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1.
PLoS One ; 15(3): e0230176, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32150599

RESUMO

Diarrheic Shellfish Poisoning toxins (DST) are a severe health risk to shellfish consumers and can be a major problem for the shellfish industry. Bivalve molluscs can accumulate DST via ingestion of toxic dinoflagellates like Dinophysis spp., which are the most prominent producers of DST. The effects of DST-containing dinoflagellate Dinophysis acuta on bivalve clearance and respiration rate were investigated in the blue mussel (Mytilus edulis) exposed to different algal densities in a controlled laboratory study. Results showed that M. edulis exposed to D. acuta displayed a reduced clearance rate compared to M. edulis exposed to equivalent bio-volumes of the non-toxic cryptophyte Rhodomonas salina. Furthermore, M. edulis ceased to feed on D. acuta after 1 to 4 h, depending on D. acuta densities. The quickest response was observed at the highest densities of D. acuta. The estimated total amount of DST accumulated in the M. edulis exceeded the regulatory limit for human consumption and furthermore, intoxication of the M. edulis seemed to occur faster at high cell toxicity rather than at high cell density. However, respiration rates were, similar, irrespective of whether M. edulis were fed single diets of R. salina, D. acuta or a mixed diet of both algal species. In conclusion, the DST-containing D. acuta had a severe negative effect on the clearance of M. edulis, which can affect the conditions of the M. edulis negatively. Hence, DST may cause low quality M. edulis, due to reduced feeding when exposed to DST-containing D. acuta.

2.
Harmful Algae ; 92: 101697, 2020 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-32113604

RESUMO

Enrichment of the oceans with CO2 may be beneficial for some marine phytoplankton, including harmful algae. Numerous laboratory experiments provided valuable insights into the effects of elevated pCO2 on the growth and physiology of harmful algal species, including the production of phycotoxins. Experiments close to natural conditions are the next step to improve predictions, as they consider the complex interplay between biotic and abiotic factors that can confound the direct effects of ocean acidification. We therefore investigated the effect of ocean acidification on the occurrence and abundance of phycotoxins in bulk plankton samples during a long-term mesocosm experiment in the Gullmar Fjord, Sweden, an area frequently experiencing harmful algal blooms. During the experimental period, a total of seven phycotoxin-producing harmful algal genera were identified in the fjord, and in accordance, six toxin classes were detected. However, within the mesocosms, only domoic acid and the corresponding producer Pseudo-nitzschia spp. was observed. Despite high variation within treatments, significantly higher particulate domoic acid contents were measured in the mesocosms with elevated pCO2. Higher particulate domoic acid contents were additionally associated with macronutrient limitation. The risks associated with potentially higher phycotoxin levels in the future ocean warrants attention and should be considered in prospective monitoring strategies for coastal marine waters.

3.
Mar Pollut Bull ; 150: 110778, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31910525

RESUMO

The aim of the present work was to unravel which environmental drivers govern the dynamics of toxic dinoflagellate abundance as well as their associated paralytic shellfish toxins (PSTs), diarrhetic shellfish toxins (DSTs) and pectenotoxin-2 (PTX2) in Ambon Bay, Eastern Indonesia. Weather, biological and physicochemical parameters were investigated weekly over a 7-month period. Both PSTs and PTX2 were detected at low levels, yet they persisted throughout the research. Meanwhile, DSTs were absent. A strong correlation was found between total particulate PST and Gymnodinium catenatum cell abundance, implying that this species was the main producer of this toxin. PTX2 was positively correlated with Dinophysis miles cell abundance. Vertical mixing, tidal elevation and irradiance attenuation were the main environmental factors that regulated both toxins and cell abundances, while nutrients showed only weak correlations. The present study indicates that dinoflagellate toxins form a potential environmental, economic and health risk in this Eastern Indonesian bay.


