Consulta: subjectFacets:"Alexandrium catenella"
Registros recuperados: 18
Data/hora: 08/06/2024 12:34:53

Contribution of several nitrogen sources to growth of Alexandrium catenella during blooms in Thau lagoon, southern France
Provedor de dados: 5
Autores: Collos, Y; Vaquer, A; Laabir, M; Abadie, Eric; Laugier, Thierry; Pastoureaud, Annie; Souchu, Philippe.
A monitoring program with a weekly sampling frequency over a 15-month period indicates that urea concentrations above a certain threshold level may trigger the blooms of Alexandrium catenella in Thau lagoon. However, urea concentrations were also sometimes related to ammonium and dissolved organic nitrogen concentrations, indicating that the role of urea may not be a direct one. An original approach is used to assess the relative contribution of several nitrogen sources (nitrate, nitrite, ammonium, urea) to growth of A. catenella by comparing nitrogen uptake rates to nitrogen-based growth rates estimated from dilution experiments during four blooms over a 4-year period (2001-2004) in Thau lagoon. Nitrate and nitrite contributed 0.1-14% and 0.1-5%...
Tipo: Text
Palavras-chave: Uptake kinetics; Ammonium; Urea; Growth; Nitrogen; HAB; Alexandrium catenella.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-6454.pdf

Influence of Environmental Factors on the Paralytic Shellfish Toxin Content and Profile of Alexandrium catenella (Dinophyceae) Isolated from the Mediterranean Sea
Provedor de dados: 5
Autores: Laabir, Mohamed; Collos, Yves; Masseret, Estelle; Grzebyk, Daniel; Abadie, Eric; Savar, Veronique; Sibat, Manoella; Amzil, Zouher.
Laboratory experiments were designed to study the toxin content and profile of the Alexandrium catenella strain ACT03 (isolated from Thau Lagoon, French Mediterranean) in response to abiotic environmental factors under nutrient-replete conditions. This dinoflagellate can produce various paralytic shellfish toxins with concentrations ranging from 2.9 to 50.3 fmol/cell. The toxin profile was characterized by carbamate toxins (GTX3, GTX4 and GTX5) and N-sulfocarbamoyl toxins (C1, C2, C3 and C4). C2 dominated at 12-18 degrees C, but only for salinities ranging from 10 to 25 psu, whereas GTX5 became dominant at temperatures ranging from 21 to 30 degrees C at almost all salinities. There was no significant variation in the cellular toxin amount from 18 degrees C...
Tipo: Text
Palavras-chave: Alexandrium catenella; PSP toxins; Temperature; Salinity; Light.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00148/25969/24056.pdf

Algicidal effects of Zostera marina L. and Zostera noltii Hornem. extracts on the neuro-toxic bloom-forming dinoflagellate Alexandrium catenella
Provedor de dados: 5
Autores: Laabir, Mohamed; Grignon-dubois, Micheline; Masseret, Estelle; Rezzonico, Bernadette; Soteras, Giselle; Rouquette, Manuel; Rieuvilleneuve, Fabien; Cecchi, Philippe.
The inhibitory effects of crude extracts of Zostera marina L and Zostera noltii Hornemann on the growth of the toxic red tide dinoflagellate Alexandrium catenella were investigated through bio-assays. Methanolic and aqueous extracts were prepared from fresh and detrital leaves of Z. marina and Z. noltii collected in the Thau lagoon and Arcachon bay (France). All the extracts exhibited significant inhibition of A. catenella growth, whatever the species and without the need of continuous addition of extracts. The effective concentrations (EC50) varied in the range 0.036-0.199 g L-1 for Z. noltii and 0.036-0.239 g L-1 for Z. marina. Methanolic extracts prepared from fresh plant tissues were the most potent, with EC50 of 0.036-0.039 and 0.036-0.045 g L-1, for...
Tipo: Text
Palavras-chave: Growth inhibition; Allelopathy; Alexandrium catenella; Zostera marina; Zostera noltii; Phenolics.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00170/28095/26720.pdf

