1016/j.jfca.2012.07.008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Yakes BJ, Prezioso SM, DeGrasse SL. Developing improved immunoassays for paralytic shellfish toxins: The need for multiple, superior antibodies. Talanta 2012; 99:668-76. [DOI: 10.1016/j.talanta.2012.06.073] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2012] [Accepted: 06/25/2012] [Indexed: 02/02/2023]
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Zhang XW, Zhang ZX. Quantification of domoic acid in shellfish samples by capillary electrophoresis-based enzyme immunoassay with electrochemical detection. Toxicon 2012; 59:626-32. [DOI: 10.1016/j.toxicon.2012.02.011] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2011] [Revised: 02/07/2012] [Accepted: 02/21/2012] [Indexed: 10/28/2022]
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Ruebhart DR, Radcliffe WL, Eaglesham GK. Alternative bioassay for the detection of saxitoxin using the speckled cockroach (Nauphoeta cinerea). JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2011; 74:621-637. [PMID: 21432713 DOI: 10.1080/15287394.2011.534426] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Paralytic shellfish poisoning (PSP) toxins produced by cyanobacteria pose a risk to public health as they occur in drinking water reservoirs and recreational lakes and accumulate in the food chain. One of these PSP toxins, saxitoxin (STX) is one of the most toxic nonprotein substances known. Accordingly, there is a requirement to monitor for these toxins. The standard bioassay used to detect these toxins is the mouse bioassay; however, its use is constrained by animal ethics guidelines and practical considerations. Reported here is the use of the globally distributed speckled cockroach Nauphoeta cinerea as a bioassay test organism for the selective detection of PSP toxicity of Anabaena circinalis aqueous extract and STX. N. cinerea was shown to be tolerant to pure cylindrospermopsin (CYN) and microcystin-LR (MC-LR) at doses 10-fold greater than mouse LD₅₀ values while being sensitive to STX. Similarly, N. cinerea was shown to be tolerant of toxin-containing aqueous extracts of Cylindrospermopsis raciborskii, Microcystis aeruginosa, and Nodularia spumigena while being sensitive to A. circinalis. Peak sensitivity to STX was 60 min postinjection with a KD₅₀ of 31.2 ng/g body weight. While this was approximately 3-fold less sensitive than the mouse bioassay, the insect test organism was around 34-fold smaller in mass than a mouse (20 g); thus one-tenth the amount of toxin in absolute quantity was required to reach an ED₅₀ level. The N. cinerea bioassay presents a selective test for PSP toxicity that is rapid, economical, efficient, and simple to perform.
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Affiliation(s)
- David R Ruebhart
- HydroTox Services Australia Pty Ltd, Croydon, Victoria 3136, Australia.
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Etheridge SM. Paralytic shellfish poisoning: Seafood safety and human health perspectives. Toxicon 2010; 56:108-22. [DOI: 10.1016/j.toxicon.2009.12.013] [Citation(s) in RCA: 163] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2009] [Revised: 11/12/2009] [Accepted: 12/11/2009] [Indexed: 10/20/2022]
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Caillaud A, de la Iglesia P, Darius HT, Pauillac S, Aligizaki K, Fraga S, Chinain M, Diogène J. Update on methodologies available for ciguatoxin determination: perspectives to confront the onset of ciguatera fish poisoning in Europe. Mar Drugs 2010; 8:1838-907. [PMID: 20631873 PMCID: PMC2901828 DOI: 10.3390/md8061838] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2010] [Revised: 05/18/2010] [Accepted: 06/10/2010] [Indexed: 11/29/2022] Open
Abstract
Ciguatera fish poisoning (CFP) occurs mainly when humans ingest finfish contaminated with ciguatoxins (CTXs). The complexity and variability of such toxins have made it difficult to develop reliable methods to routinely monitor CFP with specificity and sensitivity. This review aims to describe the methodologies available for CTX detection, including those based on the toxicological, biochemical, chemical, and pharmaceutical properties of CTXs. Selecting any of these methodological approaches for routine monitoring of ciguatera may be dependent upon the applicability of the method. However, identifying a reference validation method for CTXs is a critical and urgent issue, and is dependent upon the availability of certified CTX standards and the coordinated action of laboratories. Reports of CFP cases in European hospitals have been described in several countries, and are mostly due to travel to CFP endemic areas. Additionally, the recent detection of the CTX-producing tropical genus Gambierdiscus in the eastern Atlantic Ocean of the northern hemisphere and in the Mediterranean Sea, as well as the confirmation of CFP in the Canary Islands and possibly in Madeira, constitute other reasons to study the onset of CFP in Europe [1]. The question of the possible contribution of climate change to the distribution of toxin-producing microalgae and ciguateric fish is raised. The impact of ciguatera onset on European Union (EU) policies will be discussed with respect to EU regulations on marine toxins in seafood. Critical analysis and availability of methodologies for CTX determination is required for a rapid response to suspected CFP cases and to conduct sound CFP risk analysis.
