Consulta: creatorFacets:"Guillou, Laure"
Registros recuperados: 14
Data/hora: 09/06/2024 03:42:54

Protists Within Corals: The Hidden Diversity
Provedor de dados: 5
Autores: Clerissi, Camille; Brunet, Sebastien; Vidal-dupiol, Jeremie; Adjeroud, Mehdi; Lepage, Pierre; Guillou, Laure; Escoubas, Jean Michel; Toulza, Eve.
Previous observations suggested that microbial communities contribute to coral health and the ecological resilience of coral reefs. However, most studies of coral microbiology focused on prokaryotes and the endosymbiotic algae Symbiodinium. In contrast, knowledge concerning diversity of other protists is still lacking, possibly due to methodological constraints. As most eukaryotic DNA in coral samples was derived from hosts, protist diversity was missed in metagenome analyses. To tackle this issue, we designed blocking primers for Scleractinia sequences amplified with two primer sets that targeted variable loops of the 18S rRNA gene (18SV1V2 and 18SV4). These blocking primers were used on environmental colonies of Pocillopora damicornis sensu lato from two...
Tipo: Text
Palavras-chave: Holobiont; Protists; Symbiosis; Metabarcoding; Blocking primer; Scleractinia; Pocillopora damicornis.
Ano: 2018
URL: http://archimer.ifremer.fr/doc/00457/56823/58661.pdf

The Protist Ribosomal Reference database (PR2): a catalog of unicellular eukaryote Small Sub-Unit rRNA sequences with curated taxonomy
Provedor de dados: 5
Autores: Guillou, Laure; Bachar, Dipankar; Audic, S; Bass, David; Berney, Cedric; Bittner, Lucie; Boutte, Christophe; Burgaud, Gaetan; De Vargas, Colomban; Decelle, Johan; Del Campo, Javier; Dolan, John R.; Dunthorn, Micah; Edvardsen, Bente; Holzmann, Maria; Kooistra, Wiebe H. C. F.; Lara, Enrique; Le Bescot, Noan; Logares, Ramiro; Mahe, F; Massana, Ramon; Montresor, Marina; Morard, Raphael; Not, Fabrice; Pawlowski, Jan; Probert, Ian; Sauvadet, Anne-laure; Siano, Raffaele; Stoeck, Thorsten; Vaulot, Daniel; Zimmermann, Pascal; Christen, Richard.
The interrogation of genetic markers in environmental meta-barcoding studies is currently seriously hindered by the lack of taxonomically curated reference data sets for the targeted genes. The Protist Ribosomal Reference database (PR2, http://ssurrna. org/) provides a unique access to eukaryotic small sub-unit (SSU) ribosomal RNA and DNA sequences, with curated taxonomy. The database mainly consists of nuclear-encoded protistan sequences. However, metazoans, land plants, macrosporic fungi and eukaryotic organelles (mitochondrion, plastid and others) are also included because they are useful for the analysis of hightroughput sequencing data sets. Introns and putative chimeric sequences have been also carefully checked. Taxonomic assignation of sequences...
Tipo: Text
Ano: 2013
URL: http://archimer.ifremer.fr/doc/00114/22492/20174.pdf

From the sxtA4 Gene to Saxitoxin Production: What Controls the Variability Among Alexandrium minutum and Alexandrium pacificum Strains?
Provedor de dados: 5
Autores: Geffroy, Solene; Lechat, Marc-marie; Le Gac, Mickael; Rovillon, Georges-augustin; Marie, Dominique; Bigeard, Estelle; Malo, Florent; Amzil, Zouher; Guillou, Laure; Caruana, Amandine.
Paralytic shellfish poisoning (PSP) is a human foodborne syndrome caused by the consumption of shellfish that accumulate paralytic shellfish toxins (PSTs, saxitoxin group). In PST-producing dinoflagellates such as Alexandrium spp., toxin synthesis is encoded in the nuclear genome via a gene cluster (sxt). Toxin production is supposedly associated with the presence of a 4th domain in the sxtA gene (sxtA4), one of the core genes of the PST gene cluster. It is postulated that gene expression in dinoflagellates is partially constitutive, with both transcriptional and post-transcriptional processes potentially co-occurring. Therefore, gene structure and expression mode are two important features to explore in order to fully understand toxin production processes...
Tipo: Text
Palavras-chave: Alexandrium; Saxitoxins; SxtA4; Copy number variation; SxtA; Expression; Isoform.
Ano: 2021
URL: https://archimer.ifremer.fr/doc/00682/79402/81944.pdf

