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| Registros recuperados: 28 | |
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| Labry, Claire; Erard-le Denn, Evelyne; Chapelle, Annie; Fauchot, Juliette; Youenou, Agnes; Crassous, Marie-pierre; Le Grand, Jacqueline; Lorgeoux, Benedicte. |
| The understanding of the dominance of one species with respect to others is a pertinent challenge in HAB growth dynamics studies and the nutrient supply mode is one of the factors potentially involved. The competition for phosphorus (P) between a toxic species, Alexandrium minutum, and a non-toxic species, Heterocapsa triquetra, was studied (1) along a gradient of P depletion, (2) testing different P depletion degrees before a single PO4 supply and (3) experimenting different PO4 supply frequencies. In conditions Of PO4 depletion, H. triquetra stopped growing after two days both in monospecific and mixed batch cultures whereas A. minutum grew progressively from day 2 until the end of the experiment. This time-lag growth of A. minutum is associated to its... |
| Tipo: Text |
Palavras-chave: Semi continuous culture; Batch culture; Ecophysiology; Pulse; Phosphorus storage; Dinoflagellates; Heterocapsa triquetra; Alexandrium minutum. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-4067.pdf |
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| Baron, Regis; Couedel, Marielle; Joret, Camille; Garen, Pierre; Truquet, Philippe; Masselin, Pierre; Bardouil, Michele; Lassus, Patrick. |
| A simple system was used to simulate the effect of alternating toxic (paralytic shellfish poisoning toxins) and non-toxic microalgal diets on oyster feeding behaviors and rates of toxin accumulation. These experimental conditions were meant to reflect, to some extent, the incoming and outgoing fluxes of toxic algae observed at the mouth of the Penze estuary (Northern Brittany, France). Physiological and toxicological parameters were estimated based oil fluorescence measurements recorded continuously at the outlet of each experimental tank, which contained a single oyster. Q(tox), this variable describes toxin uptake in oysters, it was used (instead of the toxin ingestion rate): i) in simple graphical analyses, ii) as well as in one- and two-compartment... |
| Tipo: Text |
Palavras-chave: Skeletonema costatum; Alexandrium minutum; Fluorescence; Modeling; Kinetics; Toxin uptake; Shellfish toxin; PSP. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1400.pdf |
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| Lassus, Patrick; Bardouil, Michele; Masselin, Pierre; Naviner, Magali; Truquet, Philippe. |
| A sea water recirculating flume was especially designed in the framework of this study. It improves physiological and ecophysiological evaluation of a 25 oysters (c. gigas) set fed on PSP toxic A. minutum cultures and then detoxified with commonly used aquaculture species (I. galbana, T. suecica, S. costatum, T. weissflogii). Chlorophyll a levels are kept steady in each case and adjusted in order to reach the same food value in each tank (0,5 mg/l TPM). When exposed to the mildly toxic species A. minutum (0,5 pg.eq.STX.cel-1) oysters depict a reduced clearance rate, food uptake and shell-valves activity (compared to non-toxic algal diets). The same physiological parameters do not show any significant differences when oysters are exposed to the control al... |
| Tipo: Text |
Palavras-chave: Épuration; Crassostrea gigas; Alexandrium minutum; PSP; Écophysiologie; Depuration; C. gigas; A. minutum; PSP; Ecophysiology. |
| Ano: 1997 |
URL: http://archimer.ifremer.fr/doc/00139/25021/23126.pdf |
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| Gueguen, Marielle; Bardouil, Michele; Baron, Regis; Lassus, Patrick; Truquet, Philippe; Massardier, Julie; Amzil, Zouher. |
| Contamination of shellfish by paralytic shellfish poisoning ( PSP) toxins poses an economic threat to shellfish farmers. As contaminated shellfish cannot be harvested for long periods of time, it would be very useful to develop processes to optimise and shorten their detoxification. In this study, Pacific oysters Crassostrea gigas were first experimentally contaminated over a period of 13 days with a continuous flow of toxic Alexandrium minutum cultures at concentrations ranging from 150 to 200 cell ml(-1) ( toxin content after 13 days of contamination 438 mu g STX equiv. 100 g(-1) wet weight). Then, two different detoxification treatments were tested and showed detoxification rates greater than those observed in coastal environments. The first treatment... |
| Tipo: Text |
Palavras-chave: Alexandrium minutum; Crassostrea gigas; Detoxification; Inorganic matter; Organic matter; PSP; Paralytic shellfish poisoning. |
| Ano: 2008 |
URL: http://archimer.ifremer.fr/doc/2008/publication-3896.pdf |
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| Sousa, Celia; Compere, Chantal; Dreanno, Catherine; Crassous, Marie-pierre; Gas, Fabienne; Baus, Beatrice; Perrot, Hubert. |
