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| Registros recuperados: 21 | |
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| Long, Marc; Tallec, Kevin; Soudant, Philippe; Lambert, Christophe; Le Grand, Fabienne; Sarthou, Geraldine; Jolley, Dianne; Hegaret, Helene. |
| Harmful microalgal blooms are a threat to aquatic organisms, ecosystems and human health. Toxic dinoflagellates of the genus Alexandrium are known to produce paralytic shellfish toxins and to release bioactive extracellular compounds (BECs) with potent cytotoxic, hemolytic, ichtyotoxic and allelopathic activity. Negative allelochemical interactions refer to the chemicals that are released by the genus Alexandrium and that induce adverse effects on the physiology of co-occurring protists and predators. Releasing BECs gives the donor a competitive advantage that may help to form dense toxic blooms of phytoplankton. However BECs released by Alexandrium minutum are uncharacterized and it is impossible to quantify them using classical chemical methods.... |
| Tipo: Text |
Palavras-chave: Harmful algal bloom; Alexandrium; Allelopathy; Cytotoxicity; PAM fluorometry; Bioassay. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00453/56424/58116.pdf |
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| Long, Marc; Tallec, Kevin; Soudant, Philippe; Le Grand, Fabienne; Donval, Anne; Lambert, Christophe; Sarthou, Geraldine; Jolley, Dianne F.; Hegaret, Helene. |
| Allelochemical interactions are likely to be a contributing factor explaining the success of large blooms of the harmful marine dinoflagellate Alexandrium, however, the physiological mechanisms of allelochemical interactions remain poorly described. Here we investigated the sub-lethal effects (on an hourly scale) of a filtrate containing allelochemicals from Alexandrium minutum on the physiology of the common diatom Chaetoceros muelleri. The filtrate induced deleterious effects to the diatom physiology within only 30 min of exposure. Esterase activity and photosynthesis were drastically inhibited, with up to 34% of the population being metabolically inactive and up to 30% reduction in photosystem II quantum yield when exposed to the filtrate. In addition,... |
| Tipo: Text |
Palavras-chave: Allelopathy; Alexandrium; Metabolism; Photoinhibition; Lipids; Pigments. |
| Ano: 2018 |
URL: https://archimer.ifremer.fr/doc/00460/57133/59748.pdf |
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| Abadie, Eric; Zouher, Amzil; Belin, Catherine; Comps, Marie-annick; Elziere-papayanni, Panayota; Lassus, Patrick; Le Bec, Claude; Marcaillou-le Baut, Claire; Nezan, Elizabeth; Poggi, Robert. |
| A bloom of the toxic dinoflagellate Alexandrium tamarense was observed for the first time in Thau iagoon between November and December 1998. Maximum cell concentrations detected in shellfish farming areas (85 000 Cells/1) were high enough to make mussels and clams unsuitable for human consumption (max. 850 ug. STX eq.100 g'1) while toxic levels in oysters did not exceed, or even reach, the international public health threshold established for PSP toxins. This event, new to French Mediterranean waters, was investigated by both local and national veterinary services and by the Ifremer teams involved in the National Monitoring Network for Phytoplankton and Phycotoxines (Réphy). The chronological and operational description of the event was compared with data... |
| Tipo: Text |
Palavras-chave: Alexandrium; Monitoring; Toxic dinoflagellates; Thau lagoon; Alexandrium; Surveillance; Dinoflagellés toxiques; Etang de Thau. |
| Ano: 1999 |
URL: http://archimer.ifremer.fr/doc/1999/rapport-884.pdf |
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| Li, Zhun; Mertens, Kenneth; Nézan, Elisabeth; Chomérat, Nicolas; Bilien, Gwenael; Iwataki, Mitsunori; Shin, Hyeon Ho. |
| Investigation of phytoplankton from East China Sea of the Pacific Ocean, offshore Réunion Island of the Indian Ocean, and the French Atlantic coast revealed a species of poorly known armored fusiform dinoflagellate. To clarify this species, morphology and phylogeny based on mitochondrial and nuclear protein gene sequence (Cox1, Cob and Hsp90) concatenated with the SSU, ITS region and LSU rDNA sequences were analysed. Epifluorescence and scanning electron microscopy observations revealed that the nucleus of the specimen was elongated, sausage-shaped and located equatorially on the left lateral side of the cell, and that the plate formula is Po, 3′, 1a, 6″, 6C, 8S, 5‴, 1p, 2′‴. These morphological features indicate that the species can be assigned to... |
| Tipo: Text |
Palavras-chave: Fusiform dinoflagellate; Centrodinium; Alexandrium; Morphology; Phylogeny. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00483/59496/62364.pdf |
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| Long, Marc; Holland, Aleicia; Planquette, Helene; Gonzalez Santana, David; Whitby, Hannah; Soudant, Philippe; Sarthou, Geraldine; Hégaret, Helene; Jolley, Dianne F. |