Redescription and phylogenetic analyses of Durchoniella spp. (Ciliophora, Astomatida) associated with the polychaete Cirriformia tentaculata (Montagu, 1808)
Provedor de dados: 5
Autores: Sauvadet, Anne-laure; Lynn, Denis H.; Roussel, Erwan; Le Panse, Sophie; Bigeard, Estelle; Schrevel, Joseph; Guillou, Laure.
Microscopic and phylogenetic analyses were performed on endocommensal astome ciliates retrieved from the middle intestine of a marine cirratulid polychaete, Cirriformia tentaculata, collected in the bay of Roscoff (English Channel, Northwest French coast) and on the Southwest English coast. Three morphotypes of the astome genus Durchoniella were identified, two corresponding to described species (the type species Durchoniella brasili (Léger and Duboscq, 1904) de Puytorac, 1954 and Durchoniella legeriduboscqui de Puytorac, 1954) while a third morphotype remains undescribed. Their small subunit (SSU) rRNA gene sequences showed at least 97.2% identity and phylogenetic analyses grouped them at the base of the subclass Scuticociliatia (Oligohymenophorea), as a...
Tipo: Text
Palavras-chave: Astomatida; Ciliophora; Cirratulidae; Endocytoplasmic bacteria; Microscopy; Molecular phylogeny.
Ano: 2017
URL: http://archimer.ifremer.fr/doc/00392/50312/50990.pdf

Etude sur la prolifération de la micro algue Alexandrium minutum en rade de Brest. Projet Daoulex. Rapport d’avancement n° 1 : Novembre 2013
Provedor de dados: 5
Autores: Chapelle, Annie; Le Bec, Claude; Le Gac, Mickael; Labry, Claire; Amzil, Zouher; Guillou, Laure; Dreanno, Catherine; Pineau-guillou, Lucia.
Suite à l’événement de grande ampleur d’efflorescence d’Alexandrium minutum et des toxicités associées en Rade de Brest en 2012, un projet a été monté avec la Région dans le cadre du développement du port de Brest. De juillet à août 2013, l’Ifremer a organisé un échantillonnage serré dans l’estuaire de Daoulas, zone la plus touchée en 2012. De ce suivi et des mesures réalisées au laboratoire à ce jour, ainsi que des résultats du réseau Rephy et Velyger, il ressort que : * Alexandrium minutum s’est développé à nouveau en rade de Brest en 2013 mais à des teneurs inférieures à 2012. * l’épisode de bloom et de toxicité supérieur aux seuils légaux s’est déroulé plus tard qu’en 2012, du 1er juillet jusqu’à 5 août. * les efflorescences et la toxicité ont touché...
Tipo: Text
Ano: 2013
URL: https://archimer.ifremer.fr/doc/00191/30230/28644.pdf

