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Synchronization and fluctuations for interacting stochastic systems with individual and collective reinforcement
No full textThe Pólya urn is the paradigmatic example of a reinforced stochastic process. It leads to a random (non degenerated) time-limit. The Friedman urn is a natural generalization whose a.s. time-limit is not random anymore. In this work, in the stream of previous recent works, we introduce a new family of (finite) systems of reinforced stochastic processes, interacting through an additional collective reinforcement of mean field type. The two reinforcement rules strengths (one componentwise, one collective) are tuned through (possibly) different rates n −γ. In the case the reinforcement rates are like n −1 , these reinforcements are of Pólya or Friedman type as in urn contexts and may thus lead to limits which may be random or not. Different parameter regimes needs to be considered. We state two kind of results. First, we study the time-asymptotics and show that L 2 and almost sure convergence always holds. Moreover all the components share the same time-limit (so called synchronization). We study the nature of the limit (random/deterministic) according to the parameters' regime considered. Second, we study fluctuations by proving central limit theorems. Scaling coefficients vary according to the regime considered. This gives insights into the different rates of convergence
Bioinformatics and metabolic flux analysis highlight a new mechanism involved in lactate oxidation in Clostridium tyrobutyricum
No full textInternational audienceClimate change and environmental issues compel us to find alternatives to the production of molecules of interest from petrochemistry. This study aims at understanding the production of butyrate, hydrogen, and CO 2 from the oxidation of lactate with acetate in Clostridium tyrobutyricum and thus proposes an alternative carbon source to glucose. This specie is known to produce more butyrate than the other butyrate-producing clostridia species due to a lack of solvent genesis phase. The recent discoveries on flavin-based electron bifurcation and confurcation mechanism as a mode of energy conservation led us to suggest a new metabolic scheme for the formation of butyrate from lactate-acetate co-metabolism. While searching for genes encoding for EtfAB complexes and neighboring genes in the genome of C. tyrobutyricum , we identified a cluster of genes involved in butyrate formation and another cluster involved in lactate oxidation homologous to Acetobacterium woodii . A phylogenetic approach encompassing other butyrate-producing and/or lactate-oxidizing species based on EtfAB complexes confirmed these results. A metabolic scheme on the production of butyrate, hydrogen, and CO 2 from the lactate-acetate co-metabolism in C. tyrobutyricum was constructed and then confirmed with data of steady-state continuous culture. This in silico metabolic carbon flux analysis model showed the coherence of the scheme from the carbon recovery, the cofactor ratio, and the ATP yield. This study improves our understanding of the lactate oxidation metabolic pathways and the role of acetate and intracellular redox balance, and paves the way for the production of molecules of interest as butyrate and hydrogen with C. tyrobutyricum
Mother’s scent for motherless neonates: Responses of artificially reared lambs to ewe’s inguinal wax odor
No full textInternational audienceMammalian newborns depend on their mother’s milk to satisfy their initial needs of protection and nutrition. They reach the source of milk in following visual, tactile and olfactory cues. In particular, parturient ewes produce an odorous wax in the inguinal glands close to the teats. When presented separately to newly born lambs, this inguinal wax (IW) elicits arousal, head orientation, licking and increased respiratory rate indicative of their avidity for it. The present study assessed whether transferring IW into the environment of artificially fed lambs would improve their responses to the novelty of the situation. We first assessed whether suckled lambs preferred an IW-scented teat to a scentless control teat. Then, we assessed whether a teat odorized with IW was more easily learned as suckable relative to a control teat. Finally, the lambs’ growth performance from postnatal days (PND) 0 and 20 was compared in groups reared with or without IW spread on the milk-feeder in their home pen. The behavioral assays did not evidence any significant effect of IW odor on previously suckled lambs’ attraction and appetence responses. However, relative to the scentless control condition, being exposed to an IW-smeared milk-feeder led to a higher body weight at 20 days after birth. In the conditions of the present study, namely after suckling initiation, IW odor appeared not to be a strong determinant of short-term attraction or appetitive behavior in neonate lambs. The continued presence of IW, a familiar odor, in the artificial suckling context may improve artificially-reared lambs’ emotional state that may affect their weight gain
Controlled natural selection of soil microbiome through plant-soil feedback confers resistance to a foliar pathogen
