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1.
Soft Robot ; 2020 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-32109180

RESUMO

An underwater manipulator is essential for underwater robotic sampling and other service operations. Conventional rigid body underwater manipulators generally required substantial size and weight, leading to hindered general applications. Pioneering soft robotic underwater manipulators have defied this by offering dexterous and lightweight arms and grippers, but still requiring substantial actuation and control components to withstand the water pressure and achieving the desired dynamic performance. In this work, we propose a novel approach to underwater manipulator design and control, exploiting the unique characteristics of soft robots, with a hybrid structure (rigid frame+soft actuator) for improved rigidity and force output, a uniform actuator design allowing one compact hydraulic actuation system to drive all actuators, and a novel fully customizable soft bladder design that improves performances in multiple areas: (1) force output of the actuator is decoupled from the working depth, enabling wide working ranges; (2) all actuators are connected to the main hydraulic line without actuator-specific control loop, resulting in a very compact actuation system especially for high-dexterity cases; (3) dynamic responses were improved significantly compared with the counter system without bladder. A prototype soft manipulator with 4-DOFs, dual bladders, and 15 N payload was developed; the entire system (including actuation, control, and batteries) could be mounted onto a consumer-grade remotely operated vehicle, with depth-independent performances validated by various laboratory and field test results across various climatic and hydrographic conditions. Analytical models and validations of the proposed soft bladder design were also presented as a guideline for other applications.

2.
Mar Pollut Bull ; 153: 110950, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32056854

RESUMO

During the summer of 2017 we visited 33 sites with substantial coral cover across Hong Kong waters. At six sites where coral bleaching was observed, video-transect surveys were conducted, which revealed 18.7% to 56.1% bleached colonies and 5.9% to 57.6% bleached coral covered area per site. Mainly affected were three plate-like and three massive coral species. Water quality parameters were analyzed, which indicated that hyposalinity might have triggered the bleaching event. Tagging and follow-up field observation revealed a pattern of recovery depending on coral growth form, with high recovery rates (>93%) at five sites dominated by massive and submassive corals, but moderate (70%) at a site dominated by plate-like corals. Our study shows that the corals of Hong Kong exhibit differential susceptibility to bleaching and ability to recover, therefore it is imperative to establish a long-term monitoring programme to detect the changes in community structure over time.

3.
Harmful Algae ; 83: 95-108, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-31097256

RESUMO

Thirteen isolates of Prorocentrum species were established from the coral reefs of Perhentian Islands Marine Park, Malaysia and underwent morphological observations and molecular characterization. Six species were found: P. caipirignum, P. concavum, P. cf. emarginatum, P. lima, P. mexicanum and a new morphotype, herein designated as P. malayense sp. nov. Prorocentrum malayense, a species closely related to P. leve, P. cf. foraminosum, P. sp. aff. foraminossum, and P. concavum (Clade A sensu Chomérat et al. 2018), is distinguished from its congeners as having larger thecal pore size and a more deeply excavated V-shaped periflagellar area. Platelet arrangement in the periflagellar area of P. malayense is unique, with the presence of platelet 1a and 1b, platelet 2 being the most anterior platelet, and a broad calabash-shaped platelet 3. The species exhibits consistent genetic sequence divergences for the nuclear-encoded large subunit ribosomal RNA gene (LSU rDNA) and the second internal transcribed spacer (ITS2). The phylogenetic inferences further confirmed that it represents an independent lineage, closely related to species in Clade A sensu Chomérat et al. Pairwise comparison of ITS2 transcripts with its closest relatives revealed the presence of compensatory base changes (CBCs). Toxicity analysis showed detectable levels of okadaic acid in P. lima (1.0-1.6 pg cell-1) and P. caipirignum (3.1 pg cell-1); this is the first report of toxigenic P. caipirignum in the Southeast Asian region. Other Prorocentrum species tested, including the new species, however, were below the detection limit.


Assuntos
Dinoflagelados , DNA Ribossômico , Ilhas , Malásia , Filogenia
4.
Mol Neurobiol ; 55(8): 6769-6787, 2018 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-29349574

RESUMO

Consumption of fish containing ciguatera toxins or ciguatoxins (CTXs) causes ciguatera fish poisoning (CFP). In some patients, CFP recurrence occurs even years after exposure related to CTXs accumulation. Pacific CTX-1 (P-CTX-1) is one of the most potent natural substances known that causes predominantly neurological symptoms in patients; however, the underlying pathogenies of CFP remain unknown. Using clinically relevant neurobehavioral tests and electromyography (EMG) to assess effects of P-CTX-1 during the 4 months after exposure, recurrent motor strength deficit occurred in mice exposed to P-CTX-1. We detected irreversible motor strength deficits accompanied by reduced EMG activity, demyelination, and slowing of motor nerve conduction, whereas control unexposed mice fully recovered in 1 month after peripheral nerve injury. Finally, to uncover the mechanism underlying CFP, we detected reduction of spontaneous firing rate of motor cortical neurons even 6 months after exposure and increased number of glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes. Increased numbers of motor cortical neuron apoptosis were detected by dUTP-digoxigenin nick end labeling assay along with activation of caspase 3. Taken together, our study demonstrates that persistence of P-CTX-1 in the nervous system induces irreversible motor deficit that correlates well with excitotoxicity and neurodegeneration detected in the motor cortical neurons.


