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| Gervais, Ophelie. |
| L’huître plate (Ostrea edulis) est une espèce endémique des côtes de l’Europe. Sa production a fortement diminué suite à l’apparition de deux parasites Bonamia ostreae et Marteilia refringens. B. ostreae est un parasite protozoaire dont les cellules hôtes sont les cellules immunitaires (hémocytes). Les hémocytes sont un modèle de choix grâce à leur double rôle : cellules cibles du parasite et acteurs des mécanismes de défense. B. ostreae semblerait pouvoir contourner les mécanismes de défense en modulant des activités de types estérases, espèces oxygénées réactives et en modulant l’expression de gènes impliqués dans l’apoptose (mort cellulaire programmée) (OeIAP, OeFas-ligand). L’apoptose, mécanisme important de défense contre les organismes pathogènes,... |
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| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00303/41421/40608.pdf |
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| Gervais, Ophelie. |
| The flat oyster, Ostrea edulis, is the European endemic oyster species. Its production has been reduced because of overfishing and diseases including bonamiosis. Massive mortalities observed on the Pacific cupped oyster these last years explained the wish of shellfish farmers to diversify their production and their revival of interest for this patrimonial oyster species. However, bonamiosis due to the protozoan, Bonamia ostreae, is still a major problem for the production of this species. Measures to control the disease are limited and require a better knowledge of the interactions between the flat oyster and the parasite. Previous studies have suggested the involvement of apoptosis in flat oyster defense mechanisms against B. ostreae. This mechanism is... |
| Tipo: Text |
Palavras-chave: Huître plate; Ostrea edulis; Bonamia ostreae; Apoptose; Flat oyster; Ostrea edulis; Bonamia ostreae; Apoptosis. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00370/48142/48243.pdf |
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| Gervais, Ophelie; Chollet, Bruno; Renault, Tristan; Arzul, Isabelle. |
| 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.... |
| Tipo: Text |
Palavras-chave: Apoptosis; Host-parasite interactions; Parasite; Oyster; Bonamia ostreae; Ostrea edulis. |
| Ano: 2016 |
URL: http://archimer.ifremer.fr/doc/00346/45692/45312.pdf |
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| Martenot, Claire; Gervais, Ophelie; Chollet, Bruno; Houssin, Maryline; Renault, Tristan. |
| Recent transcriptomic approaches focused on anti-viral immunity in molluscs lead to the assumption that the innate immune system, such as apoptosis, plays a crucial role against ostreid herpesvirus type 1 (OsHV-1), infecting Pacific cupped oyster, Crassostrea gigas. Apoptosis constitutes a major mechanism of anti-viral response by limiting viral spread and eliminating infected cells. In this way, an OsHV-1 challenge was performed and oysters were monitored at three times post injection to investigate viral infection and host response: 2h (early after viral injection in the adductor muscle), 24h (intermediate time), and 48h (just before first oyster mortality record). Virus infection, associated with high cumulative mortality rates (74% and 100%), was... |
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| Ano: 2017 |
URL: http://archimer.ifremer.fr/doc/00386/49715/50244.pdf |
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| Gervais, Ophelie; Renault, Tristan; Arzul, Isabelle. |
| Apoptosis is a fundamental feature in the development of many organisms and tissue systems. It is also a mechanism of host defense against environmental stress factors or pathogens by contributing to the elimination of infected cells. Hemocytes play a key role in defense mechanisms in invertebrates and previous studies have shown that physical or chemical stress can increase apoptosis in hemocytes in mollusks. However this phenomenon has rarely been investigated in bivalves especially in the flat oyster Ostrea edulis. The apoptotic response of hemocytes from flat oysters, O. edulis, was investigated after exposure to UV and dexamethasone, two agents known to induce apoptosis in vertebrates. Flow cytometry and microscopy were combined to demonstrate that... |
| Tipo: Text |
Palavras-chave: Apoptosis; Hemocyte(s); Oyster; Ostrea edulis; UV; Flow cytometry; Microscopy. |
| Ano: 2015 |
URL: http://archimer.ifremer.fr/doc/00270/38160/36295.pdf |
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| Fernández-boo, Sergio; Gervais, Ophelie; Prado-alvarez, Maria; Chollet, Bruno; Claverol, Stéphane; Lecadet, Cyrielle; Dubreuil, Christine; Arzul, Isabelle. |
| Bonamia ostreae is an intrahemocytic parasite that has been responsible for severe mortalities in the flat oyster Ostrea edulis since the 1970́s. 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... |
| Tipo: Text |
Palavras-chave: Bonamia ostreae; Crassostrea gigas; Ostrea edulis; Flow cytometry; Immune response; Proteome. |
| Ano: 2020 |
URL: https://archimer.ifremer.fr/doc/00594/70602/68795.pdf |
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| Gervais, Ophelie; Renault, Tristan; Arzul, Isabelle. |
| 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... |
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| Ano: 2018 |
URL: http://archimer.ifremer.fr/doc/00454/56540/58246.pdf |
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