Michaël Roussel
Centre national de la recherche scientifique
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Featured researches published by Michaël Roussel.
Genome Biology | 2011
Michaël Roussel; Benjamin Noel; Ivan Wawrzyniak; Corinne Da Silva; Marie Diogon; Eric Viscogliosi; Céline Brochier-Armanet; Arnaud Couloux; Julie Poulain; Béatrice Segurens; Véronique Anthouard; Catherine Texier; Nicolas Blot; Philippe Poirier; G. C. Ng; Kevin Tan; François Artiguenave; Olivier Jaillon; Jean-Marc Aury; Frédéric Delbac; Patrick Wincker; Christian P. Vivarès; Hicham El Alaoui
BackgroundBlastocystis is a highly prevalent anaerobic eukaryotic parasite of humans and animals that is associated with various gastrointestinal and extraintestinal disorders. Epidemiological studies have identified different subtypes but no one subtype has been definitively correlated with disease.ResultsHere we report the 18.8 Mb genome sequence of a Blastocystis subtype 7 isolate, which is the smallest stramenopile genome sequenced to date. The genome is highly compact and contains intriguing rearrangements. Comparisons with other available stramenopile genomes (plant pathogenic oomycete and diatom genomes) revealed effector proteins potentially involved in the adaptation to the intestinal environment, which were likely acquired via horizontal gene transfer. Moreover, Blastocystis living in anaerobic conditions harbors mitochondria-like organelles. An incomplete oxidative phosphorylation chain, a partial Krebs cycle, amino acid and fatty acid metabolisms and an iron-sulfur cluster assembly are all predicted to occur in these organelles. Predicted secretory proteins possess putative activities that may alter host physiology, such as proteases, protease-inhibitors, immunophilins and glycosyltransferases. This parasite also possesses the enzymatic machinery to tolerate oxidative bursts resulting from its own metabolism or induced by the host immune system.ConclusionsThis study provides insights into the genome architecture of this unusual stramenopile. It also proposes candidate genes with which to study the physiopathology of this parasite and thus may lead to further investigations into Blastocystis-host interactions.
International Journal for Parasitology | 2008
Ivan Wawrzyniak; Michaël Roussel; Marie Diogon; Arnaud Couloux; Catherine Texier; Kevin S. W. Tan; Christian P. Vivarès; Frédéric Delbac; Patrick Wincker; Hicham El Alaoui
Blastocystis hominis is an anaerobic parasite of the human intestinal tract belonging to the Stramenopile group. Using genome sequencing project data, we describe here the complete sequence of a 29,270-bp circular DNA molecule that presents mitochondrial features (such as oxidative phosphorylation complex I subunits) but lacks complexes III, IV and V. Transmission electron microscopy analyses reveal that this molecule, as well as mitochondrial (NADH:ubiquinone oxidoreductase subunit 7 (NAD7), beta-succinyl-CoA synthetase (beta-SCS)) and hydrogenosomal (pyruvate ferredoxin oxido-reductase (PFOR), iron-hydrogenase) proteins, are located within double-membrane surrounded-compartments known as mitochondria-like organelles (MLOs). As there is no evidence for hydrogen production by this organism, we suggest that MLOs are more likely anaerobic mitochondria.
Journal of Biological Chemistry | 2010
Binhui Wu; Jing Yin; Catherine Texier; Michaël Roussel; Kevin S. W. Tan
Programmed cell death (PCD) is crucial for cellular growth and development in multicellular organisms. Although distinct PCD features have been described for unicellular eukaryotes, homology searches have failed to reveal clear PCD-related orthologues among these organisms. Our previous studies revealed that a surface-reactive monoclonal antibody (mAb) 1D5 could induce multiple PCD pathways in the protozoan Blastocystis. In this study, we identified, by two-dimensional gel electrophoresis and mass spectrometry, the target of mAb 1D5 as a surface-localized legumain, an asparagine endopeptidase that is usually found in lysosomal/acidic compartments of other organisms. Recombinant Blastocystis legumain displayed biphasic pH optima in substrate assays, with peaks at pH 4 and 7.5. Activity of Blastocystis legumain was greatly inhibited by the legumain-specific inhibitor carbobenzyloxy-Ala-Ala-AAsn-epoxycarboxylate ethyl ester (APE-RR) (where AAsn is aza-asparagine) and moderately inhibited by mAb 1D5, cystatin, and caspase-1 inhibitor. Interestingly, inhibition of legumain activity induced PCD in Blastocystis, observed by increased externalization of phosphatidylserine residues and in situ DNA fragmentation. In contrast to plants, in which legumains have been shown to play a pro-death role, legumain appears to display a pro-survival role in Blastocystis.