Assuntos
Caspase 3/metabolismo , Ciguatoxinas/toxicidade , Atividade Motora , Córtex Motor/enzimologia , Córtex Motor/fisiopatologia , Degeneração Neural/enzimologia , Degeneração Neural/fisiopatologia , Neurotoxinas/toxicidade , Animais , Apoptose/efeitos dos fármacos , Ativação Enzimática/efeitos dos fármacos , Gliose/patologia , Masculino , Camundongos Endogâmicos C57BL , Atividade Motora/efeitos dos fármacos , Córtex Motor/efeitos dos fármacos , Neurônios Motores/efeitos dos fármacos , Neurônios Motores/metabolismo , Neurônios Motores/patologia , Degeneração Neural/patologia , Traumatismos dos Nervos Periféricos/patologia , Traumatismos dos Nervos Periféricos/fisiopatologia , Recuperação de Função Fisiológica/efeitos dos fármacos , Remielinização/efeitos dos fármacos , Nervo Isquiático/efeitos dos fármacos , Nervo Isquiático/patologia , Nervo Isquiático/fisiopatologia , Sinapses/efeitos dos fármacos , Sinapses/metabolismo
5.
Harmful Algae ; 68: 206-216, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-28962981

RESUMO

This study confirms the presence of the toxigenic benthic dinoflagellates Gambierdiscus belizeanus and Ostreopsis spp. in the central Red Sea. To our knowledge, this is also the first report of these taxa in coastal waters of Saudi Arabia, indicating the potential occurrence of ciguatera fish poisoning (CFP) in that region. During field investigations carried out in 2012 and 2013, a total of 100 Turbinaria and Halimeda macroalgae samples were collected from coral reefs off the Saudi Arabian coast and examined for the presence of Gambierdiscus and Ostreopsis, two toxigenic dinoflagellate genera commonly observed in coral reef communities around the world. Both Gambierdiscus and Ostreopsis spp. were observed at low densities (<200 cells g-1 wet weight algae). Cell densities of Ostreopsis spp. were significantly higher than Gambierdiscus spp. at most of the sampling sites, and abundances of both genera were negatively correlated with seawater salinity. To assess the potential for ciguatoxicity in this region, several Gambierdiscus isolates were established in culture and examined for species identity and toxicity. All isolates were morphologically and molecularly identified as Gambierdiscus belizeanus. Toxicity analysis of two isolates using the mouse neuroblastoma cell-based assay for ciguatoxins (CTX) confirmed G. belizeanus as a CTX producer, with a maximum toxin content of 6.50±1.14×10-5pg P-CTX-1 eq. cell-1. Compared to Gambierdiscus isolates from other locations, these were low toxicity strains. The low Gambierdiscus densities observed along with their comparatively low toxin contents may explain why CFP is unidentified and unreported in this region. Nevertheless, the presence of these potentially toxigenic dinoflagellate species at multiple sites in the central Red Sea warrants future study on their possible effects on marine food webs and human health in this region.


Assuntos
Intoxicação por Ciguatera/parasitologia , Dinoflagelados/fisiologia , Ciguatoxinas/toxicidade , Dinoflagelados/citologia , Dinoflagelados/ultraestrutura , Geografia , Oceano Índico , Salinidade , Alga Marinha/fisiologia , Análise de Sequência de DNA
6.
Harmful Algae ; 67: 107-118, 2017 07.
Artigo em Inglês | MEDLINE | ID: mdl-28755713