Assuntos
Dinoflagelados , Toxinas Marinhas , Baías , Monitoramento Ambiental , Indonésia , Frutos do Mar
4.
Harmful Algae ; 90: 101708, 2019 12.
Artigo em Inglês | MEDLINE | ID: mdl-31806164

RESUMO

Within the past few decades, harmful algal blooms (HABs) have occurred frequently in Indonesian waters, resulting in environmental degradation, economic loss and human health problems. So far, HAB related studies mainly addressed ecological traits and species distribution, yet toxin measurements were virtually absent for Indonesian waters. The aim of the present study was to explore variability of the potentially toxic marine diatom genus Pseudo-nitzschia, as well as its neurotoxin domoic acid as a function of environmental conditions in Ambon Bay, eastern Indonesia. Weekly phytoplankton samples, oceanographic (CTD, nutrients) and meteorological (precipitation, wind) parameters were analyzed at 5 stations in the bay during the dry and wet seasons of 2018. Liquid chromatography - tandem mass spectrometry (LC-MS/MS) was used to detect particulate DA (pDA). Vegetative cells of Pseudo-nitzschia spp. and pDA were found in 98.6% and 51.4% of the samples, respectively. pDA levels were low, yet detected throughout the campaign, implying that Ambon Bay might potentially be subject to amnesic shellfish poisoning. The highest levels of both Pseudo-nitzschia spp. cell abundance and pDA were found in the wet season, showing a strong positive correlation between both parameters, compared to the dry season, (r = 0.87 and r = 0.66 (p < 0.01), respectively). Statistical analyses revealed that temperature and mixed layer depth positively correlated with Pseudo-nitzschia spp. and pDA during the dry season, while ammonium showed positive correlations in both seasons. This study represents the first successful investigation of the presence and variability of Pseudo-nitzschia spp. and its neurotoxin DA in Indonesian waters.


Assuntos
Diatomáceas , Cromatografia Líquida , Humanos , Indonésia , Ácido Caínico/análogos & derivados , Espectrometria de Massas em Tandem
5.
Harmful Algae ; 88: 101610, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31582156

RESUMO

The cosmopolitan, potentially toxic dinoflagellate Protoceratium reticulatum possesses a fossilizable cyst stage which is an important paleoenvironmental indicator. Slight differences in the internal transcribed spacer ribosomal DNA (ITS rDNA) sequences of P. reticulatum have been reported, and both the motile stage and cyst morphology of P. reticulatum display phenotypic plasticity, but how these morpho-molecular variations are related with ecophysiological preferences is unknown. Here, 55 single cysts or cells were isolated from localities in the Northern (Arctic to subtropics) and Southern Hemispheres (Chile and New Zealand), and in total 34 strains were established. Cysts and/or cells were examined with light microscopy and/or scanning electron microscopy. Large subunit ribosomal DNA (LSU rDNA) and/or ITS rDNA sequences were obtained for all strains/isolates. All strains/isolates of P. reticulatum shared identical LSU sequences except for one strain from the Mediterranean Sea that differs in one position, however ITS rDNA sequences displayed differences at eight positions. Molecular phylogeny was inferred using maximum likelihood and Bayesian inference based on ITS rDNA sequences. The results showed that P. reticulatum comprises at least three ribotypes (designated as A, B, and C). Ribotype A included strains from the Arctic and temperate areas, ribotype B included strains from temperate regions only, and ribotype C included strains from the subtropical and temperate areas. The average ratios of process length to cyst diameter of P. reticulatum ranged from 15% in ribotype A, 22% in ribotype B and 17% in ribotype C but cyst size could overlap. Theca morphology was indistinguishable among ribotypes. The ITS-2 secondary structures of ribotype A displayed one CBC (compensatory change on two sides of a helix pairing) compared to ribotypes B and C. Growth response of one strain from each ribotype to various temperatures was examined. The strains of ribotypes A, B and C exhibited optimum growth at 15 °C, 20 °C and 20-25 °C, respectively, thus corresponding to cold, moderate and warm ecotypes. The profiles of yessotoxins (YTXs) were examined for 25 strains using liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The parent compound yessotoxin (YTX) was produced by strains of ribotypes A and B, but not by ribotype C strains, which only produced the structural variant homoyessotoxin (homoYTX). Our results support the notion that there is significant intra-specific variability in Protoceratium reticulatum and the biogeography of the different ribotypes is consistent with specific ecological preferences.


