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Isabelle Arzul - One of the best experts on this subject based on the ideXlab platform.
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an edna erna based approach to investigate the life cycle of non cultivable shellfish micro parasites the case of bonamia Ostreae a parasite of the european flat oyster Ostrea edulis
Microbial Biotechnology, 2020Co-Authors: Nicolas Merou, Cyrielle Lecadet, Stephane Pouvreau, Isabelle ArzulAbstract:Environmental DNA approaches are increasingly used to detect microorganisms in environmental compartments, including water. They show considerable advantages to study non-cultivable microorganisms like Bonamia Ostreae, a protozoan parasite inducing significant mortality in populations of flat oyster Ostrea edulis. Although B. Ostreae development within the host has been well described, questions remain about its behaviour in the environment. As B. Ostreae transmission is direct, seawater appears as an interesting target to develop early detection tools and improve our understanding of disease transmission mechanisms. In this context, we have developed an eDNA/eRNA approach allowing detecting and quantifying B. Ostreae 18S rDNA/rRNA as well as monitoring its presence in seawater by real-time PCR. B. Ostreae DNA could be detected up to 4 days while RNA could be detected up to 30 days, suggesting a higher sensitivity of the eRNA-based tool. Additionally, more than 90% of shed parasites were no longer detected after 2 days outside the oysters. By allowing B. Ostreae detection in seawater, this approach would not only be useful to monitor the presence of the parasite in oyster production areas but also to evaluate the effect of changing environmental factors on parasite survival and transmission.
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An eDNA/eRNA-based approach to investigate the life cycle of non-cultivable shellfish micro-parasites: the case of Bonamia Ostreae, a parasite of the European flat oysterOstrea edulis
Microbial Biotechnology, 2020Co-Authors: Nicolas Merou, Cyrielle Lecadet, Stephane Pouvreau, Isabelle ArzulAbstract:Environmental DNA approaches are increasingly used to detect microorganisms in environmentalcompartments, including water. They show consider-able advantages to study non-cultivable microorgan-isms like Bonamia Ostreae,a protozoan parasite inducing significant mortality in populations of flat oyster Ostrea edulis. Although B. Ostreae development within the host has been well described, questions remain about its behaviour in the environment. As B. Ostreae transmission is direct, seawater appears as an interesting target to develop early detection tools and improve our understanding of disease transmission mechanisms. In this context,we have developed an eDNA/eRNA approach allowing detecting and quantifying B. Ostreae 18S rDNA/rRNA as well as monitoring its presence in seawaterby real-time PCR. B. Ostreae DNA could be detected up to 4 days while RNA could be detected up to 30 days, suggesting a higher sensitivity of the eRNA-based tool. Additionally, more than 90% of shed parasites were no longer detected after 2 days outside the oysters. By allowing B. Ostreae detection in seawater, this approach would not only be useful to monitor the presence of the parasite in oyster production areas but also to evaluate the effect of changing environmental factors on parasite survival and transmission.
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is pallial mucus involved in Ostrea edulis defenses against the parasite bonamia Ostreae
Journal of Invertebrate Pathology, 2020Co-Authors: Maria Pradoalvarez, Ophelie Gervais, Sergio Fernandezboo, Stephane Claverol, Cyrielle Lecadet, Christine Dubreuil, Bruno Chollet, Isabelle ArzulAbstract:Abstract Bonamia Ostreae is an intrahemocytic parasite that has been responsible for severe mortalities in the flat oyster Ostrea edulis since the 1970s. The Pacific oyster CrassOstrea gigas is considered to be resistant to the disease and appears to have mechanisms to avoid infection. Most studies carried out on the invertebrate immune system focus on the role of hemolymph, although mucus, which covers the body surface of molluscs, could also act as a barrier against pathogens. In this study, the in vitro effect of mucus from the oyster species Ostrea edulis and C. gigas on B. Ostreae was investigated using flow cytometry. Results showed an increase in esterase activities and mortality rate of parasites exposed to mucus from both oyster species. In order to better understand the potential role of mucus in the defense of the oyster against parasites such as B. Ostreae, liquid chromatography and tandem mass spectrometry were used to describe and compare mucus protein composition from both species. In all oyster species, pallial mucus contains a high level of proteins; however, O. edulis mucus produced a variety of proteins that could be involved in the immune response against the parasite, including Cu/Zn extracellular superoxide dismutase, thioxiredoxin, peroxiredon VI, heat shock protein 90 as well as several hydrolases. Conversely, a different set of antioxidant proteins, hydrolases and stress related proteins were identified in mucus from C. gigas. Our results suggest an innate immunity adaptation of oysters to develop a specific response against their respective pathogens. The mucosal protein composition also provides new insights for further investigations into the immune response in oysters.