RESUMO

Recent molecular phylogenetic studies of Gambierdiscus species flagged several new species and genotypes, thus leading to revitalizing its systematics. The inter-relationships of clades revealed by the primary sequence information of nuclear ribosomal genes (rDNA), however, can sometimes be equivocal, and therefore, in this study, the taxonomic status of a ribotype, Gambierdiscus sp. type 6, was evaluated using specimens collected from the original locality, Marakei Island, Republic of Kiribati; and specimens found in Rawa Island, Peninsular Malaysia, were further used for comparison. Morphologically, the ribotype cells resembled G. scabrosus, G. belizeanus, G. balechii, G. cheloniae and G. lapillus in thecal ornamentation, where the thecal surfaces are reticulate-foveated, but differed from G. scabrosus by its hatchet-shaped Plate 2', and G. belizeanus by the asymmetrical Plate 3'. To identify the phylogenetic relationship of this ribotype, a large dataset of the large subunit (LSU) and small subunit (SSU) rDNAs were compiled, and performed comprehensive analyses, using Bayesian-inference, maximum-parsimony, and maximum-likelihood, for the latter two incorporating the sequence-structure information of the SSU rDNA. Both the LSU and SSU rDNA phylogenetic trees displayed an identical topology and supported the hypothesis that the relationship between Gambierdiscus sp. type 6 and G. balechii was monophyletic. As a result, the taxonomic status of Gambierdiscus sp. type 6 was revised, and assigned as Gambierdiscus balechii. Toxicity analysis using neuroblastoma N2A assay confirmed that the Central Pacific strains were toxic, ranging from 1.1 to 19.9 fg P-CTX-1 eq cell-1, but no toxicity was detected in a Western Pacific strain. This suggested that the species might be one of the species contributing to the high incidence rate of ciguatera fish poisoning in Marakei Island.


Assuntos
Ciguatoxinas/toxicidade , Dinoflagelados/classificação , Filogenia , Filogeografia , Sequência de Bases , Tamanho Celular , DNA Ribossômico/química , DNA Ribossômico/genética , Dinoflagelados/citologia , Dinoflagelados/ultraestrutura , Funções Verossimilhança , Conformação de Ácido Nucleico
7.
Toxicol Res (Camb) ; 6(2): 179-187, 2017 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-30090488

RESUMO

Ciguatoxins are marine biotoxins that induce the human poisoning syndrome known as ciguatera fish poisoning (CFP). In humans, different kinds of neurological symptoms have been reported after CFP, including anxiety, depression and memory loss. Repetitive exposures to sub-threshold levels of ciguatera toxins may cause irreversible sub-clinical damage, and eventually cause more severe illness. Our previous study has shown that an acute single dose of Pacific ciguatoxin-1 (P-CTX-1) induced synaptic facilitation and blockage of the induction of electrical stimulation-induced long-term potentiation in the medial thalamus-anterior cingulate cortex pathway. Reactive astrogliosis was detected in acute ciguatera poisoning. Despite the reports of complex and prolonged neurological symptoms in patients, few studies have been conducted in animal models to investigate the emotional and cognitive deficits after chronic exposure to ciguatoxin. In the present study, using a rat model with repeated exposures to low dosage of P-CTX-1, we observed development of anxiety-like behavior by open field test and elevated plus maze test, and learning and memory deficits by the Morris water maze; further, decision-making impairment was determined in the chronic P-CTX-1-treated rats by the rats gambling task. We conclude that chronic ciguatera poisoning leads to anxiety, and to impairment of spatial reference memory and decision-making behavior.

8.
Mol Neurobiol ; 54(7): 5590-5603, 2017 09.
Artigo em Inglês | MEDLINE | ID: mdl-27613284

RESUMO

Ciguatera fish poisoning (CFP) is a common human food poisoning caused by consumption of ciguatoxin (CTX)-contaminated fish affecting over 50,000 people worldwide each year. CTXs are classified depending on their origin from the Pacific (P-CTXs), Indian Ocean (I-CTXs), and Caribbean (C-CTXs). P-CTX-1 is the most toxic CTX known and the major source of CFP causing an array of neurological symptoms. Neurological symptoms in some CFP patients last for several months or years; however, the underlying electrophysiological properties of acute exposure to CTXs remain unknown. Here, we used CTX purified from ciguatera fish sourced in the Pacific Ocean (P-CTX-1). Delta and theta electroencephalography (EEG) activity was reduced remarkably in 2 h and returned to normal in 6 h after a single exposure. However, second exposure to P-CTX-1 induced not only a further reduction in EEG activities but also a 2-week delay in returning to baseline EEG values. Ciguatoxicity was detected in the brain hours after the first and second exposure by mouse neuroblastoma assay. The spontaneous firing rate of single motor cortex neuron was reduced significantly measured by single-unit recording with high spatial resolution. Expression profile study of neurotransmitters using targeted profiling approach based on liquid chromatography-tandem mass spectrometry revealed an imbalance between excitatory and inhibitory neurotransmitters in the motor cortex. Our study provides a possible link between the brain oscillations and neurotransmitter release after acute exposure to P-CTX-1. Identification of EEG signatures and major metabolic pathways affected by P-CTX-1 provides new insight into potential biomarker development and therapeutic interventions.


