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Technique de pollinisation contrôlée du Tabebuia heterophylla ou Poirier pays : Une technique d’amélioration d’un arbre tropical produisant du bois d’œuvre : le « Poirier-Pays »
No full textL’espèce Tabebuia heterophylla, implanté dans le bassin Caraïbéen, possède la particularité de pousser dans les zones à saison sèche marquée. C’est un arbre dont la taille atteint une vingtaine de mètre de haut, fournit un excellent bois d’oeuvre très prisé par les menuisiers et les ébénistes. Les sujets aux troncs bien conformés ont été surexploités, entraînant la diminution de la population intéressante. Afin de remédier à la disparition de la ressource exploitable, l’ancienne Unité de Recherche Forestière de l’Inra de Guadeloupe fermée en 2002 a lancé une étude sur l’amélioration génétique de cet arbre. La première étape de ce travail a concerné la pollinisation contrôlée de cette espèce. Cela a commencé par la sélection d’arbres dans les Petites Antilles pour la mise en place, sur le site de Duclos, de deux parcs à clones et d’un verger à graines. Nous avons ensuite pollinisé les clones avec le mélange de pollen (polycross) et obtenu des plants aptes à subir les tests de descendance.The species Tabebuia heterophylla, implanted in the Caribbean basin, has the particularity of growing in areas with a marked dry season. It is a tree whose size reaches twenty meters high, provides excellent timber highly valued by carpenters and cabinetmakers. Subjects with well-shaped trunks have been overexploited, resulting in the decrease of the interesting population. In order to remedy the disappearance of the exploitable resource, the former Forest Research Unit of the Inra Guadeloupe closed in 2002 launched a study on the genetic improvement of this tree. The first step of this work involved the controlled pollination of this species. This began with the selection of trees in the Lesser Antilles for the establishment of two clone parks and a seed orchard on the Duclos site. We then pollinated the clones with the mixture of pollen (polycross) and obtained plants suitable for progeny tests
Des tomates mycorhizées dès la pépinière pour favoriser la nutrition et la protection des plantes : développement d’un dispositif-pilote
No full textValoriser les mycorhizes est une alternative potentielle à l’utilisation d’engrais et de produits phytosanitaires. Nous avons conçu un dispositif-pilote basé sur deux étapes : une étape de piégeage et de multiplication de champignons mycorhiziens à arbuscules indigènes et une étape de mycorhization des plants de tomates par « effet-donneur ». Nous avons montré que ce dispositif-pilote permet de la mycorhization des tomates avant leur transplantation au champ. L’objectif est que ce dispositif soit utilisable, à terme, par les pépiniéristes et les agriculteurs qui produisent des plants maraîchers sur leur exploitation.Valorizing mycorrhizae is a potential alternative to the use of fertilizers and pesticides. We designed a pilot device based on two steps: a step of trapping and multiplying native arbuscular mycorrhizal fungi and a step of mycorrhization of tomato plants by "donor effect". We have shown that this pilot device allows tomatoes mycorrhization before being transplanted into the field. The objective is that this system will eventually be usable by nurserymen and farmers who produce market gardening plants on their farms
Influence of the carbohydrate-binding module on the activity of a fungal aa9 lytic polysaccharide monooxygenase on cellulosic substrates
No full textBackground: Cellulose-active lytic polysaccharide monooxygenases (LPMOs) secreted by filamentous fungi play a key role in the degradation of recalcitrant lignocellulosic biomass. They can occur as multidomain proteins fused to a carbohydrate-binding module (CBM). From a biotech perspective, LPMOs are promising innovative tools for producing nanocelluloses and biofuels, but their direct action on cellulosic substrates is not fully understood.
Results: In this study, we probed the role of the CBM from family 1 (CBM1) appended to the LPMO9H from Podospora anserina (PaLPMO9H) using model cellulosic substrates. Deletion of the CBM1 weakened the binding to cellulose nanofibrils, amorphous and crystalline cellulose. Although the release of soluble sugars from cellulose was drastically reduced under standard conditions, the truncated LPMO retained some activity on soluble oligosaccharides. The cellulolytic action of the truncated LPMO was demonstrated using synergy experiments with a cellobiohydrolase (CBH). The truncated LPMO was still able to improve the efficiency of the CBH on cellulose nanofibrils in the same range as the full-length LPMO. Increasing the substrate concentration enhanced the performance of PaLPMO9H without CBM in terms of product release. Interestingly, removing the CBM also altered the regioselectivity of PaLPMO9H, significantly increasing cleavage at the C1 position. Analysis of the insoluble fraction of cellulosic substrates evaluated by optical and atomic force microscopy confirmed that the CBM1 module was not strictly required to promote disruption of the cellulose network.
