Molecular Mechanics: The Conjugate Nitro Group Parameters in the MM2 Force Field

The conjugated nitro group has been included in the π system calculation within the MM2 force field. New parameters have been estimated by a statistical process from X-ray molecular structures recorded in the C.S.D.S. Comparison of the corresponding results with those given by the MM2(91) force field parameters show a clear improvement for dihedral and bond angles. For N-O and C-N bond lengths a slight global improvement is also observed. A closer examination of the results for the latter bond shows that sometimes MM2(91) gives better results for six membered ring nitro compounds. By contrast the parameters proposed here are more adapted to five membered ring derivatives. The derived linear relations permit the study of molecules over a wider range of π indices. The introduction of a correction factor to the calculated molecular π dipole moment in conjunction with a necessary reestimation of some σ-bond dipole moments also leads to improved total molecular dipole moments.     

Fruit damages caused by the broad-winged bush katydid,Scudderia pistillata (Orthoptera: Tettigoniidae) in commercial cranberry bog

In August 2018, unidentified damages were reported on cranberries in a conventional bog located in Quebec (Eastern Canada). Following a field inspection, high percentage of nibbled fruits as well as katydids (Orthoptera: Tettigoniidae) were observed. Several individuals (nymphs and adults) were seen feeding directly on the fruits. Specimens were captured and sent to the “Laboratoire d'expertise et de diagnostic en phytoprotection” of the “Quebec Ministry of Agriculture, Fisheries and Food" (LEDP-MAPAQ). They were identified as Scudderia pistillata Brunner von Wattenwyl (Orthoptera: Tettigoniidae). Subsequently, a systematic fruit sampling was realized into the beds where damages were observed to assess spatial patterns of infestation. To our knowledge, it constitutes the first mention of significant damages associated to this species in cranberry bogs and, in some cases, up to 5% damages to the fruits were observed. This observation suggests that S. pistillata represents a potential pest for this crop. Additionally, a decrease of damage rates was observed when distancing from the north-eastern corner of the bog. Hypothesis in regards of damages' spatial pattern is discussed.     

Ebolavirus VP35 Coats the Backbone of Double-Stranded RNA for Interferon Antagonism

Recognition of viral double-stranded RNA (dsRNA) activates interferon production and immune signaling in host cells. Crystal structures of ebolavirus VP35 show that it caps dsRNA ends to prevent sensing by pattern recognition receptors such as RIG-I. In contrast, structures of marburgvirus VP35 show that it primarily coats the dsRNA backbone. Here, we demonstrate that ebolavirus VP35 also coats the dsRNA backbone in solution, although binding to the dsRNA ends probably constitutes the initial binding event.     

Advanced magnetic resonance imaging techniques to better understand multiple sclerosis

Magnetic resonance imaging (MRI) has considerably improved the diagnosis and monitoring of multiple sclerosis (MS). Conventional MRI such as T₂-weighted and gadolinium-enhanced T₁-weighted sequences detect focal lesions of the white matter, damage of the blood–brain barrier, and tissue loss and inflammatory activity within lesions. However, these conventional MRI metrics lack the specificity required for characterizing the underlying pathophysiology, especially diffuse damage occurring throughout the whole central nervous system. To overcome these limitations, advanced MRI techniques have been developed to get more sensitive and specific parameters of focal and diffuse brain damage. Among these techniques, magnetization transfer imaging, diffusion MRI, functional MRI, and magnetic resonance spectroscopy are the most significant. In this article, we provide an overview of these advanced MRI techniques and their contribution to the better characterization and understanding of MS.     