Assuntos
Dinoflagelados , Toxinas Marinhas , Regiões Árticas , Teorema de Bayes , Chile , Cromatografia Líquida , Mar Mediterrâneo , Nova Zelândia , Espectrometria de Massas em Tandem
6.
Harmful Algae ; 88: 101637, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31582159

RESUMO

Some species of the dinophytes Azadinium and Amphidoma (Amphidomataceae) produce azaspiracids (AZA), lipophilic polyether compounds responsible for Azaspiracid Shellfish Poisoning (AZP) in humans after consumption of contaminated seafood. Toxigenic Amphidomataceae are known to occur in the North Atlantic and the North Sea area, but little is known about their importance in Danish coastal waters. In 2016, 44 Stations were sampled on a survey along the Danish coastline, covering the German Bight, Limfjord, the Kattegat area, Great Belt and Kiel Bight. Samples were analysed by live microscopy, liquid chromatography-tandem mass spectrometry (LC-MS/MS) and quantitative polymerase-chain-reaction (qPCR) on the presence of Amphidomataceae and AZA. Amphidomataceae were widely distributed in the area, but were below detection limit on most of the inner Limfjord stations. Cell abundances of the three toxigenic species, determined with species-specific qPCR assays on Azadinium spinosum, Az. poporum and Amphidoma languida, were generally low and restricted to the North Sea and the northern Kattegat, which was in agreement with the distribution of the generally low AZA abundances in plankton samples. Among the toxigenic species, Amphidoma languida was dominant with highest cell densities up to 3 × 103 cells L-1 on North Sea stations and at the western entrance of the Limfjord. Azaspiracids detected in plankton samples include low levels of AZA-1 at one station of the North Sea, and higher levels of AZA-38 and -39 (up to 1.5 ng L-1) in the North Sea and the Limfjord entrance. Furthermore, one new AZA (named AZA-63) was discovered in plankton of two North Sea stations. Morphological, molecular, and toxinological characterisation of 26 newly established strains from the area confirmed the presence of four amphidomatacean species (Az. obesum, Az. dalianense, Az. poporum and Am. languida). The single new strain of Az. poporum turned out as a member of Ribotype A2, which was previously only known from the Mediterranean. Consistent with some of these Mediterranean A2 strains, but different to the previously established AZA-37 producing Az. poporum Ribotype A1 strains from Denmark, the new strain did not contain any AZA. Azaspiracids were also absent in all Az. obesum and Az. dalianense strains, but AZA-38 and -39 were found in all Am. languida strains with total AZA cell quotas ranging from 0.08 up to 94 fg cell-1. In conclusion, AZA-producing microalgae and their respective toxins were low in abundance but widely present in the area, and thus might be considered in local monitoring programs to preserve seafood safety in Danish coastal waters.


Assuntos
Dinoflagelados , Espectrometria de Massas em Tandem , Cromatografia Líquida , Dinamarca , Humanos , Mar do Norte
7.
Mar Drugs ; 17(9)2019 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-31443393

RESUMO

Azaspiracids (AZAs) are microalgal toxins that can accumulate in shellfish and lead to human intoxications. To facilitate their study and subsequent biomonitoring, purification from microalgae rather than shellfish is preferable; however, challenges remain with respect to maximizing toxin yields. The impacts of temperature, growth media, and photoperiod on cell densities and toxin production in Azadinium spinosum were investigated. Final cell densities were similar at 10 and 18 °C, while toxin cell quotas were higher (~3.5-fold) at 10 °C. A comparison of culture media showed higher cell densities and AZA cell quotas (2.5-5-fold) in f10k compared to f/2 and L1 media. Photoperiod also showed differences, with lower cell densities in the 8:16 L:D treatment, while toxin cell quotas were similar for 12:12 and 8:16 L:D treatments but slightly lower for the 16:8 L:D treatment. AZA1, -2 and -33 were detected during the exponential phase, while some known and new AZAs were only detected once the stationary phase was reached. These compounds were additionally detected in field water samples during an AZA event.