| In this paper, a simple detection of a toxic algae, Alexandrium minutum, was developed using highly sensitive quartz crystal microbalance. In terms of performance, compared with other conventional analytical tools, the main interest of our immunosensor is based on a fast and direct detection of these living cells. This system requires the use of one monoclonal antibody directed against the surface antigen of A. minutum. We demonstrate that the whole living and motile algae are caught and detected. The high specificity of the biosensor is also demonstrated by testing several other dinoflagellate species. The frequency shift is correlated to the A. minutum cells concentration. This simple system is potentially promising for environmental monitoring purposes. |
| Tipo: Text |
Palavras-chave: Alexandrium minutum; Quartz microbalance; Microalgae; Immunosensor. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00194/30492/28897.pdf |
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| Haberkorn, Hansy; Lambert, Christophe; Le Goic, Nelly; Moal, Jeanne; Suquet, Marc; Gueguen, Marielle; Sunila, Inke; Soudant, Philippe. |
| This study assessed the effects of an artificial bloom of the toxin-producing dinoflagellate, Alexandrium minutum, upon nutrition related processes and reproductive output of the Pacific oyster, Crassostrea gigas. Oysters were exposed to A. minutum, Paralytic Shellfish Toxins (PST) producer and compared to a control batch of oysters fed Isochrysis galbana clone Tahitian (T.Iso). The experiment was performed in June 2008, when oysters were found ripe. Several physiological variables of oysters, such as PSTs accumulation, digestive gland and histological observations as well as spermatozoa quality, were measured at the end of the exposure. Results indicate that the digestive gland was greatly impacted upon A. minutum exposure. Monoacylglycerol and... |
| Tipo: Text |
Palavras-chave: Harmful algae; Alexandrium minutum; Oyster; Nutrition-related processes; Reproductive output. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00008/11927/8653.pdf |
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| Haberkorn, Hansy; Lambert, Christophe; Le Goic, Nelly; Gueguen, Marielle; Moal, Jeanne; Palacios, Elena; Lassus, Patrick; Soudant, Philippe. |
| The effects of an artificial bloom of the toxin-producing dinoflagellate, Alexandrium minutum, upon physiological parameters of the Pacific oyster, Crassostrea gigas, were assessed. Diploid and triploid oysters were exposed to cultured A. minutum and compared to control diploid and triploid oysters fed T. Isochrysis. Experiments were repeated twice, in April and mid-May 2007, to investigate effects of maturation stage on oyster responses to A. minutum exposure. Oyster maturation stage, Paralytic Shellfish Toxin (PST) accumulation, as well as several digestive gland and hematological variables, were assessed at the ends of the exposures. In both experiments, triploid oysters accumulated more PSTs (approximately twice) than diploid oysters. Significant... |
| Tipo: Text |
Palavras-chave: Oysters; Ploidy; Physiology; Harmful-algal bloom; Alexandrium minutum; PST accumulation. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00003/11378/7988.pdf |
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| Borcier, Elodie; Morvezen, Romain; Boudry, Pierre; Miner, Philippe; Charrier, Gregory; Laroche, Jean; Hegaret, Helene. |
| Dinoflagellates of the genus Alexandrium are a major cause of harmful algal blooms (HABs) that have increasingly disrupted coastal ecosystems for the last several decades. Microalgae from the genus Alexandrium are known to produce paralytic shellfish toxins (PST) but also bioactive extracellular compounds (BEC) that can display cytotoxic, allelopathic, ichtyotoxic or haemolytic effects upon marine organisms. The objective of this experimental study was to assess the effects of PST and BEC produced by A. minutum upon juvenile great scallops Pecten maximus. Scallops were exposed for one week to two different strains of A. minutum, the first producing both PST and BEC and the second producing only BEC. Escape response to starfish, daily shell growth,... |
| Tipo: Text |
Palavras-chave: Harmful Algal Bloom (HAB); Alexandrium minutum; Pecten maximus; Paralytic Shellfish Toxins (PST); Extracellular compounds; Behaviour; Histology. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00368/47878/47893.pdf |
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| Fabioux, Caroline; Sulistiyani, Yeni; Haberkorn, Hansy; Hegaret, Helene; Amzil, Zouher; Soudant, Philippe. |
| Harmful algal blooms of Alexandrium spp. dinoflagellates regularly occur in French coastal waters contaminating shellfish. Studies have demonstrated that toxic Alexandrium spp. disrupt behavioural and physiological processes in marine filter-feeders, but molecular modifications triggered by phycotoxins are less well understood. This study analyzed the mRNA levels of 7 genes encoding antioxidant/detoxifying enzymes in gills of Pacific oysters (Crassostrea gigas) exposed to a cultured, toxic strain of A. minutum, a producer of paralytic shellfish toxins (PST) or fed Tisochrysis lutea (T. lutea, formerly Isochrysis sp., clone Tahitian (T. iso)), a non-toxic control diet, in four repeated experiments. Transcript levels of sigma-class glutathione S-transferase... |