Viability, growth and toxicity of Alexandrium catenella and Alexandrium minutum (Dinophyceae) following ingestion and gut passage in the oyster Crassostrea gigas
Provedor de dados: 5
Autores: Laabir, Mohamed; Amzil, Zouher; Lassus, Patrick; Masseret, Estelle; Tapilatu, Yosmina; De Vargas, Romain; Grzebyk, Daniel.
Adult oysters Crassostrea gigas were experimentally fed with Alexandrium catenella and Alexandrium minutum which are responsible for recurrent toxic blooms in French coastal waters. C. gigas produced faeces and pseudofaeces containing intact and viable temporary pellicular cysts of these two Paralytic toxin producing species. When incubated in favourable conditions, these pellicular cysts were able to germinate at high rates (between 74 and 94%) and the resulting vegetative cells divided with growth rates close to the non-ingested cells (control). The toxin profile of the vegetative cells originated from the germinated temporary cysts was analyzed by liquid chromatography/ fluorescence detection. Total toxin content of newly germinated cells was lower than...
Tipo: Text
Palavras-chave: Paralytic shellfish poisoning; Oysters; Cysts; Alexandrium minutum; Alexandrium catenella.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2622.pdf

Paramétrisation de la nutrition azotée et phosphorée d'Alexandrium catenella, microalgue toxique responsable d'efflorescences dans la lagune de Thau
Provedor de dados: 5
Autores: Jauzein, Cecile.
In the Thau lagoon, blooms of the toxic microalgae Alexandrium catenella have induced regular losses of shellfish production since 1998 due to bioaccumulation of toxins in oysters and mussels. This thesis was conducted to enhance knowledge of toxic bloom development regulation by environmental factors, focusing on nitrogen and phosphorus nutrients influence on A. catenella growth. These works highlighted a large variety of potential nutritive sources for this species and a major part of these nutrients appeared to be potentially regenerated in the water column. Different organic sources may contribute to the growth of A. catenella from diverse nutrition processes: direct absorption through the cell membrane (for urea), enzymatic degradation in the...
Tipo: Text
Palavras-chave: Alkaline phosphatases; Mixotrophy; Phosphate; Urea; Ammonium; Uptake kinetics; Alexandrium catenella; Phosphatases alcalines; Mixotrophie; Phosphate; Urée; Ammonium; Cinétiques d'absorption; Alexandrium catenella.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/these-6511.pdf

Effects of copper and butyltin compounds on the growth, photosynthetic activity and toxin production of two HAB dinoflagellates : the planktonic Alexandrium catenella and the benthic Ostreopsis cf. ovata
Provedor de dados: 5
Autores: Couet, Douglas; Pringault, Olivier; Bancon-montigny, Chrystelle; Briant, Nicolas; Poulichet, Francoise Elbaz; Delpoux, Sophie; Yahia, Ons Kefi-daly; Hela, Bengharbia; Charaf, M'Rabet; Herve, Fabienne; Rovillon, Georges-augustin; Amzil, Zouher; Laabir, Mohamed.
Controlled laboratory experiments were conducted to test the effects of copper (Cu2+) and butyltins (BuT) on the growth, photosynthetic activity and toxin content of two HABs (Harmful Algal Blooms) dinoflagellates, the planktonic Alexandrium catenella and the benthic Ostreopsis cf. ovata. Microalgae were exposed to increasing concentrations of Cu2+ (10−4 to 31 nM) or BuT (0.084 to 84 nM) for seven days. When considering the growth, EC50 values were 0.16 (±0.09) nM and 0.03 (±0.02) nM of Cu2+ for A. catenella and O. cf. ovata, respectively. Regarding BuT, EC50 was 14.2 (±6) nM for O. cf. ovata, while A. catenella growth inhibition appeared at BuT concentrations ≥27 nM. Photosynthetic activity of the studied dinoflagellates decreased with increasing Cu and...
Tipo: Text
Palavras-chave: Alexandrium catenella; Ostreopsis cf. ovata; Cu; Butyltin; Photosynthesis; Toxins.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00418/52970/53896.pdf

Interactions between ammonium and urea uptake by five strains of Alexandrium catenella (Dinophyceae) in culture
Provedor de dados: 5
Autores: Jauzein, Cecile; Loureiro, Sofia; Garces, Esther; Collos, Yves.
Short-term experiments were carried out to investigate whether interactions between ammonium (NH4+) and urea uptake regulate the total nitrogen assimilation of the toxic dinoflagellate Alexandrium catenella. To test for strain variability, 5 strains of A. catenella from the NW Mediterranean were used: 3 strains from the Thau lagoon (southern France) and 2 strains from the Catalonia basin (Spain). For each strain, the uptake rate of 1 nutrient (NH4+ or urea) at a reference concentration (10 mu gatN l(-1)) was measured as a function of the increasing concentration of the other nutrient (0 to 10 mu gatN l(-1)). Simultaneous N uptake rates of the distinct nitrogen sources were obtained from N-15-NH4+ and N-15-urea incorporation measurements. A strong...
Tipo: Text
Palavras-chave: Strain variability; Interactions; Urea; Ammonium; Alexandrium catenella.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-6432.pdf