8.
Environ Toxicol Chem ; 38(10): 2209-2223, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31343776

RESUMO

In the Northern Patagonian gulfs of Argentina (Golfo Nuevo and Golfo San José), blooms of toxigenic microalgae and the detection of their associated phycotoxins are recurrent phenomena. The present study evaluated the transfer of phycotoxins from toxigenic microalgae to mesozooplankton in Golfo Nuevo and Golfo San José throughout an annual cycle (December 2014-2015 and January 2015-2016, respectively). In addition, solid-phase adsorption toxin tracking (SPATT) samplers were deployed for the first time in these gulfs, to estimate the occurrence of phycotoxins in the seawater between the phytoplankton samplings. Domoic acid was present throughout the annual cycle in SPATT samplers, whereas no paralytic shellfish poisoning toxins were detected. Ten toxigenic species were identified: Alexandrium catenella, Dinophysis acuminata, Dinophysis acuta, Dinophysis tripos, Dinophysis caudata, Prorocentrum lima, Pseudo-nitzschia australis, Pseudo-nitzschia calliantha, Pseudo-nitzschia fraudulenta, and Pseudo-nitzschia pungens. Lipophilic and hydrophilic toxins were detected in phytoplankton and mesozooplankton from both gulfs. Pseudo-nitzschia spp. were the toxigenic species most frequent in these gulfs. Consequently, domoic acid was the phycotoxin most abundantly detected and transferred to upper trophic levels. Spirolides were detected in phytoplankton and mesozooplankton for the first time in the study area. Likewise, dinophysistoxins were found in mesozooplankton from both gulfs, and this is the first report of the presence of these phycotoxins in zooplankton from the Argentine Sea. The dominance of calanoid copepods indicates that they were the primary vector of phycotoxins in the pelagic trophic web. Environ Toxicol Chem 2019;38:2209-2223. © 2019 SETAC.

9.
Harmful Algae ; 87: 101622, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31349884

RESUMO

Blooms of Alexandrium spp. are a well-known phenomenon in Northern European waters. While A. tamarense/catenella, and A. pseudogonyaulax have been reported from marine waters, high densities of A. ostenfeldii are mainly observed at lower salinities in North Sea estuaries and the Baltic Sea, suggesting salinity as a driver of Alexandrium species composition and toxin distribution. To investigate this relationship, an oceanographic expedition through a natural salinity gradient was conducted in June 2016 along the coasts of Denmark. Besides hydrographic data, phytoplankton and sediment samples were collected for analyses of Alexandrium spp. cell and cyst abundances, for toxin measurement and cell isolation. Plankton data revealed the predominance of A. pseudogonyaulax at all transect stations while A. ostenfeldii and A. catenella generally contributed a minor fraction to the Alexandrium community. High abundances of A. pseudogonyaulax in the shallow enclosed Limfjord were accompanied by high amounts of goniodomin A (GDA). This toxin was also detected at low abundances along with A. pseudogonyaulax in the North Sea and the Kattegat. Genetic and morphological characterization of established strains showed high similarity of the Northern European population to distant geographic populations. Despite low cell abundances of A. ostenfeldii, different profiles of cycloimines were measured in the North Sea and in the Limfjord. This field survey revealed that salinity alone does not determine Alexandrium species and toxin distribution, but emphasizes the importance of habitat conditions such as proximity to seed banks, shelter, and high nutrient concentrations. The results show that A. pseudogonyaulax has become a prominent member of the Alexandrium spp. community over the past decade in the study area. Analyses of long term monitoring data from the Limfjord confirmed a recent shift to A. pseudogonyaulax dominance. Cyst and toxin records of the species in Kiel Bight suggest a spreading potential into the brackish Baltic Sea, which might lead to an expansion of blooms under future climate conditions.


Assuntos
Dinoflagelados , Salinidade , Éteres , Europa (Continente) , Macrolídeos , Águas Salinas
10.
Front Microbiol ; 10: 1065, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31178832

RESUMO

Empirical evidence of the cost of producing toxic compounds in harmful microalgae is completely lacking. Yet costs are often assumed to be high, implying substantial ecological benefits with adaptive significance exist. To study potential fitness costs of toxin production, 16 strains including three species of the former Alexandrium tamarense species complex were grown under both carbon limitation and unlimited conditions. Growth rates, levels of intracellular paralytic shellfish toxins (PSTs), and effects of lytic compounds were measured to provide trade-off curves of toxicity for both PST and lytic toxicity under high light (300 µmol photons m-2 s-1) and under low light (i.e., carbon limited; 20 µmol photons m-2 s-1). Fitness costs in terms of reduced growth rates with increasing PST content were only evident under unlimited conditions, but not under carbon limitation, in which case PST production was positively correlated with growth. The cost of production of lytic compounds was detected both under carbon limitation and unlimited conditions, but only in strains producing PST. The results may direct future research in understanding the evolutionary role and ecological function of algal toxins. The intrinsic growth rate costs should be accounted for in relation to quantifying benefits such as grazer avoidance or toxin-mediated prey capture in natural food web settings.

