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1.
Harmful Algae ; 92: 101730, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32113594

RESUMO

Elevated seawater temperatures are linked to the development of harmful algal blooms (HABs), which pose a growing threat to marine birds and other wildlife. During late 2015 and early 2016, a massive die-off of Common Murres (Uria aalge; hereafter, murres) was observed in the Gulf of Alaska coincident with a strong marine heat wave. Previous studies have documented illness and death among seabirds resulting from exposure to the HAB neurotoxins saxitoxin (STX) and domoic acid (DA). Given the unusual mortality event, corresponding warm water anomalies, and recent detection of STX and DA throughout coastal Alaskan waters, HABs were identified as a possible factor of concern. To evaluate whether algal toxins may have contributed to murre deaths, we tested for STX and DA in a suite of tissues obtained from beach-cast murre carcasses associated with the die-off as well as from apparently healthy murres and Black-legged Kittiwakes (Rissa tridactyla; hereafter, kittiwakes) sampled in the preceding and following summers. We also tested forage fish and marine invertebrates collected in the Gulf of Alaska in 2015-2017 to evaluate potential sources of HAB toxin exposure for seabirds. Saxitoxin was present in multiple tissue types of both die-off (36.4 %) and healthy (41.7 %) murres and healthy kittiwakes (54.2 %). Among birds, we detected the highest concentrations of STX in liver tissues (range 1.4-10.8 µg 100 g-1) of die-off murres. Saxitoxin was relatively common in forage fish (20.3 %) and invertebrates (53.8 %). No established toxicity limits currently exist for seabirds, but concentrations of STX in birds and forage fish in our study were lower than values reported from most other bird die-offs in which STX intoxication was causally linked. We detected low concentrations of DA in a single bird sample and in 33.3 % of invertebrates and 4.0 % of forage fish samples. Although these results do not support the hypothesis that acute exposure to STX or DA was a primary factor in the 2015-2016 mortality event, additional information about the sensitivity of murres to these toxins is needed before we can discount their potential role in the die-off. The widespread occurrence of STX in seabirds, forage fish, and invertebrates in the Gulf of Alaska indicates that algal toxins should be considered in future assessments of seabird health, especially given the potential for greater occurrence of HABs in the future.

2.
Harmful Algae ; 92: 101706, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32113598

RESUMO

In autumn of 2013 an immense dinoflagellate bloom developed in Kachemak Bay, AK, USA. Much of the Bay was discolored a dark amber color and raised public concerns as small scale fish kills were reported in a few locations. Light microscopy revealed a monospecific bloom of gymnodinoid dinoflagellates that were previously unknown from the Bay. Gene sequencing of SSU rDNA from cells collected from the bloom confirmed the causative species to be Karenia mikimotoi. This represents the first report of a K. mikimotoi bloom in Alaska. After the bloom organism was confirmed, a K. mikimotoi species-specific qPCR assay was developed and used to assess K. mikimotoi abundances in DNA extracted from phytoplankton samples from Kachemak Bay and Lower Cook Inlet (LCI) obtained over a six-year period. The K. mikimotoi abundances were compared with corresponding time series of environmental variables (water temperature, salinity, water column stability, nutrients, precipitation and wind speed) to assess the factors contributing to the development of the bloom. The results showed early bloom development occurred in August when snow melt reduced salinities and increased water column stability during a period of calm winds. Peak bloom concentrations occurred in late September (107 cell eq. L-1) even as water temperatures were decreasing. The bloom gradually declined over the winter but persisted until April of 2014. Karenia mikimotoi cells were not detected two years prior or three years following the bloom, suggesting cells were introduced to Kachemak Bay at a time when conditions allowed K. mikimotoi to thrive.

3.
Harmful Algae ; 91: 101655, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32057343

RESUMO

Sea surface temperatures in the world's oceans are projected to warm by 0.4-1.4 °C by mid twenty-first century causing many tropical and sub-tropical harmful dinoflagellate genera like Gambierdiscus, Fukuyoa and Ostreopsis (benthic harmful algal bloom species, BHABs) to exhibit higher growth rates over much of their current geographic range, resulting in higher population densities. The primary exception to this trend will be in the tropics where temperatures exceed species-specific upper thermal tolerances (30-31 °C) beyond which growth slows significantly. As surface waters warm, migration to deeper habitats is expected to provide refuge. Range extensions of several degrees of latitude also are anticipated, but only where species-specific habitat requirements can be met (e.g., temperature, suitable substrate, low turbulence, light, salinity, pH). The current understanding of habitat requirements that determine species distributions are reviewed to provide fuller understanding of how individual species will respond to climate change from the present to 2055 while addressing the paucity of information on environmental factors controlling small-scale distribution in localized habitats. Based on the available information, we hypothesized how complex environmental interactions can influence abundance and potential range extensions of BHAB species in different biogeographic regions and identify sentinel sites appropriate for long-term monitoring programs to detect range extensions and reduce human health risks.

