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Remarques épistémologiques sur la cryoconservation des végétaux
No full textInternational audienceLa cryoconservation consiste à préserver du matériel biologique à très basse température (-196°) pour une conservation théoriquement infinie et sans dommage. Essentielle en agronomie et pour la biodiversité, cette technique implique des protocoles expérimentaux ajustés en fonction des espèces, des génotypes et des tissus. Le processus repose sur l’optimisation continue des méthodes, adaptées au matériel végétal et à ses variations. L’article analyse successivement l’objectif pragmatique qui consiste à conserver à long terme par le froid des tissus végétaux de manière réversible, la complexité des protocoles d’optimisation et enfin le statut épistémologique des principes sous-jacents à la cryoconservation
Méthodes d’évaluation des risques sanitaires et environnementaux et des enjeux socio-économiques associés aux plantes obtenues au moyen de certaines nouvelles techniques génomiques (NTG): Avis de l'Agence nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travailRapport d’expertise collective
No full textCitation suggérée : Anses. (2023). Évaluation des risques sanitaires et environnementaux et des enjeux socioéconomiques associés aux plantes obtenues au moyen de certaines nouvelles techniques génomiques. (saisine 2021-SA-0019). Maisons-Alfort : Anses, 287 p.Depuis le 1er janvier 2022, conformément à l’ordonnance n° 2021-1325 du 13 octobre 2021 et au décret n° 2021-1905 du 30 décembre 2021, l’Anses reprend les missions du Haut conseil des biotechnologies (HCB) concernant l’évaluation des risques pour l’environnement de l’ensemble des utilisations de biotechnologies en milieu ouvert, et les impacts socioéconomiques.L’Anses a été saisie dans le cadre de ces nouvelles missions par la Direction générale de la prévention des risques (DGPR) et la Direction générale de l’alimentation (DGAl) sur l’utilisation des nouvelle techniques génomiques (NTG) sur les végétaux.Les autres instances ayant repris les missions du HCB, à savoir le Conseil économique, social et environnemental (CESE) et le Comité consultatif national d’éthique (CCNE), ont également été sollicité sur cette question sur les périmètres correspondant respectivement aux questions sociétales et éthiques. Par ailleurs, il convient de noter que de nombreux acteurs institutionnels publics, organisations professionnelles et syndicales ont également produit des rapports sur les NTG.Le rapport d’expertise collective est réalisé dans le périmètre des missions de l’Anses sur les biotechnologies, incluant l’évaluation des risques sanitaires et environnementaux et les impacts socio-économiques. Il vise à éclairer les demandeurs sur ce périmètre qui couvre seulement une partie des enjeux liés à l’utilisation des NTG dans le domaine de la sélection végétale. Les questions instruites dans ce rapport sont donc limitées à ce périmètre et les conclusions devront être prises en compte uniquement dans ce cadre et mises en perspective avec les avis des autres instances sollicitées.Il convient de noter que cette expertise a été engagée avant la proposition de règlement de la Commission du 5 juillet 20231. Suite à sa publication, l’Anses a décidé de s’autosaisir afin de mener une analyse des critères définissant les plantes NTG de catégorie 1, considérées comme équivalentes aux plantes conventionnelles, exposés dans l’annexe 1 et justifiés par une note technique diffusée par la Commission européenne en octobre (Anses 2023). Cette analyse a été réalisée en parallèle et ses conclusions n’ont donc pas été prises en compte dans le présent travail d’expertise, réalisé dans le cadre du périmètre défini précédemment, qui ne fait pas la distinction entre les plantes NTG de catégorie 1 et 2
La gouvernance des sites Natura 2000 en mer : entre procédures normatives et inventions locales, plaidoyer pour un bricolage institutionnel
No full textInternational audienceLe réseau « Natura 2000 » en mer représente à lui seul plus de 40 % des aires marines protégées du littoral métropolitain. La particularité de la gouvernance de ce type d’AMP repose sur le fait qu’elle doit être fondée sur la concertation et la participation volontaire des acteurs, tout en étant encadrée par une procédure normative définie par le code de l’Environnement. Tout l’enjeu est donc de parvenir à créer une gouvernance territoriale appropriée par les acteurs locaux, construite autour d’un dispositif adhoc, multiacteur et contractuel articulé à cette procédure normative imposée. Cet article propose alors d’interroger cette tension entre gouvernance territoriale et procédure