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| Registros recuperados: 22 | |
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| Jauffrais, Thierry; Marcaillou-le Baut, Claire; Herrenknecht, Christine; Truquet, Philippe; Sechet, Veronique; Nicolau, Elodie; Tillmann, Urban; Hess, Philipp. |
| Azadinium spinosum (Elbrächter and Tillmann), a small marine dinoflagellate, has been recently described as a de novo producer of azaspiracid-1 and -2 (AZA1 and -2) diarrhoeic toxins. A culture of A. spinosum was established in our laboratory and optimised for pilot-scale production of this organism, to evaluate and understand AZA1 and -2 accumulation and biotransformation in blue mussels (Mytilus edulis) fed with A. spinosum. Adult mussels were continuously exposed to A. spinosum over 1 week in 160 L cylindrical conical tanks. Three different diets were tested for contamination: 5000, 10 000 cells mL−1 of A. spinosum and a mixture of 5000 cells mL−1 of A. spinosum with 5000 cells mL−1 of Isochrysis aff. galbana (T-Iso, CCAP 927/14). During the subsequent... |
| Tipo: Text |
Palavras-chave: Azaspiracid; Azadinium spinosum; Marine biotoxins; AZA; Tissue distribution; Histology; Bivalve molluscs; Liquid chromatography coupled to tandem mass spectrometry. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19877/17566.pdf |
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| Choquel, Constance; Geslin, Emmanuelle; Metzger, Edouard; Filipsson, Helena L.; Risgaard-petersen, Nils; Launeau, Patrick; Giraud, Manuel; Jauffrais, Thierry; Jesus, Bruno; Mouret, Aurélia. |
| Oxygen availability impacts the marine nitrogen cycle at a range of spatial and temporal scales. Invasive organisms have shown to sustainably affect sediment geochemistry and benthic ecology. Nonionella sp. T1 was recently described as an invasive benthic foraminifer in the North Sea region. Here, we demonstrate the impact of this denitrifying species on the foraminifera fauna and the nitrogen cycle of the Gullmar Fjord (Sweden). The foraminifera contribution to benthic denitrification was estimated by coupling living foraminifera micro-distribution, denitrification rate measurement and sedimentary nitrate 2D distribution. Nonionella sp. T1 dominated the foraminifera fauna and could denitrify up to 50–100 % of nitrate porewater in oxygenated bottom waters... |
| Tipo: Text |
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| Ano: 2021 |
URL: https://archimer.ifremer.fr/doc/00643/75482/76327.pdf |
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| Jauffrais, Thierry; Kilcoyne, Jane; Herrenknecht, Christine; Truquet, Philippe; Sechet, Veronique; Miles, Christopher O.; Hess, Philipp. |
| The relationship between azaspiracid shellfish poisoning and a small dinoflagellate, Azadinium spinosum, has been shown recently. The organism produces AZA1 and -2, while AZA3 and other analogues are metabolic products formed in shellfish. We evaluated whether mussels were capable of accumulating dissolved AZA1 and -2, and compared the toxin profiles of these mussels at 24 h with profiles of those exposed to live or lysed A. spinosum. We also assessed the possibility of preparative production of AZA metabolites by exposing mussels to semi-purified AZA1. We exposed mussels to similar concentration of AZAs: dissolved AZA1+2 (crude extract) at 7.5 and 0.75 µg L-1, dissolved AZA1+2 (7.5 µg L-1) in combination with Isochrysis affinis galbana, and lysed and live... |
| Tipo: Text |
Palavras-chave: Dissolved marine biotoxins; AZA; Tissue distribution; Bivalve molluscs; LC-MS/MS; Azaspiracid. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00136/24757/22867.pdf |
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| Jauffrais, Thierry; Contreras, Andrea; Herrenknecht, Christine; Truquet, Philippe; Sechet, Veronique; Tillmann, Urban; Hess, Philipp. |
| Azadinium spinosum, a small toxic dinoflagellate, was recently isolated and identified as a primary producer of azaspiracid toxins (AZAs). Previous experiments related to AZA accumulation in blue mussels upon direct feeding with A. spinosum revealed increased mussel mortality and had negative effects on the thickness of the digestive gland tubules. Therefore we conducted follow up experiments in order to study effects of A. spinosum on mussel feeding behaviour. Individual assessment of mussel feeding time activity (FTA), clearance rate (CR), filtration rate (TFR), absorption rate (AR), faeces and pseudofaeces production were carried out on mussel fed either toxic (A. spinosum) or non-toxic (Isochrisis aff. galbana (T-Iso)) diets. Furthermore, AZA... |
