Eukaryote DIRS1-like retrotransposons: an overview

<p>Abstract</p> <p>Background</p> <p>DIRS1-like elements compose one superfamily of tyrosine recombinase-encoding retrotransposons. They have been previously reported in only a few diverse eukaryote species, describing a patchy distribution, and little is known about their origin and dynamics. Recently, we have shown that these retrotransposons are common among decapods, which calls into question the distribution of DIRS1-like retrotransposons among eukaryotes.</p> <p>Results</p> <p>To determine the distribution of DIRS1-like retrotransposons, we developed a new computational tool, ReDoSt, which allows us to identify well-conserved DIRS1-like elements. By screening 274 completely sequenced genomes, we identified more than 4000 DIRS1-like copies distributed among 30 diverse species which can be clustered into roughly 300 families. While the diversity in most species appears restricted to a low copy number, a few bursts of transposition are strongly suggested in certain species, such as <it>Danio rerio </it>and <it>Saccoglossus kowalevskii</it>.</p> <p>Conclusion</p> <p>In this study, we report 14 new species and 8 new higher taxa that were not previously known to harbor DIRS1-like retrotransposons. Now reported in 61 species, these elements appear widely distributed among eukaryotes, even if they remain undetected in streptophytes and mammals. Especially in unikonts, a broad range of taxa from Cnidaria to Sauropsida harbors such elements. Both the distribution and the similarities between the DIRS1-like element phylogeny and conventional phylogenies of the host species suggest that DIRS1-like retrotransposons emerged early during the radiation of eukaryotes.</p

Global transpiration data from sap flow measurements : the SAPFLUXNET database

Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.Peer reviewe

Etude de la coprécipitation du technétium-99 avec la sidérite (FeCO3) comme phase d'accueil

La coprécipitation des radionucléides avec des phases secondaires est un phénomène actuellement négligé dans les études de sûreté d un stockage des déchets nucléaires en formation géologique profonde. La coprécipitation peut, pourtant, jouer un rôle important dans la rétention des radionucléides en limitant leur concentration en solution. Le but de ce travail est d étudier la coprécipitation du technétium-99 avec la sidérite comme phase d accueil. Le coprécipitation a été étudiée en fonction des rapports initiaux Tc/Fe. Dans cet objectif, une méthode de coprécipitation a été mise au point en maintenant des conditions réductrices anaérobies. L étude des phases pures montre la formation de cristallites de sidérite de 450 A dont la taille diminue avec la vitesse de précipitation. Les complexes carbonates de technétium (IV) ont pour stoechiométrie TcCO3(OH)3 et sont solubles dans nos conditions de travail. L analyse de la solution (scintillation liquide) couplée avec la caractérisation de la phase solide (DRX, MET, spectroscopie infrarouge et Mössbauer) montrent la formation de deux phases dans le cas de solides ayant une faible teneur en technétium (de 1 à 2 %). La première phase est une rouille verbe carbonatée, la seconde est composée de sidérite dans laquelle le technétium est incorporé. Dans le cas de solide ayant une forte teneur, le technétium coprécipite avec une phase assimilée à une rouille verte.Coprécipitation of radionuclides with secondary phase is currently neglected in safety assessments for radioactive waste repository, although this process thought to be important in limiting radionuclide solution concentrations. The aim of this work is to study the coprecipitation of technetium-99 with siderite as host phase. The coprecipitaion has been studied as function of Tc/Fe initial concentration radio. A method of coprecipitation has been developed under reducing and anoxic conditions. The study of pure phases shows the formation of crystalline siderite phase whose crystallites size decrease with the precipitation rate. Concerning the pure carbonate of technetium (IV), the soluble complexes stoechiometry is TcCO3(OH)3. Solution analyses (liquid scintillation counting) combined with solid phase characterization (XRD, TEM, IR, spectroscopy and Mössbauer spectroscopy) show the existence of two phases in the case of a low technetium concentration into the solid (from 1 to 2 %). The first one is a carbonate green rust and the second is composed of technetium incorporated within the siderite structure. In the case of high technetium concentration into the solid, it coprecipitates with a phase assimilated to a green rust.ORSAY-PARIS 11-BU Sciences (914712101) / SudocNANTES-ENS Mines (441092314) / SudocSudocFranceF

Uranium interaction with two multi-resistant environmental bacteria: Cupriavidus metallidurans CH34 and Rhodopseudomonas palustris.

