Consulta: creatorFacets:"Hegaret, Helene"
Registros recuperados: 24
Data/hora: 06/06/2024 14:19:49

Bioactive extracellular compounds produced by the dinoflagellate Alexandrium minutum are highly detrimental for oysters
Provedor de dados: 5
Autores: Castrec, Justine; Soudant, P.; Payton, L.; Tran, D.; Miner, Philippe; Lambert, C.; Le Goic, N.; Huvet, Arnaud; Quillien, Virgile; Boullot, F.; Amzil, Zouher; Hegaret, Helene; Fabioux, C.
Blooms of the dinoflagellate Alexandrium spp., known as producers of paralytic shellfish toxins (PSTs), are regularly detected on the French coastline. PSTs accumulate into harvested shellfish species, such as the Pacific oyster Crassostrea gigas, and can cause strong disorders to consumers at high doses. The impacts of Alexandrium minutum on C. gigas have often been attributed to its production of PSTs without testing separately the effects of the bioactive extracellular compounds (BECs) with allelopathic, hemolytic, cytotoxic or ichthyotoxic properties, which can also be produced by these algae. The BECs, still uncharacterized, are excreted within the environment thereby impacting not only phytoplankton, zooplankton but also marine invertebrates and...
Tipo: Text
Palavras-chave: Harmful algal bloom (HAB); Crassostrea gigas; Paralytic shellfish toxins (PST); Bioactive extracellular compounds (BEC); Histology; Behavior.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00435/54637/56042.pdf

Remodeling of the cycling transcriptome of the oyster Crassostrea gigas by the harmful algae Alexandrium minutum
Provedor de dados: 5
Autores: Payton, Laura; Perrigault, Mickael; Hoede, Claire; Massabuau, Jean-charles; Sow, Mohamedou; Huvet, Arnaud; Boullot, Floriane; Fabioux, Caroline; Hegaret, Helene; Tran, Damien.
As a marine organism, the oyster Crassostrea gigas inhabits a complex biotope governed by interactions between the moon and the sun cycles. We used next-generation sequencing to investigate temporal regulation of oysters under light/dark entrainment and the impact of harmful algal exposure. We found that ≈6% of the gills’ transcriptome exhibits circadian expression, characterized by a nocturnal and bimodal pattern. Surprisingly, a higher number of ultradian transcripts were also detected under solely circadian entrainment. The results showed that a bloom of Alexandrium minutum generated a remodeling of the bivalve’s temporal structure, characterized by a loss of oscillations, a genesis of de novo oscillating transcripts, and a switch in the period of...
Tipo: Text
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00389/50008/50595.pdf

Exposure of marine mussels Mytilus spp. to polystyrene microplastics: Toxicity and influence on fluoranthene bioaccumulation
Provedor de dados: 5
Autores: Paul-pont, Ika; Lacroix, Camille; Gonzalez Fernandez, Carmen; Hegaret, Helene; Lambert, Christophe; Le Goic, Nelly; Frere, Laura; Cassone, Anne-laure; Sussarellu, Rossana; Fabioux, Caroline; Guyomarch, Julien; Albentosa, Marina; Huvet, Arnaud; Soudant, Philippe.
The effects of polystyrene microbeads (micro-PS; mix of 2 and 6 μm; final concentration: 32 μg L−1) alone or in combination with fluoranthene (30 μg L−1) on marine mussels Mytilus spp. were investigated after 7 days of exposure and 7 days of depuration under controlled laboratory conditions. Overall, fluoranthene was mostly associated to algae Chaetoceros muelleri (partition coefficient Log Kp = 4.8) used as a food source for mussels during the experiment. When micro-PS were added in the system, a fraction of FLU transferred from the algae to the microbeads as suggested by the higher partition coefficient of micro-PS (Log Kp = 6.6), which confirmed a high affinity of fluoranthene for polystyrene microparticles. However, this did not lead to a modification...
Tipo: Text
Palavras-chave: Microplastics; Fluoranthene; Mussel; Depuration; Oxidative system.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00344/45502/45848.pdf

Exposure to the toxic dinoflagellate Alexandrium catenella modulates juvenile oyster Crassostrea gigas hemocyte variables subjected to different biotic conditions
Provedor de dados: 5
Autores: 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