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involvement of apoptosis in the dialogue between the parasite bonamia Ostreae and the flat oyster Ostrea edulis
Fish & Shellfish Immunology, 2019Co-Authors: Ophelie Gervais, Cyrielle Lecadet, Christine Dubreuil, Serena Durante, Cyril Henard, Delphine Serpin, Renault Tristan, Bruno Chollet, Chunyan Feng, Isabelle ArzulAbstract:The protozoan parasite Bonamia Ostreae has been associated with the decline of flat oyster Ostrea edulis populations in some European countries. Control of shellfish diseases mostly relies on prevention measures including transfer restrictions and stock management measures such as breeding programmes. These prevention and mitigation measures require a better understanding of interactions between host and pathogens. Previous in vitro studies allowed identifying apoptosis as a mechanism activated by the flat oyster in response to B. Ostreae. However, these experiments also suggested that the parasite is able to regulate apoptosis in order to survive and multiply within hemocytes. By simplifying the conditions of infection, in vitro studies allow identifying most distinct features of the response of the host. In order to appreciate the relative importance of apoptosis in this response at the oyster scale, in vivo trials were carried out by injecting with parasites oysters from two French locations, Quiberon Bay (Brittany) and Diana Lagoon (Corsica). Apoptosis was investigated on pools of hemolymph from oysters collected at early and later times after injection using previously developed tools. Apoptotic cellular activities including intracytoplasmic calcium concentration, mitochondrial membrane potential and phosphatidyl serine externalization were analysed using flow cytometry. Moreover, the expression of flat oyster genes involved in both extrinsic and intrinsic pathways was measured using real time quantitative PCR.
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Molecular and cellular characterization of apoptosis in flat oyster a key mechanisms at the heart of host-parasite interactions
Scientific Reports, 2018Co-Authors: Ophelie Gervais, Tristan Renault, Isabelle ArzulAbstract:Bonamia Ostreae has been associated with the decline of flat oyster Ostrea edulis populations in some European countries. This obligatory intracellular parasite persists and multiplies into hemocytes. Previous in vitro experiments showed that apoptosis is activated in hemocytes between 1 h and 4 h of contact with the parasite. The flat oyster uses the apoptosis pathway to defend against B . Ostreae . However, the parasite might be also able to modulate this response in order to survive in its host. In order to investigate this hypothesis the apoptotic response of the host was evaluated using flow cytometry, transmission electron microscopy and by measuring the response of genes involved in the apoptotic pathway after 4 h. In parallel, the parasite response was investigated by measuring the expression of B . Ostreae genes involved in different biological functions including cell cycle and cell death. Obtained results allow describing molecular apoptotic pathways in O . edulis and confirm that apoptosis is early activated in hemocytes after a contact with B . Ostreae . Interestingly, at cellular and molecular levels this process appeared downregulated after 44 h of contact. Concurrently, parasite gene expression appeared reduced suggesting that the parasite could inhibit its own metabolism to escape the immune response.
Tristan Renault - One of the best experts on this subject based on the ideXlab platform.
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Molecular and cellular characterization of apoptosis in flat oyster a key mechanisms at the heart of host-parasite interactions
Scientific Reports, 2018Co-Authors: Ophelie Gervais, Tristan Renault, Isabelle ArzulAbstract:Bonamia Ostreae has been associated with the decline of flat oyster Ostrea edulis populations in some European countries. This obligatory intracellular parasite persists and multiplies into hemocytes. Previous in vitro experiments showed that apoptosis is activated in hemocytes between 1 h and 4 h of contact with the parasite. The flat oyster uses the apoptosis pathway to defend against B . Ostreae . However, the parasite might be also able to modulate this response in order to survive in its host. In order to investigate this hypothesis the apoptotic response of the host was evaluated using flow cytometry, transmission electron microscopy and by measuring the response of genes involved in the apoptotic pathway after 4 h. In parallel, the parasite response was investigated by measuring the expression of B . Ostreae genes involved in different biological functions including cell cycle and cell death. Obtained results allow describing molecular apoptotic pathways in O . edulis and confirm that apoptosis is early activated in hemocytes after a contact with B . Ostreae . Interestingly, at cellular and molecular levels this process appeared downregulated after 44 h of contact. Concurrently, parasite gene expression appeared reduced suggesting that the parasite could inhibit its own metabolism to escape the immune response.
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flat oyster follows the apoptosis pathway to defend against the protozoan parasite bonamia Ostreae
Fish & Shellfish Immunology, 2016Co-Authors: Ophelie Gervais, Tristan Renault, Bruno Chollet, Isabelle ArzulAbstract:The in vitro model Ostrea edulis hemocyte - Bonamia Ostreae is interesting to investigate host-parasite interactions at the cellular level. Indeed, this unicellular parasite infects the flat oyster Ostrea edulis and multiplies within hemocytes, the central effectors of oyster defenses. Apoptosis is a mechanism used by many organisms to eliminate infected cells. In order to study the potential involvement of this mechanism in the oyster response to B. Ostreae, in vitro experiments were carried out by exposing hemocytes from the naturally susceptible oyster O. edulis and a resistant oyster species CrassOstrea gigas to live and heat-inactivated parasites. Hemocyte apoptotic response was measured using a combination of flow cytometry and microscopy analyses. Whatever the host species was, the parasite was engulfed in hemocytes and induced an increase of apoptotic parameters including intracytoplasmic calcium concentration, mitochondrial membrane potential or phosphatidyl-serine externalization as well as ultrastructural modifications. However, the parasite appears more able to infect flat oyster than cupped oyster hemocytes and the apoptotic response was more important against live than dead parasites in the natural host than in C. gigas. Our results suggest that O. edulis specifically responds to B. Ostreae by inducing apoptosis of hemocytes.
