Consulta: creatorFacets:"Bigeard, Estelle"
Registros recuperados: 4
Data/hora: 01/06/2024 10:47:48

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

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

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