| Tipo: Text |
Palavras-chave: Bivalve molluscs; Mussel; Ecophysiology; AZA biotransformation; AZA accumulation; Trophic transfer; Dinoflagellate; Azaspiracid. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00090/20174/17832.pdf |
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| Jauffrais, Thierry; Sechet, Veronique; Truquet, Philippe; Amzil, Zouher; Herrenknecht, Christine; Hess, Philipp. |
| Azadinium spinosum, a small dinoflagellate has recently been discovered and identified as the primary producer of azaspiracid-1 (AZA) and -2. Since AZA poisoning has been reported following consumption of contaminated shellfish it is important to have these toxins available for toxicological studies, and a sustainable production of AZAs as calibrants in monitoring programs without having to rely on natural events. In order to address this concern, continuous pilot scale cultures were carried out to evaluate the feasibility of AZA production from A. spinosum. Algae were cultured using two 100 L chemostats in series (R1 and R2), with agitation and pH control. Four different dilution rates were tested (0.15, 0.2, 0.25 and 0.3 day−1) to evaluate chemostat... |
| Tipo: Text |
Palavras-chave: Solid phase adsorption; Chemostat; Photobioreactor; Microalgae; LC-MS/MS; Tangential flow filtration. |
| Ano: 2014 |
URL: http://archimer.ifremer.fr/doc/00152/26349/24437.pdf |
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| Jauffrais, Thierry; Sechet, Veronique; Herrenknecht, Christine; Truquet, Philippe; Savar, Veronique; Tillmann, Urban; Hess, Philipp. |
| Azadinium spinosum, a small dinoflagellate isolated from the North Sea, is a producer of azaspiracids (AZAs), a group of biotoxins associated with human illness following ingestion of contaminated shellfish. Using batch and continuous cultures of A. spinosum, the present study investigated the effects of different environmental and nutritional factors (salinity, temperature, photon flux density, aeration, culture media, nitrogen sources, phosphate source, and N/P ratios) on growth, maximum cell concentration, and AZA cell quota. Azadinium spinosum grew in a wide range of conditions; from 10 ̊C to 26 ̊C and salinities from 30 to 40, under irradiances ranging from 50 μmol m−2 s−1 to 250 μmol m−2 s−1, with or without aeration. Growth and maximum cell... |
| Tipo: Text |
Palavras-chave: AZA; Chemostat; Dinophyceae; Nutrients; N/P ratio; Photobioreactor. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00149/26054/24411.pdf |
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| Jauffrais, Thierry; Jesus, Bruno; Metzger, Edouard; Mouget, Jean-luc; Jorissen, Frans; Geslin, Emmanuelle. |
| Some benthic foraminifera have the ability to incorporate functional chloroplasts from diatoms (kleptoplasty). Our objective was to investigate chloroplast functionality of two benthic foraminifera (Haynesina germanica and Ammonia tepida) exposed to different irradiance levels (0, 25, 70 mot photon m(-2) s(-1)) using spectral reflectance, epifluorescence observations, oxygen evolution and pulse amplitude modulated (PAM) fluorometry (maximum photosystem II quantum efficiency (Fv/Fm) and rapid light curves (RLC)). Our results clearly showed that H. germanica was capable of using its kleptoplasts for more than 1 week while A. tepida showed very limited kleptoplastic ability with maximum photosystem II quantum efficiency (Fv/Fm = 0.4), much lower than H.... |
| Tipo: Text |
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| Ano: 2016 |
URL: https://archimer.ifremer.fr/doc/00457/56899/58754.pdf |
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| Marchetti, Julie; Bougaran, Gael; Jauffrais, Thierry; Lefebvre, Sebastien; Rouxel, Catherine; Saint-jean, Bruno; Lukomska, Ewa; Robert, Rene; Cadoret, Jean-paul. |