Interactions between polystyrene microplastics and marine phytoplankton lead to species-specific hetero-aggregation
Provedor de dados: 5
Autores: Long, Marc; Paul-pont, Ika; Hegaret, Helene; Moriceau, Brivaela; Lambert, Christophe; Huvet, Arnaud; Soudant, Philippe.
To understand the fate and impacts of microplastics (MP) in the marine ecosystems, it is essential to investigate their interactions with phytoplankton as these may affect MP bioavailability to marine organisms as well as their fate in the water column. However, the behaviour of MP with marine phytoplanktonic cells remains little studied and thus unpredictable. The present study assessed the potential for phytoplankton cells to form hetero-aggregates with small micro-polystyrene (micro-PS) particles depending on microalgal species and physiological status. A prymnesiophycea, Tisochrysis lutea, a dinoflagellate, Heterocapsa triquetra, and a diatom, Chaetoceros neogracile, were exposed to micro-PS (2 μm diameter; 3.96 μg L−1) during their growth culture...
Tipo: Text
Palavras-chave: Polystyrene; Microplastic; Aggregates; Microalgae; Marine; Phytoplankton.
Ano: 2017
URL: https://archimer.ifremer.fr/doc/00389/50016/50735.pdf

A rapid quantitative fluorescence-based bioassay to study allelochemical interactions from Alexandrium minutum
Provedor de dados: 5
Autores: 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

Interaction between toxic dinoflagellate Alexandrium catenella exposure and disease associated with herpesvirus OsHV-1μVar in Pacific oyster spat Crassostrea gigas
Provedor de dados: 5
Autores: 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

Effects of bioactive extracellular compounds and paralytic shellfish toxins produced by Alexandrium minutum on growth and behaviour of juvenile great scallops Pecten maximus
Provedor de dados: 5
Autores: 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

Molecular Characterization of Voltage-Gated Sodium Channels and Their Relations with Paralytic Shellfish Toxin Bioaccumulation in the Pacific Oyster Crassostrea gigas
Provedor de dados: 5
Autores: 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

Physiological responses of Manila clams Venerupis (=Ruditapes) philippinarum with varying parasite Perkinsus olseni burden to toxic algal Alexandrium ostenfeldii exposure
Provedor de dados: 5
Autores: Lassudrie, Malwenn; Soudant, Philippe; Richard, Gaelle; Henry, N.; Medhioub, Walid; Da Silva, P.m.; Donval, Anne; Bunel, M.; Le Goïc, Nelly; Lambert, Christophe; De Montaudoin, X.; Fabioux, Caroline; Hegaret, Helene.
Manila clam stock from Arcachon Bay, France, is declining, as is commercial harvest. To understand the role of environmental biotic interactions in this decrease, effects of a toxic dinoflagellate, Alexandrium ostenfeldii, which blooms regularly in Arcachon bay, and the interaction with perkinsosis on clam physiology were investigated. Manila clams from Arcachon Bay, with variable natural levels of perkinsosis, were exposed for seven days to a mix of the nutritious microalga T-Iso and the toxic dinoflagellate A. ostenfeldii, a producer of spirolides, followed by seven days of depuration fed only T-Iso. Following sacrifice and quantification of protozoan parasite Perkinsus olseni burden, clams were divided into two groups according to intensity of the...
Tipo: Text
Palavras-chave: Bivalve; Harmful algal bloom; Oxidative stress; Venerupis philippinarum; Alexandrium ostenfeldii; Perkinsus olseni.
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00189/30022/28507.pdf

Influence of temperature, irradiance and pH on the physiology of Teleaulax amphioxeia
Provedor de dados: 5
Autores: Gaillard, Sylvain; Charrier, Aurelie; Carpentier, Liliane; Malo, Florent; Bougaran, Gael; Hegaret, Helene; Hess, Philipp; Sechet, Veronique.
Tipo: Text
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00617/72958/71990.pdf

Highlights of the XVII International Conference on Harmful Algae
Provedor de dados: 5
Autores: Reguera, Beatriz; Wells, Mark; Zingone, Adriana; Fraga, Santiago; Azavedo, S.; Magalhaes, V.; Jenkinson, Ian; Rodriguez-hernandez, Francisco; Anderson, Don M.; Hallegaeff, Gustaaf; Davidson, Keith; Hess, Philipp; Hegaret, Helene.
Tipo: Text
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00621/73293/72481.pdf