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new insights in flat oyster Ostrea edulis resistance against the parasite bonamia Ostreae
Fish & Shellfish Immunology, 2012Co-Authors: Benjamin Morga, Tristan Renault, Nicole Faury, Isabelle ArzulAbstract:Bonamiosis due to the parasite Bonamia Ostreae has been associated with massive mortality in flat oyster stocks in Europe. Control of the disease currently relies on disease management practices and transfer restriction. Previously, massal selections based on survival to challenge to infection with B. Ostreae have been applied to produce flat oyster families with resistant progeny. In an attempt to understand the molecular mechanisms involved in disease resistance, differentially expressed sequence tags between resistant and wild Ostrea edulis haemocytes, both infected with the parasite, were identified using suppression subtractive hybridisation. Expression of seven ESTs has been studied using quantitative reverse-transcriptase PCR. The base-line expression of an extracellular superoxide dismutase, inhibitor of apoptosis (OeIAP), Fas ligand (OeFas-ligand) and Cathepsin B was significantly increased, whilst cyclophilin B appeared significantly decreased in resistant oysters. Considering their great interest for further studies, the open reading frames of the OeFas-ligand and OeIAP were completely sequenced.
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cellular and molecular responses of haemocytes from Ostrea edulis during in vitro infection by the parasite bonamia Ostreae
International Journal for Parasitology, 2011Co-Authors: Benjamin Morga, Tristan Renault, Nicole Faury, Bruno Chollet, Isabelle ArzulAbstract:Abstract Bonamia Ostreae is a protozoan, affiliated to the order Haplosporidia and to the phylum Cercozoa. This parasite is intracellular and infects haemocytes, cells notably involved in oyster defence mechanisms. Bonamiosis due to the parasite B. Ostreae is a disease affecting the flat oyster, Ostrea edulis. The strategies used by protozoan parasites to circumvent host defence mechanisms remain largely unknown in marine bivalve molluscs. In the present work, in vitro experiments were carried out in order to study the interactions between haemocytes from O. edulis and purified parasite, B. Ostreae. We monitored cellular and molecular responses of oyster haemocytes by light microscopy, flow cytometry and real-time PCR 1, 2, 4 and 8 h p.i. Light microscopy was used to measure parasite phagocytosis by oyster haemocytes. Parasites were observed inside haemocytes 1 h p.i. and the parasite number increased during the time course of the experiment. Moreover, some bi-nucleated and tri-nucleated parasites were found within haemocytes 2 and 4 h p.i., respectively, suggesting that the parasite can divide inside haemocytes. Host responses to B. Ostreae were investigated at the cellular and molecular levels using flow cytometry and real-time PCR. Phagocytosis capacity of haemocytes, esterase activity and production of radical oxygen species appeared modulated during the infection with B. Ostreae. Expression levels of expressed sequence tags selected in this study showed variations during the experiment as soon as 1 h p.i. An up-regulation of galectin (OeGal), cytochrome p450 (CYP450), lysozyme, omega GST (OGST), super oxide dismutase Cu/Zn (Oe-SOD Cu/Zn) and a down-regulation of the extracellular super oxide dismutase SOD (Oe-EcSOD) were observed in the presence of the parasite. Finally, the open reading frames of both SODs (Oe-SOD Cu/Zn and Oe-EcSOD) were completely sequenced. These findings provide new insights into the cellular and molecular bases of the host–parasite interactions between the flat oyster, O. edulis, and the parasite, B. Ostreae.
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molecular responses of Ostrea edulis haemocytes to an in vitro infection with bonamia Ostreae
Developmental and Comparative Immunology, 2011Co-Authors: Benjamin Morga, Nicole Faury, Amelie Segarra, Isabelle Arzul, Bruno Chollet, Tristan RenaultAbstract:Bonamiosis due to the parasite Bonamia Ostreae is a disease affecting the flat oyster Ostrea edulis. B. Ostreae is a protozoan, affiliated to the order of haplosporidia and to the cercozoan phylum. This parasite is mainly intracellular, infecting haemocytes, cells notably involved in oyster defence mechanisms. Suppression subtractive hybridisation (SSH) was carried out in order to identify oyster genes differentially expressed during an infection of haemocytes with B. Ostreae. Forward and reverse banks allowed obtaining 1104 and 1344 clones respectively, among which 391 and 480 clones showed a differential expression between both tested conditions (haemocytes alone versus haemocytes in contact with parasites). ESTs of interest including genes involved in cytoskeleton, respiratory chain, detoxification membrane receptors, and immune system were identified. The open reading frames of two selected genes (galectin and IRF-like) were completely sequenced and characterized. Real time PCR assays were developed to study the relative expression of candidate ESTs during an in vitro infection of haemocytes by live and dead parasites. Haemocyte infection with B. Ostreae induced an increased expression of omega glutathione Stransferase (OGST), superoxide dismutase (SOD), tissue inhibitor of metalloproteinase (TIMP), galectin, interferon regulatory factor (IRF-like) and filamin genes.
