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| Le Gall, G; Mialhe, Eric; Chagot, D; Grizel, Henri. |
| Rickettsia-like microorganisms were described in gill endothelial cells during mass mortalities of Saint-Jacques scallops Pecten maximus in Saint-Brieuc Bay (North Brittany, France) during winter 1985-86. In order to evaluate the epizootiological significance of rickettsiosis of scallops, an analytical and descriptive epizootiological study was undertaken. The study included the geographic distribution, incidence and severity of the disease for several northern European and French scallop populations. Since the center of French scallop production is in Saint-Brieuc Bay, epizootiological investigations were concentrated in this area. Dissemination appeared to be by horizontal transmission. The pathogenic significance of the rickettsia-like organism in... |
| Tipo: Text |
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| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/1991/publication-2758.pdf |
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| Le Gall, G; Bachere, Evelyne; Mialhe, Eric. |
| During a study of Rickettsiales-like organisms (RLO) in Pecten maximus gill, histological observation of free RLO in hemoclymph led us to consider interactions between the pathogen and the hemocytes. Firstly, the production of oxygen radicals by hemocytes was established using a luminol-enhanced chemiluminescence method with zymosan axs stimulant. The effects of serveral inhibitors of oxidative metabolism were investigated. The internalization of RLO into hemocytes was demonstrated by electron microscopy but was not related to chemiluminescent activity. The possible involvement of RLO acid phosphatase as the inhibitor of respiratory burst was assessed. |
| Tipo: Text |
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| Ano: 1991 |
URL: http://archimer.ifremer.fr/doc/1991/publication-2759.pdf |
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| Kellner-cousin, Kristell; Le Gall, G; Despres, Béatrice; Kaghad, M; Legoux, P; Shire, D; Mialhe, Eric. |
| Genomic DNA fragments of a rickettsia-like organism (RLO) of Saint-Jacques scallop, Pecten maximus, were extracted from purified RLO and cloned. A DNA sequence of 1500 bp taken from one of the sequenced clones was coupled to horseradish peroxidase and the resulting probe was assayed for the diagnosis of RLO by nucleic acid hybridization. The specificity of the probe for RLO DNA was established from its lack of hybridization with scallop DNA. The sensitivity limit of the probe detected by enhanced chemiluminescence was determined to be around 500 ng of total RLO nucleic acids, equivalent to about 2.5 X 106 copies of RLO DNA. A pair of polymerase chain reaction (PCR) primers were synthesized that amplified a 1300 bp segment of the 1500 bp RLO fragment. After... |
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| Ano: 1993 |
URL: http://archimer.ifremer.fr/doc/1993/publication-2771.pdf |
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| Le Gall, G; Mialhe, Eric. |
| Significant mortalities have been observed in populations of Saint-Jacques scallops Pecten maximus, in association with numerous intrace1lular colonies of Rickettsiales-like organisms (RLO) in the gi1ls. Isolation of the procaryotes from infected tissues and their subsequent purification were achieved by a specific protocol based on differential and isopycnic centrifugations on sucrose and renografin density gradients. The purity and integrity of purified procaryotes were verified by electron microscopy. Specific polyclonal antibodies were prepared for serological characterization. Fifteen major constituent proteins were electrophoretically identified, their molecular weights ranging between 148 and 16 kD. Ten enzyme activities were biochemica1ly... |
| Tipo: Text |
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| Ano: 1992 |
URL: http://archimer.ifremer.fr/doc/1992/publication-2769.pdf |
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