Marine protist diversity in European coastal waters and sediments as revealed by high-throughput sequencing
Provedor de dados: 5
Autores: Massana, Ramon; Gobet, Angelique; Audic, Stephane; Bass, David; Bittner, Lucie; Boutte, Christophe; Chambouvet, Aurelie; Christen, Richard; Claverie, Jean-michel; Decelle, Johan; Dolan, John R.; Dunthorn, Micah; Edvardsen, Bente; Forn, Irene; Forster, Dominik; Guillou, Laure; Jaillon, Olivier; Kooistra, Wiebe H. C. F.; Logares, Ramiro; Mahe, Frederic; Not, Fabrice; Ogata, Hiroyuki; Pawlowski, Jan; Pernice, Massimo C.; Probert, Ian; Romac, Sarah; Richards, Thomas; Santini, Sebastien; Shalchian-tabrizi, Kamran; Siano, Raffaele; Simon, Nathalie; Stoeck, Thorsten; Vaulot, Daniel; Zingone, Adriana; De Vargas, Colomban.
Although protists are critical components of marine ecosystems, they are still poorly characterized. Here we analysed the taxonomic diversity of planktonic and benthic protist communities collected in six distant European coastal sites. Environmental deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) from three size fractions (pico-, nano- and micro/mesoplankton), as well as from dissolved DNA and surface sediments were used as templates for tag pyrosequencing of the V4 region of the 18S ribosomal DNA. Beta-diversity analyses split the protist community structure into three main clusters: picoplankton-nanoplankton-dissolved DNA, micro/mesoplankton and sediments. Within each cluster, protist communities from the same site and time clustered together,...
Tipo: Text
Ano: 2015
URL: http://archimer.ifremer.fr/doc/00275/38594/37190.pdf

Significance of Plankton Community Structure and Nutrient Availability for the Control of Dinoflagellate Blooms by Parasites: A Modeling Approach
Provedor de dados: 5
Autores: Alves-de-souza, Catharina; Pecqueur, David; Le Floc'H, Emilie; Mas, Sebastien; Roques, Cecile; Mostajir, Behzad; Vidussi, Franscesca; Velo-suarez, Lourdes; Sourisseau, Marc; Fouilland, Eric; Guillou, Laure.
Dinoflagellate blooms are frequently observed under temporary eutrophication of coastal waters after heavy rains. Growth of these opportunistic microalgae is believed to be promoted by sudden input of nutrients and the absence or inefficiency of their natural enemies, such as grazers and parasites. Here, numerical simulations indicate that increasing nutrient availability not only promotes the formation of dinoflagellate blooms but can also stimulate their control by protozoan parasites. Moreover, high abundance of phytoplankton other than dinoflagellate hosts might have a significant dilution effect on the control of dinoflagellate blooms by parasites, either by resource competition with dinoflagellates (thus limiting the number of hosts available for...
Tipo: Text
Ano: 2015
URL: https://archimer.ifremer.fr/doc/00274/38478/36938.pdf

Evolutionary processes and cellular functions underlying divergence in Alexandrium minutum
Provedor de dados: 5
Autores: Le Gac, Mickael; Metegnier, Gabriel; Chomerat, Nicolas; Malestroit, Pascale; Quere, Julien; Bouchez, Olivier; Siano, Raffaele; Destombe, Christophe; Guillou, Laure; Chapelle, Annie.
Understanding divergence in the highly dispersive and seemingly homogeneous pelagic environment for organisms living as free drifters in the water column remains a challenge. Here, we analyzed the transcriptome wide mRNA sequences, as well as the morphology of 18 strains of Alexandrium minutum, a dinoflagellate responsible for Harmful Algal Blooms worldwide, to investigate the functional bases of a divergence event. Analysis of the joint site frequency spectrum (JSFS) pointed toward an ancestral divergence in complete isolations followed by a secondary contact resulting in gene flow between the two diverging groups, but heterogeneous across sites. The sites displaying fixed SNPs were associated with a highly restricted gene flow and a strong...
Tipo: Text
Palavras-chave: Dinoflagellates; Harmful algal blooms; Populations Genomics; Pseudocryptic species; Speciation.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00347/45857/45529.pdf