Benjamin Morga - One of the best experts on this subject based on the ideXlab platform.
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heat shock protein 90 of bonamia Ostreae characterization and possible correlation with infection of the flat oyster Ostrea edulis
Journal of Eukaryotic Microbiology, 2013Co-Authors: Maria Pradoalvarez, Yann Couraleau, Benjamin Morga, Bruno Chollet, Isabelle ArzulAbstract:In this study, we described the cytosolic HSP90 of Bonamia Ostreae, an intracellular parasite of Ostrea edulis hemocytes. The complete open reading frame was assembled by Rapid Amplification cDNA Ends reactions on cDNA of B. Ostreae-infected hemocytes. HSP90 amplification was corroborated in infected oysters and B. Ostreae purified cells. The functionality of the HSP90, studied by inhibitory assays with radicicol, suggests that this protein may play a role in hemocyte invasion. Our results inform the molecular basis that governs B. Ostreae-O. edulis interactions.
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new insights in flat oyster Ostrea edulis resistance against the parasite bonamia Ostreae
Fish & Shellfish Immunology, 2012Co-Authors: Benjamin Morga, Tristan Renault, Nicole Faury, Isabelle ArzulAbstract:Bonamiosis due to the parasite Bonamia Ostreae has been associated with massive mortality in flat oyster stocks in Europe. Control of the disease currently relies on disease management practices and transfer restriction. Previously, massal selections based on survival to challenge to infection with B. Ostreae have been applied to produce flat oyster families with resistant progeny. In an attempt to understand the molecular mechanisms involved in disease resistance, differentially expressed sequence tags between resistant and wild Ostrea edulis haemocytes, both infected with the parasite, were identified using suppression subtractive hybridisation. Expression of seven ESTs has been studied using quantitative reverse-transcriptase PCR. The base-line expression of an extracellular superoxide dismutase, inhibitor of apoptosis (OeIAP), Fas ligand (OeFas-ligand) and Cathepsin B was significantly increased, whilst cyclophilin B appeared significantly decreased in resistant oysters. Considering their great interest for further studies, the open reading frames of the OeFas-ligand and OeIAP were completely sequenced.
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cellular and molecular responses of haemocytes from Ostrea edulis during in vitro infection by the parasite bonamia Ostreae
International Journal for Parasitology, 2011Co-Authors: Benjamin Morga, Tristan Renault, Nicole Faury, Bruno Chollet, Isabelle ArzulAbstract:Abstract Bonamia Ostreae is a protozoan, affiliated to the order Haplosporidia and to the phylum Cercozoa. This parasite is intracellular and infects haemocytes, cells notably involved in oyster defence mechanisms. Bonamiosis due to the parasite B. Ostreae is a disease affecting the flat oyster, Ostrea edulis. The strategies used by protozoan parasites to circumvent host defence mechanisms remain largely unknown in marine bivalve molluscs. In the present work, in vitro experiments were carried out in order to study the interactions between haemocytes from O. edulis and purified parasite, B. Ostreae. We monitored cellular and molecular responses of oyster haemocytes by light microscopy, flow cytometry and real-time PCR 1, 2, 4 and 8 h p.i. Light microscopy was used to measure parasite phagocytosis by oyster haemocytes. Parasites were observed inside haemocytes 1 h p.i. and the parasite number increased during the time course of the experiment. Moreover, some bi-nucleated and tri-nucleated parasites were found within haemocytes 2 and 4 h p.i., respectively, suggesting that the parasite can divide inside haemocytes. Host responses to B. Ostreae were investigated at the cellular and molecular levels using flow cytometry and real-time PCR. Phagocytosis capacity of haemocytes, esterase activity and production of radical oxygen species appeared modulated during the infection with B. Ostreae. Expression levels of expressed sequence tags selected in this study showed variations during the experiment as soon as 1 h p.i. An up-regulation of galectin (OeGal), cytochrome p450 (CYP450), lysozyme, omega GST (OGST), super oxide dismutase Cu/Zn (Oe-SOD Cu/Zn) and a down-regulation of the extracellular super oxide dismutase SOD (Oe-EcSOD) were observed in the presence of the parasite. Finally, the open reading frames of both SODs (Oe-SOD Cu/Zn and Oe-EcSOD) were completely sequenced. These findings provide new insights into the cellular and molecular bases of the host–parasite interactions between the flat oyster, O. edulis, and the parasite, B. Ostreae.