No full textInternational audienceBackground and aims The rhizosphere microbiome has been shown to contribute to nutrient acquisition, protection against biotic and abiotic stresses and, ultimately, to changes in the development and physiology of plants. Here, using a controlled natural selection approach, we followed the microbial dynamics in the soil of Arabidopsis thaliana plants infected with the foliar pathogen Pseudomonas syringae DC3000 (Pst). Methods Plants were iteratively cultivated on a pasteurised soil inoculated with the soil microbial community of the previous iteration isolated from the rhizosphere of plants infected with Pst (pst-line) or not (mock-line). Modification of soil microbial communities was assessed through an amplicon-based metagenomic analysis targeting bacterial and fungal diversity. Plant fitness and transcript abundance of stress hormone related genes were also analysed. Results At the tenth and eleventh iterations respectively, we observed a reduction in disease severity of 81% and 85% in pst-lines as compared to mock-lines. These changes were associated with (i) an early induction of defence mechanisms mediated by salicylic acid, in pst-line as compared to mock-line, shown by the decrease in transcript abundance of salicylic acid related genes, whereas jasmonic acid, ethylene or abscisic acid related genes remained unchanged and (ii) a shift in soil bacterial, and not in fungal, composition. Conclusions Our study suggests that these changes in soil bacterial composition are mediated by plant-soil feedback in response to Pst and resulted in an activation of SA-related immune response in the plant. This supports the concept of applying plant-soil feedbacks to enhance soil suppressiveness against foliar pathogens
Management of Listeria monocytogenes on surfaces by the mean of Relative Air Humidity (RAH)
No full textInternational audienc
Are specific PDO wines sensorially recognisable? A study in the Beaujolais vineyard with different types of experts
No full textInternational audienceWine PDOs are based on their place of origin and technical product specifications. Some studies have looked at sensory differences between PDOs, but few have shown real sensory specificities for each PDO. These studies have focused on well-established PDOs, leaving aside the new appellations developed in recent years. This article investigates experts’ sensory representation (study 1) and actual descriptions of wines in blind and informed tastings (study 2). To achieve this objective, we used the Beaujolais vineyard as a case study and, more specifically, the new Beaujolais Pierres Dorées PDO. Three groups of experts were recruited and separated according to their professions: Makers, Sellers, and Critics. The results showed that the new Beaujolais Pierres Dorées PDO did not present a specific sensory description, neither in the mental representations of the experts nor during the tasting. Providing information on the PDO of the wine samples did not lead to different descriptions compared to blind tasting. However, wines from the same appellation were described more similarly in the informed tasting than in the blind one, suggesting some assimilation or contrast effects. No effect of the type of experts was observed during the tasting. However, experts store different wine attributes in memory depending on their experience and practice. The Makers stored very precise descriptions, the Sellers a few punchline descriptors, and the Critics were situated between the other two groups with both punchline descriptors and satellite descriptors
Effect of diet composition on glandular gastric disease in horses
No full textInternational audienceBackground: Nutritional factors are suggested to influence the incidence and severity of glandular gastric disease (GGD) in horses.Objectives: To retrospectively assess whether dietary fermentable carbohydrates increase the severity of GGD and to prospectively evaluate whether the partial substitution of concentrates by dehydrated alfalfa would decrease GGD severity scores.Animals: In total, 82 trotters from 4 training centers exercised ≥5 days/week.Methods: Multicenter retrospective observational study, and prospective 2-arm randomized trial. Glandular mucosae were observed by gastroscopy and scored (0-4 severity scale) at day 0 (D0). Biochemical composition of the diet fed was compared between ulcerated and nonulcerated groups. After D0, horses either received the same diet (control, n = 41) or pelleted dehydrated alfalfa substituting 50% concentrates (alfalfa, n = 41). Glandular scores were recorded in both groups after 21 (D21) and 42 days (D42). The first end point was a successful outcome, defined as a horse with a glandular score of 2 to 4 on D0, decreasing to a score of 0 to 1 on days 21 or 42.Results: Horses scored 0 to 1 at D0 ingested more (P = .01) soluble sugars from concentrates than those scored 2 to 4 before D0 (77.5 g/kg BW; 95% confidence interval [CI]: 71.1-84.0, vs 59.1 g/kg BW; 95% CI: 48.0-70.3), whereas starch intake did not differ between groups (P = .24). Among horses scored 2 to 4 at D0, fewer were scored 2 to 4 in the alfalfa group (1 out of 6) compared with the control group (6 out of 6) at D42 (P = .02). Clinical success was 47.7 times more likely in horses fed alfalfa compared with horses in the control group (95% CI: 1.6-1422.8).Conclusion and clinical importance: Relationships were found between diet composition and integrity of the glandular mucosa. Feeding pelleted dehydrated alfalfa could help to reduce the incidence and severity of GGD
Fibre Composition and Maturity of Forage-Based Diets Affects the Fluid Balance, Faecal Water-Holding Capacity and Microbial Ecosystem in French Trotters