4.
Toxins (Basel) ; 11(12)2019 Dec 11.
Artigo em Inglês | MEDLINE | ID: mdl-31835676

RESUMO

In Cuba, ciguatera poisoning associated with fish consumption is the most commonly occurring non-bacterial seafood-borne illness. Risk management through fish market regulation has existed in Cuba for decades and consists of bans on selected species above a certain weight; however, the actual occurrence of ciguatoxins (CTXs) in seafood has never been verified. From this food safety risk management perspective, a study site locally known to be at risk for ciguatera was selected. Analysis of the epiphytic dinoflagellate community identified the microalga Gambierdiscus. Gambierdiscus species included six of the seven species known to be present in Cuba (G. caribaeus, G. belizeanus, G. carpenteri, G. carolinianus, G. silvae, and F. ruetzleri). CTX-like activity in invertebrates, herbivorous and carnivorous fishes were analyzed with a radioligand receptor-binding assay and, for selected samples, with the N2A cell cytotoxicity assay. CTX activity was found in 80% of the organisms sampled, with toxin values ranging from 2 to 8 ng CTX3C equivalents g-1 tissue. Data analysis further confirmed CTXs trophic magnification. This study constitutes the first finding of CTX-like activity in marine organisms in Cuba and in herbivorous fish in the Caribbean. Elucidating the structure-activity relationship and toxicology of CTX from the Caribbean is needed before conclusions may be drawn about risk exposure in Cuba and the wider Caribbean.

5.
Toxins (Basel) ; 11(11)2019 Oct 31.
Artigo em Inglês | MEDLINE | ID: mdl-31683507

RESUMO

Paralytic shellfish poisoning (PSP) is precipitated by a family of toxins produced by harmful algae, which are consumed by filter-feeding and commercially popular shellfish. The toxins, including saxitoxin, neosaxitoxin, and gonyautoxins, accumulate in shellfish and cause intoxication when consumed by humans and animals. Symptoms can range from minor neurological dysfunction to respiratory distress and death. There are over 40 different chemical congeners of saxitoxin and its analogs, many of which are toxic and many of which have low toxicity or are non-toxic. This makes accurate toxicity assessment difficult and complicates decisions regarding whether or not shellfish are safe to consume. In this study, we describe a new antibody-based bioassay that is able to detect toxic congeners (saxitoxin, neosaxitoxin, and gonyautoxins) with little cross-reactivity with the low or non-toxic congeners (decarbamoylated or di-sulfated forms). The anti-saxitoxin antibody used in this assay detects saxitoxin and neosaxitoxin, the two most toxic congers equally well, but not the relatively highly toxic gonyautoxins. By incorporating an incubation step with L-cysteine, it is possible to convert a majority of the gonyautoxins present to saxitoxin and neosaxitoxin, which are readily detected. The assay is, therefore, capable of detecting the most toxic PSP congeners found in commercially relevant shellfish. The assay was validated against samples whose toxicity was determined using standard HPLC methods and yielded a strong linear agreement between the methods, with R2 values of 0.94-0.96. As ELISAs are rapid, inexpensive, and easy-to-use, this new commercially available PSP ELISA represents an advance in technology allowing better safety management of the seafood supply and the ability to screen large numbers of samples that can occur when monitoring is increased substantially in response to toxic bloom events.