Sources of paralytic shellfish toxin accumulation variability in the Pacific oyster Crassostrea gigas
Provedor de dados: 5
Autores: Pousse, Emilien; Flye-sainte-marie, Jonathan; Alunno-bruscia, Marianne; Hegaret, Helene; Jean, Fred.
This study was designed to assess the contribution of feeding behavior to inter-individual variability of paralytic shellfish toxin (PST) accumulation in the Pacific oyster Crassostrea gigas. For this purpose 42 oysters were exposed for 2 days to non-toxic algae and then for 2 other days to the PST producer Alexandrium minutum. Individual clearance rate (CR) of oysters was continuously monitored over the 4 days using an ecophysiological measurement system. Comparison of CR values when exposed to toxic and non toxic algae allowed to estimate a clearance rate inhibition index (CRII). Toxin concentration of oysters was quantified at the end of the experiment. These data allowed to estimate the toxin accumulation efficiency (TAE) as the ratio of toxin...
Tipo: Text
Palavras-chave: Alexandrium minutum; Paralytic shellfish poisoning; Accumulation; Clearance rate; Feeding behavior; Pacific oyster.
Ano: 2018
URL: https://archimer.ifremer.fr/doc/00416/52789/53688.pdf

Short-Term Behavioural Responses of the Great Scallop Pecten maximus Exposed to the Toxic Alga Alexandrium minutum Measured by Accelerometry and Passive Acoustics
Provedor de dados: 5
Autores: Coquereau, Laura; Jolivet, Aurelie; Hegaret, Helene; Chauvaud, Laurent.
Harmful algal blooms produced by toxic dinoflagellates have increased worldwide, impacting human health, the environment, and fisheries. Due to their potential sensitivity (e.g., environmental changes), bivalves through their valve movements can be monitored to detect harmful algal blooms. Methods that measure valve activity require bivalve-attached sensors and usually connected cables to data transfers, leading to stress animals and limit the use to sessile species. As a non-intrusive and continuously deployable tool, passive acoustics could be an effective approach to detecting harmful algal blooms in real time based on animal sound production. This study aimed to detect reaction changes in the valve movements of adult Pecten maximus exposed to the toxic...
Tipo: Text
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00616/72846/72899.pdf

The dinoflagellate Alexandrium minutum affects development of the oyster Crassostrea gigas, through parental or direct exposure
Provedor de dados: 5
Autores: Castrec, Justine; Hegaret, Helene; Alunno-bruscia, Marianne; Picard, Mailys; Soudant, Philippe; Petton, Bruno; Boulais, Myrina; Suquet, Marc; Queau, Isabelle; Ratiskol, Dominique; Foulon, Valentin; Le Goic, Nelly; Fabioux, Caroline.
Harmful algal blooms are a threat to aquatic organisms and coastal ecosystems. Among harmful species, the widespread distributed genus Alexandrium is of global importance. This genus is well-known for the synthesis of paralytic shellfish toxins which are toxic for humans through the consumption of contaminated shellfish. While the effects of Alexandrium species upon the physiology of bivalves are now well documented, consequences on reproduction remain poorly studied. In France, Alexandrium minutum blooms have been recurrent for the last decades, generally appearing during the reproduction season of most bivalves including the oyster Crassostrea gigas. These blooms could not only affect gametogenesis but also spawning, larval development or juvenile...
Tipo: Text
Palavras-chave: Harmful algal bloom (HAB); Paralytic shellfish toxin (PST); Crassostrea gigas; Gametes; Larvae.
Ano: 2019
URL: https://archimer.ifremer.fr/doc/00469/58099/60512.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

Influence of gametogenesis pattern and sex on paralytic shellfish toxin levels in triploid Pacific oyster Crassostrea gigas exposed to a natural bloom of Alexandrium minutum
Provedor de dados: 5
Autores: 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

Flow cytometric assessment of morphology, viability, and production of reactive oxygen species of Crassostrea gigas oocytes. Application to Toxic dinoflagellate (Alexandrium minutum) exposure
Provedor de dados: 5
Autores: Le Goic, Nelly; Hegaret, Helene; Boulais, Myrina; Beguel, Jean-philippe; Lambert, Christophe; Fabioux, Caroline; Soudant, Philippe.
The Pacific oyster Crassostrea gigas accounts for a large part of shellfish aquaculture production worldwide. Aspects of morphological and functional characteristics of oyster oocytes remain poorly documented, and traditional techniques, such as microscopic observations of shape or fertilization rate, are time and space consuming. The purpose of this study was to assess for the first time viability and reactive oxygen species (ROS) production of Pacific oyster oocytes using flow cytometry (FCM) and to apply this method to determine oocyte responses to in vitro exposure to the toxic dinoflagellate Alexandrium minutum. A culture of A. minutum caused a significant increase in oocyte ROS production, which gradually increased with the age of the culture, but...
Tipo: Text
Palavras-chave: Pacific oyster; Gamete quality; ROS production; Viability; Flow cytometry; Ecotoxicology.
Ano: 2014
URL: https://archimer.ifremer.fr/doc/00216/32760/31321.pdf