First Jurassic occurence of Enoploclytia M’Coy, 1849 (Crustacea: Decapoda: Erymidae)

Among the Erymidae Van Straelen, 1925, known as early as the Late Permian (Changhsingian) and widespread in the Jurassic, the genus Enoploclytia M’Coy, 1849 seems to have a late appearance because of its lack before the Cretaceous. Until now, the oldest representative was E. augustobonae Devillez, Charbonnier, Hy?ný and Leroy, 2016 from the Early Cretaceous (Barremian) of the eastern Paris basin (France). However, a new fossil collected in Normandy (France), showing the typical carapace groove pattern of Enoploclytia, attests the presence of the genus in the Late Jurassic (Oxfordian).     

Étude techno-économique du Moustérien de Pradayrol (Caniac-du-Causse,Lot) : entre mobilité des ressources lithiques et adaptation aux matériaux locaux,un exemple de gestion complémentaire des quartz et silex au Paléolithique moyen récent en Quercy

The Mousterian locus at Pradayrol (Caniac-du-Causse, Lot, France) produced an important lithic assemblage, composed primarily of quartz, alongside a varied flint component. Our technological analysis reveals the presence of several chaînes opératoires adapted to the morphology and mechanical properties of different raw materials. This is especially evident in the use of the bipolar on-anvil technique on quartz cobbles and discoidal flaking methods on both quartz and relatively local flints. Flint from the Périgord region provides evidence for a fragmented and ramified Levallois chaîne opératoire, different from that observed with local raw materials. These techno-economic features are similar to those documented for many late Middle Palaeolithic assemblages in the Quercy. The Neanderthal occupation of Pradayrol seems to reflect a balance between technical know-how and adaptations to the raw material constraints.     

Function and Compensatory Mechanisms Among the Components of the Chloroplastic Redox Network

Life on earth depends on the presence of photoautotrophic organisms that are able to input carbon into the ecosystems through the process of photosynthesis which, with a few specialized exceptions, takes place within the chloroplast. This organelle contains the most complex redox system in plants being composed of numerous players including thiol reductases, peroxidases, and glutathione-related enzymes. It seems likely that these proteins act together to adjust redox metabolism enabling plants to grow efficiently under both normal and stressed conditions. However, our knowledge concerning how these proteins interact and if they can compensate one another is relatively limited. This is in part due to the failure of considering these components from a systemic perspective. Here, we provide a systemic view of the chloroplastic-redox network highlighting how it operates and how its components co-operate to maintain efficient chloroplastic function. We further explore the cross-talk between chloroplastic-redox metabolism and that of other subcellular compartments. Given the complexity of plant redox metabolism and the compensatory role played by different redox systems, we argue that a unique possibility to understand this system is afforded by systems biology approaches and by characterizing mutants for multiple genes. Taking this into account, we highlight how gene co-expression and protein–protein network analyses coupled with different reverse genetic strategies could be used to reveal the function, potential redundancies, and complementarities among the components of the chloroplastic redox network.     

Interplay between the NADP-Linked Thioredoxin and Glutathione Systems in Arabidopsis Auxin Signaling

Intracellular redox status is a critical parameter determining plant development in response to biotic and abiotic stress. Thioredoxin (TRX) and glutathione are key regulators of redox homeostasis, and the TRX and glutathione pathways are essential for postembryonic meristematic activities. Here, we show by associating TRX reductases (ntra ntrb) and glutathione biosynthesis (cad2) mutations that these two thiol reduction pathways interfere with developmental processes through modulation of auxin signaling. The triple ntra ntrb cad2 mutant develops normally at the rosette stage, undergoes the floral transition, but produces almost naked stems, reminiscent of the phenotype of several mutants affected in auxin transport or biosynthesis. In addition, the ntra ntrb cad2 mutant shows a loss of apical dominance, vasculature defects, and reduced secondary root production, several phenotypes tightly regulated by auxin. We further show that auxin transport capacities and auxin levels are perturbed in the mutant, suggesting that the NTR-glutathione pathways alter both auxin transport and metabolism. Analysis of ntr and glutathione biosynthesis mutants suggests that glutathione homeostasis plays a major role in auxin transport as both NTR and glutathione pathways are involved in auxin homeostasis.