6.
Harmful Algae ; 86: 119-127, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31358271

RESUMO

Ciguatera poisoning is caused by the consumption of reef fish or shellfish that have accumulated ciguatoxins, neurotoxins produced by benthic dinoflagellates of the genera Gambierdiscus or Fukuyoa. Although ciguatera constitutes the primary cause of seafood intoxication in Cuba, very little information is available on the occurrence of ciguatoxins in the marine food web and the causative benthic dinoflagellate species. This study conducted on the south-central coast of Cuba reports the occurrence of Gambierdiscus and Fukuyoa genera and the associated benthic genera Ostreopsis and Prorocentrum. Gambierdiscus/Fukuyoa cells were present at low to moderate abundances depending on the site and month of sampling. This genus was notably higher on Dictyotaceae than on other macrophytes. PCR analysis of field-collected samples revealed the presence of six different Gambierdiscus and one Fukuyoa species, including G. caribaeus, G. carolinianus, G. carpenteri, G. belizeanus, F. ruetzleri, G. silvae, and Gambierdiscus sp. ribotype 2. Only Gambierdiscus excentricus was absent from the eight Gambierdiscus/Fukuyoa species known in the wider Caribbean region. Eleven clonal cultures were established and confirmed by PCR and SEM as being either G. carolinianus or G. caribaeus. Toxin production in each isolate was assessed by a radioligand receptor binding assay and found to be below the assay quantification limit. These novel findings augment the knowledge of the ciguatoxin-source dinoflagellates that are present in Cuba, however further studies are needed to better understand the correlation between their abundance, species-specific toxin production in the environment, and the risk for fish contamination, in order to develop better informed ciguatera risk management strategies.


Assuntos
Intoxicação por Ciguatera , Dinoflagelados , Animais , Região do Caribe , Cuba , Medição de Risco
7.
PLoS One ; 14(6): e0218489, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31220134

RESUMO

Blooms of the toxic microalga Karenia brevis occur seasonally in Florida, Texas and other portions of the Gulf of Mexico. Brevetoxins produced during Karenia blooms can cause neurotoxic shellfish poisoning in humans, massive fish kills, and the death of marine mammals and birds. Brevetoxin-containing aerosols are an additional problem, having a severe impact on beachgoers, triggering coughing, eye and throat irritation in healthy individuals, and more serious respiratory distress in those with asthma or other breathing disorders. The blooms and associated aerosol impacts are patchy in nature, often affecting one beach but having no impact on an adjacent beach. To provide timely information to visitors about which beaches are low-risk, we developed HABscope; a low cost (~$400) microscope system that can be used in the field by citizen scientists with cell phones to enumerate K. brevis cell concentrations in the water along each beach. The HABscope system operates by capturing short videos of collected water samples and uploading them to a central server for rapid enumeration of K. brevis cells using calibrated recognition software. The HABscope has a detection threshold of about 100,000 cells, which is the point when respiratory risk becomes evident. Higher concentrations are reliably estimated up to 10 million cells L-1. When deployed by volunteer citizen scientists, the HABscope consistently distinguished low, medium, and high concentrations of cells in the water. The volunteers were able to collect data on most days during a severe bloom. This indicates that the HABscope can provide an effective capability to significantly increase the sampling coverage during Karenia brevis blooms.


Assuntos
Asma/prevenção & controle , Proliferação Nociva de Algas , Toxinas Marinhas/efeitos adversos , Oxocinas/efeitos adversos , Intoxicação por Frutos do Mar/epidemiologia , Aerossóis/efeitos adversos , Asma/epidemiologia , Dinoflagelados , Florida/epidemiologia , Golfo do México/epidemiologia , Humanos , Microalgas/crescimento & desenvolvimento , Microalgas/patogenicidade , Intoxicação por Frutos do Mar/prevenção & controle , Texas/epidemiologia
8.
J Phycol ; 55(3): 730-732, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-30817008

RESUMO

The two most toxic Gambierdiscus species identified from the Caribbean are G. excentricus and G. silvae. These species are the primary causes of ciguatera fish poisoning and likely contribute disproportionately to the toxicity of marine food webs. While Gambierdiscus species are difficult to distinguish using light or scanning electron microscopy, reliable species-specific molecular identification methods have been developed and used successfully to identify a number of other Gambierdiscus species. Corresponding species-specific assays are not yet available for G. excentricus and G. silvae, which imposes limitations on species identification and related ecological studies. The following note describes species-specific polymerase chain reaction assays for G. excentricus and G. silvae that can be used for these purposes.


Assuntos
Intoxicação por Ciguatera , Ciguatoxinas , Dinoflagelados , Animais , Região do Caribe , Filogenia , Reação em Cadeia da Polimerase
9.
Harmful Algae ; 78: 56-68, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-30196925