Exposure to toxic Alexandrium minutum activates the detoxifying and antioxidant systems in gills of the oyster Crassostrea gigas
Provedor de dados: 5
Autores: 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

Why is Asari (= Manila) clam Ruditapes philippinarum fitness poor in Arcachon Bay: a meta-analysis to answer?
Provedor de dados: 5
Autores: De Montaudouin, X.; Lucia, M.; Binias, C.; Lassudrie, Malwenn; Baudrimont, M.; Legeay, A.; Raymond, N.; Jude-lemeilleur, F.; Lambert, C.; Le Goic, N.; Garabetian, F.; Gonzalez, P.; Hegaret, Helene; Lassus, Patrick; Mehdioub, W.; Bourasseau, L.; Daffe, G.; Paul-pont, I.; Plus, Martin; Do, V. T.; Meisterhans, G.; Mesmer-dudons, N.; Caill-milly, Nathalie; Sanchez, Florence; Soudant, P.
Asari (= Manila) clam, Ruditapes philippinarum, is the second bivalve mollusc in terms of production in the world and, in many coastal areas, can beget important socio-economic issues. In Europe, this species was introduced after 1973. In Arcachon Bay, after a decade of aquaculture attempt, Asari clam rapidly constituted neo-naturalized population which is now fished. However, recent studies emphasized the decline of population and individual performances. In the framework of a national project (REPAMEP), some elements of fitness, stressors and responses in Arcachon bay were measured and compared to international data (41 publications, 9 countries). The condition index (CI=flesh weight/shell weight) was the lowest among all compared sites. Variation in...
Tipo: Text
Palavras-chave: Ruditapes philippinarum; Condition index; Perkinsus; Brown Muscle Disease; Element contamination; Immune system; Arcachon Bay.
Ano: 2016
URL: https://archimer.ifremer.fr/doc/00280/39123/37676.pdf

Saxitoxin Modulates Immunological Parameters and Gene Transcription in Mytilus chilensis Hemocytes
Provedor de dados: 5
Autores: Astuya, Allisson; Carrera, Crisleri; Ulloa, Viviana; Aballay, Ambbar; Nunez-acuna, Gustavo; Hegaret, Helene; Gallardo-escarate, Cristian.
Saxitoxin (STX) is a neurotoxin produced by dinoflagellates in diverse species, such as Alexandrium spp., and it causes paralytic shellfish poisoning (PSP) in humans after the ingestion of contaminated shellfish. Recent studies have suggested that the immune functions of bivalves could be affected by harmful algae and/or by their toxins. Herein, hemocytes are the main effector cells of the immune cellular response. In this study, we evaluated the response of hemocytes from the mussel Mytilus chilensis to STX exposure in a primary culture. Cell cultures were characterized according to size and complexity, while reactive oxygen species (ROS) production was evaluated using a dichlorofluorescein diacetate (DCFH-DA) assay. Finally, phagocytic activity was...
Tipo: Text
Palavras-chave: Saxitoxin; Hemocytes; Immune response; Paralytic shellfish poisoning; Reactive oxygen species (ROS).
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00278/38954/73180.pdf

Modelling paralytic shellfish toxins (PST) accumulation in Crassostrea gigas by using Dynamic Energy Budgets (DEB)
Provedor de dados: 5
Autores: 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

Allelochemicals from Alexandrium minutum induce rapid inhibition of metabolism and modify the membranes from Chaetoceros muelleri
Provedor de dados: 5
Autores: 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

Effects of marine harmful algal blooms on bivalve cellular immunity and infectious diseases: A review
Provedor de dados: 5
Autores: Lassudrie Duchesne, Malwenn; Hegaret, Helene; Wikfors, Gary H; Mirella Da Silva, Patricia.
Bivalves were long thought to be “symptomless carriers” of marine microalgal toxins to human seafood consumers. In the past three decades, science has come to recognize that harmful algae and their toxins can be harmful to grazers, including bivalves. Indeed, studies have shown conclusively that some microalgal toxins function as active grazing deterrents. When responding to marine Harmful Algal Bloom (HAB) events, bivalves can reject toxic cells to minimize toxin and bioactive extracellular compound (BEC) exposure, or ingest and digest cells, incorporating nutritional components and toxins. Several studies have reported modulation of bivalve hemocyte variables in response to HAB exposure. Hemocytes are specialized cells involved in many functions in...
Tipo: Text
Palavras-chave: Bivalve; Harmful algal blooms (HABs); Pathogen; Hemocyte; Disease.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00612/72401/71346.pdf