Impact of the toxic dinoflagellate Alexandrium catenella on Pacific oyster reproductive output: application of flow cytometry assays on spermatozoa
Provedor de dados: 5
Autores: Le Goic, Nelly; Hegaret, Helene; Fabioux, Caroline; Miner, Philippe; Suquet, Marc; Lambert, Christophe; Soudant, Philippe.
The toxic dinoflagellate Alexandrium catenella recurrently blooms on the coasts of France and produces Paralytic Shellfish Toxins (PSTs) that accumulate in bivalves. These toxins can affect various physiological functions including reproduction. The present study aims to validate measurements of sperm viability, DNA content and mitochondrial membrane potential in Pacific oyster Crassostrea gigas using flow cytometry coupled with fluorescent markers, and to use these measurements to assess the cellular parameters of sperm from Pacific oysters exposed to A. catenella. These parameters may influence fertilization, embryogenesis and larval development in free-spawning shellfish. Sperm viability and DNA content estimation were assessed using SYBR-14, which only...
Tipo: Text
Palavras-chave: Harmful algal bloom; Sperm quality; Cellular parameters; Flow cytometry; Pacific oyster; Crassostrea gigas; Alexandrium catenella.
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00157/26853/24982.pdf

Oligotrophication and emergence of picocyanobacteria and a toxic dinoflagellate in Thau lagoon, southern France
Provedor de dados: 5
Autores: Collos, Yves; Bec, Beatrice; Jauzein, Cecile; Abadie, Eric; Laugier, Thierry; Lautier, Jacques; Pastoureaud, Annie; Souchu, Philippe; Vaquer, Andre.
Time series data have been examined in Thau lagoon (Southern France) from 1972 to 2006 for water temperature, salinity, nutrients and from 1987 to 2006 for phytoplankton. A first main trend identified is an increase in mean annual water temperature (1.5 degrees C over 33 years or 0.045 degrees C/year) that was not evenly distributed among seasons. The highest rate of increase was in the spring (+ 3.0 degrees C over 33 years), followed by summer (+ 2.0 degrees C and fall (+ 1.7 degrees C. In winter, no significant increase over the 33 year period could be found. A second clear trend is a large decrease in soluble reactive phosphorus (SRP) concentration over the same 33 year period (summer values decreased from 10 mu M to 1 mu M. while winter values...
Tipo: Text
Palavras-chave: Skeletonema costatum; Alexandrium catenella; Picocyanobacteria; Oligotrophication; Long term variability; Thau lagoon.
Ano: 2009
URL: http://archimer.ifremer.fr/doc/2009/publication-6420.pdf

Paralytic Toxins Accumulation and Tissue Expression of alpha-Amylase and Lipase Genes in the Pacific Oyster Crassostrea gigas Fed with the Neurotoxic Dinoflagellate Alexandrium catenella
Provedor de dados: 5
Autores: Rolland, Jean-luc; Pelletier, Kevin; Masseret, Estelle; Rieuvilleneuve, Fabien; Savar, Veronique; Santini, Adrien; Amzil, Zouher.
The pacific oyster Crassostrea gigas was experimentally exposed to the neurotoxic Alexandrium catenella and a non-producer of PSTs, Alexandrium tamarense (control algae), at concentrations corresponding to those observed during the blooming period. At fixed time intervals, from 0 to 48 h, we determined the clearance rate, the total filtered cells, the composition of the fecal ribbons, the profile of the PSP toxins and the variation of the expression of two a-amylase and triacylglecerol lipase precursor (TLP) genes through semi-quantitative RT-PCR. The results showed a significant decrease of the clearance rate of C. gigas fed with both Alexandrium species. However, from 29 to 48 h, the clearance rate and cell filtration activity increased only in oysters...
Tipo: Text
Palavras-chave: Crassostrea gigas; Alexandrium catenella; PSP toxins; Digestion; Gene expression.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00130/24170/22172.pdf

Towards an optimal sampling strategy for Alexandrium catenella (Dinophyceae) benthic resting cysts
Provedor de dados: 5
Autores: Genovesi, B; Mouillot, D; Vaquer, A; Laabir, M; Pastoureaud, Annie.
The study proposes methodological developments to optimize sampling strategy of resting cysts of Alexandrium catenella to estimate their abundance with a predefined error. This work also aims to provide information on spatial distribution of resting cysts in sediments. The distribution mode of A. catenella resting cysts related to the abundance variability was studied through sediment cores sampling on four different spatial scales and using Ludox CLX gradient density method. The quantification method underestimates by a factor of 2 the resting cysts abundance in one gram of sediment. Application of Taylor's power law allowed us to define a compromise between sampling effort and abundance estimation error. In the case of A. catenella resting cysts from...
Tipo: Text
Palavras-chave: Vertical profiles; Spatial distribution; Optimum sample size; Resting cyst; Toxic dinoflagellate; Alexandrium catenella.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-3579.pdf