Depending on speciation, U environmental contamination may be spread through the environment or inversely restrained to a limited area. Induction of U precipitation via biogenic or non-biogenic processes would reduce the dissemination of U contamination. To this aim U oxidation/reduction processes triggered by bacteria are presently intensively studied. Using X-ray absorption analysis, we describe in the present article the ability of Cupriavidus metallidurans CH34 and Rhodopseudomonas palustris, highly resistant to a variety of metals and metalloids or to organic pollutants, to withstand high concentrations of U and to immobilize it either through biosorption or through reduction to non-uraninite U(IV)-phosphate or U(IV)-carboxylate compounds. These bacterial strains are thus good candidates for U bioremediation strategies, particularly in the context of multi-pollutant or mixed-waste contaminations

Speciation of uranium in plants upon root accumulation and root-to-shoot translocation: A XAS and TEM study

International audienceUranium mobilization in surface waters and soils is highly dependent on its speciation. Links between U speciation and in planta mobility remain unclear, although understanding this relationship is essential in a view to properly develop efficient phytoremediation strategies. To address this question, we used X-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) to determine U speciation and distribution in plant roots and leaves when exposed to U in the form of different chemical species. Our results indicate that U complexation with endogenous phosphate residues leads to its precipitation and fixation in plant organs, avoiding translocation from roots to leaves. We also show that complexation with a strong ligand such as citrate in exposure solution circumvents this precipitation, and enhances root-to-shoot translocation, in a U-carboxylate complex form. These results highlight correlations between U speciation in the environment and its mobility pattern in plants, which would help for phytoremediation purposes. (C) 2011 Elsevier B.V. All rights reserved

Zinc(II) modulates specifically amyloid formation and structure in model peptides

International audienceMetal ions such as zinc and copper can have dramatic effects on the aggregation kinetics of and the structures formed by several amyloidogenic peptides/proteins. Depending on the identity of the amyloidogenic peptide/protein and the conditions, Zn(II) and Cu(II) can promote or inhibit fibril formation, and in some cases these metal ions have opposite effects. To better understand this modulation of peptide aggregation by metal ions, the impact of Zn(II) binding to three amyloidogenic peptides (Aβ14-23, Aβ11-23, and Aβ11-28) on the formation and structure of amyloid-type fibrils was investigated. Zn(II) was able to accelerate fibril formation for all three peptides as measured by thioflavin T fluorescence and transmission electron microscopy. The effects of Zn(II) on Aβ11-23 and Aβ11-28 aggregation were very different compared with the effects of Cu(II), showing that these promoting effects were metal-specific. X-ray absorption spectroscopy suggested that the Zn(II) binding to Aβ11-23 and Aβ11-28 is very different from Cu(II) binding, but that the binding is similar in the case of Aβ14-23. A model is proposed in which the different coordination chemistry of Zn(II) compared with Cu(II) explains the metal-specific effect on aggregation and the difference between peptides Aβ14-23 and Aβ11-23/Aβ11-28

Cocaine-Related Health Emergencies in Europe : A Review of Sources of Information, Trends and Implications for Service Development.

Background: Cocaine-related health consequences are difficult to observe. Data on drug users in health-emergency settings may be a useful source of information on consequences that are not visible via other information sources. Methods: Thirty European countries submit an annual national report on the drug situation to the EMCDDA. All reports for the period 2007–2010 were analyzed, with particular attention given to auditing cocaine-related mentions. Analysis was also performed in order to identify sources and case definitions, assess coverage, audit cases and, where possible, to identify long-term trends. Results: Considerable heterogeneity existed between countries in their approach to recording drug-related emergencies, with only Spain and the Netherlands having established formal indicators. The highest annual numbers of cocaine-related episodes were reported by the UK (3,502), Spain (2,845) and the Netherlands (1,211). A considerable (2- to 3-fold) increase in the numbers of cocaine-related episodes has been reported since the end of the 1990s in these countries; these increases peaked in Spain and England around 2007/08. Conclusions: The analysis reported here suggests the need to develop more standardized approaches to monitoring drug-related emergencies. It points to the potential value of developing effective referral links between the emergency and specialized drug services working with cocaine users.Peer reviewe

