Actin filament reorganisation controlled by the SCAR/WAVE complex mediates stomatal response to darkness.

This is the final version of the article. Available from the publisher via the DOI in this record.Stomata respond to darkness by closing to prevent excessive water loss during the night. Although the reorganisation of actin filaments during stomatal closure is documented, the underlying mechanisms responsible for dark-induced cytoskeletal arrangement remain largely unknown. We used genetic, physiological and cell biological approaches to show that reorganisation of the actin cytoskeleton is required for dark-induced stomatal closure. The opal5 mutant does not close in response to darkness but exhibits wild-type (WT) behaviour when exposed to abscisic acid (ABA) or CaCl2 . The mutation was mapped to At5g18410, encoding the PIR/SRA1/KLK subunit of the ArabidopsisSCAR/WAVE complex. Stomata of an independent allele of the PIR gene (Atpir-1) showed reduced sensitivity to darkness and F1 progenies of the cross between opal5 and Atpir-1 displayed distorted leaf trichomes, suggesting that the two mutants are allelic. Darkness induced changes in the extent of actin filament bundling in WT. These were abolished in opal5. Disruption of filamentous actin using latrunculin B or cytochalasin D restored wild-type stomatal sensitivity to darkness in opal5. Our findings suggest that the stomatal response to darkness is mediated by reorganisation of guard cell actin filaments, a process that is finely tuned by the conserved SCAR/WAVE-Arp2/3 actin regulatory module.This work was supported by grants from the BBSRC (BB/ N001168/1; BB/J002364/1; BBF001177/1), The Gatsby Charitable Foundation and the Leverhulme Trust to A.M.H. and grants from the National Natural Science Foundation of China (nos. 31300213 and 31670408 to K.J.). This work was also supported by the Centre National de la Recherche Scientifique and the Commissariat a l’Energie Atomique et aux Energies Alternatives (for the IR camera) and the European Union Marie Curie FP5 Research Training Network (program no. STRESSIMAGING HNRT-CT-2002-00254 to J.M.C. and B.G.). J.M.C. was in addition supported by a scholarship of the Fundac ~ao para a Ci^encia e Tecnologia, Portugal (grant no. SFRH/BPD/34429/2006)

A statistical TEM investigation of dislocation channeling mechanism in neutron irradiated zirconium alloys.

Plastic deformation in irradiated zirconium alloys occurs in a very heterogeneous manner at the grain scale by the clearing up of radiation-induced prismatic loops by gliding dislocations and the channeling of these dislocations inside narrow bands of the grain. A statistical TEM investigation of this mechanism has been performed on neutron irradiated recrystallized Zr alloys tested at 350 degreesC. Due to the strong anisotropy of plastic deformation, different loading conditions have been investigated. It is shown that for transverse tensile tests and closed end burst tests, only basal channels are observed, whereas for axial tensile tests, prismatic and pyramidal channels are observed. This phenomenon can be understood in terms of texture and interactions between dislocations and irradiation induced loops. From Schmid factor calculations, we have also been able to prove that irradiation leads to a higher increase of critical resolved shear stresses for prismatic and pyramidal slip systems than for basal slip system

A statistical TEM investigation of dislocation channeling mechanism in neutron irradiated zirconium alloys.

Plastic deformation in irradiated zirconium alloys occurs in a very heterogeneous manner at the grain scale by the clearing up of radiation-induced prismatic loops by gliding dislocations and the channeling of these dislocations inside narrow bands of the grain. A statistical TEM investigation of this mechanism has been performed on neutron irradiated recrystallized Zr alloys tested at 350 degreesC. Due to the strong anisotropy of plastic deformation, different loading conditions have been investigated. It is shown that for transverse tensile tests and closed end burst tests, only basal channels are observed, whereas for axial tensile tests, prismatic and pyramidal channels are observed. This phenomenon can be understood in terms of texture and interactions between dislocations and irradiation induced loops. From Schmid factor calculations, we have also been able to prove that irradiation leads to a higher increase of critical resolved shear stresses for prismatic and pyramidal slip systems than for basal slip system

Effect of Zinc on Primary and Secondary Metabolism of Datura innoxia and Datura sanguinea.

absen

Singlet Oxygen-Induced Cell Death in Arabidopsis under High Light Stress is Controlled by OXI1 Kinase

International audienc

SDN-based Wi-Fi Direct Clustering for Cloud Access in Campus Networks

International audienceMobile cloud is changing the way to enroll teaching activities in university campus. Lectures and lab sessions can be carried out directly from tablets in a class room by accessing a server in the cloud. In this paper, we address the problem of high density cloud access with wireless devices in campus networks. We propose to use Wi-Fi Direct clustering to solve the problem of Quality of Service (QoS) degradation when a high number of wireless devices want to access a content in the cloud at the same time. A centralized software-defined network controller is used in our proposed architecture to capture the network state and organize the Wi-Fi Direct groups. The optimized number of clusters can be calculated in function of the number of devices in the room. By simulations, we show that we can provide a better QoS in terms of download time and application's throughput by reducing the interference in this dense wireless network environment

Facteurs anatomo-cliniques et moléculaires influençant le délai de rechute des méningiomes opérés (étude de 38 cas)

Tumeur la plus fréquente du système nerveux central et de comportement habituellement bénin, les méningiomes posent un problème thérapeutique, de surveillance post-opératoire et d évaluation pronostique. A partir d une série rétrospective de 38 cas de méningiomes avec rechute diagnostiqués au CHU de Saint Etienne, nous avons réalisé une étude clinique, histologique, immunohistochimique et moléculaire recueillant les données suivantes : délai de rechute, âge, sexe, localisation, taille tumorale, qualité et type de l exérèse, paramètres histologiques intégrés dans la classification OMS 2007 et non intégrés tels que l envahissement dure-mérien, osseux et des tissus mous. Après avoir réalisé une étude descriptive, nous avons corrélé l ensemble de ces paramètres au délai de rechute. Nos résultats montrent avec une analyse multivariée que le sexe masculin apparaît comme un facteur corrélé à une récidive plus précoce avec un délai de récidive de 3 ans versus 5 ans et 1 mois chez les femmes (p=0.0202). La présence d un envahissement dure-mérien est également corrélé à un délai de récidive discrètement plus court en analyse mutivariée (4 ans et 7 mois versus 3 ans et 10 mois) (p=0.0465). L ensemble des autres paramètres étudiés ne montrant pas de corrélation significative avec le délai de récidive. Il n y avait pas de mutation BRAFV600E dans notre série. De plus, nos résultats montrent que 58% de ces méningiomes ayant récidivé étaient de grade I soulignant l imperfection des classifications pronostiques actuelles. Ce travail original montrant un délai de récidive plus précoce chez les hommes vient en complément de données de la littérature montrant un risque de récidive plus important dans cette population.ST ETIENNE-BU Médecine (422182102) / SudocSudocFranceF