Reversibility of enzymatic reactions might limit biotransformation of organic micropollutants

This is the accepted manuscript version of the published article: Gonzalez-Gil, L., Carballa, M., Corvini, P., & Lema, J. (2019). Reversibility of enzymatic reactions might limit biotransformation of organic micropollutants. Science Of The Total Environment, 665, 574-578. doi: 10.1016/j.scitotenv.2019.02.143Biotransformation of many organic micropollutants (OMPs) in sewage treatment plants is incomplete leading to their release into the environment. Recent findings suggest that thermodynamic aspects of the reaction as chemical equilibrium limit biotransformation, while kinetic parameters have a lower influence. Reversibility of enzymatic reactions might result in a chemical equilibrium between the OMP and the transformation product, thus impeding a total removal of the compound. To the best of our knowledge, no study has focused on proving the reversible action of enzymes towards OMPs so far. Therefore, we aimed at demonstrating this hypothesis through in vitro assays with bisphenol A (BPA) in the presence of kinase enzymes, namely acetate kinase and hexokinase, which are key enzymes in anaerobic processes. Results suggest that BPA is phosphorylated by acetate kinase and hexokinase in the presence of ATP (adenosine 5-triphosphate), but when the concentration of this co-substrate decreases and the enzymes loss their activity, the backward reaction occurs, revealing a reversible biotransformation mechanism. This information is particularly relevant to address new removal strategies, which up to now were mainly focused on modifying the kinetic parameters of the reactionThis research was funded by the Spanish Government (AEI) through COMETT project (CTQ2016-80847-R) and by FPU program with a contract (FPU13/01255) and a short research stay grant (EST16/00138). Authors from Universidade de Santiago de Compostela belong to CRETUS Strategic Partnership (AGRUP2015/02) and to Galicia Competitive Research Group (GRC ED431C 2017/29) which are co-funded by FEDER (EU)S

A microscopic 2D lattice model of dimer granular compaction with friction

We study by Monte Carlo simulation the compaction dynamics of hard dimers in 2D under the action of gravity, subjected to vertical and horizontal shaking, considering also the case in which a friction force acts for horizontal displacements of the dimers. These forces are modeled by introducing effective probabilities for all kinds of moves of the particles. We analyze the dynamics for different values of the time $\tau$ during which the shaking is applied to the system and for different intensities of the forces. It turns out that the density evolution in time follows a stretched exponential behavior if $\tau$ is not very large, while a power law tail develops for larger values of $\tau$. Moreover, in the absence of friction, a critical value $\tau^*$ exists which signals the crossover between two different regimes: for $\tau < \tau^*$ the asymptotic density scales with a power law of $\tau$, while for $\tau > \tau^*$ it reaches logarithmically a maximal saturation value. Such behavior smears out when a finite friction force is present. In this situation the dynamics is slower and lower asymptotic densities are attained. In particular, for significant friction forces, the final density decreases linearly with the friction coefficient. We also compare the frictionless single tap dynamics to the sequential tapping dynamics, observing in the latter case an inverse logarithmic behavior of the density evolution, as found in the experiments.Comment: 10 pages, 15 figures, to be published in Phys. Rev.

Autoantibodies against type I IFNs in patients with life-threatening COVID-19

Interindividual clinical variability in the course of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is vast. We report that at least 101 of 987 patients with life-threatening coronavirus disease 2019 (COVID-19) pneumonia had neutralizing immunoglobulin G (IgG) autoantibodies (auto-Abs) against interferon-w (IFN-w) (13 patients), against the 13 types of IFN-a (36), or against both (52) at the onset of critical disease; a few also had auto-Abs against the other three type I IFNs. The auto-Abs neutralize the ability of the corresponding type I IFNs to block SARS-CoV-2 infection in vitro. These auto-Abs were not found in 663 individuals with asymptomatic or mild SARS-CoV-2 infection and were present in only 4 of 1227 healthy individuals. Patients with auto-Abs were aged 25 to 87 years and 95 of the 101 were men. A B cell autoimmune phenocopy of inborn errors of type I IFN immunity accounts for life-threatening COVID-19 pneumonia in at least 2.6% of women and 12.5% of men

Etude de la compétition souterraine entre merisiers et graminées dans un système sylvopastoral

National audienceCet article reprend les conclusions d’une publication scientifique initialement parue en anglais et permet de comprendre et donc de mieux gérer la compétition racinaire entre la pâture et l’arbre dans les systèmes sylvopastoraux. Cette étude fournit notamment des données précieuses concernant les mécanismes qui conduisent au stress hydrique chez les arbres plantés en présence de graminées

Problématique de recherche sur les systèmes sylvo-pastoraux du Massif-Central

International audienc

Agroforesterie en Europe de l'Ouest: pratiques et expérimentations sylvopastorales des montagnes de la zone tempérée

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Programme recherche développement de systèmes agroforestiers

Ce document vise à décrire rapidement l'ensemble des question traitées, des moyens mis en oeuvre, des résultats en cours ou acquis et à privilégier la présentation de certains thèmes particulièrement développés dans le cours de l'année en matière d'agroforesterie

Compétition pour l'azote entre arbre et herbe dans des plantations de noisetier (Corylus avellana L.)et de merisier (Prunus avium L.)

*INRA Unité d'Agronomie Clermont-Ferrand (FRA) Diffusion du document : INRA Unité d'Agronomie Clermont-Ferrand (FRA)National audienc