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molecular responses of Ostrea edulis haemocytes to an in vitro infection with bonamia Ostreae
Developmental and Comparative Immunology, 2011Co-Authors: Benjamin Morga, Nicole Faury, Amelie Segarra, Isabelle Arzul, Bruno Chollet, Tristan RenaultAbstract:Bonamiosis due to the parasite Bonamia Ostreae is a disease affecting the flat oyster Ostrea edulis. B. Ostreae is a protozoan, affiliated to the order of haplosporidia and to the cercozoan phylum. This parasite is mainly intracellular, infecting haemocytes, cells notably involved in oyster defence mechanisms. Suppression subtractive hybridisation (SSH) was carried out in order to identify oyster genes differentially expressed during an infection of haemocytes with B. Ostreae. Forward and reverse banks allowed obtaining 1104 and 1344 clones respectively, among which 391 and 480 clones showed a differential expression between both tested conditions (haemocytes alone versus haemocytes in contact with parasites). ESTs of interest including genes involved in cytoskeleton, respiratory chain, detoxification membrane receptors, and immune system were identified. The open reading frames of two selected genes (galectin and IRF-like) were completely sequenced and characterized. Real time PCR assays were developed to study the relative expression of candidate ESTs during an in vitro infection of haemocytes by live and dead parasites. Haemocyte infection with B. Ostreae induced an increased expression of omega glutathione Stransferase (OGST), superoxide dismutase (SOD), tissue inhibitor of metalloproteinase (TIMP), galectin, interferon regulatory factor (IRF-like) and filamin genes.
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etude des interactions hote parasite chez l huitre plate Ostrea edulis et son parasite bonamia Ostreae
2010Co-Authors: Benjamin MorgaAbstract:L’histoire de l’ostreiculture francaise met en evidence la fragilite de cette production face a la surexploitation des stocks et l’apparition de maladies. En particulier, la production d’huitre plate, Ostrea edulis, a fortement diminue suite a l’apparition de deux maladies parasitaires dont la bonamiose. Les moyens de lutte contre la bonamiose sont relativement restreints. Ils sont essentiellement bases sur la surveillance de la sante des huitres afin de limiter la dissemination et la propagation de la maladie. Cependant l’utilisation de modeles predictifs de l’evolution de la maladie en zone infectee permettrait d’optimiser la gestion des stocks et minimiser l’impact des agents pathogenes. De plus, le developpement d’animaux resistants a l’infection pourrait permettre de relancer cette production. Ces differentes approches necessitent des outils diagnostiques adaptes, une bonne connaissance du cycle de vie de l’agent pathogene, et, plus particulierement des interactions du parasite avec son hote. Dans ce contexte, l’objectif principal du travail de these propose est de comprendre les interactions entre l’huitre plate Ostrea edulis et son parasite Bonamia Ostreae, et, plus particulierement les bases moleculaires de la resistance au parasite. Dans un premier temps, la realisation d’une banque soustractive d’ADNc a permis d’identifier des ESTs differentiellement exprimees chez des hemocytes en reponse au parasite. L’expression de certains genes dont une galectine a ete mesuree en PCR en temps reel dans le contexte d’infections in vitro. En complement, la reponse cellulaire a ete etudiee par cytometrie en flux et l’infection controlee en microscopie. Ces experiences ont montre une multiplication parasitaire dans les hemocytes au cours du temps associee a une diminution de la production d’EOR et d’esterases. Dans un second temps, il a ete entrepris une etude comparative entre une population d’huitres plates resistantes a la bonamiose et une population naturelle. Les resultats obtenus tendent a montrer qu’une modulation de l’apoptose et une diminution de la phagocytose seraient impliquees dans les mecanismes lies a la resistance a la bonamiose. Ce travail est le premier a etudier la reponse des hemocytes d’huitres plates a une infection par le parasite Bonamia Ostreae au niveau cellulaire et moleculaire.
Sarah C Culloty - One of the best experts on this subject based on the ideXlab platform.
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The role of invasive tunicates as reservoirs of molluscan pathogens
Biological Invasions, 2020Co-Authors: Katie E. Costello, Sharon A Lynch, Rob Mcallen, Ruth M. O’riordan, Sarah C CullotyAbstract:Ascidian tunicates frequently display rapid expansion when introduced beyond their native range and are considered successful invaders. This invasive potential may be exacerbated by a warming climate, allowing for the occupation of environmental niches previously held by native species. Research into tunicate invasion ecology is prevalent, but less is known about their role in pathogen maintenance. This study investigated the impact of invasive tunicates on the maintenance of pathogens that affect commercial bivalves, including the cultured species Ostrea edulis (European flat oyster) and CrassOstrea gigas (Pacific oyster), and the fished species Cerastoderma edule (Common cockle). Focal pathogens included ostreid herpesvirus OsHV-1 μVar, Vibrio aestuarianus , Bonamia Ostreae and Minchinia spp. The range of pathogens in their molluscan hosts was determined and the tunicates Botrylloides violaceus , Didemnum vexillum and Styela clava were then screened for these same pathogens, using both field samples from oyster culture sites and marinas and a series of laboratory cohabitation trials. Sample sites reflected areas close to and further away from known pathogen sources. PCR, Sanger sequencing and histology confirmed the presence of B. Ostreae and Minchinia mercenariae -like in S. clava , and V. aestuarianus was confirmed by qPCR in B. violaceus and D. vexillum . Furthermore, histology confirmed Minchinia mercenariae -like sporonts in S. clava suggesting that the tunicate can facilitate replication of this species. S. clava also maintained B. Ostreae in tanks with no oysters present. The results indicate that tunicates can act as reservoirs of infection in areas where disease occurs and potentially transport diseases to uninfected sites.