Dark metabolism and carbon-nitrogen uncoupling in the toxic dinoflagellate Alexandrium catenella (Dinophyceae)
Provedor de dados: 5
Autores: Jauzein, Cecile; Collos, Yves; Laabir, Mohamed; Vaquer, Andre.
Uptake rates of three potential N-sources (ammonium, nitrate and N-urea) and two potential C-sources (HCO(3)(-) and C-urea) were estimated during growth of Alexandrium catenella in both light and dark phases. According to the variations observed in (13)C-isotopic ratio, A. catenella cells were not able to use C-urea. Furthermore, decreases in (13)C cell content during darkness revealed a probably high involvement of C recently fixed in dark respiration. Dark N-uptake capacities of A. catenella were characterized by dark/light uptake ratio of 27%, 43% and 65% for NO(3)(-), NH(4)(+) and N-urea, respectively. An accumulation of C-rich compounds during the light period was highlighted through strong diel variations in C:N ratio and would provide C and energy...
Tipo: Text
Palavras-chave: Diel cycle; Dark uptake; Nitrogen; Carbon; Uncoupling; Alexandrium catenella.
Ano: 2011
URL: http://archimer.ifremer.fr/doc/00056/16699/14199.pdf

Interactions between a marine dinoflagellate (Alexandrium catenella) and a bacterial community utilizing reverine humic substances
Provedor de dados: 5
Autores: Carlsoon, Per; Edling, Hélène; Bechemin, Christian.
Dissolved organic matter in the form of riverine humic substances stimulated the growth of both axenic nitrogen-limited Alexandrium catenella cultures and nitrogen-limited cultures with a marine bacterial community present. The biomass increase of A. catenella could not be accounted for by utilization of inorganic nitrogen compounds. However, there was a considerable release of dissolved free and combined amino acids from the humic substances that was utilized by A. catenella. About 40% of the nitrogen used by A. catenella in the axenic treatment with humic substances added was taken up as organic nitrogen. Bacterial aminopeptidase and beta -glucosidase activity was stimulated by the addition of humic substances and bacterial growth increased several-fold....
Tipo: Text
Palavras-chave: Alexandrium catenella; Dinoflagellates; Bacteria; DOM; Humic substances.
Ano: 1998
URL: https://archimer.ifremer.fr/doc/00173/28431/26763.pdf

Modelling the accumulation of PSP toxins in Thau Lagoon oysters (Crassostrea gigas) from trials using mixed cultures of Alexandrium catenella and Thalassiosira weissflogii
Provedor de dados: 5
Autores: Lassus, Patrick; Amzil, Zouher; Baron, Regis; Sechet, Veronique; Barille, Laurent; Abadie, Eric; Bardouil, Michele; Sibat, Manoella; Truquet, Philippe; Berard, Jean-baptiste; Gueguen, Marielle.
In October and November 2003 a bloom of the toxic dinoflagellate Alexandrium catenella was observed in the North-east zone of Thau lagoon (French Mediterranean coast). Sea water samples were collected every hours to evaluate time-related variations of phytoplankton concentrations and to compare the relative ratio of A. catenella versus other phytoplankton species during the outbreak. From these observations, trials using recirculated sea water systems were performed to: i) evaluate the physiological effects on oyster of increasing proportions of A. catenella within a mixed microalgal diet where the non-toxic diatom Thalassiosira weissflogii was present at concentration: 1500 cells ml(-1), ii) compare the effect of two temperatures (12 degrees C and 18...
Tipo: Text
Palavras-chave: Mediterranean Sea; Alexandrium catenella; Toxin content; Model; Crassostrea gigas; Paralytic shellfish poisoning.
Ano: 2007
URL: http://archimer.ifremer.fr/doc/2007/publication-2624.pdf