11.
Harmful Algae ; 84: 244-260, 2019 04.
Artigo em Inglês | MEDLINE | ID: mdl-31128809

RESUMO

Azaspiracids (AZA) are the most recently discovered group of lipophilic marine biotoxins of microalgal origin, and associated with human incidents of shellfish poisoning. They are produced by a few species of Amphidomataceae, but diversity and occurrence of the small-sized dinophytes remain poorly explored for many regions of the world. In order to analyze the presence and importance of Amphidomataceae in a highly productive area of Argentinean coastal waters (El Rincón area, SW Atlantic), a scientific cruise was performed in 2015 to sample the early spring bloom. In a multi-method approach, light microscopy was combined with real-time PCR molecular detection of Amphidomataceae, with chemical analysis of AZA, and with the establishment and characterization of amphidomatacean strains. Both light microscopy and PCR revealed that Amphidomataceae were widely present in spring plankton communities along the El Rincón area. They were particularly abundant offshore at the shelf front, reaching peak densities of 2.8 × 105 cells L-1, but no AZA were detected in field samples. In total, 31 new strains were determined as Az. dalianense and Az. spinosum, respectively. All Az. dalianense were non-toxigenic and shared the same rRNA sequences. The large majority of the new Az. spinosum strains revealed for the first time the presence of a non-toxigenic ribotype of this species, which is otherwise the most important AZA producer in European waters. One of the new Az. spinosum strains, with a particular slender shape and some other morphological peculiarities, clustered with toxigenic strains of Az. spinosum from Norway and, exceptionally for the species, produced only AZA-2 but not AZA-1. Results indicate a wide diversity within Az. spinosum, both in terms of sequence data and toxin profiles, which also will affect the qualitative and quantitative performance of the specific qPCR assay for this species. Overall, the new data provide a more differentiated perspective of diversity, toxin productivity and occurrence of Amphidomataceae in a poorly explored region of the global ocean.


Assuntos
Dinoflagelados , Humanos , Noruega , Plâncton , Ribotipagem
12.
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
13.
Harmful Algae ; 82: 1-8, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30928006

RESUMO

Two novel azaspiracids (AZA) with a molecular mass of 869 Da were found in Pacific strains of Azadinium poporum and characterized by tandem mass spectrometry and high resolution mass spectrometry (HRMS). One compound, AZA-42, was found in Az. poporum strains AZFC25 and AZFC26, both isolated from the South China Sea. AZA-42 belongs to the 360-type AZA that in comparison to AZA-1 has an additional double bond in the F-I ring system of AZA comprising C28-C40. The other compound, AZA-62, was detected in Az. poporum strain 1D5 isolated off Chañaral, Northern Chile. Mass spectral data indicate that AZA-62 is a variant of AZA-11 with an additional double bond in the C1-C9 region of AZA. In addition to the description of the two novel AZA, a comprehensive list of all AZA known to be produced by species of the genera Azadinium and Amphidoma comprising 26 AZA variants is presented.


Assuntos
Dinoflagelados , Toxinas Marinhas , Chile , China , Compostos de Espiro
14.
BMC Mol Biol ; 20(1): 7, 2019 02 26.
Artigo em Inglês | MEDLINE | ID: mdl-30808304

RESUMO

BACKGROUND: A major cause of phytoplankton mortality is predation by zooplankton. Strategies to avoid grazers have probably played a major role in the evolution of phytoplankton and impacted bloom dynamics and trophic energy transport. Certain species of the genus Pseudo-nitzschia produce the neurotoxin, domoic acid (DA), as a response to the presence of copepod grazers, suggesting that DA is a defense compound. The biosynthesis of DA comprises fusion of two precursors, a C10 isoprenoid geranyl pyrophosphate and L-glutamate. Geranyl pyrophosphate (GPP) may derive from the mevalonate isoprenoid (MEV) pathway in the cytosol or from the methyl-erythritol phosphate (MEP) pathway in the plastid. L-glutamate is suggested to derive from the citric acid cycle. Fragilariopsis, a phylogenetically related but nontoxic genus of diatoms, does not appear to possess a similar defense mechanism. We acquired information on genes involved in biosynthesis, precursor pathways and regulatory functions for DA production in the toxigenic Pseudo-nitzschia seriata, as well as genes involved in responses to grazers to resolve common responses for defense strategies in diatoms. RESULTS: Several genes are expressed in cells of Pseudo-nitzschia when these are exposed to predator cues. No genes are expressed in Fragilariopsis when treated similarly, indicating that the two taxa have evolved different strategies to avoid predation. Genes involved in signal transduction indicate that Pseudo-nitzschia cells receive signals from copepods that transduce cascading molecular precursors leading to the formation of DA. Five out of seven genes in the MEP pathway for synthesis of GPP are upregulated, but none in the conventional MEV pathway. Five genes with known or suggested functions in later steps of DA formation are upregulated. We conclude that no gene regulation supports that L-glutamate derives from the citric acid cycle, and we suggest the proline metabolism to be a downstream precursor. CONCLUSIONS: Pseudo-nitzschia cells, but not Fragilariopsis, receive and respond to copepod cues. The cellular route for the C10 isoprenoid product for biosynthesis of DA arises from the MEP metabolic pathway and we suggest proline metabolism to be a downstream precursor for L-glutamate. We suggest 13 genes with unknown function to be involved in diatom responses to grazers.