RESUMO

Few studies have investigated the effect of fine-scale habitat differences on the dynamics of benthic harmful dinoflagellate assemblages. To determine how these microhabitat differences affect the distribution and abundance of the major benthic harmful dinoflagellate genera in a tropical coral reef ecosystem, a field study was undertaken between April-September 2015 and January 2016 on the shallow reef flat of the fringing reef of Rawa Island, Terengganu, Malaysia. Sampling of benthic dinoflagellates was carried out using an artificial substrate sampling method (fiberglass screens). Benthic microhabitats surrounding the sampling screens were characterized simultaneously from photographs of a 0.25-m2 quadrat based on categories of bottom substrate types. Five taxonomic groups of benthic dinoflagellates, Ostreopsis, Gambierdiscus, Prorocentrum, Amphidinium, and Coolia were identified, and cells were enumerated using a light microscope. The results showed Gambierdiscus was less abundant than other genera throughout the study period, with maximum abundance of 1.2 × 103 cells 100 cm-2. While most taxa were present on reefs with high coral cover, higher cell abundances were observed in reefs with high turf algal cover and coral rubble, with the exception of Ostreopsis, where the abundance reached a maximum of 3.4 × 104 cells 100 cm-2 in habitats with high coral cover. Microhabitat heterogeneity was identified as a key factor governing the benthic harmful dinoflagellate assemblages and may account for much of the observed variability in dominant taxa. This finding has significant implications for the role of variability in the benthic harmful algal bloom (BHAB) outbreaks and the potential in identifying BHAB-related toxin transfer pathways and the key vectors in the food webs.


Assuntos
Recifes de Corais , Dinoflagelados/fisiologia , Biota , Malásia , Dinâmica Populacional
10.
Harmful Algae ; 77: 81-92, 2018 07.
Artigo em Inglês | MEDLINE | ID: mdl-30005804

RESUMO

Despite the long history of paralytic shellfish poisoning (PSP) events in Alaska, little is known about the seasonal distribution and abundance of the causative organism, Alexandrium, or the environmental factors that govern toxic bloom development. To address this issue, a five year study (2012-2017) was undertaken in Kachemak Bay and lower Cook Inlet Alaska to determine how the occurrence of Alexandrium catenella, the dominant PSP-causing Alexandrium species, was influenced by temperature, salinity, nutrient concentrations, and other environmental factors. Cell concentrations from 572 surface water samples were estimated using quantitative PCR. Monthly sampling revealed a seasonal pattern of A. catenella bloom development that was positively correlated with water temperature. Prevailing salinity conditions did not significantly affect abundance, nor was nutrient limitation a direct factor. Elevated cell concentrations were detected in 35 samples from Kachemak Bay (100-3050 cell eq. L-1) while a maximum abundance of 67 cell eq. L-1 was detected in samples from lower Cook Inlet sites. Monitoring data showed average water temperatures in Kachemak Bay increased by ∼2 °C over the course of the study and were accompanied by an increase in Alexandrium abundance. Based on these findings, 7-8 °C appears to represent a temperature threshold for significant bloom development in Kachemak Bay, with the greatest risk of shellfish toxicity occurring when temperatures exceed 10-12 °C. The role of temperature is further supported by time series data from the Alaska Coastal Current (station GAK1), which showed that summertime shellfish toxicity events in Kachemak Bay generally followed periods of anomalously high winter water temperatures. These data indicate monitoring changes in water temperatures may be used as an early warning signal for subsequent development of shellfish toxicity in Kachemak Bay.


Assuntos
Dinoflagelados/fisiologia , Proliferação Nociva de Algas , Alaska , Baías , Contaminação de Alimentos/análise , Reação em Cadeia da Polimerase , Dinâmica Populacional , Frutos do Mar/análise
11.
PLoS One ; 13(6): e0198358, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29924826

RESUMO

Lionfish, native to reef ecosystems of the tropical and sub-tropical Indo-Pacific, were introduced to Florida waters in the 1980s, and have spread rapidly throughout the northwestern Atlantic, Caribbean Sea and the Gulf of Mexico. These invasive, carnivorous fish significantly reduce other fish and benthic invertebrate biomass, fish recruitment, and species richness in reef ecosystems. Fisheries resource managers have proposed the establishment of a commercial fishery to reduce lionfish populations and mitigate adverse effects on reef communities. The potential for a commercial fishery for lionfish is the primary reason to identify locations where lionfish accumulate sufficient amounts of ciguatoxin (CTX) to cause ciguatera fish poisoning (CFP), the leading cause of non-bacterial seafood poisoning associated with fish consumption. To address this issue, an initial geographic assessment of CTX toxicity in lionfish from the Caribbean and Gulf of Mexico was conducted. Lionfish samples (n = 293) were collected by spearfishing from 13 locations (74 sampling sites) around the Caribbean and Gulf of Mexico between 2012 and 2015. The highest frequencies of lionfish containing measurable CTX occurred in areas known to be high-risk regions for CFP in the central to eastern Caribbean (e.g., 53% British Virgin Islands and 5% Florida Keys). Though measurable CTX was found in some locations, the majority of the samples (99.3%) contained CTX concentrations below the United States Food and Drug Administration guidance level of 0.1 ppb Caribbean ciguatoxin-1 (C-CTX-1) equivalents (eq.). Only 0.7% of lionfish tested contained more than 0.1 ppb C-CTX-1 eq. As of 2018, there has been one suspected case of CFP from eating lionfish. Given this finding, current risk reduction techniques used to manage CTX accumulating fish are discussed.