Short-term temporal variability of ammonium and urea uptake by Alexandrium catenella (Dinophyta) in cultures
Provedor de dados: 5
Autores: Jauzein, Cecile; Collos, Yves; Garces, E; Vila, M; Maso, M.
In batch cultures of four Mediterranean strains (from France, Italy, and Spain) of Alexandrium catenella (Whedon et Kof.) Balech growing on a daily light cycle, ammonium and urea uptake were estimated by the N-15 tracer technique. Ammonium uptake could be described by Michaelis-Menten kinetics along a substrate gradient of 0.1-10 mu gat N.L-1 for the four strains, while two different patterns were observed for urea uptake with Michaelis-Menten kinetics for one strain and linear kinetics for the others. In all cases, an increase in uptake rates with time was noted over the daylight period. This trend led to a net increase in the maximum uptake rate (V-max; for saturable kinetics) and in the initial slope alpha. For ammonium, V-max increased by a factor of...
Tipo: Text
Palavras-chave: Urea; Uptake kinetics; Temporal variability; Ammonium release; Ammonium; Alexandrium catenella.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-6416.pdf

Growth and phosphorus uptake by the toxic dinoflagellate Alexandrium catenella (dinophyceae) in response to phosphate limitation
Provedor de dados: 5
Autores: Jauzein, Cecile; Labry, Claire; Youenou, Agnes; Quere, Julien; Delmas, Daniel; Collos, Yves.
Alexandrium catenella (Whedon et Kof.) Balech has exhibited seasonal recurrent blooms in the Thau lagoon (South of France) since first reported in 1995. Its appearance followed a strong decrease (90%) in phosphate (PO(4)3-) concentrations in this environment over the 1970-1995 period. To determine if this dinoflagellate species has a competitive advantage in PO(4)3--limited conditions in terms of nutrient acquisition, semicontinuous cultures were carried out to characterize phosphorus (P) uptake by A. catenella cells along a P-limitation gradient using different dilution rates (DRs). Use of both inorganic and organic P was investigated from measurements of 33PO(4)3- uptake and alkaline phosphatase activity (APA), respectively. P status was estimated from...
Tipo: Text
Palavras-chave: Alexandrium catenella; Alkaline phosphatase; Limitation; Phosphorus; Semicontinuous cultures.
Ano: 2010
URL: http://archimer.ifremer.fr/doc/00015/12641/9570.pdf

Patrones de distribución espacial y temporal de floraciones de Alexandrium catenella (Whedon &amp;amp; Kofoid) Balech 1985, en aguas interiores de la Patagonia noroccidental de Chile
Provedor de dados: 97
Autores: MOLINET,CARLOS; LAFON,ALEJANDRA; LEMBEYE,GEORGINA; MORENO,CARLOS A.
La presencia del dinoflagelado tóxico Alexandrium catenella en las aguas interiores de la Patagonia noroccidental, fue registrada en la década de los 90. A partir de 1995 se iniciaron programas de monitoreo de fitoplancton orientados al seguimiento de este dinoflagelado y sus efectos sobre los mariscos en la Décima y Undécima Región de Chile, financiados por distintas instituciones. Esto permitió recolectar una importante base de datos, aunque incompleta en muchos aspectos debido a la independencia de objetivos de los diferentes estudios. En esta revisión se agruparon todos los datos disponibles para buscar patrones que ayuden a la formulación de hipótesis sobre la dispersión e incidencia espacial y temporal de A. catenella en esta amplia zona y mucho más...
Tipo: Journal article
Palavras-chave: Alexandrium catenella; Distribución; Aguas interiores; Sur de Chile.
Ano: 2003
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2003000400011

Susceptibilidad a la radiación ultravioleta_B del dinoflagelado Alexandrium catenella Kofoid Balech y de la diatomea Phaeodactylum tricornutum Bohlin
Provedor de dados: 97
Autores: MARTINEZ,GINGER; MOLINA,XIMENA; OLMEDO,MARIA ISABEL; MONTECINO,VIVIAN.
La susceptibilidad diferencial de microalgas a la radiación UV-B (RUV-B, 280 - 320 nm) genera patrones de predominio numérico dentro de los ensambles del fitoplancton. Sin embargo, a pesar que algunos eventos de floraciones algales nocivas (FAN) del dinoflagelado Alexandrium catenella han sido coincidentes con episodios de alta RUV-B en el extremo sur de Chile, se desconoce alguna relación de causalidad entre estos procesos. A través de los parámetros poblacionales tasa intrínseca de crecimiento (µ) y capacidad de carga (K), se determinó el efecto de la RUV-B sobre la dinámica poblacional de cultivos de A. catenella, la que fue comparada con la respuesta demográfica de cultivos de una diatomea susceptible a la RUV-B, Phaeodactylum tricornutum. Los...
Tipo: Journal article
Palavras-chave: RUV-B; Alexandrium catenella; Phaeodactylum tricornutum; Crecimiento; Capacidad de carga.
Ano: 2000
URL: http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0716-078X2000000200007