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a naive population of european oyster Ostrea edulis with reduced susceptibility to the pathogen bonamia Ostreae are s strategy life traits providing protection
Integrative and Comparative Biology, 2020Co-Authors: Sian Egerton, Maria Pradoalvarez, Grace Flannery, Tristan Hughjones, David Hughjones, Elaine Brennan, Sharon A Lynch, Sarah C CullotyAbstract:European populations of the native flat oyster, Ostrea edulis, have been heavily depleted by two protozoan parasites, Marteila refringens and Bonamia Ostreae, with mortalities of up to 90% reported in naive populations. However, in studies carried out over a 10-year period, researching the parasite-host relationship of B. Ostreae and O. edulis in several age cohorts within a naive O. edulis population from Loch Ryan (LR), Scotland, 1364 specimens were challenged and only 64 (5%), across multiple testing protocols, screened positive for B. Ostreae. This article presents a case for the development of S-strategy life traits in the LR population that coincide with enhanced immune function and survival. Oysters are considered typical r-strategists (small in size with fast development and high fecundity) while S-strategists, as outlined in Grime's (1977) competitor-stress tolerant-ruderal (C-S-R) triangle theory, are characterized by slow growth and investment in the durability of individuals. This study hypothesizes that slower growth and reduced reproductive output in LR oysters has resulted in the investment of an enhanced immune function and reduced susceptibility to B. Ostreae that is, r-strategists with S-strategy life traits equates to protection from significant pathogens. The findings presented here within provide a strong case study for local adaptation of energy allocation and provides empirical support for the C-S-R triangle theory in a marine organism.
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a naive population of european oyster Ostrea edulis with reduced susceptibility to the pathogen bonamia Ostreae are s strategy life traits providing protection
Integrative and Comparative Biology, 2020Co-Authors: Sian Egerton, Maria Pradoalvarez, Grace Flannery, Tristan Hughjones, David Hughjones, Elaine Brennan, Sharon A Lynch, Sarah C CullotyAbstract:European populations of the native flat oyster, Ostrea edulis, have been heavily depleted by two protozoan parasites, Marteila refringens and Bonamia Ostreae, with mortalities of up to 90% reported in naive populations. However, in studies carried out over a ten-year period, researching the parasite-host relationship of B. Ostreae and O. edulis in several age cohorts within a naive O. edulis population from Loch Ryan (LR), Scotland, 1,364 specimens were challenged and only 64 (5%), across multiple testing protocols, screened positive for B. Ostreae. This article presents a case for the development of S-strategy life traits in the LR population that coincide with enhanced immune function and survival. Oysters are considered typical r-strategists (small in size with fast development and high fecundity) while S-strategists, as outlined in Grime's (1977) C-S-R (competitor-stress tolerant-ruderal) triangle theory, are characterized by slow growth and investment in the durability of individuals. This study hypothesises that slower growth and reduced reproductive output in LR oysters has resulted in the investment of an enhanced immune function and reduced susceptibility to B. Ostreae i.e. r-strategists with S-strategy life traits equates to protection from significant pathogens. The findings presented here within provide a strong case study for local adaptation of energy allocation and provides empirical support for the C-S-R triangle theory in a marine organism.
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oral immunostimulation of the oyster Ostrea edulis impacts on the parasite bonamia Ostreae
Fish & Shellfish Immunology, 2015Co-Authors: Maria Pradoalvarez, Grainne Darmody, Tim Wontnersmith, Sharon A Lynch, A. Kane, John Cotterill, Belén G Pardo, Paulino Martínez, Sarah C CullotyAbstract:Abstract Bioactive compounds were orally administered to the native European oyster Ostrea edulis to evaluate the immune response and the progression of infection of the protozoan parasite Bonamia Ostreae . The immunostimulants lipopolysaccharide and zymosan directly administrated to the water column induced an increase in lysozyme activity and the percentage of granulocytes in naive oysters over a period of 7 days. In another set of experiments, zymosan and curdlan were microencapsulated in alginate and also administered to the water column to naive and B. Ostreae infected O. edulis . Oyster mortality, prevalence and intensity of infection and several immune parameters were evaluated up to 28 days post-administration. Lysozyme activity, nitric oxide production and the expression of galectin, lysozyme and superoxide dismutase increased after 24 h in both infected and uninfected oysters. Zymosan immunostimulated oysters displayed a decrease in the prevalence of B. Ostreae infection not attributed to mortalities but which could be associated to the enhanced ability of immunostimulants to evoke an enhanced immune response in the oysters and reduce infection.