Assuntos
Diatomáceas/genética , Diatomáceas/metabolismo , Ácido Caínico/análogos & derivados , Toxinas Marinhas/genética , Toxinas Marinhas/metabolismo , Redes e Vias Metabólicas/genética , Eritritol/análogos & derivados , Eritritol/metabolismo , Herbivoria , Ácido Caínico/metabolismo , Fosfatos de Poli-Isoprenil/metabolismo , Fosfatos Açúcares/metabolismo
15.
Fish Shellfish Immunol ; 84: 414-422, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30316945

RESUMO

Multiple toxic and bioactive compounds produced by Alexandrium spp. cause adverse effects on bivalves, but these effects are frequently difficult to attribute to a single compound class. To disentangle the effect of neurotoxic vs lytic secondary metabolites, we exposed blue mussels to either a paralytic shellfish toxin (PST) producing Alexandrium spp. strain, or to an exclusively lytic compound (LC) producing strain, or a strain containing both compound classes, to evaluate the time dependent effects after 3 and 7 days of feeding. Tested parameters comprised signs of paralysis, feeding activity, and immune cell integrity (hemocyte numbers and viability; lysosomal membrane destabilization) and function (ROS production). Both compound classes caused paralysis and immune impairment. The only effect attributable exclusively to PST was increased phagocytic activity after 3 days and impaired feeding activity after 7 days, which curtailed toxin accumulation in digestive glands. Lysosomal membrane destabilization were more closely, but not exclusively, matched with LC exposure. Effects on circulating hemocyte integrity and immune related functions were mostly transient or remained stable within 7 days; except for increased lysosomal labialization and decreased extracellular ROS production when mussels were exposed to the toxin combination. M. edulis displays adaptive fitness traits to survive and maintain immune capacity upon prolonged exposure to environmentally relevant concentrations of PST and/or LC producing Alexandrium strains.


Assuntos
Dinoflagelados/fisiologia , Hemócitos/efeitos dos fármacos , Toxinas Marinhas/farmacologia , Mytilus edulis/efeitos dos fármacos , Animais , Aprendizagem da Esquiva/efeitos dos fármacos , Comportamento Alimentar/efeitos dos fármacos , Hemócitos/metabolismo , Mytilus edulis/fisiologia
16.
Harmful Algae ; 80: 15-34, 2018 12.
Artigo em Inglês | MEDLINE | ID: mdl-30502808

