Alimentation

Pour donner une image fidèle de l’alimentation des Berbères depuis les origines et suivre son évolution il aurait fallu disposer de documents et de textes qui font malheureusement défaut, aussi plutôt que de se livrer à une étude diachronique impossible à rédiger dans l’état actuel de la recherche nous avons choisi de présenter ce que l’on sait de l’alimentation des Paléoberbères des temps préhistoriques antérieurs à l’élevage et à l’agriculture puis de regrouper nos connaissances sur l’alime..

Light-mediated K-leaf induction and contribution of both the PIP1s and PIP2s aquaporins in five tree species: walnut (Juglans regia) case study

International audienceUnderstanding the response of leaf hydraulic conductance (K-leaf) to light is a challenge in elucidating plant-water relationships. Recent data have shown that the effect of light on K-leaf is not systematically related to aquaporin regulation, leading to conflicting conclusions. Here we investigated the relationship between light, K-leaf, and aquaporin transcript levels in five tree species (Juglans regia L., Fagus sylvatica L., Quercus robur L., Salix alba L. and Populus tremula L.) grown in the same environmental conditions, but differing in their K-leaf responses to light. Moreover, the K-leaf was measured by two independent methods (high-pressure flow metre (HPFM) and evaporative flux method (EFM)) in the most (J. regia) and least (S. alba) responsive species and the transcript levels of aquaporins were analyzed in perfused and unperfused leaves. Here, we found that the light-induced K-leaf value was closely related to stronger expression of both the PIP1 and PIP2 aquaporin genes in walnut (J. regia), but to stimulation of PIP1 aquaporins alone in F. sylvatica and Q. robur. In walnut, all newly identified aquaporins were found to be upregulated in the light and downregulated in the dark, further supporting the relationship between the light-mediated induction of K-leaf and aquaporin expression in walnut. We also demonstrated that the K-leaf response to light was quality-dependent, K-leaf being 60% lower in the absence of blue light. This decrease in K-leaf was correlated with strong downregulation of three PIP2 aquaporins and of all the PIP1 aquaporins tested. These data support a relationship between light-mediated K-leaf regulation and the abundance of aquaporin transcripts in the walnut tree

Formation and characterization of carbon-metal nano-contacts

Electrical contacts between iron nanoparticles and different sp(2)- and sp(1)-hybridized carbon nanomaterials are established in an in situ experiment in the transmission electron microscope. The starting material, consisting of FeO nanoparticles, is reduced in situ when contacted to graphitic carbon and by passing an electrical current. The remaining Fe particles form covalent bonds with the graphitic electrodes, thus allowing the extraction of different types of nanostructures by retracting one electrode. Graphene ribbons, nanotube-like objects, and monoatomic carbon chains are formed in such a technique that also allows the measurement of the electrical properties of the respective carbon nanostructures. (C) 2014 Elsevier Ltd. All rights reserved