Ces bonnes vaches aux yeux si doux

Analyse de l'engouement récent pour les représentations artistiques et publicitaires de la vach

Mais qu'ont-ils donc à tous s'occuper des animaux ?

Pourquoi cet intérêt général pour le rapport aux animaux ? A partir d'une proposition pour distinguer les animaux selon cinq catégories nouvelles, l'auteur suggère une autre manière de les ranger

Purification and characterization of a three-component salicylate 1-hydroxylase from Sphingomonas CHY-1

International audienceIn the bacterial degradation of polycyclic aromatic hydrocarbons (PAHs), salicylate hydroxylases catalyze essential reactions at the junction between the so-called upper and lower catabolic pathways. Unlike the salicylate 1-hydroxylase from pseudomonads, which is a well-characterized flavoprotein, the enzyme found in sphingomonads appears to be a three-component Fe-S protein complex, which has not so far been characterized. Here, the salicylate 1-hydroxylase from Sphingomonas CHY-1 has been purified and characterized with respect to its biochemical and catalytic properties. The oxygenase component called PhnII, exhibited an α3β3 heterohexameric structure and contained one Rieske-type [2Fe-2S] cluster and one mononuclear iron per α subunit. In the presence of purified reductase (PhnA4) and ferredoxin (PhnA3) components, PhnII catalyzed the hydroxylation of salicylate to catechol with a maximal specific activity of 0.89 U/mg and showed an apparent Km for salicylate of 1.1 ± 0.2 µM. The hydroxylase exhibited similar activity levels with methylsalicylates and low activity with salicylate analogues bearing additional hydroxyl or electron-withdrawing substituents. PhnII converted anthranilate to 2-aminophenol and exhibited a relatively low affinity for this substrate (Km = 28 ± 6 µM). 1-Hydroxy-2-naphthoate, which is an intermediate in phenanthrene degradation, was not hydroxylated by PhnII, but induced a high rate of uncoupled oxidation of NADH. It also exerted a strong competitive inhibition of salicylate hydroxylation, with a Ki of 0.68 µM. The properties of this three-component hydroxylase are compared with those of analogous bacterial hydroxylases and discussed in the light of our current knowledge of PAH degradation by sphingomonads

SPIRAL 2 coupler preparation and RF conditioning

Proc. On LineInternational audienceFive radiofrequency coupler prototypes have been manufactured. Three of them will be mounted in the cryomodules of the SPIRAL 2 superconducting LINAC (LINear ACcelerator). This paper describes the coupler preparation and the first results of their conditioning

Et si nous prenions nos désirs en compte?

Réponse à l’À propos de Gilles Laferté & Nicolas Renahy, « “Campagne de tous nos désirs”... d’ethnologues », publié p. 225-234