| The dinoflagellate Alexandrium minutum produces toxic compounds, including paralytic shellfish toxins, but also some unknown extracellular toxins. Although copper (Cu) is an essential element, it can impair microalgal physiology and increase their toxic potency. This study investigated the effect of different concentrations of dissolved Cu (7 nM, 79 nM and 164 nM) on A. minutum allelochemical potency, here defined as negative effects of a protist on competing protists through the release of chemicals. This was studied in relation to its physiology. The effects of Cu were assessed on A. minutum growth, reactive oxygen species level, photosynthesis proxies, lipid metabolism, exudation of dissolved organic compounds, allelochemical potency and on the... |
| Tipo: Text |
Palavras-chave: Alexandrium; Copper; Toxicity; Allelopathy; Physiology; Exudate. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00484/59612/62629.pdf |
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| Lassudrie, Malwenn; Soudant, Philippe; Nicolas, Jean-louis; Miner, Philippe; Le Grand, Jacqueline; Lambert, Christophe; Le Goic, Nelly; Hegaret, Helene; Fabioux, Caroline. |
| The Pacific oyster Crassostrea gigas is an important commercial species cultured throughout the world. Oyster production practices often include transfers of animals into new environments that can be stressful, especially at young ages. This study was undertaken to determine if a toxic Alexandrium bloom, occurring repeatedly in French oyster beds, could modulate juvenile oyster cellular immune responses (i.e. hemocyte variables). We simulated planting on commercial beds by conducting a cohabitation exposure of juvenile, “specific pathogen-free” (SPF) oysters (naïve from the environment) with previously field-exposed oysters to induce interactions with new microorganisms. Indeed, toxic Alexandrium spp. exposures have been reported to modulate bivalve... |
| Tipo: Text |
Palavras-chave: Crassostrea gigas; Alexandrium; Harmful algal blooms; Hemocyte; Microbial challenge. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00314/42523/41894.pdf |
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| Geffroy, Solene; Lechat, Marc-marie; Le Gac, Mickael; Rovillon, Georges-augustin; Marie, Dominique; Bigeard, Estelle; Malo, Florent; Amzil, Zouher; Guillou, Laure; Caruana, Amandine. |
| Paralytic shellfish poisoning (PSP) is a human foodborne syndrome caused by the consumption of shellfish that accumulate paralytic shellfish toxins (PSTs, saxitoxin group). In PST-producing dinoflagellates such as Alexandrium spp., toxin synthesis is encoded in the nuclear genome via a gene cluster (sxt). Toxin production is supposedly associated with the presence of a 4th domain in the sxtA gene (sxtA4), one of the core genes of the PST gene cluster. It is postulated that gene expression in dinoflagellates is partially constitutive, with both transcriptional and post-transcriptional processes potentially co-occurring. Therefore, gene structure and expression mode are two important features to explore in order to fully understand toxin production processes... |
| Tipo: Text |
Palavras-chave: Alexandrium; Saxitoxins; SxtA4; Copy number variation; SxtA; Expression; Isoform. |
| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00682/79402/81944.pdf |
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| Lassudrie, Malwenn; Soudant, Philippe; Nicolas, Jean-louis; Fabioux, Caroline; Lambert, Christophe; Miner, Philippe; Le Grand, Jacqueline; Petton, Bruno; Hegaret, Helene. |
| Blooms of toxic dinoflagellates can co-occur with mass mortality events associated with herpesvirus OsHV-1 μVar infection that have been decimating Pacific oyster Crassostrea gigas spat and juveniles every summer since 2008 in France. This study investigated the possible effect of a harmful dinoflagellate, Alexandrium catenella, a producer of Paralytic Shellfish Toxins (PSTs), upon the oyster spat–herpesvirus interaction. Oyster spat from a hatchery were challenged by cohabitation with oysters contaminated in the field with OsHV-1 μVar and possibly other pathogens. Simultaneously, the oysters were exposed to cultured A. catenella. Infection with OsHV-1 μVar and PST accumulation were measured after 4 days of experimental exposure. Exposure to Alexandrium... |
| Tipo: Text |
Palavras-chave: Crassostrea gigas; OsHV-1 mu Var; Harmful algal blooms; Alexandrium; Host-pathogen interaction; PST accumulation. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00269/38000/36101.pdf |
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| Laporte, Martin; Shao, Zhaojun; Berrebi, Patrick; Laabir, Mohamed; Abadie, Eric; Faivre, Nicolas; Rieuvilleneuve, Fabien; Masseret, Estelle. |