Assuntos
Ciguatoxinas/análise , Ciguatoxinas/toxicidade , Perciformes/metabolismo , Animais , Região do Caribe/epidemiologia , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Intoxicação por Ciguatera/epidemiologia , Pesqueiros , Golfo do México/epidemiologia , Humanos , Espécies Introduzidas , Perciformes/crescimento & desenvolvimento , Filogeografia
12.
Harmful Algae ; 73: 30-43, 2018 03.
Artigo em Inglês | MEDLINE | ID: mdl-29602505

RESUMO

A brown tide bloom of Aureoumbra lagunensis developed in Guantánamo Bay, Cuba during a period of drought in 2013 that followed heavy winds and rainfall from Hurricane Sandy in late October 2012. Based on satellite images and water turbidity measurements, the bloom appeared to initiate in January 2013. The causative species (A. lagunensis) was confirmed by microscopic observation, and pigment and genetic analyses of bloom samples collected on May 28 of that year. During that time, A. lagunensis reached concentrations of 900,000 cells ml-1 (28 ppm by biovolume) in the middle portion of the Bay. Samples could not be collected from the northern (Cuban) half of the Bay because of political considerations. Subsequent sampling of the southern half of the Bay in November 2013, April 2014, and October 2014 showed persistent lower concentrations of A. lagunensis, with dominance shifting to the cyanobacterium Synechococcus (up to 33 ppm in April), an algal group that comprised a minor bloom component on May 28. Thus, unlike the brown tide bloom in Laguna Madre, which lasted 8 years, the bloom in Guantánamo Bay was short-lived, much like recent blooms in the Indian River, Florida. Although hypersaline conditions have been linked to brown tide development in the lagoons of Texas and Florida, observed euhaline conditions in Guantánamo Bay (salinity 35-36) indicate that strong hypersalinity is not a requirement for A. lagunensis bloom formation. Microzooplankton biomass dominated by ciliates was high during the observed peak of the brown tide, and ciliate abundance was high compared to other systems not impacted by brown tide. Preferential grazing by zooplankton on non-brown tide species, as shown in A. lagunensis blooms in Texas and Florida, may have been a factor in the development of the Cuban brown tide bloom. However, subsequent selection of microzooplankton capable of utilizing A. lagunensis as a primary food source may have contributed to the short-lived duration of the brown tide bloom in Guantánamo Bay.


Assuntos
Baías , Cianobactérias/classificação , Cianobactérias/fisiologia , Proliferação Nociva de Algas , Cuba , Monitoramento Ambiental , Oxigênio/química , Reação em Cadeia da Polimerase , Salinidade , Água do Mar/química , Especificidade da Espécie , Temperatura Ambiente , Ondas de Maré , Fatores de Tempo
13.
Mar Drugs ; 16(4)2018 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-29642418

RESUMO

The sea urchin Tripneustes gratilla (Toxopneustidae, Echinoids) is a source of protein for many islanders in the Indo-West Pacific. It was previously reported to occasionally cause ciguatera-like poisoning; however, the exact nature of the causative agent was not confirmed. In April and July 2015, ciguatera poisonings were reported following the consumption of T.gratilla in Anaho Bay (Nuku Hiva Island, Marquesas archipelago, French Polynesia). Patient symptomatology was recorded and sea urchin samples were collected from Anaho Bay in July 2015 and November 2016. Toxicity analysis using the neuroblastoma cell-based assay (CBA-N2a) detected the presence of ciguatoxins (CTXs) in T.gratilla samples. Gambierdiscus species were predominant in the benthic assemblages of Anaho Bay, and G.polynesiensis was highly prevalent in in vitro cultures according to qPCR results. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses revealed that P-CTX-3B was the major ciguatoxin congener in toxic sea urchin samples, followed by 51-OH-P-CTX-3C, P-CTX-3C, P-CTX-4A, and P-CTX-4B. Between July 2015 and November 2016, the toxin content in T.gratilla decreased, but was consistently above the safety limit allowed for human consumption. This study provides evidence of CTX bioaccumulation in T.gratilla as a cause of ciguatera-like poisoning associated with a documented symptomatology.