normative en s’attachant à identifier les processus de bricolage institutionnel. À travers dix-huit études de cas qualitatives réalisées le long du littoral métropolitain, une typologie des différents modes de gouvernance de Natura 2000 en mer est proposée. Quatre modes de gouvernance sont identifiés, reflétant la capacité des structures gestionnaires à mobiliser les proximités organisées pour construire une gouvernance territoriale. Au sein de ces idéaux types, nous mettons en évidence que le bricolage institutionnel intervient différemment, au sein d’une organisation, entre des organisations ou entre elles et des parties prenantes, tout en étant toujours indispensable à la gouvernance territoriale. Sur cette base, nous discutons les rapports de force entre procédures normatives imposées par l’État et capacités des territoires locaux às’engager dans des processus d’inventions locales
Effect of starch source in pelleted diets on growth performance of pigs
No full textInternational audienceIn European pig diets, wheat (W) and barley (B) are major energy suppliers. Their contrasted proportions in rapid and slowly digestible starch may alter the positive effect of pelleting on digestibility and metabolic use of energy. This study aimed to compare performance of growing pigs fed with pelleted diets, formulated for being iso-net energy (NE), either based on W, B or a balanced mixture of both cereals (so-called WB). Two batches of 224 gilts and entire males were studied between 31 and 117 kg body weight (16 pens of 7 pigs/treatment). Pigs were fed ad libitum with a 2-phase strategy. Based on chemical and nutritional (assessed with Evapig® for diets produced without any heating process) characteristics of feedstuffs, all diets were formulated to 9.40 MJ NE, 47 g crude fibre and 30 g crude fat/kg. Digestible lysine content was 0.93 and 0.85 g/MJ NE and starch content was 438 and 441 g/kg in Phase-1 and Phase-2 diets, respectively. All diets were pelleted (pellets temperature = 78±2°C). The average daily feed intake of W pigs was lower than that of B and WB pigs (2.62 vs. 2.69 kg/d on average for B and WB, P=0.03), without any difference in growth rate (1029 g/d on average for all groups, P=0.55). The resulting feed conversion ratio tended to be lower in W pigs (2.53 vs. 2.59, P=0.07). The hot carcass yield was better in W pigs (79.8 vs. 79.4%, P=0.02), but no difference was observed on carcass leanness (61.5%, on average for all groups, P=0.28). These results would agree with a greater improvement of the digestibility and/or metabolic utilisation after pelleting of W diets (compared to B), but more investigations are required to understand why results with WB were not intermediate between W and B
Influence of process parameters on nutritional profile and physical stability of innovative infant follow-on formulas based on animal and plant oil bodies
No full textInternational audienceInfant follow-on formulas (IFF) are usually under the form of oil-in-water emulsions stabilized by protein interfaces with lipids of predominantly plant oils. These oils derived from extraction processes employing organic solvents posing environmental issues and are unstructured affecting the bioaccessibility of nutrients. The aim of this study was to introduce animal and plant oil bodies (OB) obtained from more sustainable procedure into IFF to improve their nutritional profile and assess their stability under different processing conditions. Three IFF (40% dry matter) were formulated: PO based on plant oils, PO/aOB based on plant oils and animal OB, and pOB/aOB based on plant and animal OB. Different operating conditions were tested: 2 passes at 80/20 bar and 140/40 bar for homogenization and 73°C, 1 min and 80°C, 1 min for heat treatment. After 7 days of storage at room temperature, no change in droplet size profile was observed with a mode between 1.2 and 1.4 µm or 0.7 and 1.3 µm for homogenizing pressures of 80/20 and 140/40 bar, respectively. aOB/pOB was characterized by particle aggregation and had a similar size profile to the other IFF in the SDS. A phase separation was observed for aOB/pOB, which was all the more important for less homogenization and heat treatment. It was reversible and probably due to the different nature of the proteins and phospholipids endogenous to the plant OB. A low level of protein denaturation (< 15%) was measured in all IFF. Despite a low initial microbiological load, the best efficiency was attributed to the heat treatment of 1 minute at 80°C. There results demonstrated the feasibility of homogenization and heat treatment on innovative IFF. The influence of spray drying on the bioaccessibility of nutrients using in-vitro models will be necessary to evaluate the overall processability of these IFF