| In aquaculture, particularly in bivalve hatcheries, the biochemical composition of algal diets has a strong influence on larval and post-larval development. Biochemical composition is known to be related to culture conditions, among which light represents a major source of variation. The effects of blue light on biochemical composition and photosynthetic rate of Isochrysis sp. (T-iso) CCAP 927/14 were assessed in chemostat at a single irradiance (300 μmol photons m−2 s−1) and compared with white light. Two different dilution (renewal) rates were also tested: 0.7 and 0.2 d−1. Relative carbohydrate content was lower under blue light than under white light at both dilution rates, whereas chlorophyll a and photosynthesis activity were higher. In contrast,... |
| Tipo: Text |
Palavras-chave: Isochrysis; Blue light; Photosynthesis; Proximate composition; Chemostat. |
| Ano: 2013 |
URL: http://archimer.ifremer.fr/doc/00085/19599/17237.pdf |
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| Coulombier, Noémie; Nicolau, Elodie; Le Déan, Loic; Barthelemy, Vanille; Schreiber, Nathalie; Brun, Pierre; Lebouvier, Nicolas; Jauffrais, Thierry. |
| Nephroselmis sp. was previously identified as a species of interest for its antioxidant properties owing to its high carotenoid content. In addition, nitrogen availability can impact biomass and specific metabolites’ production of microalgae. To optimize parameters of antioxidant production, Nephroselmis sp. was cultivated in batch and continuous culture conditions in stirred closed photobioreactors under different nitrogen conditions (N-repletion, N-limitation, and N-starvation). The aim was to determine the influence of nitrogen availability on the peroxyl radical scavenging activity (oxygen radical absorbance capacity (ORAC) assay) and carotenoid content of Nephroselmis sp. Pigment analysis revealed a specific and unusual photosynthetic system with... |
| Tipo: Text |
Palavras-chave: Lutein; Natural products; Nutrients; Peroxyl radical; Siphonaxanthin. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00645/75699/76604.pdf |
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| Martin-jezequel, Veronique; Calu, Guillaume; Candela, Leo; Amzil, Zouher; Jauffrais, Thierry; Sechet, Veronique; Weigel, Pierre. |
| Over the last century, human activities have altered the global nitrogen cycle, and anthropogenic inputs of both inorganic and organic nitrogen species have increased around the world, causing significant changes to the functioning of aquatic ecosystems. The increasing frequency of Pseudo-nitzschia spp. in estuarine and coastal waters reinforces the need to understand better the environmental control of its growth and domoic acid (DA) production. Here, we document Pseudo-nitzschia spp. growth and toxicity on a large set of inorganic and organic nitrogen (nitrate, ammonium, urea, glutamate, glutamine, arginine and taurine). Our study focused on two species isolated from European coastal waters: P. multiseries CCL70 and P. australis PNC1. The nitrogen... |
| Tipo: Text |
Palavras-chave: Pseudo-nitzschia; Toxic diatoms; Nitrogen; Amino acids; Domoic acid. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00308/41912/41188.pdf |
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| Jauffrais, Thierry; Sechet, Veronique; Herrenknecht, Christine; Tillmann, Urban; Krock, Bernd; Amzil, Zouher; Hess, Philipp. |
| Azaspiracids are lipophilic marine biotoxins causing gastrointestinal symptoms similar to DSP toxins. Since 1995, azaspiracids have been encountered in Europe, Africa and more recently in North and South America and Japan. The biological primary producer remained undiscovered during many years and has now been identified as Azadinium spinosum. The organism was grown using K modified medium, at 18°C with a PFD of 200 μmol.m-2.s-1 and a photoperiod of 16L/8D. Batch cultures were carried out using 75mL and 10L flasks, while continuous cultures were produced in 100L chemostats. Cells were recovered using centrifugation or filtration. Different extraction solvents and procedures as well as evaporation modes were evaluated for yield. Quantitation was carried out... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00152/26348/24431.pdf |