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assessment of the impact of a pathogen bonamia Ostreae on Ostrea edulis oyster stocks with different histories of exposure to the parasite in ireland
Aquaculture, 2014Co-Authors: Grace Flannery, T F Cross, Sharon A Lynch, Jens Carlsson, Sarah C CullotyAbstract:Abstract The protozoan parasite Bonamia Ostreae has decimated Ostrea edulis stocks throughout Europe over the past four decades. A study of two stocks of O. edulis in Ireland with varying periods of exposure to B. Ostreae , 5 years and 22 years, was undertaken. The objective of the study was to determine if varying lengths of exposure would translate into observations of differing susceptibilities to B. Ostreae . A number of oyster beds within each area were screened. The study was carried out over 13 months to investigate seasonality and the role of environmental parameters, population density and size on disease development. Of particular interest was the fact that prevalence of infection in both stocks was very similar. The stock that had been exposed for 22 years had a similar prevalence, intensity and seasonality of infection as the stock infected for 5 years. B. Ostreae was detected in both stocks throughout the year with the highest prevalence in spring, possibly related to the increase in water temperature and/or oysters directing their energy towards gametogenesis. The study indicated that oyster stocks can maintain themselves over extended periods of time in B. Ostreae endemic areas. However, prevalence of B. Ostreae will remain relatively stable within the stock without some intervention to improve resistance levels e.g. by breeding for resistance over a number of years. Some natural resistance to infection will build up in individual oysters but in natural populations this will continually be diluted by cross fertilisation with more susceptible oysters.
Ophelie Gervais - One of the best experts on this subject based on the ideXlab platform.
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is pallial mucus involved in Ostrea edulis defenses against the parasite bonamia Ostreae
Journal of Invertebrate Pathology, 2020Co-Authors: Maria Pradoalvarez, Ophelie Gervais, Sergio Fernandezboo, Stephane Claverol, Cyrielle Lecadet, Christine Dubreuil, Bruno Chollet, Isabelle ArzulAbstract:Abstract Bonamia Ostreae is an intrahemocytic parasite that has been responsible for severe mortalities in the flat oyster Ostrea edulis since the 1970s. The Pacific oyster CrassOstrea gigas is considered to be resistant to the disease and appears to have mechanisms to avoid infection. Most studies carried out on the invertebrate immune system focus on the role of hemolymph, although mucus, which covers the body surface of molluscs, could also act as a barrier against pathogens. In this study, the in vitro effect of mucus from the oyster species Ostrea edulis and C. gigas on B. Ostreae was investigated using flow cytometry. Results showed an increase in esterase activities and mortality rate of parasites exposed to mucus from both oyster species. In order to better understand the potential role of mucus in the defense of the oyster against parasites such as B. Ostreae, liquid chromatography and tandem mass spectrometry were used to describe and compare mucus protein composition from both species. In all oyster species, pallial mucus contains a high level of proteins; however, O. edulis mucus produced a variety of proteins that could be involved in the immune response against the parasite, including Cu/Zn extracellular superoxide dismutase, thioxiredoxin, peroxiredon VI, heat shock protein 90 as well as several hydrolases. Conversely, a different set of antioxidant proteins, hydrolases and stress related proteins were identified in mucus from C. gigas. Our results suggest an innate immunity adaptation of oysters to develop a specific response against their respective pathogens. The mucosal protein composition also provides new insights for further investigations into the immune response in oysters.
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involvement of apoptosis in the dialogue between the parasite bonamia Ostreae and the flat oyster Ostrea edulis
Fish & Shellfish Immunology, 2019Co-Authors: Ophelie Gervais, Cyrielle Lecadet, Christine Dubreuil, Serena Durante, Cyril Henard, Delphine Serpin, Renault Tristan, Bruno Chollet, Chunyan Feng, Isabelle ArzulAbstract:The protozoan parasite Bonamia Ostreae has been associated with the decline of flat oyster Ostrea edulis populations in some European countries. Control of shellfish diseases mostly relies on prevention measures including transfer restrictions and stock management measures such as breeding programmes. These prevention and mitigation measures require a better understanding of interactions between host and pathogens. Previous in vitro studies allowed identifying apoptosis as a mechanism activated by the flat oyster in response to B. Ostreae. However, these experiments also suggested that the parasite is able to regulate apoptosis in order to survive and multiply within hemocytes. By simplifying the conditions of infection, in vitro studies allow identifying most distinct features of the response of the host. In order to appreciate the relative importance of apoptosis in this response at the oyster scale, in vivo trials were carried out by injecting with parasites oysters from two French locations, Quiberon Bay (Brittany) and Diana Lagoon (Corsica). Apoptosis was investigated on pools of hemolymph from oysters collected at early and later times after injection using previously developed tools. Apoptotic cellular activities including intracytoplasmic calcium concentration, mitochondrial membrane potential and phosphatidyl serine externalization were analysed using flow cytometry. Moreover, the expression of flat oyster genes involved in both extrinsic and intrinsic pathways was measured using real time quantitative PCR.