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Affiliation(s)
- Amandine Caillaud
- IRTA, Ctra. Poble Nou, Km 5,5. 43540 Sant Carles de la Ràpita, Spain; E-Mails: (A.C.); (P.I.)
| | - Pablo de la Iglesia
- IRTA, Ctra. Poble Nou, Km 5,5. 43540 Sant Carles de la Ràpita, Spain; E-Mails: (A.C.); (P.I.)
| | - H. Taiana Darius
- Laboratoire des micro-algues toxiques, Institut Louis Malardé, BP30, 98713 Papeete Tahiti, French Polynesia; E-Mails: (H.T.D.); (M.C.)
| | - Serge Pauillac
- Institut Pasteur, 25-28 rue du docteur Roux, 75 015 Paris, France; E-Mail: (S.P.)
| | - Katerina Aligizaki
- Department of Botany, School of Biology, Faculty of Sciences, Aristotle University, 54 124 Thessaloniki, Greece; E-Mail: (K.A.)
| | - Santiago Fraga
- Instituto Español de Oceanografía, Subida a Radio Faro, 50, 36390 Vigo, Spain; E-Mail: (S.F.)
| | - Mireille Chinain
- Laboratoire des micro-algues toxiques, Institut Louis Malardé, BP30, 98713 Papeete Tahiti, French Polynesia; E-Mails: (H.T.D.); (M.C.)
| | - Jorge Diogène
- IRTA, Ctra. Poble Nou, Km 5,5. 43540 Sant Carles de la Ràpita, Spain; E-Mails: (A.C.); (P.I.)
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Comparison of analytical tools and biological assays for detection of paralytic shellfish poisoning toxins. Anal Bioanal Chem 2010; 397:1655-71. [DOI: 10.1007/s00216-010-3459-4] [Citation(s) in RCA: 91] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 12/22/2009] [Accepted: 01/04/2010] [Indexed: 11/25/2022]
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Comparative determination of paralytic shellfish toxins (PSTs) using five different toxin detection methods in shellfish species collected in the Aleutian Islands, Alaska. Toxicon 2009; 54:313-20. [DOI: 10.1016/j.toxicon.2009.04.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2009] [Revised: 04/16/2009] [Accepted: 04/16/2009] [Indexed: 11/18/2022]
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Wu W, Wu X, Lin X, Xie Z, Giesy JP. Quantification of domoic acid in shellfish tissues by pressurized capillary electrochromatography. J Sep Sci 2009; 32:2117-22. [DOI: 10.1002/jssc.200900017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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43
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Iwamoto O, Shinohara R, Nagasawa K. Total Synthesis of (−)- and (+)-Decarbamoyloxysaxitoxin and (+)-Saxitoxin. Chem Asian J 2009; 4:277-85. [DOI: 10.1002/asia.200800382] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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Vale C, Alfonso A, Vieytes MR, Romarís XM, Arévalo F, Botana AM, Botana LM. In Vitro and in Vivo Evaluation of Paralytic Shellfish Poisoning Toxin Potency and the Influence of the pH of Extraction. Anal Chem 2008; 80:1770-6. [DOI: 10.1021/ac7022266] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Carmen Vale
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus Universitario s/n, 27002, Lugo, Spain, Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain, INTECMAR, Vilaxoan, Pontevedra, Spain, and Departamento de Química Analítica, Facultad de Ciencias, Universidad de Santiago de Compostela, Lugo, Spain
| | - Amparo Alfonso
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus Universitario s/n, 27002, Lugo, Spain, Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain, INTECMAR, Vilaxoan, Pontevedra, Spain, and Departamento de Química Analítica, Facultad de Ciencias, Universidad de Santiago de Compostela, Lugo, Spain
| | - Mercedes R. Vieytes
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus Universitario s/n, 27002, Lugo, Spain, Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain, INTECMAR, Vilaxoan, Pontevedra, Spain, and Departamento de Química Analítica, Facultad de Ciencias, Universidad de Santiago de Compostela, Lugo, Spain
| | - Xosé Manuel Romarís
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus Universitario s/n, 27002, Lugo, Spain, Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain, INTECMAR, Vilaxoan, Pontevedra, Spain, and Departamento de Química Analítica, Facultad de Ciencias, Universidad de Santiago de Compostela, Lugo, Spain
| | - Fabiola Arévalo
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus Universitario s/n, 27002, Lugo, Spain, Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain, INTECMAR, Vilaxoan, Pontevedra, Spain, and Departamento de Química Analítica, Facultad de Ciencias, Universidad de Santiago de Compostela, Lugo, Spain
| | - Ana M. Botana
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus Universitario s/n, 27002, Lugo, Spain, Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain, INTECMAR, Vilaxoan, Pontevedra, Spain, and Departamento de Química Analítica, Facultad de Ciencias, Universidad de Santiago de Compostela, Lugo, Spain
| | - Luis M. Botana
- Departamento de Farmacología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Campus Universitario s/n, 27002, Lugo, Spain, Departamento de Fisiología, Facultad de Veterinaria, Universidad de Santiago de Compostela, Lugo, Spain, INTECMAR, Vilaxoan, Pontevedra, Spain, and Departamento de Química Analítica, Facultad de Ciencias, Universidad de Santiago de Compostela, Lugo, Spain