Assuntos
Intoxicação por Ciguatera/etiologia , Ciguatoxinas/análise , Dinoflagelados , Ouriços-do-Mar/microbiologia , Alimentos Marinhos/toxicidade , Idoso , Animais , Baías , Bioensaio/métodos , Linhagem Celular Tumoral , Intoxicação por Ciguatera/epidemiologia , Intoxicação por Ciguatera/prevenção & controle , Ciguatoxinas/toxicidade , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Polinésia/epidemiologia , Alimentos Crus/microbiologia , Alimentos Crus/toxicidade , Alimentos Marinhos/microbiologia , Testes de Toxicidade/métodos
14.
Toxins (Basel) ; 10(1)2017 12 21.
Artigo em Inglês | MEDLINE | ID: mdl-29267222

RESUMO

Ciguatera fish poisoning (CFP) is a foodborne disease caused by the consumption of seafood (fish and marine invertebrates) contaminated with ciguatoxins (CTXs) produced by dinoflagellates in the genus Gambierdiscus. The report of a CFP-like mass-poisoning outbreak following the consumption of Tectus niloticus (Tegulidae, Gastropod) from Anaho Bay on Nuku Hiva Island (Marquesas archipelago, French Polynesia) prompted field investigations to assess the presence of CTXs in T. niloticus. Samples were collected from Anaho Bay, 1, 6 and 28 months after this poisoning outbreak, as well as in Taiohae and Taipivai bays. Toxicity analysis using the neuroblastoma cell-based assay (CBA-N2a) detected the presence of CTXs only in Anaho Bay T. niloticus samples. This is consistent with qPCR results on window screen samples indicating the presence of Gambierdiscus communities dominated by the species G. polynesiensis in Anaho Bay. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyses revealed that P-CTX-3B was the major congener, followed by P-CTX-3C, P-CTX-4A and P-CTX-4B in toxic samples. Between July 2014 and November 2016, toxin content in T. niloticus progressively decreased, but was consistently above the safety limit recommended for human consumption. This study confirms for the first time T. niloticus as a novel vector of CFP in French Polynesia.


Assuntos
Intoxicação por Ciguatera , Ciguatoxinas/análise , Gastrópodes/química , Animais , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Ciguatoxinas/toxicidade , Dinoflagelados , Monitoramento Ambiental , Contaminação de Alimentos/análise , Camundongos , Polinésia
16.
PLoS One ; 12(10): e0185776, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29045489

RESUMO

Dinoflagellate species belonging to the genera Gambierdiscus and Fukuyoa produce ciguatoxins (CTXs), potent neurotoxins that concentrate in fish causing ciguatera fish poisoning (CFP) in humans. While the structures and toxicities of ciguatoxins isolated from fish in the Pacific and Caribbean are known, there are few data on the variation in toxicity between and among species of Gambierdiscus and Fukuyoa. Quantifying the differences in species-specific toxicity is especially important to developing an effective cell-based risk assessment strategy for CFP. This study analyzed the ciguatoxicity of 33 strains representing seven Gambierdiscus and one Fukuyoa species using a cell based Neuro-2a cytotoxicity assay. All strains were isolated from either the Caribbean or Gulf of Mexico. The average toxicity of each species was inversely proportional to growth rate, suggesting an evolutionary trade-off between an investment in growth versus the production of defensive compounds. While there is 2- to 27-fold variation in toxicity within species, there was a 1740-fold difference between the least and most toxic species. Consequently, production of CTX or CTX-like compounds is more dependent on the species present than on the random occurrence of high or low toxicity strains. Seven of the eight species tested (G. belizeanus, G. caribaeus, G. carolinianus, G. carpenteri, Gambierdiscus ribotype 2, G. silvae and F. ruetzleri) exhibited low toxicities, ranging from 0 to 24.5 fg CTX3C equivalents cell-1, relative to G. excentricus, which had a toxicity of 469 fg CTX3C eq. cell-1. Isolates of G. excentricus from other regions have shown similarly high toxicities. If the hypothesis that G. excentricus is the primary source of ciguatoxins in the Atlantic is confirmed, it should be possible to identify areas where CFP risk is greatest by monitoring only G. excentricus abundance using species-specific molecular assays.