Assuntos
Ciguatoxinas/toxicidade , Eletroencefalografia/efeitos dos fármacos , Redes e Vias Metabólicas/efeitos dos fármacos , Córtex Motor/efeitos dos fármacos , Neurotransmissores/metabolismo , Animais , Cromatografia Líquida de Alta Pressão/métodos , Cromatografia Líquida/métodos , Intoxicação por Ciguatera/metabolismo , Peixes , Masculino , Camundongos Endogâmicos C57BL
9.
Sci Rep ; 6: 26809, 2016 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-27229176

RESUMO

Ciguatera fish poisoning (CFP) results from consumption of tropical reef fish containing ciguatoxins (CTXs). Pacific (P)-CTX-1 is among the most potent known CTXs and the predominant source of CFP in the endemic region responsible for the majority of neurological symptoms in patients. Chronic and persistent neurological symptoms occur in some CFP patients, which often result in incomplete functional recovery for years. However, the direct effects of exposure to CTXs remain largely unknown. In present study, we exposed mice to CTX purified from ciguatera fish sourced from the Pacific region. P-CTX-1 was detected in peripheral nerves within hours and persisted for two months after exposure. P-CTX-1 inhibited axonal regrowth from axotomized peripheral neurons in culture. P-CTX-1 exposure reduced motor function in mice within the first two weeks of exposure before returning to baseline levels. These pre-exposed animals exhibited delayed sensory and motor functional recovery, and irreversible motor deficits after peripheral nerve injury in which formation of functional synapses was impaired. These findings are consistent with reduced muscle function, as assessed by electromyography recordings. Our study provides strong evidence that the persistence of P-CTX-1 in peripheral nerves reduces the intrinsic growth capacity of peripheral neurons, resulting in delayed functional recovery after injury.


Assuntos
Ciguatoxinas/toxicidade , Gânglios Espinais/efeitos dos fármacos , Regeneração Nervosa/efeitos dos fármacos , Neurônios/efeitos dos fármacos , Traumatismos dos Nervos Periféricos/fisiopatologia , Venenos/toxicidade , Animais , Axotomia , Sobrevivência Celular/efeitos dos fármacos , Células Cultivadas , Ciguatoxinas/análise , Gânglios Espinais/patologia , Gânglios Espinais/fisiopatologia , Masculino , Camundongos Endogâmicos C57BL , Movimento/efeitos dos fármacos , Crescimento Neuronal/efeitos dos fármacos , Neurônios/patologia , Neurônios/fisiologia , Traumatismos dos Nervos Periféricos/patologia , Venenos/administração & dosagem , Recuperação de Função Fisiológica
10.
Environ Sci Technol ; 50(8): 4430-8, 2016 Apr 19.
Artigo em Inglês | MEDLINE | ID: mdl-27002339

RESUMO

A photorefreshable and photoenhanced electrochemical sensing platform for bisphenol A (BPA) detection based on Au nanoparticles (NPs) decorated carbon doped TiO2 nanotube arrays (TiO2/Au NTAs) is described. The TiO2/Au NTAs were prepared by quick annealing of anodized nanotubes in argon, followed by controllable electrodeposition of Au NPs. The decoration of Au NPs not only improved photoelectrochemical behavior but also enhanced electrocatalytic activities of the resulted hybrid NTAs. Meanwhile, the high photocatalytic activity of the NTAs allowed the electrode to be readily renewed without damaging the microstructures and surface states after a short UV treatment. The electrochemical detection of BPA on TiO2/Au NTAs electrode was significantly improved under UV irradiation as the electrode could provide fresh reaction surface continuously and the further increased photocurrent resulting from the improved separation efficiency of the photogenerated electron-hole pairs derived from the consumption of holes by BPA. The results showed that the refreshable TiO2/Au NTAs electrode is a promising sensor for long-term BPA monitoring with the detection limit (S/N = 3) of 6.2 nM and the sensitivity of 2.8 µA·µM(-1)·cm(-2).


Assuntos
Compostos Benzidrílicos/análise , Técnicas Eletroquímicas/métodos , Nanopartículas/química , Nanotubos/química , Fenóis/análise , Titânio/química , Carbono/química , Eletrodos , Ouro/química , Limite de Detecção
11.
Ecotoxicology ; 24(7-8): 1744-53, 2015 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-26239440

RESUMO

Paralytic shellfish toxins (PSTs) are originated from cyanobacteria and dinoflagellates, including Alexandrium tamarense, the common dinoflagellate species. In this study, a toxic dinoflagellate strain of A. tamarense CI01 was selected for studying the PSTs' concentration and the related protein variation during the whole cell cycle under different nutrient conditions. High-performance liquid chromatography, 2-D DIGE and Western blotting were used collectively for protein profiling and identification. Results showed that the toxin content was suppressed under nitrogen limiting condition, but enhanced in phosphorous limiting medium. Based on the results of proteomics analysis, 7 proteins were discovered to be related to the PSTs biosynthesis of A. tamarense CI01, including S-adenosylhomocysteine hydrolase, ornithine cyclodeaminase, argininosuccinate synthase, methyluridine methyltransferase cystine ABC transporter, phosphoserine phosphatase, argininosuccinate synthase and acyl-CoA dehydrogenase, which corresponds to the metabolism of the methionine, cysteine, ornithine, arginine and proline. Moreover, some photosynthesis relating proteins also increased their expression during PST synthesis period in A. tamarense CI01, such as phosphoenolpyruvate carboxylase, chloroplast phosphoglycerate kinase, peridinin-chlorophyll α-binding protein, Mg(2+) transporter protein and chloroplast phosphoglycerate kinase. The above findings are in support of our hypothesis that these proteins are involved in toxin biosynthesis of A. tamarense CI01, but cause-and-effect mechanisms need to be investigated in further studies.