RESUMO

Azaspiracids (AZA) are a group of lipophilic polyether compounds which have been implicated in shellfish poisoning incidents around Europe. They are produced by a few species of the dinophycean genera Azadinium and Amphidoma (Amphidomataceae). The presence of AZA toxins in Norway is well documented, but knowledge of the distribution and diversity of Azadinium and other Amphidomataceae along the Norwegian coast is rather limited and poorly documented. On a research survey along the Norwegian coast in 2015 from the Skagerrak in the South to Trondheimsfjorden in the North, plankton samples from 67 stations were analysed for the presence of Azadinium and Amphidoma and their respective AZA by on-board live microscopy, real-time PCR assays specific for Amphidomataceae, and liquid chromatography-tandem mass spectrometry (LC-MS/MS). Microscopy using live samples and positive real-time PCR assays using a general family probe and two species specific probes revealed the presence of Amphidomataceae distributed throughout the sampling area. Overall abundance was low, however, and was in agreement with a lack of detectable AZA in plankton samples. Single cell isolation and morphological and molecular characterisation of established strains revealed the presence of 7 amphidomatacean species (Azadiniun spinosum, Az. poporum, Az. obesum, Az. dalianense, Az. trinitatum, Az. polongum, Amphidoma languida) in the area. Azaspiracids were produced by the known AZA producing species Az. spinosum, Az. poporum and Am. languida only. LC-MS/MS analysis further revealed that Norwegian strains produce previously unreported AZA for Norway (AZA-11 by Az. spinosum, AZA-37 by Az. poporum, AZA-38 and AZA-39 by Am. languida), and also four novel compounds (AZA-50, -51 by Az. spinosum, AZA-52, -53 by Am. languida), whose structural properties are described and which now can be included in existing analytical protocols. A maximum likelihood analysis of concatenated rDNA regions (SSU, ITS1-ITS2, partial LSU) showed that the strains of Az. spinosum fell in two well supported clades, where most but not all new Norwegian strains formed the new Ribotype B. Ribotype differentiation was supported by a minor morphological difference with respect to the presence/absence of a rim around the pore plate, and was consistently reflected by different AZA profiles. Strains of Az. spinosum from ribotype A produce AZA-1, -2 and -33, whereas the new strains of ribotype B produce mainly AZA-11 and AZA-51. Significant sequence differences between both Az. spinosum ribotypes underline the need to redesign the currently used qPCR probes in order to detect all AZA producing Az. spinosum. The results generally underline the conclusion that for the Norwegian coast area it is important that amphidomatacean species are taken into account in future studies and monitoring programs.


Assuntos
Dinoflagelados/química , Monitoramento Ambiental , Toxinas Marinhas/análise , Plâncton/química , Compostos de Espiro/análise , Biodiversidade , Cromatografia Líquida , Demografia , Noruega , Densidade Demográfica , Espectrometria de Massas em Tandem
17.
Mar Drugs ; 16(11)2018 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-30441860

RESUMO

Cyclic imine toxins are neurotoxic, macrocyclic compounds produced by marine dinoflagellates. Mass spectrometric screenings of extracts from natural plankton assemblages revealed a high chemical diversity among this toxin class, yet only few toxins are structurally known. Here we report the structural characterization of four novel cyclic-imine toxins (two gymnodimines (GYMs) and two spirolides (SPXs)) from cultures of Alexandrium ostenfeldii. A GYM with m/z 510 (1) was identified as 16-desmethylGYM D. A GYM with m/z 526 was identified as the hydroxylated degradation product of (1) with an exocyclic methylene at C-17 and an allylic hydroxyl group at C-18. This compound was named GYM E (2). We further identified a SPX with m/z 694 as 20-hydroxy-13,19-didesmethylSPX C (10) and a SPX with m/z 696 as 20-hydroxy-13,19-didesmethylSPX D (11). This is the first report of GYMs without a methyl group at ring D and SPXs with hydroxyl groups at position C-20. These compounds can be conceived as derivatives of the same nascent polyketide chain, supporting the hypothesis that GYMs and SPXs are produced through common biosynthetic genes. Both novel GYMs 1 and 2 were detected in significant amounts in extracts from natural plankton assemblages (1: 447 pg; 2: 1250 pg; 11: 40 pg per mL filtered seawater respectively).


Assuntos
Dinoflagelados/química , Compostos Heterocíclicos com 3 Anéis/química , Hidrocarbonetos Cíclicos/química , Iminas/química , Toxinas Marinhas/química , Fitoplâncton/química , Compostos de Espiro/química , Compostos Heterocíclicos com 3 Anéis/isolamento & purificação , Hidrocarbonetos Cíclicos/isolamento & purificação , Iminas/isolamento & purificação , Toxinas Marinhas/isolamento & purificação , Estrutura Molecular , Compostos de Espiro/isolamento & purificação
18.
Harmful Algae ; 79: 50-52, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30420015

RESUMO

Copepods are important grazers on toxic phytoplankton and serve as vectors for algal toxins up the marine food web. Success of phytoplankton depends among other factors on protection against grazers like copepods, and same way copepod survival and population resilience relies on their ability to escape predators. Little is, however, known about the effect of toxins on the escape response of copepods. In this study we experimentally tested the hypothesis that the neurotoxin domoic acid (DA) produced by the diatom Pseudo-nitzschia affects escape responses of planktonic copepods. We found that the arctic copepods Calanus hyperboreus and C. glacialis reduced their escape response after feeding on a DA-producing diatom. The two species were not affected the same way; C. hyperboreus was affected after shorter exposure and less intake of DA. The negative effect on escape response was not related to the amount of DA accumulated in the copepods. Our results suggest that further research on the effects of DA on copepod behavior and DA toxicity mechanisms is required to evaluate the anti-grazing function of DA.