dTALE approach demonstrates that induction of common bean OVATE Family Protein 7 (PvOFP7) promotes resistance to common bacterial blight
No full textInternational audienceCommon bacterial blight of bean (CBB) is a devastating seed-transmitted disease caused by Xanthomonas phaseoli pv. phaseoli and Xanthomonas citri pv. fuscans on common bean (Phaseolus vulgaris L.). The genes responsible for CBB resistance are largely unknown. Moreover, the lack of a reproducible and universal transformation protocol limits the study of genetic traits in common bean. We produced X. phaseoli pv. phaseoli strains expressing artificially-designed Transcription-Activator Like Effectors (dTALEs) to target 14 candidate genes for resistance to CBB based on previous transcriptomic data. In planta assays in a susceptible common bean genotype showed that induction of PvOFP7, PvAP2 ‐ ERF71 or PvExpansinA17 expression by dTALEs resulted in CBB symptom reduction. After PvOFP7 induction, in planta bacterial growth was reduced at early colonisation stages and RNA-Seq analysis revealed up-regulation of cell wall formation and primary metabolism, together with major down-regulation of Heat Shock Proteins. Our results demonstrate that PvOFP7 contributes to CBB resistance, and underline the usefulness of dTALEs for functional validation of genes whose induction impacts Xanthomonas-plant interaction
New insights on pentadecanoic acid with special focus on its controversial essentiality: a mini-review
No full textInternational audiencePentadecanoic acid (C15:0, PDA) is an odd and minor fatty acid that has been neglected in the literature until the last decade. Indeed, as a specific fatty acid of dairy fat, PDA was only used as a biomarker of dairy fat consumption. Lately, PDA was first correlated negatively with the incidence of metabolic syndrome disorder, then its physiological effects have been investigated as a protective FA. PDA supplementation has been demonstrated as negatively correlated with elevated levels of leptin, plasminogen activator inhibitor-1 and insulin, and has been shown to exhibit sensitizing insulin effects with activation of AMPK pathway. PDA also reduced the severity of metabolic dysfunction-associated steatohepatitis (MASH), notably through reduced alanine transaminase and pro-inflammatory cytokines levels. The final effect described for PDA is its ability to display anti-inflammatory properties in several pathology models. Hence, considering these multiple effects, the presence of PDA could be associated with a healthier physiological state, this raises the question of whether the presence of PDA in the body, in adequate quantities, is needed to participate to health maintenance. PDA is not synthesized in sufficient quantities endogenously, so it must be provided by the diet, mainly through dairy fat, although other types of food can also contribute to the dietary intake of PDA. Essential fatty acids are described as not being endogenously synthesized in sufficient and required quantities to maintain physiological health. Thus, PDA might gather both conditions to be described as essential, yet further investigations on both criteria are needed to enhance knowledge on this odd chain fatty acid with promising impact as potential protective supplement nutrient
New insights on fouling mechanisms explored by rheo-fluidics at the microscale
No full textInternational audienceFouling is an unsolved and costly question for the dairy industry and consists in the gradual deposit of the solid fraction of a liquid stream on stainless-steel surfaces due to the combined action of thermal and concentration gradients. Understanding this phenomenon and preventing its consequences is of paramount relevance to optimize the operation unit efficiency and to improve the quality of the products. Until now, most of the studies available in the literature focused on the fouling dynamics in heat exchangers and led to contradictory results based on the off-line analysis of the solid layers. Conversely, the fouling mechanisms have been rarely explored in vacuum evaporators despite their systematic use in dairy industry (e.g., infant formula production) nowadays. In this work, we show that the initiation of the fouling process is not exclusively linked to protein thermal denaturation above a critical temperature (T>65 °C), as usually assumed, but also to the high shear rates in proximity of the equipment walls. Dispersions of whey proteins with different overall concentrations were processed by a rheometer, undergoing the range of shear rates (100-200 s-1) typical