| Alexandrium catenella (group IV) and Alexandrium tamarense (group III) (Dinophyceae) are two cryptic invasive phytoplankton species belonging to the A. tamarense species complex. Their worldwide spread is favored by the human activities, transportation and climate change. In order to describe their diversity in the Mediterranean Sea and understand their settlements and maintenances in this area, new microsatellite markers were developed based on Thau lagoon (France) samples of A. catenella and A. tamarense strains. In this study twelve new microsatellite markers are proposed. Five of these microsatellite markers show amplifications on A. tamarense and ten on A. catenella. Three of these 12 microsatellite markers allowed amplifications on both cryptic... |
| Tipo: Text |
Palavras-chave: Invasive species; Phytoplankton; Alexandrium; Dinophyceae; Microsatellite markers; Biogeography. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00189/30026/29398.pdf |
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| Belin, Catherine; Raffin, Bernard. |
| This document presents the results obtained through the French Phytoplankton and Phycotoxins Monitoring Network (REPHY), concerning the presence of toxic and harmful phytoplankton species along the French coast, from 1984 to 1995. The network REPHY is briefly described. Then the different species, and their associated events, are reviewed : first, species toxic to shellfish consumers, e.g. Dinophysis spp. and Alexandrium minutum, which respectively produce diarrheic and paralytic toxins ; then, species which are toxic or harmful for marine fauna (fish, shellfish). The monitoring results are preceded by the main knowledge on taxonomy, distribution, biology, ecology and toxicity of the concerned species. A final synthesis illustrates the distribution of... |
| Tipo: Text |
Palavras-chave: Phytoplancton; Phycotoxines; Surveillance; Espèces toxiques; Espèces nuisibles; Dinophysis; Alexandrium; DSP; PSP; Secteurs fermés; Phytoplankton; Phcotoxins; Monitoring; Toxic species; Harmful species; Dinophysis; Alexandrium; DSP; PSP; Closed areas. |
| Ano: 1998 |
URL: http://archimer.ifremer.fr/doc/00094/20514/18184.pdf |
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| Menesguen, Alain; Aminot, Alain; Belin, Catherine; Chapelle, Annie; Guillaud, Jean-francois; Joanny, Michel; Lefebvre, Alain; Merceron, Michel; Piriou, Jean-yves; Souchu, Philippe. |
| In order to be able to count the cases of coastal eutrophication and to propose methods to monitor as well as to reduce these phenomena, first of all it is necessary to precisely define the word eutrophication itself. Instead of the strict etymological definition, that is to say a progression of the enrichment of a medium, we will rather retain the concept of a state enriched at a point such as it causes harmful effects on the ecosystem, and nuisances to man's activities. Based on the average chemical equations of the organic matter synthesis/degradation in the sea, this operational definition thus puts forwards the harmful consequences of enrichment, i.e. the production of an excessive algal biomass, sometimes unbalanced from the point of view of... |
| Tipo: Text |
Palavras-chave: Alexandrium; Phaeocystis; Monostroma; Ulva; Dilution plume; Water trapping; Anoxia; Nitrogen and phosphorus loadings; Red tides; Phytoplankton blooms; Green tides; Eutrophication; Alexandrium; Phaeocystis; Monostroma; Ulva; Panache de dilution; Confinement; Anoxie; Phosphate; Nitrate; Apports terrigènes; Eaux colorées; Blooms phytoplanctoniques; Marées vertes; Eutrophisation. |
| Ano: 2001 |
URL: http://archimer.ifremer.fr/doc/2001/rapport-22.pdf |
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| Delebecq, Gaspard; Schmidt, Sabine; Ehrhold, Axel; Latimier, Marie; Siano, Raffaele. |
| The biological processes involved in the preservation, viability, and revival of long‐term dormant dinoflagellate cysts buried in sediments remain unknown. Based on studies of plant seed physiology, we tested whether the revival of ancient cysts preserved in century‐old sediments from the Bay of Brest (France) could be stimulated by melatonin and gibberellic acid, two molecules commonly used in seed priming. Dinoflagellates were revived from sediments dated to approximately 150 years ago (156 ± 27, 32 cm depth), extending the known record age of cyst viability previously established as around one century. A culture suspension of sediments mixed with melatonin and gibberellic acid solutions as biostimulants exhibited germination of 11 dinoflagellate taxa... |
| Tipo: Text |
Palavras-chave: Alexandrium; Cyst; Dinoflagellate; Gibberellic acid; Melatonin; Paleoecology; Priming; Scrippsiella; Resurrection ecology. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00627/73960/73321.pdf |
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| Registros recuperados: 21 | |
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