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Iwamoto O, Koshino H, Hashizume D, Nagasawa K. Total Synthesis of (−)-Decarbamoyloxysaxitoxin. Angew Chem Int Ed Engl 2007. [DOI: 10.1002/ange.200703326] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Iwamoto O, Koshino H, Hashizume D, Nagasawa K. Total Synthesis of (−)-Decarbamoyloxysaxitoxin. Angew Chem Int Ed Engl 2007; 46:8625-8. [DOI: 10.1002/anie.200703326] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Llewellyn LE. Predictive toxinology: an initial foray using calculated molecular descriptors to describe toxicity using saxitoxins as a model. Toxicon 2007; 50:901-13. [PMID: 17675202 DOI: 10.1016/j.toxicon.2007.06.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2007] [Revised: 06/20/2007] [Accepted: 06/21/2007] [Indexed: 11/30/2022]
Abstract
Molecular descriptors and their mathematical combination have been used for predictive toxicology and risk assessments of environmental pollutants and pharmaceutical leads. However, this approach has not yet been used for natural toxins and may contribute to health and environmental risk assessments of newly discovered toxins without having to undertake whole animal toxicology. To explore this approach, over 3000 descriptors were calculated for each of the 30 saxitoxins for which mouse toxicities have been reported. This dataset was reduced to only 87 descriptors by firstly eliminating descriptors that were the same for all toxins or could not be calculated for all 30 toxins, and then removing those descriptors that did not have a statistically significant linear relationship with toxicity values. From the remaining 87 descriptors, a subset of seven descriptors was identified upon which various mathematical approaches were assessed for their ability to fit the dataset both with and without leave-one-out cross-validation. K-nearest neighbours and support vector machine regression along with various combinations of these seven descriptors fit the toxicity data almost perfectly and also achieved high predictability as measured by leave-one-out cross-validation. Of these seven descriptors, five incorporated weighting by estimates of atomic polarizability and electronic states. Predicted toxicities of several saxitoxins of unknown toxicity bore similarities to the pattern of known potencies of these toxins on various isoforms of the voltage-gated sodium channel. Some of these predicted toxicity values however would not be expected if there was a direct relationship between mammalian sodium channel affinity of the saxitoxins and whole animal toxicity.
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Affiliation(s)
- Lyndon E Llewellyn
- Australian Institute of Marine Science, PMB 3, Townsville MC, Qld 4810, Australia.
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Llewellyn LE. The Behavior of Mixtures of Paralytic Shellfish Toxins in Competitive Binding Assays. Chem Res Toxicol 2006; 19:661-7. [PMID: 16696568 DOI: 10.1021/tx050277i] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Organisms that contain paralytic shellfish toxins (PSTs) may contain many members of this toxin family. PSTs block voltage-gated sodium channels (Na channel) and elicit neurotoxicity. Animals, including humans, may encounter PST mixtures via consumption of tainted seafood, contaminated water, or the microalgae that produce the toxins. PST binding by the Na channel as well as other proteins such as antibodies and saxiphilin have been used to develop biomolecular assays for PSTs. An equation that predicts the combined effects of binary and ternary PST mixtures has been experimentally validated for two unrelated STX-binding proteins, the rat brain Na channel and a saxiphilin from the xanthid crab Liomera tristis. It was found that the most potent toxin or toxins in any mixture profoundly affect the cumulative potency of the mixture, overwhelming weaker toxins with the transition from strong to weak toxicity and changing in a curvilinear manner. Less active PSTs must be several orders of magnitude more concentrated than stronger toxins for the mixture to reflect their potency. This behavior is important in understanding how toxin mixtures may act at the Na channel receptor via which PSTs exert their neurotoxicity and that the presence of weaker toxins does not dilute the effect of stronger toxins in a linear fashion. This strong dominance of a mixture by the most potent toxins also has implications for measurement of toxic test samples and for standards that may contain low levels of highly potent bioactive impurities. This equation has been extended to mixtures of PSTs containing more than three toxins and may be applicable to other natural contaminants and any competitive binding assays used to detect their presence and measure their concentration.
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Affiliation(s)
- Lyndon E Llewellyn
- Australian Institute of Marine Science, PMB 3, Townsville MC, Queensland, 4810, Australia.
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