Assuntos
Proteínas de Algas/genética , Dinoflagelados/genética , Dinoflagelados/metabolismo , Toxinas Marinhas/biossíntese , Nitrogênio/metabolismo , Fósforo/metabolismo , Proteoma , Proteínas de Algas/metabolismo , Ciclo Celular , Luz , Proteômica
12.
Ecotoxicology ; 24(6): 1395-406, 2015 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-26197730

RESUMO

Three methods for extraction and preparation of high-quality proteins from both toxic and non-toxic dinoflagellates for proteomics analysis, including Trizol method, Lysis method and Tris method, were compared with the subsequent protein separation profiles using 2-D differential gel electrophoresis (2-D DIGE), Coomassie Blue and silver staining. These methods showed suitability for proteins with different pIs and molecular weights. Tris method was better for low molecular weight and low pI protein isolation; whereas both Lysis and Trizol method were better for high-molecular weight and high pI protein purification. Trizol method showed good results with Alexandrium species and Gynodinium species, and the background in gel was much clearer than the other two methods. At the same time, only Lysis method caused breaking down of the target proteins. On the other hand, Trizol method obtained higher concentration of ribulose-1,5-bisphosphate carboxylase/oxygenase proteins by Western-blotting, while Tris method was the best for peridinin-chlorophyll-protein complexes protein and T1 protein preparation. DIGE was better than Coomassie Blue and silver staining, except for some limitations, such as the high cost of the dyes, relatively short shelf life and the requirements for extensive and special image capturing equipment. Some proteins related to PSTs synthesis in dinoflagellates are hydrophobic with high molecular weight or binding on membranes and Trizol method performed better than Tris method for these proteins. The Trizol method and 2-D DIGE were effective combination for proteomics investigations of dinoflagellates. This procedure allows reliable and high recovery efficiency of proteins from dinoflagellates for better understanding on their occurrence and toxin-production for physiological and biochemical information.


Assuntos
Proteínas de Algas/isolamento & purificação , Dinoflagelados/genética , Proteômica/métodos , Dinoflagelados/química , Eletroforese em Gel Bidimensional , Corantes de Rosanilina/química , Coloração pela Prata/métodos
13.
Toxicon ; 77: 16-25, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24184516

RESUMO

Saxitoxin (STX) is the most potent paralytic shellfish poisoning toxin in crustaceans and molluscs, and is known to cause intoxication to humans and marine animals due to its neurotoxicity. However, the extent of its early developmental toxicity to marine species remains unknown. In this study, we examined the early developmental toxicity of STX using marine medaka (Oryzias melastigma) embryos as model. The medaka embryos were exposed to STX for four days, from the early blastula stage onwards, and this exposure period covered the main developmental stage of the central nervous system and somites. After exposure, the treated medaka eleutheroembryos at 15 day post fertilization exhibited abnormal growth with longer body length and relatively smaller yolk sac size. High cell proliferation, neuron development, and metabolism were confirmed using whole-mount immunostaining and two-dimensional electrophoresis. In summary, STX disturbed the normal growth of medaka embryos probably by affecting the metabolic rate in the exposed medaka embryos.


Assuntos
Embrião não Mamífero/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Antagonistas de Estrogênios/toxicidade , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Saxitoxina/toxicidade , Animais , Pesos e Medidas Corporais , Proliferação de Células/efeitos dos fármacos , Eletroforese em Gel Bidimensional , Antagonistas de Estrogênios/química , Microscopia de Fluorescência , Estrutura Molecular , Neurônios/citologia , Neurônios/efeitos dos fármacos , Oryzias , Saxitoxina/química
14.
Neuromolecular Med ; 15(2): 310-23, 2013 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-23494292

