A mathematical analysis of the GW0 method for computing electronic excited energies of molecules

This paper analyses the GW method for finite electronic systems. In a first step, we provide a mathematical framework for the usual one-body operators that appear naturally in many-body perturbation theory. We then discuss the GW equations which construct an approximation of the one-body Green's function, and give a rigorous mathematical formulation of these equations. Finally, we study the well-posedness of the GW0 equations, proving the existence of a unique solution to these equations in a perturbative regime

Phase transition in the Peierls model for polyacetylene

We consider the Peierls model for closed polyactetylene chains with an even number of carbon atoms as well as infinite chains, in the presence of temperature. We prove the existence of a critical temperature below which the chain is dimerized, and above which it is 1-periodic. The chain behaves like an insulator below the critical temperature and like a metal above it. We characterize the critical temperature in the thermodynamic limit model, and prove that it is exponentially small in the rigidity of the chain. We study the phase transition around this critical temperature.Comment: Final version to appear in Ann. Henri Poincar{\'e

Contribution of tissue textural pattern and conventional index to glioma staging in FDopa-PET/CT

National audienceAim: We studied whether the characterization of tumor texture in FDopa-PET/CT could assist in the identification of tumor grades in both primitive and recurrent gliomas. Materials and Methods: Eighty one patients with gliomas were studied, including 52 newly diagnosed tumors and 29 recurrent tumors. For each tumor, the SUVpeak and metabolic volume (MV) were measured, as well as 32 textural indices (TI). The ability of SUVpeak, MV and TI was investigated by using each index alone first (with ROC analyses), and then by using couples consisting of one TI with SUVpeak in a binomial model (with ROC analyses and a reclassification method). The pathological examination was assumed to provide the gold standard grade. Results: Neither SUVpeak nor MV could discriminate low-grade tumors (LG) from high-grade tumors (HG) in newly-diagnosed tumors, while SUVpeak alone could discriminate LG from HG in recurrent tumors (p=0.02). Combining a TI with SUVpeak led to a significant LG / HG discrimination for newly-diagnosed tumors (p = 0.01). Among all TI, entropy led to the best reclassification performance. Conclusion: The co-analysis of FDopa-PET/CT SUVpeak and well-selected TI (such as entropy) made it possible to improve the classification of newly-diagnosed gliomas

Comparison of anti-oomycete activities of essential oils and fungicidal substances against the agent of potato late blight disease Phytophthora infestans

The Oomycete Phytophthora infestans causing late blight disease represents one of the major threats for potato crop. Particular attention is given to specific genotypes known to be either persistent or having recently emerged in the agroecosystems of northern Europe. To fight this disease, farmers in conventional agriculture still heavily rely on the use of synthetic pesticides. As a consequence, some populations appear with reduced sensitivity to commonly employed molecules. Given these environmental concerns, alternative methods of management are encouraged. In this context, plants secondary metabolites (PSM) such as essential oils (EOs) have become extensively studied and seem promising to develop sustainable and efficient biopesticides. This work aims at comparing the anti-oomycete potential of 5 essential oils (bergamot - Citrus bergamia, rosemary - Rosmarinus officinalis, oregano - Origanum vulgare, clove - Syzygium aromoticum and Ceylan cinnamon - Cinnamomum zeylanicum) with 3 fungicidal active substances (including two organic molecules: mandipropamid, fluazinam and one mineral: copper sulfate) on 3 genotypes of P. infestans (EU-13, EU-36 and EU-37 that has been listed as less sensitive to fluazinam). EOs chemical compositions were determined by GC-MS. All products were tested according to an adjusted range of concentrations. The inhibition of the mycelium was evaluated on solid medium by contact for all substances and by fumigation for essential oils only. Then, fungistatic or fungicidal properties were assessed. On the other hand, the median inhibitory concentration (IC50) of each product in liquid medium was calculated in regard of spores’ germination. Inhibitory tests by contact on solid medium showed the best inhibition of the mycelium with clove and oregano EO. In liquid media, the smallest IC50 are associated with cinnamon which indicates its greatest activity against spore germination of all the three genotypes. Finally, mandipropamid showed by far the highest activity both on solid and in liquid media followed by fluazinam and copper sulfate although significant sensitivities were identified between EU-13, EU-36 and EU-37. In conclusion, the three isolates of P. infestans globally follow the same trends toward the inhibition of their mycelium caused by the essential oils, both by contact and fumigation. However, radically different levels of activities on spore germination have been quantified through the IC50. Further experiments must be carried out to evaluate not only essential oils phytotoxicity on potato leaves but also their biofungicidal properties of the formulated EOs on late blight disease.PHYTOI

Anti-oomycete activities of 5 essential oils against 3 genotypes of Phytophthora infestans the causing agent of late blight disease