Conclusions: Absence of the CBM1 does not preclude the activity of the LPMO on cellulose but its presence has an important role in driving the enzyme to the substrate and releasing more soluble sugars (both oxidized and nonoxidized), thus facilitating the detection of LPMO activity at low substrate concentration. These results provide insights into the mechanism of action of fungal LPMOs on cellulose to produce nanocelluloses and biofuels
Renforcer les capacités d’adaptation des systèmes d’élevage de ruminants: Cadres théoriques, leviers d’action et démarche d’accompagnement
No full textDans le contexte de changement global, face à une augmentation des aléas et des extrêmes, les systèmes d’élevage doivent renforcer
leurs capacités d’adaptation. L’analyse des capacités d’adaptation nécessite d’adopter une approche systémique, considérant à la fois des
moteurs de changements internes et externes à l’exploitation. Cette analyse peut s’appuyer sur des concepts comme la résilience, la flexibilité
et la vulnérabilité. Les leviers d’adaptation techniques, réactifs ou proactifs, relèvent de trois principes : i) accroissement des marges de
manœuvre ; ii) diversification ; iii) management adaptatif. Ces trois principes sont déclinés au niveau du troupeau, des ressources et de l’éleveur. Les leviers externes correspondent aux réseaux et à l’action collective. Sur le long terme, les « logiques d’action » des éleveurs balisent
le type de leviers pouvant être mobilisés. Cette mise en œuvre peut être incrémentale ou « transformationnelle », lorsqu’elle bouleverse la
localisation ou les objectifs de l’activité d’élevage. Dans une optique d’accompagnement, une démarche en quatre étapes est proposée :
i) prendre conscience de son exposition aux aléas ; ii) comprendre sa sensibilité ; iii) se projeter en concevant des scénarios d’alternatives ;
iv) mettre en œuvre ces alternatives, les suivre, et les évaluer. Chaque étape est associée à des outils et dispositifs spécifiques, comme des
indicateurs, des focus groups, des visites en fermes et des outils dédiés à l’adaptation. Cette démarche doit permettre une prise en compte
plus systématique des enjeux d’adaptation dans le conseil. Pour l’avenir, un enjeu essentiel est sa mise à l’épreuve pour l’accompagnement
des adaptations transformationnelles.In the context of global change, livestock farming systems are facing an increase of uncertainties and extreme events, so they have to strengthen
their adaptive capacities. The analysis of adaptive capacities requires a systemic approach considering internal and external drivers of change.
This analysis can be structured with concepts such as resilience, flexibility and vulnerability. Technical levers of action, reactive or proactive, are
related to three principles: i) increasing room for manoeuvre; ii) diversification; iii) adaptive management. These three principles are illustrated at
the levels of the herd, resources and farmer. External levers corresponds to networks and collective action. In the long term, the “logic of action” of
livestock farmers determine the kind of levers of action possibly activated. This activation can be incremental or transformational, when it changes
deeply the localization or the objectives of livestock farming activities. To facilitate the adaptation of livestock farms, a development approach in
four stages is proposed: i) Becoming aware of the farm exposition to hazards; ii) Understanding the sensitivity of the system; iii) Exploring alternative scenarios; iv) Implementing and assessing of selected alternative practices. Each stage is associated with specific tools and devices, such as
indicators, focus groups, farm’ visit and dedicated tools. This approach enables a more systematic integration of adaptation issues. In the future,
an essential perspective is to better integrate transformational adaptations
Vers une maîtrise de la reproduction sans hormones chez les petits ruminants
No full textReproduction mastering in sheep and goat farms is important for out-of-season breeding, birth grouping and artificial insemination (Al) performance. The use of hormones to induce and synchronise oestrus and ovulations is the most effective way to achieve these goals. The use of photoperiodic treatments and/or the male effect appears as an alternative solution to limit the use of hormones in small ruminant breeding. This article discusses the specificities of the ovulatory and behavioural response of females to the "male effect': as well as the physiological bases that contribute to the success of this practice in sheep and goats. Pre-treatment of animals with photoperiodic strategies is required so that the male effect is successful, especially in highly seasonal breeds such as the Alpine and Saanen goat breeds. Light treatments are currently available for reproduction by the male effect in any season, but the use of melatonin is necessary at some periods of the year. New light treatments without melatonin are currently under study. Al protocols using the male effect are emerging. Some of them combine the male effect with progestagens and/or prostaglandins, and allow a single Al at a predetermined time. Hormone-free Al protocols based on the male effect are also available. In goats, these protocols include 1 or 2 Al times, with or without previous heat detection. In sheep, heat detection is mandatory for Al following ram effect without the use of hormones. In both species, the development of automated heat detection methods will facilitate the deployment of hormone-free Al protocols.Dans les élevages ovins et caprins, la maîtrise de la reproduction est importante pour une reproduction hors saison sexuelle, pour grouper les mises bas et pour la pratique de l’Insémination Artificielle (IA). Le traitement hormonal d’induction et de synchronisation de l’oestrus et de l’ovulation est aujourd’hui le moyen le plus efficace pour atteindre ces objectifs. Le recours à des traitements photopériodiques et/ou à l’effet mâle apparaît comme une solution pour limiter l’utilisation d’hormones dans ces filières. Cet article rappelle les spécificités de la réponse ovulatoire et comportementale des femelles à « l’effet mâle », ainsi que les bases physiologiques qui contribuent à la réussite de cette pratique chez les ovins et les caprins. Le prétraitement des animaux avec des traitements photopériodiques de désaisonnement est un prérequis pour une réponse à l’effet mâle efficace, notamment chez des races très saisonnées comme les races caprines alpine et saanen. Des traitements lumineux sont actuellement disponibles en élevage pour une reproduction par effet mâle en toute saison. Toutefois, ils requièrent l’utilisation de mélatonine à certaines périodes de l’année (notamment pour une reproduction en période estivale). Cet article expose différents travaux réalisés pour développer de nouveaux
