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Does substrate diversity affect microbial heat dissipation in soil?
No full textInternational audienceMost studies exploring the relation between the quality of organic substrates and microbial activity have been carried out with individual substrates. However, they have largely overlooked potential effects that might occur when microorganisms simultaneously process a heterogeneous mixture of organic substances. We investigated whether the degree of molecular richness of substrate mixtures had an impact on the overall activity of microbial communities, measured as heat dissipation over a day, in a laboratory incubation experiment. Topsoil samples were taken from a Swedish long-term field trial, established in 1983, in which a crop rotation dominated by spring cereals was either under-sown with perennial ryegrass as a cover crop or was without cover crops. No significant differences in the cumulative heat dissipation between soil with or without cover crops were observed. When all substrate mixtures were evaluated, the substrate richness was not significantly correlated with the overall microbial activity. However, we observed a bell-shaped curve between the total microbial activity and the nominal oxidation state of carbon (C) in the substrate mixtures. In most cases, the measured heat dissipated from soils that received substrate mixtures was significantly higher than the theoretically expected heat dissipation. The latter was based on the weighted sum of heat dissipated of individual substrates. This pattern was more visible in soil without cover crops than in soil with cover crops. The higher-than-expected heat dissipation from substrate mixtures suggests that the response of soil microbial communities to diverse substrates is not simply additive. There are several possible explanations for the observations made: (i) interactions among microbial metabolic pathways, (ii) added substrates may be preferentially used, and (iii) concentration of all the substrates in the mixtures was lower than when added individually, and therefore the metabolic pathways for each substrate was less likely to be saturated. Chemodiversity, the diversity of organic chemical compounds, is often not considered in models evaluating the dynamics of soil organic matter. Our results warrant further investigations into microbial metabolism and the processing of heterogeneous organic substances in order to constrain microbial-and substrate-specific models of soil organic matter
Les inégalités sociales et territoriales face aux canicules
No full textCe policy brief synthétise les résultats d'une évaluation des inégalités sociales et territoriales face aux fortes chaleurs en France. En exploitant une nouvelle base de données mensuelle couvrant 34 000 communes métropolitaines de 1980 à 2019, l'étude montre que les épisodes de forte chaleur accroissent significativement la mortalité, surtout chez les personnes âgées de plus de 75 ans, avec des effets plus marqués dans les zones urbaines et les communes les plus défavorisées. Depuis la grande canicule de 2003, la mise en place du Plan national canicule a nettement réduit l'impact des fortes chaleurs, mais des inégalités importantes demeurent
Sweetness exposure modulates brain networks in children responding to sucrose solutions: a functional MRI study
No full textInternational audienceContextChildhood obesity is a pervasive health issue, with sugar consumption implicated not only in its development but also in adverse effects on brain health. While extensive research has explored adult brain processes in response to sweet taste, there is limited understanding of how children's brains activate in similar, contexts.MethodIn this study, 34 children aged 8-12 undent food frequency and sweetness liking assessments before participating in a functional magnetic resonance imaging (fMRI) scan during a gustatory paradigm involving varying sweetness levels. Utilizing independent component analysis (ICA), we examined functional networks engaged during sweet taste perception and after swallowing.ResultsOur study identified distinct brain networks for tasting, swallowing, and a transitional stage linking the two. Children with lower BMI and higher sugar intake showed greater activation in the transition network, suggesting enhanced interoceptive sensitivity.ConclusionThis novel investigation provides a foundational understanding of how sweetness exposure modulates brain networks in children responding to sucrose solutions, offering valuable insights into the interplay between sugar consumption, childhood obesity, and neural responses
Neonatal Listeria-meningitis in San Luis, Argentina: a three-case report.
No full textInternational audienceBetween November 1996 and December 2006, two cases of early-onset and one case of late-onset neonatal listeriosis were reported in San Luis, Argentina. This article describes clinical and laboratory findings as well as treatment and outcome for newborns treated for Listeria monocytogenes meningitis or septicaemia. In one of the newborns with early-onset listeriosis, meningitis led to important complications including hydrocephalus. The two other newborns showed complete recovery following adequate treatment. The L. monocytogenes isolates from two patients belonged to PCR group IVb (including serovar 4b strains) and to PCR group IIb (including serovar 1/2b strains) in the third patient. Listeriosis, especially the maternal-fetal presentation, is still rare in Argentina for unknown reasons. Our data can be used in the future as an epidemiological survey
The crazy ovary 2: a tribute to Ken McNatty
No full textInternational audienceIn 2021, Ken McNatty, Danielle Monniaux, and I published a review essay illustrating how ovarian folliculogenesis can sometimes be bizarre, amazing, or even almost incomprehensible. Examples included the mechanisms underlying intra- and inter-species differences in ovulation rates; the possibility of awakening human primordial follicles in vitro, maturing and fertilizing them to produce viable offspring; and a model in which inactivation of a single oocyte gene results in sterile mice with follicular growth blocked at the primary stage but normal steroid cyclicity maintained. The aim of this second essay is to present further examples of the extraordinary diversity of ovarian function across animal species and, where possible, to propose hypotheses that may explain them. These concern: 1) the presence of oogonial stem cells in the ovaries of invertebrates and non-mammalian vertebrates, and their very probable absence in mammals; 2) the many and varied strategies of ovarian development and oogenesis in teleosts; 3)the metabolic dialog between cumulus cells and oocytes across mammalian species; 4) the presence of numerous germline genes, specifically or even exclusively expressed in the mammalian oocyte, whose invalidation has no phenotypic consequence on fertility in the mouse; 5) the unique features of ovarian function in the dog, particularly the frequent presence of polyovular follicles and the distinctive mode of post-ovulatory oocyte maturation; and 6) the absence of an intra-ovarian dominance factor in mono-ovulating species, disproving an old hypothesis: the selection of a single follicle is instead due to a succession of negative and then positive feedback between follicles and the hypothalamic–pituitary axis. This essay is also a final tribute to Ken McNatty, who liked to say that the ovary could be crazy
