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| Ayache, Nour; Hervé, Fabienne; Lundholm, Nina; Amzil, Zouher; Caruana, Amandine. |
| oxic Pseudo‐nitzschia australis strains isolated from French coastal waters were studied to investigate their capacity to adapt to different salinities. Their acclimation to different salinity conditions (10, 20, 30, 35 and 40) was studied on growth, photosynthetic capacity, cell biovolume and domoic acid (DA) content. The strains showed ability to acclimate to a salinity range from 20 to 40, with optimal growth rates between salinities 30 and 40. The highest cell biovolume was observed at the lowest salinity 20 and was associated with the lowest growth rate. Salinity did not affect the photosynthetic activity; Fv/Fm values and the pigment contents remained high with no significant difference among salinities. An enhanced production of zeaxanthin was,... |
| Tipo: Text |
Palavras-chave: Acclimation; Climate change; Domoic acid; Pseudo-nitzschia australis; Physiology; Salinity. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00585/69684/67552.pdf |
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| Nef, Charlotte; Henry, Céline; Nicolau, Elodie; Bérard, Jean-baptiste; Hervé, Fabienne; Caruana, Amandine; Kaas, Raymond; Mairet, Francis; Garnier, Matthieu. |
| Cobalamin (vitamin B12) is a cobalt-containing enzymatic cofactor involved in methionine synthesis. Provided only by select bacteria and archaea in marine systems, this vitamin is known to limit primary production in different oceanic areas. Understanding the consequences of cobalamin limitation on phytoplankton physiology is of great interest, notably for cobalamin-dependent haptophytes that significantly contribute to oceanic carbon fixation and sulfur cycle through dimethyl sulfonio propionate (DMSP) synthesis. Here, the effect of cobalamin limitation was compared to nitrogen limitation on the model haptophyte Tisochrysis lutea grown in chemostats, combining comparative proteomics with the analysis of major macromolecules and specific osmolytes. Our... |
| Tipo: Text |
Palavras-chave: Cobalamin; Vitamin B-12; Haptophyte microalgae; Tisochrysis lutea; DMSP; Chemostat; Comparative proteomics; Metabolism. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00654/76575/77711.pdf |
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| Caruana, Amandine; Ayache, Nour; Raimbault, Virginie; Rétho, Michael; Hervé, Fabienne; Bilien, Gwenael; Amzil, Zouher; Chomérat, Nicolas. |
| We confirm an amnesic shellfish poisoning risk associated with domoic acid production by the species Pseudo-nitzschia plurisecta and determine the toxin profile, which includes three domoic acid isomers. Although the species was reported once in European waters, along the Spanish Atlantic coast, here we describe and characterize P. plurisecta collected during the first occurrence in French Atlantic waters. Three strains (IFR-PPL-15.1, 15.2 and 15.3) were isolated from French coastal water samples in June 2015. These strains were identified and characterized by microscopic observation, molecular (ITS region sequencing and phylogenetic analysis) and metabolite (toxins and pigments) analyses. The cell shape is lanceolate and the valve contains a central... |
| Tipo: Text |
Palavras-chave: Coastal monitoring; Domoic acid; Pigment composition; Pseudo-nitzschia plurisecta; Taxonomic identification; Toxic diatoms. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00505/61687/66033.pdf |
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| Caruana, Amandine. |
| Dimethylsulphoniopropionate (DMSP) is the biogenic precursor of the climatecooling gas dimethylsulphide (DMS). DMSP is produced by certain phytoplankton groups including dinoflagellates. DMSP is a multifunctional compound potentially acting as an osmolyte, cryoprotectant, antioxidant, methyl donor, grazer deterrent and overflow exudate but its primary biological role and the variation in DMSP content in dinoflagellates remain unclear. As dinoflagellates can be sensitive to agitation, the methods for DMSP measurements in cultures were assessed and the measurement of total DMSP as a surrogate for intracellular DMSP was retained for most experiments. I collected all the published DMSP data in dinoflagellates and measured DMSP in 9 species. The obtained... |
| Tipo: Text |
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| Ano: 2010 |
URL: http://archimer.ifremer.fr/doc/00177/28866/27353.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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| Ayache, Nour; Hervé, Fabienne; Martin-jézéquel, Veronique; Amzil, Zouher; Caruana, Amandine. |
| Several coastal countries including France have experienced serious and increasing problems related to Pseudo‐nitzschia toxic blooms. These toxic blooms occur in estuarine and coastal waters potentially subject to fluctuations in salinity. In this study, we document for the first time the viability, growth, photosynthetic efficiency and toxin production of two strains of Pseudo‐nitzschia australis grown under conditions with sudden salinity changes. Following salinity variation, the two strains survived over a restricted salinity range of 30 to 35, with favorable physiological responses, as the growth, effective quantum yield and toxin content were high compared to the other conditions. In addition, high cellular quotas of domoic acid (DA) were observed at... |
| Tipo: Text |
Palavras-chave: Amnesic shellfish poisoning; Domoic acid; Harmful algae; Pseudo-nitzschia australis; Salinity stress. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00462/57385/59465.pdf |
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| Georges Des Aulnois, Maxime; Roux, Pauline; Caruana, Amandine; Réveillon, Damien; Briand, Enora; Hervé, Fabienne; Savar, Veronique; Bormans, Myriam; Amzil, Zouher; Atomi, Haruyuki. |
| Proliferation of microcystin (MC)-producing Microcystis aeruginosa in brackish waters has been described in several locations and represents a new concern for public and environmental health. While the impact of a sudden salinity increase on M. aeruginosa physiology has been studied, less is known about the mechanisms involved in salt tolerance after acclimation. This study aims to compare the physiological responses of two strains of M. aeruginosa (PCC 7820 and PCC 7806), which were isolated from contrasted environments, to increasing salinities. After acclimation, growth and MC production rates were determined and metabolomic analyses were conducted. For both strains, salinity decreased the biovolume, growth, and MC production rates and induced the... |
| Tipo: Text |
Palavras-chave: Acclimation; Metabolomic; Microcystis; Salinity; Sucrose; Trehalose; Ecophysiology. |
| Ano: 2019 |
URL: https://archimer.ifremer.fr/doc/00588/70031/68012.pdf |
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| Georges Des Aulnois, Maxime; Réveillon, Damien; Robert, Elise; Caruana, Amandine; Briand, Enora; Guljamow, Arthur; Dittmann, Elke; Amzil, Zouher; Bormans, Myriam. |
| The transfer of Microcystis aeruginosa from freshwater to estuaries has been described worldwide and salinity is reported as the main factor controlling the expansion of M. aeruginosa to coastal environments. Analyzing the expression levels of targeted genes and employing both targeted and non-targeted metabolomic approaches, this study investigated the e ect of a sudden salt increase on the physiological and metabolic responses of two toxic M. aeruginosa strains separately isolated from fresh and brackish waters, respectively, PCC 7820 and 7806. Supported by di erences in gene expressions and metabolic profiles, salt tolerance was found to be strain specific. An increase in salinity decreased the growth of M. aeruginosa with a lesser impact on the... |
| Tipo: Text |
Palavras-chave: Microcystis aeruginosa; Microcystin; Salt stress; Metabolomic; Transcript. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00615/72689/71692.pdf |
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