| Tipo: Text |
Palavras-chave: Crassostrea gigas; Alexandrium minutum; Paralytic shellfish toxins; Antioxidant enzymes; Detoxification enzymes; MRNA. |
| Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00275/38601/38623.pdf |
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| Guallar, Carles; Bacher, Cedric; Chapelle, Annie. |
| The dinoflagellate Alexandrium minutum is a toxic bloom-forming species distributed worldwide. The mechanisms driving and promoting the species blooms and their toxicity are studied and presented here. Most previously published work focuses on local and/or short-term scales. In this study, a broad temporal and spatial approach is addressed using time series covering several sites over several years and combining environmental variables and A. minutum abundances from the French English Channel − Atlantic coasts. Data were explored by means of phenology and threshold analysis. The A. minutum bloom characteristics are defined. Only one bloom per year is measured and it may reach more than a million of cells L−1. Bloom period extends from April to October and... |
| Tipo: Text |
Palavras-chave: Alexandrium minutum; PSP toxicity; HAB; Bloom phenology; Threshold analysis; Monitoring long time-series. |
| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00390/50130/51076.pdf |
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| Remize, Marine; Planchon, Frederic; Loh, Ai Ning; Le Grand, Fabienne; Lambert, Christophe; Bideau, Antoine; Bidault, Adeline; Corvaisier, Rudolph; Volety, Aswani; Soudant, Philippe. |
| The synthetic pathways responsible for the production of the polyunsaturated fatty acids 22:6n-3 and 20:5n-3 were studied in the Dinophyte Alexandrium minutum. The purpose of this work was to follow the progressive incorporation of an isotopic label (13CO2) into 11 fatty acids to better understand the fatty acid synthesis pathways in A. minutum. The Dinophyte growth was monitored for 54 h using high-frequency sampling. A. minutum presented a growth in two phases. A lag phase was observed during the first 30 h of development and had been associated with the probable temporary encystment of Dinophyte cells. An exponential growth phase was then observed after t30. A. minutum rapidly incorporated 13C into 22:6n-3, which ended up being the most 13C-enriched... |
| Tipo: Text |
Palavras-chave: PUFA synthesis; 22:6n-3; DHA; PKS pathway; Dinophyte; Alexandrium minutum; Encystment. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00654/76562/77688.pdf |
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| Hermabessiere, Ludovic; Fabioux, C.; Lassudrie, Malwenn; Boullot, F.; Long, Marc; Lambert, Christophe; Le Goic, N.; Gouriou, Jeremie; Le Gac, Mickael; Chapelle, Annie; Soudant, P.; Hegaret, Helene. |
| This study investigated the effect of gametogenesis pattern and sex on levels of paralytic shellfish toxins (PST) accumulated by triploid oysters Crassostrea gigas exposed to a natural bloom of the toxic dinoflagellate Alexandrium minutum in the Bay of Brest (Western Brittany, France), over the summer 2014. Toxin accumulation in oysters was proposed to be influenced by the proportion of energy allocated to reproduction versus other metabolisms, as proposed by Haberkorn et al. (2010). Thus, we hypothesized that triploid oysters with different gametogenesis patterns (α or β, producing respectively numerous gametes or rare gametes) could result in differences in toxin accumulation. Toxin level could also be different according to the gender of the oysters. To... |
| Tipo: Text |
Palavras-chave: Crassostrea gigas; Alexandrium minutum; Harmful algal bloom (HAB); Paralytic shellfish toxin (PST); Gametogenesis pattern; Triploid. |
| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00307/41801/41010.pdf |
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| Le Gland, Guillaume. |
| Since 2010, planktonic algae Alexandrium minutum, cause of the PSP (Paralytic Shellfish Poisoning) syndrome, has been proliferating in early summer in the bay of Daoulas, within the roadstead of Brest. During this internship, a model has been designed in order to derive these blooms from physical parameters (temperature, irradiance, nutrient supply, dilution rate …). In the model, A.minutum competes with 50 other plankton species with randomly attributed optimal temperature and nutrient uptake abilities. It turns out to reproduce well the bloom of 2012, with a correct date of maximum concentration and a relevant order of magnitude. It reproduces the order of magnitude of 2013 concentrations, but the bloom then is too spread in time around the maximum.... |
| Tipo: Text |
