Different mutations in the ZmCAD2 gene underlie the maize brown-midrib1 (bm1) phenotype with similar effects on lignin characteristics and have potential interest for bioenergy production

The maize ZmCAD2 gene has been fully sequenced in several normal and bm1 maize lines, highlighting a large diversity of mutations underlying the bm1 phenotype. Mutations in three bm1 lines (F2bm1, A619bm1, and 511Jbm1) were found corresponding to short InDels inducing premature stop codons and truncated proteins. In two lines (511Kbm1 and 5803Cbm1), mutations were limited to an only SNP or to a few SNP, modifying the catalytic sites, and likely inactivating the proteins. Results also established that the 5803Ibm7 mutant was in fact a bm1 mutant, with a sequence fully identical to the 5803Cbm1 sequence. The two new F7803bm1 (natural mutant) and Ev2210bm1 (transposon tagging Mutator investigations) both had a transposon insertion in the ZmCAD2 DNA, resulting in a truncated protein, even if the mRNA was produced. The biochemical characteristics of the Ev2210bm1 lignins corroborated the signature of CAD2 deficiency in plants, with the presence of aldehydes and atypical compounds and linkages. Considering lignin structure and content, CAD2 is likely a good target for the improvement of energy production based on maize and grass lignocellulosic biomass, including a greater susceptibility to environmentally friendly pretreatments, as it was shown in bmr sorghum. The interest in maize bm1 hybrids for cattle feeding also should be considered because there seem to be little or limited negative effects of CAD2 mutations on other agronomical traits

Different mutations in the ZmCAD2 gene underlie the maize brown-midrib1 (bm1) phenotype with similar effects on lignin characteristics and have potential interest for bioenergy production

The maize ZmCAD2 gene has been fully sequenced in several normal and bm1 maize lines, highlighting a large diversity of mutations underlying the bm1 phenotype. Mutations in three bm1 lines (F2bm1, A619bm1, and 511Jbm1) were found corresponding to short InDels inducing premature stop codons and truncated proteins. In two lines (511Kbm1 and 5803Cbm1), mutations were limited to an only SNP or to a few SNP, modifying the catalytic sites, and likely inactivating the proteins. Results also established that the 5803Ibm7 mutant was in fact a bm1 mutant, with a sequence fully identical to the 5803Cbm1 sequence. The two new F7803bm1 (natural mutant) and Ev2210bm1 (transposon tagging Mutator investigations) both had a transposon insertion in the ZmCAD2 DNA, resulting in a truncated protein, even if the mRNA was produced. The biochemical characteristics of the Ev2210bm1 lignins corroborated the signature of CAD2 deficiency in plants, with the presence of aldehydes and atypical compounds and linkages. Considering lignin structure and content, CAD2 is likely a good target for the improvement of energy production based on maize and grass lignocellulosic biomass, including a greater susceptibility to environmentally friendly pretreatments, as it was shown in bmr sorghum. The interest in maize bm1 hybrids for cattle feeding also should be considered because there seem to be little or limited negative effects of CAD2 mutations on other agronomical traits

Site-specific ubiquitination exposes a linear motif to promote interferon-α receptor endocytosis

Ligand-induced endocytosis and lysosomal degradation of cognate receptors regulate the extent of cell signaling. Along with linear endocytic motifs that recruit the adaptin protein complex 2 (AP2)–clathrin molecules, monoubiquitination of receptors has emerged as a major endocytic signal. By investigating ubiquitin-dependent lysosomal degradation of the interferon (IFN)-α/β receptor 1 (IFNAR1) subunit of the type I IFN receptor, we reveal that IFNAR1 is polyubiquitinated via both Lys48- and Lys63-linked chains. The SCFβTrcp (Skp1–Cullin1–F-box complex) E3 ubiquitin ligase that mediates IFNAR1 ubiquitination and degradation in cells can conjugate both types of chains in vitro. Although either polyubiquitin linkage suffices for postinternalization sorting, both types of chains are necessary but not sufficient for robust IFNAR1 turnover and internalization. These processes also depend on the proximity of ubiquitin-acceptor lysines to a linear endocytic motif and on its integrity. Furthermore, ubiquitination of IFNAR1 promotes its interaction with the AP2 adaptin complex that is required for the robust internalization of IFNAR1, implicating cooperation between site-specific ubiquitination and the linear endocytic motif in regulating this process

Atténuation et dispersion des ondes P en milieu poreux partiellement saturé (approche expérimentale)