Assuntos
Ciguatoxinas/toxicidade , Dinoflagelados/química , Análise de Variância , Animais , Região do Caribe , Linhagem Celular , Golfo do México , Camundongos , Especificidade da Espécie , Testes de Toxicidade
17.
Mar Drugs ; 15(7)2017 Jul 11.
Artigo em Inglês | MEDLINE | ID: mdl-28696398

RESUMO

Maitotoxins (MTXs) are among the most potent toxins known. These toxins are produced by epi-benthic dinoflagellates of the genera Gambierdiscus and Fukuyoa and may play a role in causing the symptoms associated with Ciguatera Fish Poisoning. A recent survey revealed that, of the species tested, the newly described species from the Canary Islands, G. excentricus, is one of the most maitotoxic. The goal of the present study was to characterize MTX-related compounds produced by this species. Initially, lysates of cells from two Canary Island G. excentricus strains VGO791 and VGO792 were partially purified by (i) liquid-liquid partitioning between dichloromethane and aqueous methanol followed by (ii) size-exclusion chromatography. Fractions from chromatographic separation were screened for MTX toxicity using both the neuroblastoma neuro-2a (N2a) cytotoxicity and Ca2+ flux functional assays. Fractions containing MTX activity were analyzed using liquid chromatography coupled to high-resolution mass spectrometry (LC-HRMS) to pinpoint potential MTX analogs. Subsequent non-targeted HRMS analysis permitted the identification of a novel MTX analog, maitotoxin-4 (MTX4, accurate mono-isotopic mass of 3292.4860 Da, as free acid form) in the most toxic fractions. HRMS/MS spectra of MTX4 as well as of MTX are presented. In addition, crude methanolic extracts of five other strains of G. excentricus and 37 other strains representing one Fukuyoa species and ten species, one ribotype and one undetermined strain/species of Gambierdiscus were screened for the presence of MTXs using low resolution tandem mass spectrometry (LRMS/MS). This targeted analysis indicated the original maitotoxin (MTX) was only present in one strain (G. australes S080911_1). Putative maitotoxin-2 (p-MTX2) and maitotoxin-3 (p-MTX3) were identified in several other species, but confirmation was not possible because of the lack of reference material. Maitotoxin-4 was detected in all seven strains of G. excentricus examined, independently of their origin (Brazil, Canary Islands and Caribbean), and not detected in any other species. MTX4 may therefore serve as a biomarker for the highly toxic G. excentricus in the Atlantic area.


Assuntos
Dinoflagelados/química , Toxinas Marinhas/química , Toxinas Marinhas/toxicidade , Oxocinas/química , Oxocinas/toxicidade , Animais , Bioensaio/métodos , Brasil , Região do Caribe , Linhagem Celular Tumoral , Intoxicação por Ciguatera/genética , Intoxicação por Ciguatera/parasitologia , Ciguatoxinas/toxicidade , Camundongos , Filogenia , Espanha , Especificidade da Espécie
18.
Proc Natl Acad Sci U S A ; 114(19): 4975-4980, 2017 05 09.
Artigo em Inglês | MEDLINE | ID: mdl-28439007

RESUMO

Global ocean temperatures are rising, yet the impacts of such changes on harmful algal blooms (HABs) are not fully understood. Here we used high-resolution sea-surface temperature records (1982 to 2016) and temperature-dependent growth rates of two algae that produce potent biotoxins, Alexandrium fundyense and Dinophysis acuminata, to evaluate recent changes in these HABs. For both species, potential mean annual growth rates and duration of bloom seasons significantly increased within many coastal Atlantic regions between 40°N and 60°N, where incidents of these HABs have emerged and expanded in recent decades. Widespread trends were less evident across the North Pacific, although regions were identified across the Salish Sea and along the Alaskan coastline where blooms have recently emerged, and there have been significant increases in the potential growth rates and duration of these HAB events. We conclude that increasing ocean temperature is an important factor facilitating the intensification of these, and likely other, HABs and thus contributes to an expanding human health threat.


Assuntos
Dinoflagelados/crescimento & desenvolvimento , Eutrofização , Aquecimento Global , Ácido Okadáico/metabolismo , Saxitoxina/biossíntese , Oceano Atlântico , Humanos , Ácido Okadáico/toxicidade , Oceano Pacífico , Saxitoxina/toxicidade
19.
Harmful Algae ; 63: 173-183, 2017 03.
Artigo em Inglês | MEDLINE | ID: mdl-28366392

