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Integrative metabolomics of the adaptation of rainbow trout (Oncorhynchus mykiss) metabolism to new feeds based on plant and alternative ingredients
No full textCette thèse s’inscrit dans le contexte du développement d’une alimentation durable en aquaculture. Les aliments aquacoles, historiquement à base de ressources marines, sont aujourd’hui principalement à base de ressources végétales. Cependant, l’utilisation d’aliments exclusivement végétaux chez les espèces carnivores est limitée par les faibles performances de croissance résultant notamment d’effets négatifs sur la digestion et le métabolisme. De nouveaux aliments à base de matières premières végétales complétés par des ingrédients alternatifs, extraits protéiques de levures (Saccharomyces cerevisiae), insectes (Hermetia illucens) et microalgues (Spirulina platensis), ont été formulés pour proposer des aliments performants sans ressources marines. L’objectif de cette thèse est de caractériser les composés solubles de ces aliments alternatifs testés pour les performances de croissance de la truite en pisciculture expérimentale, et d’évaluer les effets engendrés sur le métabolisme par une approche métabolomique basée sur la RMN du proton. Ce type d’approche intégrée combinant les métabolomes de l’aliment et de l’animal est original chez les poissons. La caractérisation des composés solubles des aliments alternatifs a permis de mettre en évidence des marqueurs des matières premières alternatives et des composés jusque-là non identifiés par les techniques d’analyses ciblées utilisées en routine pour la caractérisation des aliments : par exemple marqueur de type quinone pour les microalgues, et composé glycérol pour les insectes. Certains de ces composés sont également actifs sur le métabolisme de la truite. Les effets métaboliques ont été étudiés spécifiquement pour les aliments comprenant des taux d’incorporation croissants d’ingrédient levure et insecte ayant des effets significatifs sur la croissance. Les effets métaboliques observés au niveau du métabolome plasmatique, hépatique et musculaire des truites nourries avec ces aliments alternatifs suggèrent que l’amélioration de la croissance résulte de la réduction des matières premières végétales des aliments, et d’effets spécifiques des matières premières alternatives. La réduction de la teneur en farines végétales affecte le métabolisme musculaire notamment par des modifications des teneurs en histidine et taurine. Ces métabolites attestent de la restauration de fonctions importantes dans le muscle : la régulation du pouvoir tampon et de l’osmolarité. Les aliments contenant l’ingrédient levure induisent un effet spécifique sur le métabolisme énergétique et sur le statut de la bétaïne hépatique. Les aliments contenant l’ingrédient insecte induisent un effet sur le métabolisme protéique musculaire grâce à l’apport d’acides aminés libres utilisés pour la protéosynthèse et la fourniture d’énergie. L’intégration des données métabolomiques et zootechniques montre l’histidine comme un marqueur original de la croissance. Afin de proposer une méthode d’analyse non-invasive du métabolome hépatique et musculaire, nous avons testé la prédiction de la variation des métabolites tissulaires à partir du métabolome plasmatique. Cette thèse ouvre de nouvelles perspectives pour améliorer l’évaluation (i) de la qualité des aliments aquacoles, et (ii) des effets nutritionnels de nouveaux aliments par l’identification de voies métaboliques et de fonctions utiles en relation avec la croissance chez la truite.This thesis work is in line with the development of sustainable aquaculture feed. Aquaculture feeds that have been historically based on marine resources are now mainly based on plant resources. However, the use of feeds exclusively based on plant ingredients in carnivorous species, is limited by poor growth performance resulting in particular from the negative effects on digestion and metabolism. Alternative feeds based on plant raw materials and containing alternative ingredients, protein extracts from yeasts (Saccharomyces cerevisiae), insects (Hermetia illucens) and microalgae (Spirulina platensis), have been formulated to provide efficient feeds without marine resources. The objective of this thesis is to characterize the soluble compounds of these alternative feeds tested for the growth performance of trout in experimental fish farming, and to evaluate dietary-induced effects on metabolism by a metabolomics approach based on proton NMR. This type of integrated metabolomic approach combining feed and animal metabolome remains rare in fish. The characterization of soluble compounds in alternative feeds allowed identifying markers of alternative raw materials and compounds not previously identified by the targeted analytical techniques routinely used for feed characterization: e.g. a quinone marker for microalgae and glycerol compound for insects. Several compounds are also active on trout metabolism. Metabolic effects were studied in particular with feeds containing increasing incorporation levels of yeast and insect ingredients with significant growth effects. The metabolic effects observed in the plasma, liver and muscle metabolome of trout fed these alternative feeds suggested that the improvement in growth results both from the reduction in the plant raw materials in the feed, and from specific effects of the alternative raw materials. The effect of the reduction in plant flour contents was observed on muscle metabolism notably through changes in histidine and taurine contents. These two metabolites suggest the restoration of two crucial functions in the muscle: regulation of buffer capacity and of osmolarity. Feeds containing the yeast ingredient had a specific effect on energy metabolism and on the status of hepatic betaine. Feeds containing the insect ingredient induced an effect on muscle protein metabolism by providing free amino acids used for protein synthesis and energy supply. The integration of metabolomic and zootechnical data highlighted histidine as an original marker of growth. To propose a non-invasive method of analysis of the hepatic and muscle metabolome, we tested the prediction of tissue metabolite variations from the plasma metabolome. This thesis opens new perspectives to improve the assessment of (i) the quality of aquaculture feed, and (ii) the nutritional effects of new feeds by identifying metabolic pathways and useful functions related to trout growth
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Partial substitution of protein by a single amino acid or an organic acid in rainbow trout diets
No full textInternational audienc
Fish muscle quality assessment
No full textReport on current research programs of different institutions in Northern Europe (October 1990). Cooperative Research Project on Biological Resource Management (OECD)Countries of Northern Europe are producers of salmonid fish: Atlantic salmon and rainbow trout. Sorne of them have also large marine fishery activities and related industries (Scotland, Norway and Denmark) and freshwater fisheries (Finland). These countries are similar to France with respect to production but less dependent upon importation
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