Coordination of early cellular reactions during activation of bone resorption in the rat mandible periosteum: An immunohistochemical study

The activation step of bone remodeling remains poorly characterized. Activation comprises determination of the site to be remodeled, osteoclast precursor recruitment, their migration to the site of remodeling, and differentiation. These actions involve different compartments and cell types. The aim of this study was to investigate events and cell types involved during activation. We used a bone remodeling model in rats where extractions of the upper jaw molars initiate remodeling of the antagonist lower jaw (mandible) cortex along the periosteum. In this model osteoclastic resorption peaks 4 days after extractions. We previously reported that mast cell activation in the periosteum fibrous compartment is an early event of activation, associated with recruitment of circulating monocyte osteoclast precursors. By using immunohistochemistry, we observed 9 hours after induction a spatially oriented expression of InterCellular Adhesion Molecule-1 in the vessels that was inhibited by antagonists of histamine receptors 1 and 2. It was followed at 12 hours by the recruitment of ED1+ monocytes. In parallel, at 9 hours, Vascular Cellular Adhesion Molecule-1+ fibroblast-like cells scattered in the fibrous compartment of the periosteum between the vessels and the osteogenic compartment increased; these cells may be implicated in osteoclast precursor migration. Receptor Activator of NF KappaB Ligand+ cells increased at 12 hours in the osteogenic compartment and reached a peak at 18 hours. At 24 hours the numbers of osteogenic cells and subjacent osteocytes expressing semaphorin 3a, a repulsive for osteoclast precursors, decreased before returning to baseline at 48 hours. These data show that during activation the two periosteum compartments and several cell types are coordinated to recruit and guide osteoclast precursors towards the bone surface

Establishing Efficient Cobalt-Based Catalytic Sites for Oxygen Evolution on a Ta₃N₅ Photocatalyst

In a photocatalytic suspension system with a powder semiconductor, the interface between the photocatalyst semiconductor and catalyst should be constructed to minimize resistance for charge transfer of excited carriers. This study demonstrates an in-depth understanding of pretreatment effects on the photocatalytic O₂ evolution reaction (OER) activity of visible-light-responsive Ta₃N₅ decorated with CoO_<i>x</i> nanoparticles. The CoO_<i>x</i>/Ta₃N₅ sample was synthesized by impregnation followed by sequential heat treatments under NH₃ flow and air flow at various temperatures. Various characterization techniques, including X-ray diffraction (XRD), X-ray absorption spectroscopy (XAS), scanning transmission electron microscopy (STEM), and X-ray photoelectron spectroscopy (XPS), were used to clarify the state and role of cobalt. No improvement in photocatalytic activity for OER over the bare Ta₃N₅ was observed for the as-impregnated CoO_<i>x</i>/Ta₃N₅, likely because of insufficient contact between CoO_<i>x</i> and Ta₃N₅. When the sample was treated in NH₃ at high temperature, a substantial improvement in the photocatalytic activity was observed. After NH₃ treatment at 700 °C, the Co⁰–CoO_<i>x</i> core–shell agglomerated cobalt structure was identified by XAS and STEM. No metallic cobalt species was evident after the photocatalytic OER, indicating that the metallic cobalt itself is not essential for the reaction. Accordingly, mild oxidation (200 °C) of the NH₃-treated CoO_<i>x</i>/Ta₃N₅ sample enhanced photocatalytic OER activity. Oxidation at higher temperatures drastically eliminated the photocatalytic activity, most likely because of unfavorable Ta₃N₅ oxidation. These results suggest that the intimate contact between cobalt species and Ta₃N₅ facilitated at high temperature is beneficial to enhancing hole transport and that the cobalt oxide provides electrocatalytic sites for OER

VOx/SiO2 Catalyst Prepared by Grafting VOCl3 on Silica for Oxidative Dehydrogenation of Propane

SSCI-VIDE+ECI2D+SOC:ILLInternational audienc