RESUMO

Species in the epi-benthic dinoflagellate genus Gambierdiscus produce ciguatoxins (CTXs) and maitotoxins (MTXs), which are among the most potent marine toxins known. Consumption of fish contaminated with sufficient quantities of CTXs causes Ciguatera Fish Poisoning (CFP), the largest cause of non-bacterial food poisoning worldwide. Maitotoxins, which can be found in the digestive system of fish, could also contribute to CFP if such tissues are consumed. Recently, an increasing number of Gambierdiscus species have been identified; yet, little is known about the variation in toxicity among Gambierdiscus strains or species. This study is the first assessment of relative CTX- and MTX-toxicity of Gambierdiscus species from areas as widespread as the North-Eastern Atlantic Ocean, Pacific Ocean and the Mediterranean Sea. A total of 13 strains were screened: (i) seven Pacific strains of G. australes, G. balechii, G. caribaeus, G. carpenteri, G. pacificus, G. scabrosus and one strain of an undetermined species (Gambierdiscus sp. Viet Nam), (ii) five strains from the North-Eastern Atlantic Ocean (two G. australes, a single G. excentricus and two G. silvae strains), and (iii) one G. carolinianus strain from the Mediterranean Sea. Cell pellets of Gambierdiscus were extracted with methanol and the crude extracts partitioned into a CTX-containing dichloromethane fraction and a MTX-containing aqueous methanol fraction. CTX-toxicity was estimated using the neuro-2a cytoxicity assay, and MTX-toxicity via a human erythrocyte lysis assay. Different species were grouped into different ratios of CTX- and MTX-toxicity, however, the ratio was not related to the geographical origin of species (Atlantic, Mediterranean, Pacific). All strains showed MTX-toxicity, ranging from 1.5 to 86pg MTX equivalents (eq) cell-1. All but one of the strains showed relatively low CTX-toxicity ranging from 0.6 to 50 fg CTX3C eq cell-1. The exception was the highly toxic G. excentricus strain from the Canary Islands, which produced 1426 fg CTX3C eq cell-1. As was true for CTX, the highest MTX-toxicity was also found in G. excentricus. Thus, the present study confirmed that at least one species from the Atlantic Ocean demonstrates similar toxicity as the most toxic strains from the Pacific, even if the metabolites in fish have so far been shown to be more toxic in the Pacific Ocean.


Assuntos
Bioensaio/métodos , Dinoflagelados/metabolismo , Toxinas Marinhas/análise , Animais , Intoxicação por Ciguatera , Ciguatoxinas/análise , Ciguatoxinas/toxicidade , Eritrócitos/efeitos dos fármacos , Toxinas Marinhas/toxicidade , Oxocinas/análise , Oxocinas/toxicidade , Filogenia
20.
PLoS One ; 11(7): e0160006, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27467390

RESUMO

BACKGROUND: Ciguatera is a circumtropical disease produced by polyether sodium channel toxins (ciguatoxins) that enter the marine food chain and accumulate in otherwise edible fish. Ciguatoxins, as well as potent water-soluble polyethers known as maitotoxins, are produced by certain dinoflagellate species in the genus Gambierdiscus and Fukuyoa spp. in the Pacific but little is known of the potential of related Caribbean species to produce these toxins. METHODS: We established a simplified procedure for extracting polyether toxins from Gambierdiscus and Fukuyoa spp. based on the ciguatoxin rapid extraction method (CREM). Fractionated extracts from identified Pacific and Caribbean isolates were analysed using a functional bioassay that recorded intracellular calcium changes (Ca2+) in response to sample addition in SH-SY5Y cells. Maitotoxin directly elevated Ca2+i, while low levels of ciguatoxin-like toxins were detected using veratridine to enhance responses. RESULTS: We identified significant maitotoxin production in 11 of 12 isolates analysed, with 6 of 12 producing at least two forms of maitotoxin. In contrast, only 2 Caribbean isolates produced detectable levels of ciguatoxin-like activity despite a detection limit of >30 pM. Significant strain-dependent differences in the levels and types of ciguatoxins and maitotoxins produced by the same Gambierdiscus spp. were also identified. CONCLUSIONS: The ability to rapidly identify polyether toxins produced by Gambierdiscus spp. in culture has the potential to distinguish ciguatoxin-producing species prior to large-scale culture and in naturally occurring blooms of Gambierdiscus and Fukuyoa spp. Our results have implications for the evaluation of ciguatera risk associated with Gambierdiscus and related species.


Assuntos
Bioensaio , Ciguatoxinas/isolamento & purificação , Dinoflagelados/química , Toxinas Marinhas/isolamento & purificação , Oxocinas/isolamento & purificação , Animais , Linhagem Celular Tumoral , Cromatografia Líquida de Alta Pressão , Humanos , Oceano Pacífico , Espectrometria de Fluorescência
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