RESUMO

Ciguatoxins (CTXs) cause long-term disturbance of cerebral functions. The primary mechanism of neurotoxicity is related to their interaction with voltage-gated sodium channels. However, until now, the neurological targets for CTXs in the brain of intact animals have not been described. In our study, 1 day following oral exposure to 0.26 ng/g of Pacific ciguatoxin 1 (P-CTX-1), we performed in vivo electrophysiological recordings in the rat anterior cingulate cortex (ACC) and identified the increase in spontaneous firings and enhanced responses to visceral noxious stimulation. Local field recordings characterized the P-CTX-1-induced synaptic potentiation and blockage of the induction of electrical stimulation-induced long-term potentiation in the medial thalamus (MT)-ACC pathway. Furthermore, intracerebroventricular administration of P-CTX-1 at doses of 1.0, 5.0, and 10 nM produced a dose-dependent increase in ACC neuronal firings and MT-ACC synaptic transmission. Further studies showed upregulated Na(+) channel expression in astrocytes under pathological conditions. We hypothesized that the astrocytes might have been activated in the ciguatera poisoning in vivo. Increases in glial fibrillary acid protein expression were detected in reactive astrocytes in the rat ACC. The activation of astroglia was further indicated by activation of the gap junction protein connexin 43 and upregulation of excitatory amino acid transporter 2 expression suggesting that glutamate was normally rapidly cleared from the synaptic cleft during acute ciguatera poisoning. However, neurotoxicity and reactive astrogliosis were not detected in the ACC after 7 days of P-CTX-1 exposure. The present results are the first characterization of P-CTX-1-invoked brain cortex neuronal excitotoxicity in vivo and supported the theme that neuron and astroglia signals might play roles in acute ciguatera poisoning.


Assuntos
Astrócitos/efeitos dos fármacos , Intoxicação por Ciguatera/patologia , Ciguatoxinas/toxicidade , Gliose/etiologia , Giro do Cíngulo/patologia , Transmissão Sináptica/efeitos dos fármacos , Potenciais de Ação/efeitos dos fármacos , Administração Oral , Animais , Astrócitos/patologia , Peso Corporal/efeitos dos fármacos , Intoxicação por Ciguatera/fisiopatologia , Ciguatoxinas/administração & dosagem , Conexina 43/metabolismo , Convalescença , Relação Dose-Resposta a Droga , Estimulação Elétrica , Antagonistas de Aminoácidos Excitatórios/farmacologia , Transportador 2 de Aminoácido Excitatório/metabolismo , Gliose/patologia , Giro do Cíngulo/efeitos dos fármacos , Giro do Cíngulo/fisiopatologia , Injeções Intraperitoneais , Injeções Intraventriculares , Potenciação de Longa Duração/efeitos dos fármacos , Masculino , Microdiálise , Neurônios/efeitos dos fármacos , Distribuição Aleatória , Ratos , Ratos Sprague-Dawley , Tálamo/efeitos dos fármacos , Tálamo/fisiopatologia , Canais de Sódio Disparados por Voltagem/efeitos dos fármacos
15.
Mar Pollut Bull ; 63(5-12): 309-17, 2011.
Artigo em Inglês | MEDLINE | ID: mdl-21708389

RESUMO

Oryzias melastigma, also called O. dancena, is becoming a very useful model for estuarine and marine ecotoxicity studies. With O. melastigma being adopted by ILSI Health and Environmental Science Institute (HESI) for embryo toxicity testing, improved knowledge of biomarker based embryonic development becomes especially important for mechanism-based toxicity evaluations. Using whole mount in situ hybridization and immunostaining techniques together with widely used molecular markers, this study describes the molecular development of marine medaka embryos, focusing on the brain, eye, heart, pectoral fin, pancreas, liver, muscle and neuron system. These organs are targets of environmental pollutants that disrupt normal embryonic development in medaka and other fish.


Assuntos
Modelos Animais , Oryzias/metabolismo , Poluentes Químicos da Água/toxicidade , Animais , Sequência de Bases , Biomarcadores/metabolismo , Encéfalo/anormalidades , Encéfalo/efeitos dos fármacos , Encéfalo/embriologia , Ecotoxicologia , Embrião não Mamífero/efeitos dos fármacos , Embrião não Mamífero/metabolismo , Anormalidades do Olho/induzido quimicamente , Anormalidades do Olho/embriologia , Cardiopatias Congênitas/induzido quimicamente , Cardiopatias Congênitas/embriologia , Fígado/anormalidades , Fígado/embriologia , Dados de Sequência Molecular , Músculos/anormalidades , Músculos/embriologia , Proteína MyoD/genética , Oryzias/embriologia , Oryzias/genética , Pâncreas/anormalidades , Pâncreas/embriologia
16.
Aquat Toxicol ; 104(3-4): 211-7, 2011 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-21632025

RESUMO

Although brevetoxins (PbTxs) produced by the marine dinoflagellate Karenia brevis are known to be absorbed across gill membranes and exert their acute toxic effects through an ion-channel mediated pathway in neural tissue, the exact biochemical mechanism concerning PbTxs neurotoxicity in neural tissue and gas-exchange organs has not been well elucidated. In this study, we calculated the LC(50) value of PbTx-1 using the medaka fish model, and presented the molecular responses of sub-acute exposure to PbTx-1 with proteomic method. By adopting two-dimensional electrophoresis, the abundances of 14 and 24 proteins were found to be remarkably altered in the gills and brains, respectively, in response to toxin exposure. Thirteen gill and twenty brain proteins were identified using matrix-assisted laser desorption/ionization tandem time-of-flight mass spectrometry analysis. These proteins could be categorized into diverse functional classes such as cell structure, macromolecule metabolism, signal transduction and neurotransmitter release. These findings can help to elucidate the possible pathways by which aquatic toxins affect marine organisms within target organs.