of falling film evaporators at fixed temperature (65 °C) and shearing time (10 min). The combined effect of heat and shear on the different stages of protein accumulation was evaluated on glass surfaces, by observing the development of the deposits (density, size, shape) using optical and digital microscopy. Our outcomes highlighted the formation of complex structures at the surface with increasing shear strength and protein concentration, characterized by a fractal arborescence. The morphology of the deposits was further characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM), which allowed to hypothesize possible mechanisms of initiation and propagation of protein layers. On the basis of these promising results, we also performed preliminary tests by microfluidic devices with the aim of providing a direct observation of the fouling dynamics in dairy mixes. The challenging question is to discriminate the mechanisms governing protein denaturation and aggregation in the bulk solution and those occurring at the surface and leading to growing deposits
Evidence of a rebound effect in agriculture: Crop-livestock reconnection beyond the farm gate does not always lead to more sustainable nitrogen management
No full textInternational audienceCONTEXT: Reconnecting crop and livestock production beyond the farm gate by exchanging raw materials (e.g., feed, manure) between farms is seen as a promising solution for improving the environmental performance of farms, since it should reduce the use of imported nitrogen (N) inputs. However, such a circular economy does not necessarily lead to a positive outcome, since cooperating farms might simultaneously intensify their production, which could cancel out the benefits of reconnecting crops and livestock: this is known as a rebound effect. OBJECTIVE: The aim of our study was to identify and analyze a potential rebound effect due to reconnection of crop and livestock farms. METHODS: We collected data on 18 case-study farms in a small territory in Spain. We then calculated two indicators of the N rebound effect: one based on potential savings of inorganic N fertilizer for cooperating crop farms and another based on potential savings of N losses to the environment for cooperating livestock farms. RESULTS AND CONCLUSIONS: On cooperating crop farms, importing manure did not lead to replacement of inorganic N fertilizer and could lead more inorganic N fertilizer being used. Thus, their mean N rebound effect was 520 %, which constituted a backfire effect. This mean, however, covered large differences among farms. On cooperating dairy farms, exporting manure resulted in a mean negative rebound effect of-17 %, meaning that they achieved higher savings in the N balance than expected compared to non-cooperating dairy farms. SIGNIFICANCE: Our main contribution is to show that there may be a rebound effect when reconnecting crop and livestock production beyond the farm gate due to the intensification of farms. The indicators of the N rebound effect developed can thus help identify situations that improve or degrade environmental performance. They should be used to complement existing indicators, such as N-use efficiency and the N balance, to design efficient farming systems while avoiding a rebound effect
Amino acid requirements of the infant: the amino acid composition of human breast milk
No full textInternational audienceThe recommended amino acid requirements of the infant are based on the amino acid composition of mature human breast milk. The amino acid composition of breast milk is usually determined following either acid or alkaline (for tryptophan) hydrolysis. For accuracy, however, the known effect of hydrolysis time on amino acid composition should be accounted for. Also, ideally the amino acid composition of breast milk should be given in units of digested (assumed to be absorbed) amino acids. A review of the literature is presented which gives mean total amino acid concentrations in mature human milk (n = 26 studies), mean hydrolysis correction factors (n = 3 studies) and mean true ileal amino acid digestibility coefficients (n = 3 studies, suckling piglet). There were differences between the estimates of amino acid concentration corrected for hydrolysis time and digestibility, and current FAO (2013) recommendations that were not corrected for these factors. The values based on the published literature up until 2023 (mg/g true protein) corrected for hydrolysis time and digestibility gave higher values (more than 16% higher) for leucine, lysine and threonine, and considerably higher values (greater than 30%) for histidine and tryptophan. Current recommendations may need revision