Assuntos
Copépodes/fisiologia , Diatomáceas/química , Reação de Fuga/efeitos dos fármacos , Ácido Caínico/análogos & derivados , Neurotoxinas/toxicidade , Animais , Copépodes/efeitos dos fármacos , Cadeia Alimentar , Ácido Caínico/toxicidade , Fitoplâncton
19.
Harmful Algae ; 79: 64-73, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-30420018

RESUMO

Grazers can induce toxin (domoic acid, DA) production in diatoms. The toxic response has been observed in two species of Pseudo-nitzschia and was induced by Calanus copepods. In this study, interactions between diatoms and copepods were further explored using different species of diatoms and copepods. All herbivorous copepods induced toxin production, whereas exposure to carnivorous copepods did not. In line with this, increasing the number of herbivorous copepods resulted in even higher toxin production. The induced response is thus only elicited by copepods that pose a real threat to the responding cells, which supports that the induced toxin production in diatoms evolved as an inducible defense. The cellular toxin content in Pseudo-nitzschia was positively correlated to the concentration of a group of specific polar lipids called copepodamides that are excreted by the copepods. This suggests that copepodamides are the chemical cues responsible for triggering the toxin production. Carnivorous copepods were found to produce less or no copepodamides. Among the diatoms exposed to grazing herbivorous copepods, only two of six species of Pseudo-nitzschia and none of the Nitzschia or Fragilariopsis strains responded by producing DA, indicating that not all Pseudo-nitzschia species/strains are able to produce DA, and that different diatom species might have different strategies for coping with grazing pressure. Growth rate was negatively correlated to cellular domoic acid content indicating an allocation cost associated with toxin production. Long-term grazing experiments showed higher mortality rates of grazers fed toxic diatoms, supporting the hypothesis that DA production is an induced defense mechanism.


Assuntos
Copépodes/fisiologia , Diatomáceas/fisiologia , Ácido Caínico/análogos & derivados , Animais , Coevolução Biológica , Herbivoria , Ácido Caínico/metabolismo , Ácido Caínico/toxicidade
20.
Toxicon ; 155: 51-60, 2018 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-30321574

RESUMO

An external standard of goniodomin A (GDA) was prepared from a strain of Alexandrium pseudogonyaulax originating from New Zealand and its chemical structure was confirmed by nuclear magnetic resonance (NMR) spectroscopy. Using the GDA standard, an ultra-performance liquid chromatography-tandem mass spectrometric (UPLC-MS/MS) method in selected reaction monitoring (SRM) mode was developed for separation and quantification of GDA. This method was successfully applied to planktonic field samples collected during an oceanographic expedition conducted with R/V Uthörn along the Danish west coast, Limfjord and Kattegat in June 2016. In addition, this method was used to characterize goniodomin (GD) profiles of 17 A. pseudogonyaulax strains from the coastal North Sea and from Limfjord. Highest GDA levels were found in Limfjord (up to 590 ng NT-1 m-1), but GDA was also detected in the North Sea appearing at the latitude of Sylt Island northwards and in Kattegat from the eastern mouth of Limfjord down to the Kiel Bight, but at lower abundances than within Limfjord. This is the first reported detection of GDA in planktonic field samples. Chemical analysis of 17 strains of A. pseudogonyaulax revealed that all strains were producers of GDA (5-35 pg cell-1) as well as in most cases minor amounts (0.01-0.07 pg cell-1, expressed as GDA equivalents) of goniodomin B (GDB).


Assuntos
Cromatografia Líquida/métodos , Dinoflagelados/química , Éteres/análise , Macrolídeos/análise , Plâncton/química , Espectrometria de Massas em Tandem/métodos , Dinamarca , Água do Mar
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