Afin d'analyser le rôle de la saturation partielle sur la vitesse de phase et l'atténuation des ondes P directes, nous avons élaboré une expérience en laboratoire dans la gamme du kiloHertz. Celle-ci permet une corrélation avec les mesures de terrain et limite les effets d'échelle induits par l'utilisation des traditionnelles mesures ultrasoniques. Le montage expérimental est composé d'un container rempli de sable, équipé d'accéléromètres et de sondes de teneur en eau. Une propagation d'onde est générée par une source mécanique constituée d'une bille en métal frappant une plaque de granite. Plusieurs cycles d'imbibition/drainage sont réalisés entre les saturations résiduelles en eau et en air. Une transformée continue en ondelette a été choisie pour le traitement des données sismiques et validée numériquement par une simulation de propagation d'ondes dans un milieu viscoélastique 2D (code Specfem2D). En imbibition et en drainage, la vitesse de phase décroît avec l'augmentation de la saturation, ce qui peut être expliqué par la limite Biot-Gassmann-Wood (BGW) de la théorie de Biot. Ce comportement, typique des mesures de terrain, indique qu'il est possible de considérer le mélange de fluides (eau et air) comme un fluide effectif. L'interprétation de l'atténuation est plus complexe et ne peut être expliquée par le mécanisme de relaxation de flux macroscopique de la théorie de Biot. Il est nécessaire d'introduire une contribution viscoélastique reliée aux pertes frictionelles grain-à-grain et décrite par un modèle à Q constant. De plus, un hystérésis entre imbibition et drainage est observé et expliqué en introduisant une perméabilité effective du mélange, dépendante des perméabilités relatives à l'eau et à l'air.In order to analyse the role of partial saturation on direct P-waves phase velocity and attenuation, we performed a laboratory experiment in the kiloHertz range to avoid scale effects between field studies and traditional ultrasonic laboratory measurements. This experiment consists in a sand-filled tank equiped with accelerometers and water capacitance probes, were seismic propagation is generated by hitting a steel ball on a granite plate. Several imbibition/drainage cycles were performed between the water and gas residual saturations. Seismic data were processed by a Continuous Wavelet Transform using the complex Morlet wavelet which was numerically validated using a viscoelastic 2D code for wave propagation (Specfem2D). Phase velocity of direct P-wave decreases with the increase of water content, which is quite consistent with Biot-Gassmann-Wood (BGW) limit of the Biot's theory for both imbibition and drainage. This behaviour indicates that the fluid mixture (gaz and water) can be considered as an effective fluid, which is typical of field seismic applications. In this experiment, attenuation is very strong and cannot be fully explained by the macroscopic fluid flow of Biot's theory. It is necessary to introduce a viscoelastic contribution linked to the grain to grain overall losses, which are described by a constant Q-model. Moreover, hysteresis between imbibition and drainage are observed and explained by introducing an effective permeability of the mixture depending on water and gas relative permeabilities.PAU-BU Sciences (644452103) / SudocSudocFranceF

CFTR (protéine de régulation)

Cette étude a permis de mettre en évidence deux aspects régulateurs de la protéine CFTR. En étudiant le rôle physiologique de CFTR dans les cultures primaires de reins de souris CFTR+/+ et CFTR -/-, nous avons démontré qu elle régule le volume cellulaire lors d un choc hypotonique. Ainsi, elle permet une sortie d ATP qui est hydrolysée en adénosine. L adénosine en se fixant sur les récepteurs de type A1 entraîne une entrée calcium sous membranaire nécessaire à l activation des canaux Cl-. Ce mécanisme disparaît dans les cultures de cellules de souris CFTR -/-. A l inverse du tubule distal, le tubule proximal n exprime pas de courant Cl- CFTR activés par l AMPc. Cette absence serait due à un épissage alternatif de l exon 10. Il conduit à une isoforme qui conserve ses propriétés de régulation du volume cellulaire. Chez la souris CFTR -/-, les courants Cl- volume dépendants sont présents et la perte de régulation du volume cellulaire est la conséquence d une absence de libération d ATP. Le deuxième aspect régulateur de CFTR concerne son intervention dans l apoptose par la modulation du pH intracellulaire. L apoptose induite par la lovastatine a été étudiée dans des lignées de fibroblaste de poumon de hamster. Nous avons démontré que l expression de CFTR augmentait le nombre de cellules apoptotiques en favorisant une meilleure acidification des cellules par une modulation de l échangeur Cl-/HC03-. En conclusion, CFTR n est pas un simple canal Cl- présent à la surface des cellules épithéliales, mais c est aussi une protéine de régulation complexe qui contrôle des mécanismes comme le maintien du volume cellulaire ou encore l activité des échangeurs dans le processus d apoptose.NICE-BU Sciences (060882101) / SudocSudocFranceF

The Double Chooz antineutrino detectors

This article describes the setup and performance of the near and far detectors in the Double Chooz experiment. The electron antineutrinos of the Chooz nuclear power plant were measured in two identically designed detectors with different average baselines of about 400 m and 1050 m from the two reactor cores. Over many years of data taking the neutrino signals were extracted from interactions in the detectors with the goal of measuring a fundamental parameter in the context of neutrino oscillation, the mixing angle θ13. The central part of the Double Chooz detectors was a main detector comprising four cylindrical volumes filled with organic liquids. From the inside towards the outside there were volumes containing gadolinium-loaded scintillator, gadolinium-free scintillator, a buffer oil and, optically separated, another liquid scintillator acting as veto system. Above this main detector an additional outer veto system using plastic scintillator strips was installed. The technologies developed in Double Chooz were inspiration for several other antineutrino detectors in the field. The detector design allowed implementation of efficient background rejection techniques including use of pulse shape information provided by the data acquisition system. The Double Chooz detectors featured remarkable stability, in particular for the detected photons, as well as high radiopurity of the detector components