Genetic variation in molting time and its effects on growth and color traits in the Pacific blue shrimp Litopenaeus stylirostris
No full textInternational audienceTo grow and develop, shrimps must shed their exoskeletons. In shrimp an inter-individual variability in molting time is spread over about a week. The genetic basis of this variability and its implications for selective breeding programs to improve growth or quality traits remains largely unexplored.We estimated the effect of molting stage on genetic parameters of growth and color traits in the Pacific blue shrimp Litopenaeus stylirostris. As the variability of molting time may also be partly genetically determined, we estimated the heritabilities of molt stages and molting time under the hypothesis that some families may have the additive genetic potential to molt earlier (or later) than others.To address these questions, 1200 shrimp progenies (mean body weight 14.5 g) from 49 full- and half-sib families, bred according to a partly factorial design with double-sire insemination, were phenotyped over 3 successive days, 3 to 5 days before the full moon. Body weight, body length, head length and molt stage were recorded on uncooked shrimp and external color traits on uncooked or both uncooked and cooked shrimp.Molt stage had a significant phenotypic effect on all traits except for body length and head-to-length ratio. The heritability estimates for both growth and color traits were, however, similar in models with or without molting, and the estimated breeding values were highly correlated between these models.The heritability of molt stage with a four-class threshold model was low (0.07 [0.02–0.28]). When the stage classes were combined into just two to simplify the description of the molting process, the heritability of early or late molting was intermediate (from 0.16 [0.10–0.28] to 0.22 [0.13–0.40]), indicating that this trait is partly under additive genetic determinism rather than solely under environmental control. The genetic correlations of molting traits with body weight were not different from zero.These results are discussed for selective breeding practices and shrimp molting biology to consider in future study molting as a factor to improve selection practices for disease resistance, feed efficiency and robustness
Surface oscillations of a liquid-solid fluidized bed
No full textInternational audienceWe report experimental investigations of an unconfined liquid-solid fluidized bed at low to moderate Reynolds number. The fluidization velocity U f is measured when an upward flow is imposed, and the sedimentation velocity U sed is measured when the flow is stopped. Only when the level of inlet flow fluctuation is sufficiently low will these two velocities coincide, as expected for an unbound system. A systematic comparison between U f and U sed should therefore be made when attempting to determine fluidization laws. Comparisons with previous studies show that U f measurements gather on a single function of the ratio Φ/Φ pack between the particle volume fraction Φ and its packing value Φ pack , except for a factor K that encompasses all effects other than concentration:Stokes number, Reynolds number, confinement and inlet condition. Time-resolved measurements of the fluidized bed surface show two contributions: uncorrelated high-frequency fluctuations and low-frequency oscillations that remain correlated over minutes. The coherent oscillations correspond to the arrival of upward concentration waves at the bed surface. Their wavelength, which characterizes the length scale of large-scale heterogeneities, was known to diverge as the packing state is approached. Here, we found that it also increases with decreasing concentration, suggesting that the loss of global bed stability observed in previous work at high expansions may be related to the development of heterogeneous structures of a size comparable to that of the column.</p
Paenidepsins are a Family of Lipopeptides from <i>Paenibacillus</i>
No full textInternational audienceA new 12-membered cyclic lipopeptide with antifungal activity, paenidepsin A (1), was isolated from the common-wheat-associated bacterial strain Paenibacillus apiarius MW-14. Its chemical structure was elucidated using a combination of extensive tandem mass spectrometry (MS/MS) and nuclear magnetic resonance (NMR) spectroscopy experiments. Further paenidepsin analogs B-F (2-6) produced by the same strain were detected through molecular networking and structurally characterized via MS/MS analyses. Peptidogenomic analysis revealed the corresponding nonribosomal peptide synthetase (NRPS) biosynthetic gene cluster (BGC), while through genome mining, 72 homologous BGCs were identified from publicly available bacterial genomes. Comprehensive phylogenetic and comparative analyses demonstrated that paenidepsin-like BGCs constitute a new gene cluster family from Paenibacillus. Detailed NRPS domain-level analyses provided bioinformatic evidence for recombination-driven diversification of this BGC. Our findings illustrate the utility of integrating mass spectrometric and genomic tools to discover diverse natural products, and highlight the significant biosynthetic capacity of Paenibacillus species
The Deterrent Effect of the Death Penalty? Evidence from British Commutations During World War I
No full textNational audienceDuring World War I, the British military condemned over 3,000 soldiers to death, but only executed 12% of them; the others received commuted sentences. Many historians believe that the military command confirmed or commuted sentences for reasons unrelated to the circumstances of a particular case and that the application of the death penalty was essentially a random, “pitiless lottery.” Using a dataset on all capital cases during World War I, I statistically investigate this claim and find that the data are consistent with an essentially random process. Using this result, I exploit variation in commutations and executions within military units to identify the deterrent effect of executions, with deterrence measured by the elapsed time within a unit between the resolution of a death sentence (i.e., a commutation or execution) and subsequent absences within that unit. Absences are measured via handwritten trial records and “wanted” lists prepared by British military police units searching for deserters and preserved in war diaries and police gazettes. I find some limited evidence that executing deserters deterred absences, while executing Irish soldiers, regardless of the crime, spurred absences, particularly Irish absences. I present a model where perceived legitimacy of authority affects why people obey the law