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Molecular and cellular characterization of apoptosis in flat oyster a key mechanisms at the heart of host-parasite interactions
Scientific Reports, 2018Co-Authors: Ophelie Gervais, Tristan Renault, Isabelle ArzulAbstract:Bonamia Ostreae has been associated with the decline of flat oyster Ostrea edulis populations in some European countries. This obligatory intracellular parasite persists and multiplies into hemocytes. Previous in vitro experiments showed that apoptosis is activated in hemocytes between 1 h and 4 h of contact with the parasite. The flat oyster uses the apoptosis pathway to defend against B . Ostreae . However, the parasite might be also able to modulate this response in order to survive in its host. In order to investigate this hypothesis the apoptotic response of the host was evaluated using flow cytometry, transmission electron microscopy and by measuring the response of genes involved in the apoptotic pathway after 4 h. In parallel, the parasite response was investigated by measuring the expression of B . Ostreae genes involved in different biological functions including cell cycle and cell death. Obtained results allow describing molecular apoptotic pathways in O . edulis and confirm that apoptosis is early activated in hemocytes after a contact with B . Ostreae . Interestingly, at cellular and molecular levels this process appeared downregulated after 44 h of contact. Concurrently, parasite gene expression appeared reduced suggesting that the parasite could inhibit its own metabolism to escape the immune response.
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etude cellulaire et moleculaire de l apoptose chez l huitre plate Ostrea edulis en reponse au parasite bonamia Ostreae
2016Co-Authors: Ophelie GervaisAbstract:L’huitre plate, Ostrea edulis, est l’espece d’huitre endemique europeenne. Sa production est aujourd’hui reduite en raison de surpeches historiques et de maladies dont la bonamiose. En raison des fortes mortalites observees chez l’huitre creuse ces dernieres annees les conchyliculteurs tendent a vouloir diversifier leur production et manifestent un regain d’interet pour cette espece patrimoniale. Neanmoins, la bonamiose, maladie due au parasite protozoaire, Bonamia Ostreae, reste un probleme majeur pour la production de cette espece. Les moyens de lutte contre cette maladie sont limites, mais necessitent de meilleures connaissances sur les interactions entre l’huitre plate et le parasite. De precedentes etudes ont suggere que l’apoptose est activee par l’huitre plate pour se defendre contre le parasite. Ce mecanisme est connu pour etre implique dans de nombreux processus biologiques dont la defense contre des organismes pathogenes. Dans ce contexte, l’objectif general de ce travail de these est de mieux caracteriser l’implication de l’apoptose dans la reponse de l’huitre plate a une infection a B. Ostreae. Des outils ont tout d’abord ete developpes afin d’etudier le processus apoptotique d’un point de vue cellulaire en cytometrie en flux et microscopie ainsi que d’un point de vue moleculaire en mesurant l’expression de genes impliques dans l’apoptose. Ces outils ont alors ete utilises pour etudier les interactions entre O. edulis et B. Ostreae in vitro et in vivo. Les resultats obtenus confirment l’implication de l’apoptose dans les mecanismes de defense de l’huitre plate en reponse a B. Ostreae et mettent en evidence la capacite du parasite a dejouer ce mecanisme afin de survivre et se multiplier dans les hemocytes. Enfin, la reponse apoptotique a ete apprehendee chez l’huitre plate et l’huitre creuse dans le cadre d’expositions a divers micro-organismes : OsHV-1, Vibrio aestuarianus et des micro-algues.
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flat oyster follows the apoptosis pathway to defend against the protozoan parasite bonamia Ostreae
Fish & Shellfish Immunology, 2016Co-Authors: Ophelie Gervais, Tristan Renault, Bruno Chollet, Isabelle ArzulAbstract:The in vitro model Ostrea edulis hemocyte - Bonamia Ostreae is interesting to investigate host-parasite interactions at the cellular level. Indeed, this unicellular parasite infects the flat oyster Ostrea edulis and multiplies within hemocytes, the central effectors of oyster defenses. Apoptosis is a mechanism used by many organisms to eliminate infected cells. In order to study the potential involvement of this mechanism in the oyster response to B. Ostreae, in vitro experiments were carried out by exposing hemocytes from the naturally susceptible oyster O. edulis and a resistant oyster species CrassOstrea gigas to live and heat-inactivated parasites. Hemocyte apoptotic response was measured using a combination of flow cytometry and microscopy analyses. Whatever the host species was, the parasite was engulfed in hemocytes and induced an increase of apoptotic parameters including intracytoplasmic calcium concentration, mitochondrial membrane potential or phosphatidyl-serine externalization as well as ultrastructural modifications. However, the parasite appears more able to infect flat oyster than cupped oyster hemocytes and the apoptotic response was more important against live than dead parasites in the natural host than in C. gigas. Our results suggest that O. edulis specifically responds to B. Ostreae by inducing apoptosis of hemocytes.
