Portail des publications scientifiques de VetAgro Sup
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Rôle des cardiolipides dans les flux transmembranaires des protons et dans leur localisation
No full textInternational audienceIn eukaryotic cells, the phospholipid cardiolipin (CL) is a crucial component that influences the function and organization of the mitochondrial inner membrane. In this study, we examined its potential role in passive proton transmembrane flux using unilamellar vesicles composed of natural egg phosphatidylcholine (PC) alone or with the inclusion of 18 or 34 mol % CL. A membrane potential was induced by a potassium gradient, and oxonol VI dye was used to monitor membrane potential dissipation resulting from proton transmembrane efflux. Increasing the CL content led to a net increase in proton efflux, which was also dependent on the magnitude of the membrane potential. The same increase in proton efflux was measured in the presence of the equally negatively charged phosphatidylglycerol, indicating that the charge of CL plays a more important role than its structure in this mechanism. When varying the proton membrane permeability () using the protonophore CCCP, we observed that unlike PC liposomes, where a small amount of CCCP was sufficient to achieve maximum flux, a significantly larger amount of protonophore was required in the presence of CL. Conversely, increasing the buffer capacity increased proton flux, indicating that proton availability, rather than membrane permeability, may be the limiting factor for proton leak. Our findings demonstrated that a higher proton content associated with the membrane was correlated with an increasing leak in the presence of CL. Additionally, smaller liposome diameters appeared to favor proton leak. Taken together, our results suggest that the presence of negatively charged CL in a membrane traps protons and increases their leakage, potentially in a manner dependent on membrane curvature. We discuss the possible mechanisms and implications of these findings for mitochondrial respiration function
Structural investigation of vitamin K epoxide reductase domain-containing protein in Leptospira species: a potential target for the development of new leptospirosis treatments as an alternative to antibiotics
No full textInternational audienceLeptospirosis is a worldwide zoonosis caused by the motile bacterium Leptospira. This disease can cause hemorrhagic symptoms, multi-visceral and renal failures, resulting in one million cases and approximately 60,000 deaths each year. The motility of Leptospira is highly involved in its virulence and is ensured by the presence of two flagella in the periplasm. Several proteins that require the formation of disulfide bridges are essential for flagellar function. In Leptospira, these redox reactions are catalysed by the vitamin K epoxide reductase domain-containing protein (VKORdcp). The aim of the present work was to study the conservation of VKORdcp among Leptospira species and its interactions with putative substrates and inhibitor. Our results evidenced the presence of ten amino acids specific to either pathogenic or saprophytic species. Furthermore, structural studies revealed a higher affinity of the enzyme for vitamin K1 quinone, compared to ubiquinone. Finally, characterisation of the binding of a potential inhibitor revealed the involvement of some VKORdcp amino acids that have not been present in the human enzyme, in particular the polar residue D114. Our study thus paves the way for the future development of Leptospira VKORdcp inhibitors, capable of blocking bacterial motility. Such molecules could therefore offer a promising therapeutic alternative to antibiotics, especially in the event of the emergence of antibiotic-resistant strains.Communicated by Ramaswamy H. Sarm
Efficacy of <i>Cinnamomum cassia</i> essential oil as a natural preservative and flavoring agent to improve orange juice quality and safety
No full textInternational audienceEssential oils (EOs) are promising safe and natural alternatives for pasteurization and synthetic preservation of orange juice. The current research investigates the efficacy of Cinnamomum cassia essential oil (CCEO) as a natural food preservative and flavoring agent in orange juice. We evaluated the physicochemical, microbiological, and sensorial qualities of the juice treated with CCEO over 28 days of storage at 4°C, with measurements taken on every day 7. Results showed that CCEO significantly improved quality indicators by reducing browning reactions and inhibiting pectin methyl esterase activity (p < 0.05). However, potential hydrogen and titratable acidity remained unaffected (p > 0.05). CCEO significantly (p < 0.05) enhanced the microbiological and sensory properties of orange juice by reducing microbial load and enhancing taste, color, flavor, and the overall acceptability parameters. These findings demonstrated the potential of CCEO as a natural food preservative and flavoring agent for orange juice.Essential oils (EOs) are promising safe and natural alternatives for pasteurization and synthetic preservation of orange juice. The current research investigates the efficacy of Cinnamomum cassia essential oil (CCEO) as a natural food preservative and flavoring agent in orange juice. We evaluated the physicochemical, microbiological, and sensorial qualities of the juice treated with CCEO over 28 days of storage at 4 degrees C, with measurements taken on every day 7. Results showed that CCEO significantly improved quality indicators by reducing browning reactions and inhibiting pectin methyl esterase activity (p < 0.05). However, potential hydrogen and titratable acidity remained unaffected (p > 0.05). CCEO significantly (p < 0.05) enhanced the microbiological and sensory properties of orange juice by reducing microbial load and enhancing taste, color, flavor, and the overall acceptability parameters. These findings demonstrated the potential of CCEO as a natural food preservative and flavoring agent for orange juice
