La Statistique de norme endogène dans l’analyse de textes

En linguistique textuelle, la statistique est appelée pour aider à la formalisation des niveaux de structuration, et à la liaison des macro- et des micro-analyses, notamment dans le domaine stylistique. Comme cette dernière, elle doit être reconçue en rupture avec la problématique des écarts exogènes, en faveur au contraire de la recherche des reliefs internes des œuvres : le texte se décrit et s’élabore dans l’analyse, comme un système d’écarts à sa propre “norme”, notamment grâce aux techniques distributionnelles que l’on expérimente d’abord sur le vocabulaire. Les approches multidimensionnelles (benzécristes) sont privilégiées, mais aussi questionnées ; les résultats graphiques sont reçus comme de bons outils de repérage dans la perspective hypertextuelle.In text linguistics, statistics are useful to help formalizing levels of structuration, and linking together macro- and micro-analysis, particularly in stylistic matters. As well as stylistics, statistics must be thought anew, far away from ideas of exogenous deviations. They would profitfully search about internal reliefs of works: one can describe and elaborate texts through analysis, as systems of deviations from its own “norm”, provided that he uses distributional techniques, firstly upon vocabulary. Multidimensional approaches (benzecrist ones) are emphasized and also critically tested; we show graphic outputs as good orientation and browsing tools in hypertextual outlooks

Un de ces [syntagmes] qui… (à propos de la locution un(e) de ces […] qui)

Un de ces (syntagmes) qui… (à propos de la locution un(e) de ces […] qui) Cet article a pour objet de montrer, sur une question déjà soulevée en stylistique française, ce que nous semble pouvoir apporter la dimension des vastes corpus et des outils logiciels d’exploration assistée. La locution un(e) de ces […] qui, déjà étudiée comme stylème dix-neuviémiste (Bordas), vecteur d’exophore mémorielle (Fraser & Joly), est redéfinie comme support d’un décrochage discursif dans le cadre de la polyphonie du récit (Bakhtine). Elle fait ici l’objet d’un relevé systématique dans un vaste corpus littéraire, qui permet de quantifier les proportions d’une typologie (notamment quant à la concordance aspectuo-temporelle) et d’en affiner la distribution diachronique et par auteurs. On observe alors le fonctionnement de cette locution comme filtre du vocabulaire et l’on montre que non seulement des unités isolées, mais des pôles lexico-thématiques de sa structure polycooccurrentielle (mise en évidence par l’AFC) sont significativement sur et sous-représentés dans les phrases d’emploi. On avance ainsi vers une meilleure connaissance de cette structure-frontière de la langue et du style en français.About the phrase un(e) de ces […] qui This paper raises a question which has already been worked upon in French stylistics and shows what we think to be brought by large corpuses problematics and assisted exploration software tools. The phrase un(e) de ces […] qui, previously studied as an nineteenth century styleme (Bordas), carrying the memorial exophora (Fraser & Joly), is here defined as vector of a discursive shift determined by narrative polyphony (Bakhtin). Its occurrences are systematically collected from a large literary corpus, which allows a typological proportional quantification (especially about the sequence of aspects and tenses), and spharpening diachronic and auctorial distributions. We then observe the functions of this phrase as a filter for vocabulary, showing that not only single units, but lexico-thematic areas of its polycooccurrential structure (built by FAC) are significantly over and under-represented within the concerned sentences. One should get here a deeper knowledge about a frontier structure between language and style in French

Présentation

Le thème de la cooccurrence en sciences du langage et en analyse du discours, s’il plonge ses racines beaucoup plus haut, a attendu les dernières années du xxe siècle pour s’imposer, à travers notamment l’approche statistique exploratoire. C’est d’un véritable foisonnement qu’il s’agit aujourd’hui, au sein duquel il a paru utile d’entreprendre de mettre de l’ordre sans dévitaliser les démarches. Historiquement, c’est dans la « London School of linguistics » et dans l’immédiat après-guerre que..

Corpus de textes, textes en corpus. Problématique et présentation.

En prenant l’initiative de ce volume de Corpus, nous avions choisi de procéder à un appel assez large, afin de faire le point sur des tendances actuelles des travaux sur corpus ancrés dans la textualité des faits de discours. En nous associant, nous pensions attirer des chercheurs d’horizons différents et notre attente n’a pas été déçue. Les propositions furent très nombreuses et de sélection en sélection, en regrettant quelques contributions abandonnées pour des raisons de délais de rédactio..

Corpus de textes, textes en corpus. Problématique et présentation.

En prenant l’initiative de ce volume de Corpus, nous avions choisi de procéder à un appel assez large, afin de faire le point sur des tendances actuelles des travaux sur corpus ancrés dans la textualité des faits de discours. En nous associant, nous pensions attirer des chercheurs d’horizons différents et notre attente n’a pas été déçue. Les propositions furent très nombreuses et de sélection en sélection, en regrettant quelques contributions abandonnées pour des raisons de délais de rédactio..