Assuntos
Encéfalo/efeitos dos fármacos , Brânquias/efeitos dos fármacos , Toxinas Marinhas/toxicidade , Oryzias , Oxocinas/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Encéfalo/metabolismo , Dinoflagelados , Brânquias/metabolismo , Proteoma/metabolismo , Intoxicação por Frutos do Mar , Canais de Sódio/efeitos dos fármacos , Canais de Sódio/metabolismo
17.
Chemosphere ; 84(1): 117-23, 2011 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-21397295

RESUMO

Ciguatera is food poisoning caused by human consumption of reef fish contaminated with ciguatoxins (CTXs). The expanding international trade of tropical fish species from ciguatera-endemic regions has resulted in increased global incidence of ciguatera, and more than 50000 people are estimated to suffer from ciguatera each year worldwide. The Republic of Kiribati is located in the Pacific Ocean; two of its islands, Marakei and Tarawa, have been suggested as high-risk areas for ciguatera. The toxicities of coral reef fish collected from these islands, including herbivorous, omnivorous and carnivorous fish (24% [n=41], 8% [n=13] and 68% [n=117], respectively), were analyzed using the mouse neuroblastoma assay (MNA) after CTX extraction. The MNA results indicated that 156 fish specimens, or 91% of the fish samples, were ciguatoxic (CTX levels >0.01 ng g(-1)). Groupers and moray eels were generally more toxic by an order of magnitude than other fish species. All of the collected individuals of eight species (n=3-19) were toxic. Toxicity varied within species and among locations by up to 10000-fold. Cephalapholis argus and Gymnothorax spp. collected from Tarawa Island were significantly less toxic than those from Marakei Island, although all individuals were toxic based on the 0.01 ng g(-1) threshold. CTX concentrations in the livers of individuals of two moray eel species (Gymnothorax spp., n=6) were nine times greater than those in muscle, and toxicity in liver and muscle showed a strong positive correlation with body weight. The present study provides quantitative information on the ciguatoxicity and distribution of toxicity in fish for use in fisheries management and public health.


Assuntos
Ciguatoxinas/metabolismo , Peixes/metabolismo , Venenos/metabolismo , Animais , Intoxicação por Ciguatera/epidemiologia , Ciguatoxinas/toxicidade , Recifes de Corais , Monitoramento Ambiental , Monitoramento Epidemiológico , Humanos , Fígado/efeitos dos fármacos , Fígado/metabolismo , Micronésia/epidemiologia , Músculos/efeitos dos fármacos , Músculos/metabolismo , Venenos/toxicidade
18.
Toxicon ; 48(2): 138-51, 2006 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-16859722

RESUMO

Paralytic shellfish toxin (PST) profiles of 16 Alexandrium isolates from the Southeast China Sea were analyzed by high-pressure liquid chromatography. Toxin content and composition of three A. tamarense isolates, ATDH01, ATGX02 and ATMJ02, were also investigated at different growth phases and under various culture conditions. Our results showed that six strains of A. affine were non-toxic, while 10 strains of A. tamarense and A. catenella were toxic. These toxic isolates grown in the same culture conditions consistently produced an unusually high proportion of the N-sulfocarbamoyl toxin C1/2 (around 60-80% of total toxins) and medium amounts of gonyautoxin GTX5 (around 15-30% of total) with only trace quantities (<5% of total) of other saxitoxin derivatives (i.e. GTX1, GTX3, GTX4 and neoSTX). The toxin composition of three A. tamarense isolates did not vary with the growth phases, although higher toxin contents (Qt, fmolcell(-1)) were found in the exponential phase. Variations in temperature, salinity and nutrient levels affected toxin content of three A. tamarense isolates but they did not have pronounced effects on the toxin composition (mole %). These results indicate that toxin composition remained relatively constant under various culture conditions, suggesting that toxin composition could be used as a stable biomarker for the Alexandrium species in this region. However, comparison of toxin profiles between isolates from different localities require special caution since isolates even from the same region can have distinct toxin profiles.