Palavras-chave: Alexandrium minutum; Phytoplancton; Efflorescence (bloom); Nutriments; Lumière; Température; Dilution; Absorption (uptake); Quota cellulaire; Croissance; Compétition; Modèle; Rade de Brest. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00209/32004/30442.pdf |
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| Pousse, Emilien; Flye-sainte-marie, Jonathan; Alunno-bruscia, Marianne; Hegaret, Helene; Rannou, Eric; Pecquerie, Laure; Marques, Goncalo M.; Thomas, Yoann; Castrec, Justine; Fabioux, Caroline; Long, Marc; Lassudrie, Malwenn; Hermabessiere, Ludovic; Amzil, Zouher; Soudant, Philippe; Jean, Fred. |
| As other filter-feeders, Crassostrea gigas can concentrate paralytic shellfish toxins (PST) by consuming dinoflagellate phytoplankton species like Alexandrium minutum. Intake of PST in oyster tissues mainly results from feeding processes, i.e. clearance rate, pre-ingestive sorting and ingestion that are directly influenced by environmental conditions (trophic sources, temperature). This study aimed to develop a mechanistic model coupling the kinetics of PST accumulation and bioenergetics in C. gigas based on Dynamic Energy Budget (DEB) theory. For the first time, the Synthesizing Units (SU) concept was applied to formalize the feeding preference of oysters between non-toxic and toxic microalgae. Toxin intake and accumulation were both dependent on the... |
| Tipo: Text |
Palavras-chave: Alexandrium minutum; Paralytic shellfish toxins (PST); Dynamic Energy Budget (DEB); Modelling; Pacific oyster. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00455/56662/58407.pdf |
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| Boullot, Floriane; Castrec, Justine; Bidault, Adeline; Dantas, Natanael; Payton, Laura; Perrigault, Mickael; Tran, Damien; Amzil, Zouher; Boudry, Pierre; Soudant, Philippe; Hegaret, Helene; Fabioux, Caroline. |
| Paralytic shellfish toxins (PST) bind to voltage-gated sodium channels (Nav) and block conduction of action potential in excitable cells. This study aimed to (i) characterize Nav sequences in Crassostrea gigas and (ii) investigate a putative relation between Nav and PST-bioaccumulation in oysters. The phylogenetic analysis highlighted two types of Nav in C. gigas: a Nav1 (CgNav1) and a Nav2 (CgNav2) with sequence properties of sodium-selective and sodium/calcium-selective channels, respectively. Three alternative splice transcripts of CgNav1 named A, B and C, were characterized. The expression of CgNav1, analyzed by in situ hybridization, is specific to nervous cells and to structures corresponding to neuromuscular junctions. Real-time PCR analyses showed... |
| Tipo: Text |
Palavras-chave: Crassostrea gigas; Sodium channel; Alternative splicing; Alexandrium minutum; Paralytic shellfish toxins. |
| Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00368/47877/47892.pdf |
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| Lazerges, M; Perrot, H; Antoine, Elisabeth; Defontaine, Audrey; Compere, Chantal. |
| We report the immobilization on a gold surface of a 20-base DNA probe labeled with disulfide group and on the selective hybridization with the complementary 20-base DNA strand. The oligonucleotide probe is the complementary strand of a partial sequence of the gene encoding for a large ribosomal RNA sub-unit which is a coding sequence of Alexandrium minutum DNA, a microalgae that produces neurotoxins responsible for paralytic shellfish poisoning on European and Asian coasts. The kinetics of DNA probe immobilization and hybridization were monitored in situ by using a 27 MHz quartz crystal microbalance under controlled hydrodynamic conditions. The frequency of the setup is stable to within a few hertz, corresponding to the nanogram, scale, for 3 h and makes... |
| Tipo: Text |
Palavras-chave: DNA; Alexandrium minutum; Microbalance. |
| Ano: 2006 |
URL: http://archimer.ifremer.fr/doc/2006/publication-1354.pdf |
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| Gas, Fabienne; Baus, Beatrice; Pinto, Laetitia; Compere, Chantal; Tanchou, Valerie; Quemeneur, Eric. |
| Harmful algal blooms represent a major threat to marine production, and particularly to shellfish farming. Current methods for analyzing environmental samples are tedious and time consuming because they require taxonomists and animal experiments. New rapid detection methods, such as immunoassays, are sought for alerting purposes and for the study of algal ecodynamics in their natural environment. Alexandrium minutum, which causes paralytic shellfish poisoning, occurs with increasing frequency along European coasts. We have developed a one step immunochromatographic assay which is based on the principle of immunochromatographic analysis and involves the use of two distinct monoclonal antibodies directed against surface antigens of A. minutum. The primary... |
| Tipo: Text |
Palavras-chave: Antibody; Alexandrium minutum; Immunochromatographic assay (ICA); Rapid detection. |
| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00000/11153/7819.pdf |
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| Registros recuperados: 28 | |
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