Carbohydrate Polymers | 2015
Michaël Roussel; Aurore Villay; Frédéric Delbac; Philippe Michaud; Céline Laroche; D. Roriz; H. El Alaoui; Marie Diogon
Nosemosis is one of the most common and widespread diseases of adult honeybees. The causative agents, Nosema apis and Nosema ceranae, belong to microsporidia some obligate intracellular eukaryotic parasites. In this study, 10 sulphated polysaccharides from algae were evaluated for their antimicrosporidian activity. They were first shown to inhibit the in vitro growth of the mammal microsporidian model, Encephalitozoon cuniculi. The most efficient polysaccharides were then tested for their ability to inhibit the growth of Nosema ceranae in experimentally-infected adult honeybees. Two polysaccharides extracted from Porphyridium spp. did not show any toxicity in honeybees and one of them allowed a decrease of both parasite load and mortality rate due to N. ceranae infection. A decrease in parasite abundance but not in mortality rate was also observed with an iota carrageenan. Our results are promising and suggest that algal sulphated polysaccharides could be used to prevent and/or control bee nosemosis.
Fems Microbiology Letters | 2013
Valérie Polonais; Abdel Belkorchia; Michaël Roussel; Eric Peyretaillade; Pierre Peyret; Marie Diogon; Frédéric Delbac
Microsporidia are obligate intracellular eukaryotic parasites with a broad host spectrum characterized by a unique and highly sophisticated invasion apparatus, the polar tube (PT). In a previous study, two PT proteins, named AlPTP1 (50 kDa) and AlPTP2 (35 kDa), were identified in Antonospora locustae, an orthoptera parasite that is used as a biological control agent against locusts. Antibodies raised against AlPTP2 cross-reacted with a band migrating at ~70 kDa, suggesting that this 70-kDa antigen is closely related to AlPTP2. A blastp search against the A. locustae genome database allowed the identification of two further PTP2-like proteins named AlPTP2b (568 aa) and AlPTP2c (599 aa). Both proteins are characterized by a specific serine- and glycine-rich N-terminal extension with elastomeric structural features and share a common C-terminal end conserved with AlPTP2 (~88% identity for the last 250 aa). MS analysis of the 70-kDa band revealed the presence of AlPTP2b. Specific anti-AlPTP2b antibodies labelled the extruded PTs of the A. locustae spores, confirming that this antigen is a PT component. Finally, we showed that several PTP2-like proteins are also present in other phylogenetically related insect microsporidia, including Anncaliia algerae and Paranosema grylli.
Microbial Biotechnology | 2017
Laurianne Paris; Michaël Roussel; Bruno Pereira; Frédéric Delbac; Marie Diogon
The causes underlying the increased mortality of honeybee colonies remain unclear and may involve multiple stressors acting together, including both pathogens and pesticides. Previous studies suggested that infection by the gut parasite Nosema ceranae combined with chronic exposure to sublethal doses of the insecticide fipronil generated an increase in oxidative stress in the midgut of honeybees. To explore the impact of these two stressors on oxidative balance, we experimentally infected bees with N. ceranae and/or chronically exposed to fipronil at low doses for 22 days, and we measured soluble reactive oxygen species (ROS) and ROS damage by quantifying both protein and lipid oxidation in the midgut. Our results revealed a disruption of the oxidative balance, with a decrease in both the amount of ROS and ROS damage in the presence of the parasite alone. However, protein oxidation was significantly increased in the N. ceranae/fipronil combination, revealing an increase in oxidative damage and suggesting higher fipronil toxicity in infected bees. Furthermore, our results highlighted a temporal order in the appearance of oxidation events in the intestinal cells and revealed that all samples tended to undergo protein oxidation during ageing, regardless of treatment.
Archive | 2013
Philippe Michaud; Céline Laroche; Aurore Villay; Michaël Roussel; Marie Diogon; Hicham El Alaoui; Frédéric Delbac
Archive | 2013
Philippe Michaud; Céline Laroche; Aurore Villay; Michaël Roussel; Marie Diogon; Alaoui Hicham El; Frédéric Delbac
Archive | 2013
Philippe Michaud; Céline Laroche; Aurore Villay; Michaël Roussel; Marie Diogon; H. El Alaoui; Frédéric Delbac
Archive | 2012
Philippe Michaud; Céline Laroche; Aurore Villay; Michaël Roussel; Marie Diogon; Alaoui Hicham El; Frédéric Delbac