Phenolic Compounds in Natural Solutions of a Coniferous Forest

Phenolic compounds have been identified previously as potentially responsible for allelopathic interferences in spruce forest at high altitude. They have now been analyzed in canopy leachates, snow, and soil solutions collected from the three layers of the podsolic soil: OA, E. and B. Leachates were characterized by high tanning capacity and by p-hydroxyacetophenone (found at 10−6 M) also detected as the major (10−7 M) monomeric compound in snow. At least 10 phenolic monomers, including vanillic, p-hydroxybenzoic, and protocatechuic acids were identified in capillary waters extracted from the OA layer with their sum reaching 2 × 10−6 M. These monomers were only a small part (1%) of the total phenolics. In soil solutions, significant decreases in phenolic concentrations with depth were observed between the E and B layers, with qualitative modifications of the phenolic pattern. Spruce leachates and soil solutions exhibited high temporal variability, resulting in transitory allelopathic potential towards both aerial and subterranean parts of spruce seedlings. The occurrence of various and soluble phenolic coumpounds in the whole forest system, including p-hydroxyacetophenone, which persist from green needles to soil solutions, suggests that they could be involved in complex and interactive processes occurring during organic matter accumulation on the coniferous forest floo

Approche agronomique de l'allélopathie

International audienceL’allélopathie est l’objet d’un nombre croissant de recherches. Des progrès importants ont été réalisés dans la compréhension des mécanismes à l’origine des phénomènes observés, et dans « l’établissement de la preuve » que ces phénomènes n’étaient ni dus à un artefact expérimental, ni confondus avec d’autres phénomènes. Cependant, peu de tentatives ont été menées dans l’optique d’une maîtrise agronomique de ces phénomènes. Une meilleure connaissance des relations entre pratiques agricoles et allélopathie serait nécessaire afin de valoriser cette dernière dans des stratégies de protection intégrée des cultures, et/ou de mieux maîtriser les « effets précédent » des cultures. Un recensement des connaissances actuellement disponibles est effectué, insistant notamment sur les facteurs responsables des variations de potentiel phytotoxique, et sur leur contrôle en vue de l’application agronomique de l’allélopathie. Plusieurs orientations pour une approche agronomique de l’allélopathie sont proposées, en particulier : replacer les mécanismes de l’allélopathie dans le contexte du fonctionnement du champ cultivé, identifier les mécanismes-clés qui varient en fonction des pratiques, et étudier les effets d’une gamme de pratiques agricoles sur ces mécanismes ; vérifier l’occurrence du phénomène en parcelles agricoles en s’appuyant sur des études analytiques ; appréhender simultanément l’allélopathie et les autres dimensions agronomiques majeures de l’activité agricole, en particulier l’élaboration du rendement des cultures

The adhesion molecule Necl-3/SynCAM-2 localizes to myelinated axons, binds to oligodendrocytes and promotes cell adhesion

Background: Cell adhesion molecules are plasma membrane proteins specialized in cell-cell recognition and adhesion. Two related adhesion molecules, Necl-1 and Necl-2/SynCAM, were recently described and shown to fulfill important functions in the central nervous system. The purpose of the work was to investigate the distribution, and the properties of Necl-3/SynCAM-2, a previously uncharacterized member of the Necl family with which it shares a conserved modular organization and extensive sequence homology. Results: We show that Necl-3/SynCAM-2 is a plasma membrane protein that accumulates in several tissues, including those of the central and peripheral nervous system. There, Necl-3/SynCAM-2 is expressed in ependymal cells and in myelinated axons, and sits at the interface between the axon shaft and the myelin sheath. Several independent assays demonstrate that Necl-3/SynCAM-2 functionally and selectively interacts with oligodendrocytes. We finally prove that Necl-3/SynCAM-2 is a bona fide adhesion molecule that engages in homo- and heterophilic interactions with the other Necl family members, leading to cell aggregation. Conclusion: Collectively, our manuscripts and the works onNecl-1 and SynCAM/Necl-2 reveal a complex set of interactions engaged in by the Necl proteins in the nervous system. Our work also support the notion that the family of Necl proteins fulfils key adhesion and recognition functions in the nervous system, in particular between different cell types

Les Juilléras (Mondragon, Vaucluse) site d'habitat et funéraire du Néolithique récent, Néolithique final, Campaniforme - Bronze ancien et Bronze final 2b : Premiers résultats

Le site des Juilléras a fait l'objet d'une fouille de sauvetage sur le tracé du TGV Méditerranée. Plusieurs occupations successives ont pu être mises en évidence. Un ensemble mégalithique à vocation funéraire est mis en place au Néolithique récent. Deux fosses indiquent une occupation au Néolithique final. Le site est ensuite occupé au Campaniforme-Bronze ancien et livre une petite nécropole en marge d'une aire d'occupation domestique. Il est réutilisé une dernière fois au Bronze final 2b par l'implantation d'un four à galets chauffés indiquant la présence d'une aire d'activité particulière