Assuntos
Dinoflagelados/metabolismo , Saxitoxina/química , Animais , Biomarcadores , Cromatografia Líquida de Alta Pressão , Dinoflagelados/genética , Dinoflagelados/crescimento & desenvolvimento , Eucariotos/química , Oceanos e Mares , RNA de Protozoário/análise , Saxitoxina/isolamento & purificação , Especificidade da Espécie
19.
Proteomics ; 6(2): 654-66, 2006 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-16342137

RESUMO

The objective of this study was to identify and characterize a "biomarker of toxicity" from the proteome of Alexandrium tamarense, a paralytic shellfish toxin (PST)-producing dinoflagellate. A combination of 2-DE and MS approaches was employed to identify proteins of interest in the vegetative cells of several strains of A. tamarense with different toxin compositions and from different geographical locations. The electrophoretic analysis of the total water-soluble proteins from these toxic strains by 2-DE showed that several abundant proteins, namely AT-T1, AT-T2 and AT-T3, differing slightly in apparent Mr and pIs, were consistently present in all toxic strains of A. tamarense. Further analysis by MALDI-TOF MS and N-terminal amino acid sequencing revealed that they are isoforms of the same protein. Even more intriguing is that these proteins in A. tamarense have similar amino acid sequences and are closely related to a "biomarker of toxicity" previously reported in A. minutum. Unambiguous and highly species-specific identification was later achieved by comparing the PMFs of proteins in these two species. An initial attempt to characterize these proteins by generation of murine polyclonal antibodies against the AT-T1 protein was successful. Western blot analysis using the murine AT-T1-polycolonal antibodies identified all the toxic strains of A. tamarense and A. minutum, but not the nontoxic strain of A. tamarense. These results indicate that these protein characteristics for toxic strains are species-specific and that they are stable properties of the tested algae which are clearly distinguishable irrespective of geographical location and toxin composition. To our knowledge, this is the first study to demonstrate the use of polyclonal antibodies against marker proteins purified from 2-DE gels to distinguish different strains and species of the PST-producing dinoflagellate Alexandrium. It provides the basis for the production of monoclonal antibody probes against the "biomarkers of toxicity" for those dinoflagellates whose genome is incompletely characterized. Potentially, immunoassays could be developed to detect the presence of toxic algae in routine monitoring programs as well as to predict bloom development and movement.


Assuntos
Biomarcadores/metabolismo , Dinoflagelados/metabolismo , Toxinas Marinhas/análise , Toxinas Marinhas/metabolismo , Proteoma/metabolismo , Frutos do Mar/toxicidade , Animais , Western Blotting , Dinoflagelados/classificação , Eletroforese em Gel Bidimensional , Geografia , Imunoglobulina G/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Proteoma/imunologia , Frutos do Mar/parasitologia , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
20.
Proteomics ; 5(6): 1580-93, 2005 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-15800974

RESUMO

Contamination of shellfish with paralytic shellfish poisoning toxins (PST) produced by toxic harmful algal blooms (HABs) have been negatively affecting the shellfish and aquaculture industries worldwide. Therefore, accurate and early identification of toxic phytoplankton species is crucial in HABs surveillance programs that allow fish-farmers to take appropriate preventive measures in shellfish harvesting and other aquaculture activities to overcome the negative impacts of HABs on human health. The identification of toxic dinoflagellates present in the water is currently a time-consuming operation since it requires skillful taxonomists and toxicologists equipped with optical and scanning electron microscopes as well as sophisticated equipment, for example, high-performance liquid chromotography-fluorescence detection. In this paper, a two-dimensional gel electrophoresis (2-DE)-based proteomic approach was applied to discriminate between toxic and nontoxic strains of Alexandrium minutum. Variation in morphological features between toxic and nontoxic strains was minimal and not significant. Also, variation in 2-DE protein patterns within either toxic or nontoxic strains was low, but pronounced differences were detected between toxic and nontoxic strains. The most notable differences between these strains were several abundant proteins with pIs ranging from 4.8 to 5.3 and apparent molecular masses between 17.5 and 21.5 kDa. Groups of proteins, namely NT1, NT2, NT3, and NT4, were consistently found in all nontoxic strains, while T1 and T2 were prominent in the toxic strains. These specific protein spots characteristic for toxic and nontoxic strains remained clearly distinguishable irrespective of the various growth conditions tested. Therefore, they have the potential to serve as "taxonomic markers" to distinguish toxic and nontoxic strains within A. minutum. Initial studies revealed that the expression pattern of T1 was tightly correlated to toxin biosynthesis in the examined alga and may be used to serve as a potential toxin indicator.


Assuntos
Dinoflagelados/metabolismo , Toxinas Marinhas/metabolismo , Proteoma/metabolismo , Frutos do Mar/parasitologia , Sequência de Aminoácidos , Animais , Dinoflagelados/classificação , Eletroforese em Gel Bidimensional , Toxinas Marinhas/envenenamento , Microscopia Eletrônica de Varredura , Dados de Sequência Molecular , Intoxicação por Frutos do Mar , Espectrometria de Massas por Ionização e Dessorção a Laser Assistida por Matriz
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