The Oomycete Phytophthora infestans causing late blight disease represents one of the major threats for potato crop. Particular attention is given to specific genotypes known to be either persistent, resistant to some fungicides or for having recently emerged in the agroecosystems of northern Europe. To fight this disease, farmers still heavily rely on the use of synthetic pesticides in conventional agriculture. Given the actual environmental context, alternative management are encouraged. For this reason, plants secondary metabolites (PSM) such as essential oils (EOs) become widely studied and seem promising to develop innovative biopesticides. This study aims at screening the anti-oomycete potential of 5 essential oils on 3 genotypes of P. infestans (EU-13, EU-36 and EU-37): bergamot (Citrus bergamia), rosemary (Rosmarinus officinalis), oregano (Origanum vulgare), clove (Syzygium aromoticum) and Ceylan cinnamon (Cinnamomum zeylanicum). EOs were characterized by GC-MS and have been tested according to a range of concentration. The inhibition of the mycelium was evaluated on solid medium both by fumigation and by contact. Fungistatic or fungicidal properties were then established. In addition, the median inhibitory concentration (IC50) of each oil in liquid medium was calculated in regard of spores’ germination. Inhibitory tests by contact in solid medium showed total inhibition with clove, oregano and cinnamon EOs from 0,5 µL/mL. An inhibition of up to 70% compared to control (non-treated) was obtained with both clove and oregano EOs. Conversely, higher inhibition is achieved by fumigation with bergamot and rosemary oils (which are monoterpenes-rich EOs with respectively limonene and camphor/α-pinene as major compounds) than with oregano, clove or cinnamon oils (mainly containing respectively carvacrol, eugenol and cinnamaldehyde). Lower vapor pressure prevented those from causing significant inhibition of the mycelium even at 1 µL/mL of air. In addition, bergamot and rosemary EOs have proven themselves fungistatic whereas the other three exhibited fungicidal properties. In liquid media, the smallest IC50 (from 0,08 to 0,013 mg/mL) were associated with cinnamon EO and did not vary significantly among the three genotypes. This indicates the greatest activity against spore germination. Hence, although the three isolates of P. infestans globally respond the same, all 5 EOs demonstrated distinct activities towards either the mycelium or the spores. Further experiments must be carried out to evaluate not only the phytotoxicity on potato plants but also the biofungicidal properties of the formulated EOs on late blight disease.PHYTOIL12. Responsible consumption and productio

Molecular cloning and functional characterization of psoralen synthase, the first committed monooxygenase of furanocoumarin biosynthesis

Ammi majus L. accumulates linear furanocoumarins by cytochrome P450 (CYP)-dependent conversion of 6-prenylumbelliferone via (؉)-marmesin to psoralen. Relevant activities, i.e. psoralen synthase, are induced rapidly from negligible background levels upon elicitation of A. majus cultures with transient maxima at 9 -10 h and were recovered in labile microsomes. Expressed sequence tags were cloned from elicited Ammi cells by a nested DD-RT-PCR strategy with CYP-specific primers, and full-size cDNAs were generated from those fragments correlated in abundance with the induction profile of furanocoumarin-specific activities. One of these cDNAs representing a transcript of maximal abundance at 4 h of elicitation was assigned CYP71AJ1. Functional expression in Escherichia coli or yeast cells initially failed but was accomplished eventually in yeast cells after swapping the N-terminal membrane anchor domain with that of CYP73A1. The recombinant enzyme was identified as psoralen synthase with narrow substrate specificity for (؉)-marmesin. Psoralen synthase catalyzes a unique carbon-chain cleavage reaction concomitantly releasing acetone by syn-elimination. Related plants, i.e. Heracleum mantegazzianum, are known to produce both linear and angular furanocoumarins by analogous conversion of 8-prenylumbelliferone via (؉)-columbianetin to angelicin, and it was suggested that angelicin synthase has evolved from psoralen synthase. However, (؉)-columbianetin failed as substrate but competitively inhibited psoralen synthase activity. Analogy modeling and docked solutions defined the conditions for high affinity substrate binding and predicted the minimal requirements to accommodate (؉)-columbianetin in the active site cavity. The studies suggested that several point mutations are necessary to pave the road toward angelicin synthase evolution. Furanocoumarins are produced by many plants, mostly of the Apiaceae, Rutaceae, Moraceae, or the Coronilla and Psoralea genera of the Fabaceae (1-3). Multiple pharmacological effects have been ascribed to several of these metabolites (4 -6), which were included in clinical screenings but received attention also for their inhibitory effect on monooxygenases involved in drug metabolism (7-9) and potential toxicity (10). The (dihydro)furan-substituted 2H-1-benzopyran-2-one forms the characteristic core structure, and the annulation type distinguishes the linear furanocoumarins or psoralens from the angular furanocoumarin