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| Bird, Clare; Lekieffre, Charlotte; Jauffrais, Thierry; Meibom, Anders; Geslin, Emmanuelle; Filipsson, Helena L.; Maire, Olivier; Russell, Ann D.; Fehrenbacher, Jennifer S.. |
| Nitrogen availability often limits biological productivity in marine systems, where inorganic nitrogen, such as ammonium is assimilated into the food web by bacteria and photoautotrophic eukaryotes. Recently, ammonium assimilation was observed in kleptoplast-containing protists of the phylum foraminifera, possibly via the glutamine synthetase/glutamate synthase (GS/GOGAT) assimilation pathway imported with the kleptoplasts. However, it is not known if the ubiquitous and diverse heterotrophic protists have an innate ability for ammonium assimilation. Using stable isotope incubations (15N-ammonium and 13C-bicarbonate) and combining transmission electron microscopy (TEM) with quantitative nanoscale secondary ion mass spectrometry (NanoSIMS) imaging, we... |
| Tipo: Text |
Palavras-chave: Nitrogen cycle; Heterotrophic protists; Foraminifera; Ammonium assimilation; Heterotrophy; Marine. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00662/77421/79087.pdf |
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| Coulombier, Noémie; Nicolau, Elodie; Le Déan, Loic; Antheaume, Cyril; Jauffrais, Thierry; Lebouvier, Nicolas. |
| Twelve microalgae species isolated in tropical lagoons of New Caledonia were screened as a new source of antioxidants. Microalgae were cultivated at two light intensities to investigate their influence on antioxidant capacity. To assess antioxidant property of microalgae extracts, four assays with different modes of action were used: 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2’-azinobis (3-éthylbenzothiazoline-6-sulphonique) (ABTS), oxygen radical absorbance capacity (ORAC), and thiobabituric acid reactive substances (TBARS). This screening was coupled to pigment analysis to link antioxidant activity and carotenoid content. The results showed that none of the microalgae studied can scavenge DPPH and ABTS radicals, but Chaetoceros sp., Nephroselmis sp., and... |
| Tipo: Text |
Palavras-chave: Nephroselmis; Light intensity; In vitro antioxidant activity; Siphonaxanthin; Carotenoid; Bioactive compounds. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00609/72152/70900.pdf |
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| Kilcoyne, Jane; Nulty, Ciara; Jauffrais, Thierry; Mccarron, Pearse; Herve, Fabienne; Foley, Barry; Rise, Frode; Crain, Sheila; Wilkins, Alistair L.; Twiner, Michael J.; Hess, Philipp; Miles, Christopher O.. |
| We identified three new azaspiracids (AZAs) with molecular weights of 715, 815, and 829 (AZA33 (3), AZA34 (4), and AZA35, respectively) in mussels, seawater, and Azadinium spinosum culture. Approximately 700 mu g of 3 and 250 mu g of 4 were isolated from a bulk culture of A. spinosum, and their structures determined by MS and NMR spectroscopy. These compounds differ significantly at the carboxyl end of the molecule from known AZA analogues and therefore provide valuable information on structure-activity relationships. Initial toxicological assessment was performed using an in vitro model system based on Jurkat T lymphocyte cytotoxicity, and the potencies of 3 and 4 were found to be 0.22- and 5.5-fold that of AZA1 (1), respectively. Thus, major changes in... |
| Tipo: Text |
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| Ano: 2014 |
URL: https://archimer.ifremer.fr/doc/00245/35606/34414.pdf |
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| Jauffrais, Thierry; Lekieffre, Charlotte; Schweizer, Magali; Geslin, Emmanuelle; Metzger, Edouard; Bernhard, Joan M.; Jesus, Bruno; Filipsson, Helena L.; Maire, Olivier; Meibom, Anders. |
| The assimilation of inorganic compounds in foraminiferal metabolism compared to predation or organic matter assimilation is unknown. Here we investigate possible inorganic‐compound assimilation in Nonionellina labradorica, a common kleptoplastidic benthic foraminifer from Arctic and North Atlantic sublittoral regions. The objectives were to identify the source of the foraminiferal kleptoplasts, assess their photosynthetic functionality in light and darkness, and investigate inorganic nitrogen and sulfate assimilation. We used DNA barcoding of a ~830 bp fragment from the SSU rDNA to identify the kleptoplasts, and correlated transmission electron microscopy and nanometer‐scale secondary ion mass spectrometry (TEM‐NanoSIMS) isotopic imaging to study... |