Picoplankton diversity in the South-East Pacific Ocean from cultures

International audienceIn late 2004, the BIOSOPE cruise sailed between the equatorial influenced waters off Marquesas islands and the nutrient enriched waters of the Chilean upwelling. Along the way, it explored the Southeast Pacific gyre centred around Easter Island, which is probably the most oligotrophic oceanic region on earth. During this cruise, we undertook a vigorous effort to isolate novel photosynthetic picoplanktonic eukaryotes. Two strategies were attempted on board: enrichment of samples with culture medium and sorting of specific populations by flow cytometry based on chlorophyll fluorescence. Over 1900 pre-cultures were started and then further purified by flow cytometry, serial dilution or pipette isolation to yield a total of 212 strains. These strains were characterized morphologically and for more than 50% of them, genetically, through partial sequencing of the 18 S rRNA gene. Among the characterized strains, the largest number are stramenopiles (Heterokontophyta) with a record of 38 strains belonging to the species Pelagomonas calceolata (Pelagophyceae). Strains from the recently described genera Bolidomonas and Florenciella have been re-isolated for the first time since their description. Two other abundant groups are the Chlorophyta, especially Prasinophyceae, and the Haptophyta, especially the genera Phaeocystis and Emiliania. A limited number of heterotrophic flagellates have also been isolated, all of them closely related to known species. Finally over a dozen of unicellular cyanobacteria strains have been obtained, some forming unusual short chains. Overall our strategy was quite successful since it allowed us to isolate a large number of picoplankton strains but failed in two respects. First, apparently very few novel taxa have been obtained. One set of strains is related to Prasinoderma coloniale (Prasinococcales, Prasinophyceae) but their sequences are sufficiently different from the latter to probably belong to a new genus or species. The sequences of two other strains are phylogenetically affiliated to stramenopile environmental sequences, probably corresponding a new algal class. Second, very few strains have been obtained from the very oligotrophic central gyre itself. Future work should probably combine flow cytometry sorting with culture media and cultivation approaches specifically developed for oligotrophic water species

Groups without cultured representatives dominate eukaryotic picophytoplankton in the oligotrophic South East Pacific Ocean

Background: Photosynthetic picoeukaryotes (PPE) with a cell size less than 3 µm play a critical role in oceanic primary production. In recent years, the composition of marine picoeukaryote communities has been intensively investigated by molecular approaches, but their photosynthetic fraction remains poorly characterized. This is largely because the classical approach that relies on constructing 18S rRNA gene clone libraries from filtered seawater samples using universal eukaryotic primers is heavily biased toward heterotrophs, especially alveolates and stramenopiles, despite the fact that autotrophic cells in general outnumber heterotrophic ones in the euphotic zone. Methodology/Principal Findings: In order to better assess the composition of the eukaryotic picophytoplankton in the South East Pacific Ocean, encompassing the most oligotrophic oceanic regions on earth, we used a novel approach based on flow cytometry sorting followed by construction of 18S rRNA gene clone libraries. This strategy dramatically increased the recovery of sequences from putative autotrophic groups. The composition of the PPE community appeared highly variable both vertically down the water column and horizontally across the South East Pacific Ocean. In the central gyre, uncultivated lineages dominated: a recently discovered clade of Prasinophyceae (IX), clades of marine Chrysophyceae and Haptophyta, the latter division containing a potentially new class besides Prymnesiophyceae and Pavlophyceae. In contrast, on the edge of the gyre and in the coastal Chilean upwelling, groups with cultivated representatives (Prasinophyceae clade VII and Mamiellales) dominated. Conclusions/Significance: Our data demonstrate that a very large fraction of the eukaryotic picophytoplankton still escapes cultivation. The use of flow cytometry sorting should prove very useful to better characterize specific plankton populations by molecular approaches such as gene cloning or metagenomics, and also to obtain into culture strains representative of these novel groups

Endoscopic mucosal resection with anchoring of the snare tip: multicenter retrospective evaluation of effectiveness and safety

International audienc

Metagenomes of the Picoalga Bathycoccus from the Chile Coastal Upwelling

Among small photosynthetic eukaryotes that play a key role in oceanic food webs, picoplanktonic Mamiellophyceae such as Bathycoccus, Micromonas, and Ostreococcus are particularly important in coastal regions. By using a combination of cell sorting by flow cytometry, whole genome amplification (WGA), and 454 pyrosequencing, we obtained metagenomic data for two natural picophytoplankton populations from the coastal upwelling waters off central Chile. About 60% of the reads of each sample could be mapped to the genome of Bathycoccus strain from the Mediterranean Sea (RCC1105), representing a total of 9 Mbp (sample T142) and 13 Mbp (sample T149) of non-redundant Bathycoccus genome sequences. WGA did not amplify all regions uniformly, resulting in unequal coverage along a given chromosome and between chromosomes. The identity at the DNA level between the metagenomes and the cultured genome was very high (96.3% identical bases for the three larger chromosomes over a 360 kbp alignment). At least two to three different genotypes seemed to be present in each natural sample based on read mapping to Bathycoccus RCC1105 genome

Genome of Herbaspirillum seropedicae Strain SmR1, a Specialized Diazotrophic Endophyte of Tropical Grasses

The molecular mechanisms of plant recognition, colonization, and nutrient exchange between diazotrophic endophytes and plants are scarcely known. Herbaspirillum seropedicae is an endophytic bacterium capable of colonizing intercellular spaces of grasses such as rice and sugar cane. The genome of H. seropedicae strain SmR1 was sequenced and annotated by The Paraná State Genome Programme—GENOPAR. The genome is composed of a circular chromosome of 5,513,887 bp and contains a total of 4,804 genes. The genome sequence revealed that H. seropedicae is a highly versatile microorganism with capacity to metabolize a wide range of carbon and nitrogen sources and with possession of four distinct terminal oxidases. The genome contains a multitude of protein secretion systems, including type I, type II, type III, type V, and type VI secretion systems, and type IV pili, suggesting a high potential to interact with host plants. H. seropedicae is able to synthesize indole acetic acid as reflected by the four IAA biosynthetic pathways present. A gene coding for ACC deaminase, which may be involved in modulating the associated plant ethylene-signaling pathway, is also present. Genes for hemagglutinins/hemolysins/adhesins were found and may play a role in plant cell surface adhesion. These features may endow H. seropedicae with the ability to establish an endophytic life-style in a large number of plant species