traitements lumineux sans mélatonine, pouvant être appliqués en bâtiment ouvert. Des protocoles d’IA qui font appel à « l’effet mâle » sont en train d’émerger. Il s’agit pour certains de protocoles basés sur l’association de l’effet mâle avec des progestatifs et/ou des prostaglandines, et qui permettent de pratiquer une seule IA à un moment prédéterminé. Des protocoles d’IA après effet mâle seul (sans hormones) sont également disponibles, et notamment basés sur une détection des chaleurs. Chez les caprins, ils comportent 1 ou 2 moments d’IA, avec ou sans détection de chaleurs préalable. Chez les ovins, la détection des chaleurs est obligatoire pour la pratique de l’IA après un effet bélier seul. Dans les deux espèces, le développement de la détection automatisée des chaleurs facilitera le déploiement des protocoles d’IA sans utilisation d’hormones
Modelling metabolism to test alternative hypotheses on intraspecific life-history variation
No full textLignocellulosic biomass fractionation by mineral acids and resulting extract purification processes: Conditions, yields, and purities
No full textFractionation of lignocellulose is a fundamental step in the valorization of cellulose, hemicelluloses, and lignin to produce various sustainable fuels and chemicals. Mineral acid fractionation is one of the most applied process and leads to the solubilization and hydrolysis of cellulose and hemicelluloses, whereas most of the lignin remains insoluble and can be separated from the extract. The obtained monomeric sugars in the acid extract are in solution with salts, sugar degradation products, and phenolic molecules. Downstream processing is required to purify the sugars and further valorize them into fuels or chemicals with the use of chemical or biochemical reactions. This purification step also allows the recycling of the mineral acid and the valorization of the sugar degradation products and the co-extracted phenolic molecules, adding value to the whole biorefinery scheme. Many purification techniques have been studied, providing several options in terms of yields, purities, and cost of the process. This review presents the conditions used for the mineral acid fractionation step and a wide variety of purification techniques applied on the obtained hydrolysate, with a focus on the associated yields and purities. Values from the literature are expressed in a standard way in order to simplify comparison between the different processes
Evolution of liver fattening and foie gras technological yield during the overfeeding period in mule duck
No full textIn foie gras production the technological yield after the cooking process is one of the main issues of processors as it is closely linked to the cooking melting rate. This rate is subjected to strict laws and regulations since it directly affects the organoleptic and technological qualities of this gourmet product. The objective of the study was to better understand the liver fattening and the technological yield decrease during the overfeeding kinetics. A flock of 210 mule ducks was reared and then overfed during 12 D with 2 overfeeding programs; in the test group the amounts of corn in the first meals were higher than in the control group (+430 g during the whole period). Ducks were slaughtered at the end of the rearing period (D0, n = 15) and every other day (D2 to D12, n = 15 by group). Duck performances, anatomical dissections and physical and biochemical liver characteristics were registered. The performances were equivalent in the groups (P > 0.1). The evolution of the liver weight was then analyzed in detail in relation with the evolution of its biochemical composition. A two-step evolution occurred in the liver metabolism, first a main glycogen storage and then a strong lipid storage. A model to predict the liver weight was established with only BWs and feed intakes (R-2 = 0.83). The technological yield was determined on foie gras weighing more than 300 g (D6 to D12). The melting process was high during the last 2 D. The technological yield reached 72% at D12, for 758 g foie gras, and a strong negative correlation was observed with liver weight (-0.83; P < 0.001). A model to predict the technological yield was established with the liver weight and the liver color parameters (R-2 = 0.71). This study highlights the compromise between foie gras weight and its quality
In vitro toxicity assessment of stilbene extract for its potential use as antioxidant in the wine industry
No full textThe reduction of sulfur dioxide in wine is a consumer's demand, considering the allergic effects that may occur in people who are sensitive to it. Stilbenes are candidates of great interest for this purpose because of their antioxidant/antimicrobial activities and health properties, and also because they are naturally found in the grapevine. In the present study, the in vitro toxicity of an extract from grapevine shoots (with a stilbene richness of 45.4%) was assessed in two human cell lines. Significant damage was observed from 30 μg/mL after 24 h, and 40 µg/mL after 48 h of exposure. Similarly, the ultrastructural study revealed a significant impairment of cell growing. The extract was able to protect cells against an induced oxidative stress at all concentrations studied. In view of the promising results, a more exhaustive toxicological assessment of the extract is needed to confirm the safety of its further use as additive in wine