| Tipo: Text |
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| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00460/57188/59151.pdf |
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| Jauffrais, Thierry; Kilcoyne, Jane; Sechet, Veronique; Herrenknecht, Christine; Truquet, Philippe; Herve, Fabienne; Berard, Jean-baptiste; Nulty, Ciara; Taylor, Sarah; Tillmann, Urban; Miles, Christopher O.; Hess, Philipp. |
| Azaspiracid (AZA) poisoning has been reported following consumption of contaminated shellfish, and is of human health concern. Hence, it is important to have sustainable amounts of the causative toxins available for toxicological studies and for instrument calibration in monitoring programs, without having to rely on natural toxin events. Continuous pilot scale culturing was carried out to evaluate the feasibility of AZA production using Azadinium spinosum cultures. Algae were harvested using tangential flow filtration or continuous centrifugation. AZAs were extracted using solid phase extraction (SPE) procedures, and subsequently purified. When coupling two stirred photobioreactors in series, cell concentrations reached 190,000 and 210,000 cell·mL−1 at... |
| Tipo: Text |
Palavras-chave: Solid phase extraction; Photobioreactor; Chemostat; Dinoflagellate; Micro-algae; LC-MS/MS; Tangential flow filtration; Azaspiracid; HP-20. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00088/19875/17526.pdf |
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| Jauffrais, Thierry; Herrenknecht, Christine; Sechet, Veronique; Sibat, Manoella; Tillmann, Urban; Krock, Bernd; Kilcoyne, Jane; Miles, Christopher O.; Mccarron, Pearse; Amzil, Zouher; Hess, Philipp. |
| Azaspiracids (AZAs) are secondary metabolites of Azadinium spinosum, that have been shown to cause diarrhetic shellfish poisoning when accumulated in bivalve molluscs. We describe here an analytical procedure for the determination of AZAs in cultures of A. spinosum with a focus on the potential formation of AZA methyl-esters as artefacts in the extraction and sample pre-treatment. A. spinosum cells were collected from bioreactor cultures, using centrifugation or filtration. Different extraction procedures were evaluated for formation of methyl-ester artefacts, yield, and matrix effects. Filtration of cultures using glass-fibre filters led to increased formation of methyl-esters. Hence centrifugation is recommended for recovery of cells. The type of... |
| Tipo: Text |
Palavras-chave: Extraction procedure; Extraction artefact; Matrix effects; LC-MS/MS; Azaspiracid methyl ester; Dinoflagellate; Liquid chromatography-mass spectrometry. |
| Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00077/18812/16463.pdf |
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| Jauffrais, Thierry; Lekieffre, Charlotte; Schweizer, Magali; Jesus, Bruno; Metzger, Edouard; Geslin, Emmanuelle. |
| The aim of this work is to document the complex nutritional strategy developed by kleptoplastic intertidal foraminifera. We study the mixotrophic ability of a common intertidal foraminifer, E. williamsoni, by (1) investigating the phylogenetic identity of the foraminiferal kleptoplasts, (2) following their oxygenic photosynthetic capacity, and (3) observing the modification in cellular ultrastructural features in response to photoautotrophic conditions. This was achieved by coupling molecular phylogenetic analyses and TEM observations with non-destructive measurements of kleptoplast O2 production over a 15-day experimental study. Results show that the studied E. williamsoni actively selected kleptoplasts mainly from pennate diatoms and had the ability to... |
| Tipo: Text |
Palavras-chave: Foraminifera; Electron microscopy; DNA barcoding; Kleptoplasty; Lipids. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00487/59894/63074.pdf |
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| Registros recuperados: 22 | |
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