Rendre compte de la vulnérabilité énergétique logement-mobilité des ménages d’un territoire – un système d’indicateurs pour outiller les politiques publiques locales
No full textInternational audienceIn a context where the social challenges of the energy transition are increasingly strong, this article focuses on the structural elements of a territory likely to weaken the resident population to rising energy prices. It proposes a system of six territorial indicators which is based on two main principles. On the one hand, it focuses on a transversal approach to traditional sectors of public action by dealing with both housing and the daily mobility of households. On the other hand, it is based on the notion of vulnerability, understood as the combination of the three dimensions of sensitivity, exposure and adaptability. Simple and easily reproducible across the entire national territory, these indicators were developed as part of research involving academics and practitioners. They were thus designed to be integrated into an operational platform intended to help local stakeholders with their territorial forecasts and to be able to be returned in the form of easily understandable maps and graphs. Their objective is to allow stakeholders to assess the relevance of their interventions in relation to the types of energy vulnerability that emerge in their territory - according to the two sectors, housing or mobility, and according to the three dimensions of vulnerability. As part of this article, they were applied to the case of Roannais Agglomération, an Agglomeration Community of 40 municipalities and 100,000 inhabitants located in the south-east of France, making it possible to show how they reflect the diversity and spatial structuring of the situations of the municipalities in this area.Dans un contexte où les enjeux sociaux de la transition énergétique sont de plus en plus forts, cet article s’intéresse aux éléments structurels d’un territoire susceptibles de fragiliser la population résidente face au renchérissement de l’énergie. Il propose un système d’indicateurs territoriaux reposant sur deux grands principes. D’une part, il s’attache à une démarche transversale aux secteurs traditionnels de l’action publique en traitant à la fois du logement et de la mobilité quotidienne des ménages. D’autre part, il s’adosse à la notion de vulnérabilité, entendue comme la combinaison des trois dimensions que sont la sensibilité, l’exposition et l’adaptabilité. Simples et facilement reproductibles sur l’ensemble du territoire national, ces indicateurs sont appliqués au cas de la Communauté d’Agglomération de Roannais Agglomération, permettant d’illustrer la diversité et la structuration spatiale des situations des quarante communes de ce territoire
Thematic factsheet - Pasture access in ruminants and equines
No full textThis thematic factsheet summarises the knowledge on pasture access in ruminants and equines from a welfare point of view. The benefits and risks of pasture access along with associated recommendations to ensure adequate pasture access are summarised in this factsheet
Indicator factsheet - Group housing of calves
No full textThis indicator factsheet provides key factors to appropriately manage group housing of calves as well as recommendations for inspection
Pansement chélatant pour le traitement de plaies complexes
No full textL'invention concerne une composition aqueuse, ayant une viscosité newtonienne entre 0,5 Pa.s et 1000 Pa.s, comprenant au moins un polysaccharide statistique B, ayant une masse molaire moyenne en poids d'entre 100 kDa et 1000 kDa, de formule I : et facultativement un chitosane A, ledit polysaccharide statistique B étant dans une concentration massique CB, ledit chitosane A étant dans une concentration massique CA, la somme de CB plus CA étant d'au moins 10 g.L-1. L'invention concerne également la composition aqueuse susmentionnée pour son utilisation dans le traitement de plaies complexes, telles que des plaies liées au diabète, des brûlures et des plaies contenant un ou plusieurs métaux, et un pansement comprenant ladite composition aqueuse
Effects of host sex, age and behaviour on co-infection patterns in a wild ungulate
No full textInternational audienceRecent zoonotic disease emergences emphasize the importance of studying wildlife parasite communities. As wild hosts frequently harbour diverse parasite species, understanding the drivers of multiple infection patterns in free-ranging hosts is critical for elucidating the ecological and epidemiological dynamics of parasite communities. In this study, we analysed co-infection patterns in European roe deer (Capreolus capreolus) inhabiting a fragmented rural landscape in southwestern France. Using data from 130 samples of GPS-tracked deer, we examined the influence of proximity to livestock, host activity levels, age, sex, and between-parasite interactions on the presence of 11 parasitic taxa. Hierarchical modelling of species communities (HMSC) revealed that proximity to livestock significantly increased the likelihood of infection with orofecally transmitted parasites (Toxoplasma gondii, gastrointestinal parasites). Sex and age were other key predictors, with males and juveniles exhibiting a higher frequency of parasite presence, likely influenced by hormonal and immune system differences. Activity levels showed distinct age-related effects, with higher activity levels being positively associated with increased parasite prevalence in yearlings, but not in adults. In contrast, parasite association patterns within individual hosts were weak, suggesting minimal interactions between parasite species. Our findings highlight the interplay between exposure and susceptibility in shaping co-infection patterns and underscore the value of hierarchical modelling approaches in multi-parasite systems