No full textInternational audienceRacing events challenge the fluid balance of athletic horses. The equine large intestine functions as a fluid reservoir, since the properties of dietary forage fibre affect the digesta water content and the milieu of this ecosystem. This study aimed to investigate the effect of grass maturity and legume forage on the faecal water-holding capacity (WHC) and microbial ecosystem, and the fluid balance and body weight (BW) of French trotters in race training. Six geldings were offered three diets with different fibre compositions: concentrate and late-harvested mature grass haylage (35:65 energy ratio) (CMGH); early-harvested grass haylage and mature grass haylage (80:20) (EGH); and lucerne and mature grass haylage (80:20) (LH), for 24 days in a Latin square design. Body weights were lower and faecal WHC higher when the horses were fed EGH compared to CMGH and LH (485 vs. 492 and 492 kg, p < 0.001; 12.6 vs. 11.1 and 11.4 g H2O/g dry faeces, p = 0.014, respectively). Total water intake and output did not differ between diets, but water excretion via faeces was lower and via urine was greater on EGH compared to CMGH and LH (13.1 vs. 18.8 and 17.6 kg, p = 0.001; 10.5 vs. 7.6 and 7.9 kg, p = 0.032, respectively). Total bacteria concentrations were higher on EGH than CMGH and LH (5.4 × 1011 vs. 2.8 × 1011 and 2.8 × 1011 CFU/mL, p = 0.018, respectively). Concentrations of butyrate were greater, and pH was lower when fed EGH compared to CMGH and LH (3.0 vs. 2.0 and 1.6 mmol/L, p = 0.034; 6.5 vs. 6.9 and 7.2, p = 0.005, respectively). In conclusion, forage harvested at an early stage of maturity could benefit athletic horses’ fluid balance by providing a more available large intestine fluid reservoir without increasing BW
Évaluation des impacts sur la santé publique de la dynamique des populations de renards
No full textCitation suggérée : Anses. (2023). Évaluation des impacts sur la santé publique de la dynamique des populations de renards. (Saisine 2022-SA-0049). Maisons-Alfort : Anses, 200 p.Le Renard roux (Vulpes vulpes) est une espèce de la faune sauvage. En tant que gibier, il peut être chassé par différents moyens. Il est de plus susceptible d’être inscrit, dans certains territoires, comme espèce susceptible d’occasionner des dégâts (ESOD) par arrêté ministériel triennal pris en application de l’article R.427-6 du Code de l’environnement. Nonobstant les restrictions sur les périodes de chasse, les animaux classés ESOD peuvent être éliminés toute l’année. En 2019 et pour trois ans, suite à des consultations départementales et un arbitrage ministériel, le renard a été classé ESOD dans 90 départements français.La décision de classement doit être motivée. Plusieurs arguments sont avancés pour ce classement : pertes dans les élevages avicoles ou de gibier, raisons sanitaires (par ex. : échinococcose alvéolaire, gale sarcoptique). Inversement, des bénéfices liés à la présence des renards sont également avancés, tels que la prédation de rongeurs (campagnols notamment), porteurs d’agents zoonotiques, la réduction d’utilisation de raticides, etc. ... Dans un rapport et avis sur le rôle épidémiologique du renard dans le système multihôtes de la tuberculose bovine (Anses 2021), l’Anses notait que l’importance des nuisances attribuées aux renards faisait l’objet de controverses et de polémiques en France.La présente saisine s’inscrit ainsi dans un contexte sociétal sensible impliquant notamment les associations de protection de la nature et les chasseurs ou les éleveurs. Les réponses à cette saisine visent à clarifier le rôle du renard dans l’épidémiologie de certaines zoonoses pour lesquelles il est présenté comme premier responsable de la transmission à l’humain, ce qui motive certains acteurs à proposer son classement en tant qu’ESOD
Determination of Polystyrene Microplastic in Soil by Pyrolysis – Gas Chromatography – Mass Spectrometry (pyr-GC-MS)
No full textInternational audiencePyrolysis-gas chromatography-mass spectrometry (pyr-GC-MS) is emerging as a promising alternative for the detection and quantification of microplastic pollution. For a robust quantification it is essential to improve our understanding of interferences in the pyrolysis of microplastics. Here we investigate the effects of different soil matrices, mainly differing by their organic carbon content (Corg, 1.0–13.6%), and of the polymer molecular weight (Mw) on the pyr-GC-MS analysis of polystyrene (PS) microplastics. In addition, we evaluated the effectiveness of adding poly(4-fluorostyrene) (PSF) as internal standard to circumvent the matrix effects. The three main markers of PS pyrolysis, i.e., styrene, styrene-dimer and styrene-trimer, were monitored. The ratio between the dimer and the trimer significantly varied between the matrices and tended to decrease with the increasing of the Corg in the soil, mainly due to an increased trimer formation. A strong matrix effect affected the slope of the calibration curves by 2 to 8-fold and was correlated with the Corg in the soils. This effect was mitigated when the areas of the markers were normalized by the area of the corresponding marker of PSF. PS of low Mw (Mw 35,000) presented a reduced formation of the three markers compared to PS of high Mw (Mw 400,000), and styrene-dimer was proportionally less formed than the other two markers. Differences in the slopes of calibration curves depended on the marker chosen, highlighting the relevance of selecting the pyrolysis marker in the quantification of microplastics using pyr-GC-MS