Historical records from dated sediment cores reveal the multidecadal dynamic of the toxic dinoflagellate     Alexandrium minutum     in the Bay of Brest (France)
Provedor de dados: 5
Autores: Klouch, Khadidja; Schmidt, Sabine; Andrieux-loyer, Francoise; Le Gac, Mickael; Hervio-heath, Dominique; Qui-minet, Zujaila Nohemi; Quere, Julien; Bigeard, Estelle; Guillou, Laure; Siano, Raffaele.
The multiannual dynamic of the cyst-forming and toxic marine dinoflagellate Alexandrium minutum was studied over a time scale of about 150 years by a paleoecological approach based on ancient DNA (aDNA) quantification and cyst revivification data obtained from two dated sediment cores of the Bay of Brest (Brittany, France). The first genetic traces of the species presence in the study area dated back to 1873 ± 6. Specific aDNA could be quantified by a newly-developed real-time PCR assay in the upper core layers, in which the germination of the species (in up to 17–19 year-old sediments) was also obtained. In both cores studied, our quantitative paleogenetic data showed a statistically significant increasing trend in the abundance of A. minutum ITS1 rDNA...
Tipo: Text
Palavras-chave: Paleoecology; Ancient DNA; Real-time PCR; Harmful algal blooms (HAB); Dinoflagellates; Coastal ecology.
Ano: 2016
URL: http://archimer.ifremer.fr/doc/00334/44516/44212.pdf

The parasitic dinoflagellates Blastodinium spp. inhabiting the gut of marine, planktonic copepods: morphology, ecology, and unrecognized species diversity
Provedor de dados: 5
Autores: Skovgaard, Alf; Karpov, Sergey A.; Guillou, Laure.
Blastodinium is a genus of dinoflagellates that live as parasites in the gut of marine, planktonic copepods in theWorld’s oceans and coastal waters. The taxonomy, phylogeny, and physiology of the genus have only been explored to a limited degree and, based on recent investigations, we hypothesize that the morphological and genetic diversity within this genus may be considerably larger than presently recognized. To address these issues, we obtained 18S rDNA and ITS gene sequences for Blastodinium specimens of different geographical origins, including representatives of the type species. This genetic information was in some cases complemented with new morphological, ultrastructural, physiological, and ecological data. Because most current knowledge about...
Tipo: Text
Palavras-chave: Blastodinium; Copepod; Parasite; Symbiont; Plankton; Uttrastructure; Phylogeny.
Ano: 2012
URL: http://archimer.ifremer.fr/doc/00133/24407/22401.pdf

Unveiling protist diversity associated with the Pacific oyster Crassostrea gigas using blocking and excluding primers
Provedor de dados: 5
Autores: Clerissi, Camille; Guillou, Laure; Escoubas, Jean Michel; Toulza, Eve.
Background Microbiome of macroorganisms might directly or indirectly influence host development and homeostasis. Many studies focused on the diversity and distribution of prokaryotes within these assemblages, but the eukaryotic microbial compartment remains underexplored so far. Results To tackle this issue, we compared blocking and excluding primers to analyze microeukaryotic communities associated with Crassostrea gigas oysters. High-throughput sequencing of 18S rRNA genes variable loops revealed that excluding primers performed better by not amplifying oyster DNA, whereas the blocking primer did not totally prevent host contaminations. However, blocking and excluding primers showed similar pattern of alpha and beta diversities when protist communities...
Tipo: Text
Palavras-chave: Holobiont; Metabarcoding; Microbiome; Ostreoida; Crassostrea.
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00636/74799/75165.pdf