A Glucose BioFuel Cell Implanted in Rats

Powering future generations of implanted medical devices will require cumbersome transcutaneous energy transfer or harvesting energy from the human body. No functional solution that harvests power from the body is currently available, despite attempts to use the Seebeck thermoelectric effect, vibrations or body movements. Glucose fuel cells appear more promising, since they produce electrical energy from glucose and dioxygen, two substrates present in physiological fluids. The most powerful ones, Glucose BioFuel Cells (GBFCs), are based on enzymes electrically wired by redox mediators. However, GBFCs cannot be implanted in animals, mainly because the enzymes they rely on either require low pH or are inhibited by chloride or urate anions, present in the Extra Cellular Fluid (ECF). Here we present the first functional implantable GBFC, working in the retroperitoneal space of freely moving rats. The breakthrough relies on the design of a new family of GBFCs, characterized by an innovative and simple mechanical confinement of various enzymes and redox mediators: enzymes are no longer covalently bound to the surface of the electron collectors, which enables use of a wide variety of enzymes and redox mediators, augments the quantity of active enzymes, and simplifies GBFC construction. Our most efficient GBFC was based on composite graphite discs containing glucose oxidase and ubiquinone at the anode, polyphenol oxidase (PPO) and quinone at the cathode. PPO reduces dioxygen into water, at pH 7 and in the presence of chloride ions and urates at physiological concentrations. This GBFC, with electrodes of 0.133 mL, produced a peak specific power of 24.4 µW mL−1, which is better than pacemakers' requirements and paves the way for the development of a new generation of implantable artificial organs, covering a wide range of medical applications

Wild bee larval food composition in five European cities

Urbanization poses threats and opportunities for the biodiversity of wild bees. At the same time, cities can harbor diverse wild bee assemblages, partly due to the unique plant assemblages that provide resources. While bee dietary preferences have been investigated in various studies, bee dietary studies have been conducted mostly in nonurban ecosystems and data based on plant visitation observations or palynological techniques. This data set describes the larval food preferences of four wild bee species (i.e., Chelostoma florisomne, Hylaeus communis, Osmia bicornis, and O. cornuta) common in urban areas in five different European cities (i.e., Antwerp, Belgium; Paris, France; Poznan, Poland; Tartu, Estonia; and Zurich, Switzerland). In addition, the data set describes the larval food preferences of individuals from three wild bee genera (i.e., Chelostoma sp., Hylaeus sp., and Osmia sp.) that could not be identified to the species level. These data were obtained from a Europe-level study aimed at understanding the effects of urbanization on biodiversity across different cities and cityscapes and a Swiss project aimed at understanding the effects of urban ecosystems in wild bee feeding behavior. Wild bees were sampled using standardized trap nests at 80 sites (32 in Zurich and 12 in each of the remaining cities), selected following a double gradient of available habitat at local and landscape scales. Larval pollen was obtained from the bee nests and identified using DNA metabarcoding. The data provide the plant composition at the species or genus level preferred by each bee. These unique data can be used for a wide array of research questions, including urban ecology (e.g., diversity of food sources along urban gradients), bee ecology (characterization of bee feeding preferences), or comparative studies on the urban evolution of behavioral traits between urban and nonurban sites. In addition, the data can be used to inform urban planning and conservation strategies, particularly concerning flower resources (e.g., importance of exotic species and, thus, management activities). This data set can be freely used for noncommercial purposes, and this data paper should be cited if the data is used; we request that collaboration with the data set contact person to be considered if this data set represents an important part of the data analyzed in a study.info:eu-repo/semantics/publishedVersio

How genomics can help biodiversity conservation

The availability of public genomic resources can greatly assist biodiversity assessment, conservation, and restoration efforts by providing evidence for scientifically informed management decisions. Here we survey the main approaches and applications in biodiversity and conservation genomics, considering practical factors, such as cost, time, prerequisite skills, and current shortcomings of applications. Most approaches perform best in combination with reference genomes from the target species or closely related species. We review case studies to illustrate how reference genomes can facilitate biodiversity research and conservation across the tree of life. We conclude that the time is ripe to view reference genomes as fundamental resources and to integrate their use as a best practice in conservation genomics.info:eu-repo/semantics/publishedVersio

The era of reference genomes in conservation genomics

Progress in genome sequencing now enables the large-scale generation of reference genomes. Various international initiatives aim to generate reference genomes representing global biodiversity. These genomes provide unique insights into genomic diversity and architecture, thereby enabling comprehensive analyses of population and functional genomics, and are expected to revolutionize conservation genomics

The era of reference genomes in conservation genomics

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