Optimization of the Culture Medium Composition to Improve the Production of Hyoscyamine in Elicited Datura stramonium L. Hairy Roots Using the Response Surface Methodology (RSM)

Traditionally, optimization in biological analyses has been carried out by monitoring the influence of one factor at a time; this technique is called one-variable-at-a-time. The disadvantage of this technique is that it does not include any interactive effects among the variables studied and requires a large number of experiments. Therefore, in recent years, the Response Surface Methodology (RSM) has become the most popular optimization method. It is an effective mathematical and statistical technique which has been widely used in optimization studies with minimal experimental trials where interactive factors may be involved. This present study follows on from our previous work, where RSM was used to optimize the B5 medium composition in [NO3−], [Ca2+] and sucrose to attain the best production of hyoscyamine (HS) from the hairy roots (HRs) of Datura stramonium elicited by Jasmonic Acid (JA). The present paper focuses on the use of the RSM in biological studies, such as plant material, to establish a predictive model with the planning of experiments, analysis of the model, diagnostics and adjustment for the accuracy of the model. With the RSM, only 20 experiments were necessary to determine optimal concentrations. The model could be employed to carry out interpolations and predict the response to elicitation. Applying this model, the optimization of the HS level was 212.7% for the elicited HRs of Datura stramonium, cultured in B5-OP medium (optimized), in comparison with elicited HRs cultured in B5 medium (control). The optimal concentrations, under experimental conditions, were determined to be: 79.1 mM [NO3−], 11.4 mM [Ca2+] and 42.9 mg/L of sucrose

Evaluation of Acute and Subacute Toxicity of Fumaria officinalis Alkaloids in Mice

Background: Fumaria officinalis is largely used in traditional medicine due to its efficiency in the treatment and prevention of numerous diseases and its large spectrum of therapeutic effects. Its multiple beneficial properties are due to its richness in bioactive substances, particularly isoquinoline alkaloids. However, few studies have addressed the toxicity of this plant. Objectives: The present work aimed to study acute and subacute toxicity of alkaloids extracted from F. officinalis using Swiss albino mice as the in vivo model. Methods: Alkaloids from the aerial parts of F. officinalis were extracted and administered to male and female Swiss albino mice. The acute and subacute toxicities were studied by monitoring the weight and histopathological study of animal bodies and organs (e.g., liver, heart, spleen, and kidneys). Results: The results revealed that mice treated with increasing doses developed serious symptoms of toxicity (i.e., respiratory problems, tremors, coma, and paralysis leading the death) and lost weight. The LD50 was estimated at 1341.11 mg/kg permitting its classification as a low-toxic plant. The microscopic observations demonstrated disturbances in the kidney and liver, but not the heart and spleen. Conclusion: The alkaloids of the aerial parts of F. officinalis expressed severe toxicity in mice, particularly at high doses. Nevertheless, the neutral fraction of alkaloids is more indicated

A “BioEcoAgro” integrated research approach for new/renew valorizations of ancient traditional medicines and today/tomorrow’s uses of plant secondary metabolites

peer reviewedThe immense diversity of wild plants has been naturally selected over thousands/millions of generations within their changing biotic and abiotic environments. The pressure of natural selection led to necessary adaptations which conditioned the survival of true phylogenic groups. Beyond basic physiological needs, branches of the plant kingdom subjected to spontaneous mutations have developed an incredible capacity to synthesize biomolecules with useful properties to defend these non-mobile individual organisms. Called “secondary metabolites”, and more recently “specialized metabolites”, some of these molecules are biologically associated with the living environment. Thus, many biological activities became interesting for the plants and, later, for humankind when modern medicine did not yet exist

XLF and APLF bind Ku80 at two remote sites to ensure DNA repair by non-homologous end joining

International audienceThe Ku70-Ku80 (Ku) heterodimer binds rapidly and tightly to the ends of DNA double-strand breaks and recruits factors of the non-homologous end-joining (NHEJ) repair pathway through molecular interactions that remain unclear. We have determined crystal structures of the Ku-binding motifs (KBM) of the NHEJ proteins APLF (A-KBM) and XLF (X-KBM) bound to a Ku-DNA complex. The two KBM motifs bind remote sites of the Ku80 alpha/beta domain. The X-KBM occupies an internal pocket formed by an unprecedented large outward rotation of the Ku80 alpha/beta domain. We observe independent recruitment of the APLF-interacting protein XRCC4 and of XLF to laser-irradiated sites via binding of A- and X-KBMs, respectively, to Ku80. Finally, we show that mutation of the X-KBM and A-KBM binding sites in Ku80 compromises both the efficiency and accuracy of end joining and cellular radiosensitivity. A- and X-KBMs may represent two initial anchor points to build the intricate interaction network required for NHEJ