Étude sur la prolifération de la micro algue Alexandrium minutum en rade de Brest
Provedor de dados: 5
Autores: Chapelle, Annie; Le Bec, Claude; Amzil, Zouher; Dreanno, Catherine; Guillou, Laure; Klouch, Khadidja; Labry, Claire; Le Gac, Mickael; Pineau-guillou, Lucia; Siano, Raffaele; Abernot, Chantal; Andrieux, Francoise; Caradec, Florian; Destombe, Christophe; Dia, A.; Doner, Anne; Duval, Julia; Gouriou, Jeremie; Lazure, Pascal; Le Brun, Luc; Le Gal, Dominique; Malestroit, Pascale; Petton, Sebastien; Plus, Martin; Quere, Julien; Savar, Veronique; Schmitt, Sophie; Terre, A.; Youenou, Agnes.
Suite à l’événement de grande ampleur d’efflorescence d’Alexandrium minutum et des toxicités associées en Rade de Brest en 2012, un projet a été élaboré avec la Région Bretagne dans le cadre du développement du port de Brest. L’Ifremer a organisé un échantillonnage dans l’estuaire de la rivière de Daoulas, zone la plus touchée en 2012, au cours des printemps-été 2013 et 2014. Un suivi de la présence d’A. minutum dans les sédiments a également été réalisé en hiver 2014. De ces suivis, des mesures réalisées au laboratoire à ce jour, des simulations du modèle Prévimer ainsi que des résultats du réseau Rephy et Velyger, il ressort que: * La rade de Brest peut aujourd’hui être considérée comme une zone à risque pour Alexandrium minutum. En effet, depuis 2012...
Tipo: Text
Ano: 2014
URL: http://archimer.ifremer.fr/doc/00254/36487/35029.pdf

Phylogenetic and morphological characterisation of the green algae infecting blue mussel Mytilus edulis in the North and South Atlantic oceans
Provedor de dados: 5
Autores: Rodriguez, Francisco; Feist, Stephen; Guillou, Laure; Harkestad, Lisbeth; Bateman, Kelly; Renault, Tristan; Mortensen, Stein.
Blue mussels Mytilus edulis with shell deformations and green pustules containing parasitic algae were collected at 3 coastal sites (Burøy, Norway; Bockholm, Denmark; Goose Green, Falkland Islands). A comparative study, including mussel histopathology, algal morphology, ultrastructure and phylogenetic position was performed. Green pustules were mainly located in the posterior portion of the mantle and gonad tissues and the posterior adductor muscle. Electron microscopy confirmed the presence of algal cells with similar morphology to Coccomyxa parasitica. Algae were oval shaped with a single nucleus and chloroplast, 1 or 2 mitochondria and a dense granular cytoplasm with a lipid inclusion body, Golgi apparatus and small vesicles. Partial small subunit (SSU)...
Tipo: Text
Palavras-chave: Phylogeny; Parasitic alga; Mytilus edulis chilensis; Mytilus edulis; Coccomyxa parasitica; Blue mussels.
Ano: 2008
URL: http://archimer.ifremer.fr/doc/2008/publication-4581.pdf

Cryptic species in the parasitic Amoebophrya species complex revealed by a polyphasic approach
Provedor de dados: 5
Autores: Cai, Ruibo; Kayal, Ehsan; Alves-de-souza, Catharina; Bigeard, Estelle; Corre, Erwan; Jeanthon, Christian; Marie, Dominique; Porcel, Betina M.; Siano, Raffaele; Szymczak, Jeremy; Wolf, Matthias; Guillou, Laure.
As critical primary producers and recyclers of organic matter, the diversity of marine protists has been extensively explored by high-throughput barcode sequencing. However, classification of short metabarcoding sequences into traditional taxonomic units is not trivial, especially for lineages mainly known by their genetic fingerprints. This is the case for the widespread Amoebophrya ceratii species complex, parasites of their dinoflagellate congeners. We used genetic and phenotypic characters, applied to 119 Amoebophrya individuals sampled from the same geographic area, to construct practical guidelines for species delineation that could be applied in DNA/RNA based diversity analyses. Based on the internal transcribed spacer (ITS) regions, ITS2...
Tipo: Text
Ano: 2020
URL: https://archimer.ifremer.fr/doc/00609/72156/70916.pdf