Regression trees for identifying synergies and antagonisms interactions among farming practices influencing milk quality indicators
No full textInternational audienceIntroduction Farming practices can interact with each other and have antagonistic or synergistic effects on different compounds. Therefore, this study aimed to investigate the use of regression trees (RT) to study the synergies and antagonisms interactions of farming practices on milk quality indicators.Material and methods Two hundred-thirty samples of bulk tank milk were collected in French dairy farms and analysed for milk quality indicators: vitamin B2, calcium (Ca) and sums of omega 3 and omega 6 fatty acids content. A survey on the farming practices (herd characteristics, feeding management, housing conditions, milking and milk storage conditions) applied on the day of collection was also conducted. The RT were then applied to predict the milk quality indicators from the combinations of farming practices and validated by cross-validation.Results and discussion The RT identified combinations of practices that lead to different predicted values for vitamin B2 (R2cv=0.39), ω6/ω3 ratio (R2cv=0.67) and Ca (R2cv=0.14)(Figure 1). Comparison of the RT revealed: i) a synergistic effect of the dominant breed on vitamin B2 and Ca contents, with higher levels observed in Montbéliarde herds compared to those of Holstein Friesian for both indicators; ii) an antagonistic effect of the proportion of concentrates in the total diet dry matter with increased vitamin B2 content when the proportion of concentrates was lower (<22% or < 26%) and higher ω6/ω3 ratio when concentrates accounted for less than 8% in case of corn-silage (CS)-based diets. This suggests a nutritional benefit for vitamin B2 but a nutritional drawback for the ω6/ω3 ratio; ii) an antagonistic effect of concentrate proportion on the ω6/ω3 ratio, with a lower ratio observed in CS-based diets as concentrate proportion increased, and a higher ratio observed in other forage-based diets when concentrate proportion increased. Conclusion and implications RT allowed identifying synergistic and antagonist interactions on farming practices on a same indicator and/or on different indicators. We also developed RT for around 30 indicators. No single practice improved all indicators, meaning that various trade-offs will need to be made depending on the farmers' goals and the specific dairy sector they are part of
La transmission des agents pathogènes dans le complexe Tiques-Carnivores domestiques : quels enjeux en épidémiologie des maladies vectorielles à tiques et pour la prévention ?
No full textInternational audienceTicks are major vectors of animal and human diseases in France and Europe. In the north, center, and west of France, the most frequently encountered tick species is Ixodes ricinus . Ticks of the genus Dermacentor have a distribution area quite similar to Ixodes ticks. In Mediterranean climate, ticks of the genera Rhipicephalus and Hyalomma are prevalent because of their lower sensitivity to heat and drought. Global warming and animal movements are likely to modify tick distribution in the future. Each tick species is associated with a contingent of pathogens that they are likely to transmit. The distribution of pathogens and diseases is therefore directly correlated with the distribution of tick species. Transmission of pathogens to carnivores most often occurs through a tick bite. The time between the onset of the bite and infection can represent a real challenge for the médical ou mechanical prevention of the desease. Pathogens have undergone several adaptations and thus use several possible routes of transmission from one tick to another in order to increase the probability of infection and therefore transmission. Preventing bites and preventing tick multiplication in the environment are complementary in the prophylaxis of vector-borne diseases.Les tiques sont les premiers vecteurs de maladies animales et humaines en France et en Europe. Dans le nord, le centre et l’ouest du territoire français, la tique la plus fréquemment rencontrée est Ixodes ricinus . Les tiques du genre Dermacentor présentent une aire de distribution assez similaire aux tiques Ixodes . En climat méditerranéen, on trouve les tiques des genres Rhipicephalus et Hyalomma , plus adaptées à la chaleur et à la sécheresse. L’évolution du climat avec une tendance au réchauffement, et les mouvements des animaux sont susceptibles de modifier la distribution des tiques dans le futur. Chaque espèce de tique est associée à un contingent plus ou moins large d’agents pathogènes qu’elles sont susceptibles de transmettre. La distribution des agents pathogènes et des maladies est donc directement corrélée à la distribution des espèces de tiques. La transmission des agents pathogènes aux carnivores se produit le plus souvent à la faveur d’une piqûre de tique. Le délai entre le début de la piqûre et l’infection peut représenter un véritable challenge pour la prévention. Les agents pathogènes ont subi un certain nombre d’adaptations et utilisent ainsi plusieurs voies possibles de transmission d’une tique à l’autre afin d’augmenter la probabilité d’infection et donc de transmission. La prévention des piqûres et la prévention de la multiplication des tiques dans l’environnement sont complémentaires dans la prophylaxie des maladies vectorielles