A physical map of the heterozygous grapevine 'Cabernet Sauvignon' allows mapping candidate genes for disease resistance

<p>Abstract</p> <p>Background</p> <p>Whole-genome physical maps facilitate genome sequencing, sequence assembly, mapping of candidate genes, and the design of targeted genetic markers. An automated protocol was used to construct a <it>Vitis vinifera </it>'Cabernet Sauvignon' physical map. The quality of the result was addressed with regard to the effect of high heterozygosity on the accuracy of contig assembly. Its usefulness for the genome-wide mapping of genes for disease resistance, which is an important trait for grapevine, was then assessed.</p> <p>Results</p> <p>The physical map included 29,727 BAC clones assembled into 1,770 contigs, spanning 715,684 kbp, and corresponding to 1.5-fold the genome size. Map inflation was due to high heterozygosity, which caused either the separation of allelic BACs in two different contigs, or local mis-assembly in contigs containing BACs from the two haplotypes. Genetic markers anchored 395 contigs or 255,476 kbp to chromosomes. The fully automated assembly and anchorage procedures were validated by BAC-by-BAC blast of the end sequences against the grape genome sequence, unveiling 7.3% of chimerical contigs. The distribution across the physical map of candidate genes for non-host and host resistance, and for defence signalling pathways was then studied. NBS-LRR and RLK genes for host resistance were found in 424 contigs, 133 of them (32%) were assigned to chromosomes, on which they are mostly organised in clusters. Non-host and defence signalling genes were found in 99 contigs dispersed without a discernable pattern across the genome.</p> <p>Conclusion</p> <p>Despite some limitations that interfere with the correct assembly of heterozygous clones into contigs, the 'Cabernet Sauvignon' physical map is a useful and reliable intermediary step between a genetic map and the genome sequence. This tool was successfully exploited for a quick mapping of complex families of genes, and it strengthened previous clues of co-localisation of major NBS-LRR clusters and disease resistance <it>loci </it>in grapevine.</p

Establishment and analysis of a reference transcriptome for Spodoptera frugiperda

International audienceBackground Spodoptera frugiperda (Noctuidae) is a major agricultural pest throughout the American continent. The highly polyphagous larvae are frequently devastating crops of importance such as corn, sorghum, cotton and grass. In addition, the Sf9 cell line, widely used in biochemistry for in vitro protein production, is derived from S. frugiperda tissues. Many research groups are using S. frugiperda as a model organism to investigate questions such as plant adaptation, pest behavior or resistance to pesticides.ResultsIn this study, we constructed a reference transcriptome assembly (Sf_TR2012b) of RNA sequences obtained from more than 35 S. frugiperda developmental time-points and tissue samples. We assessed the quality of this reference transcriptome by annotating a ubiquitous gene family - ribosomal proteins - as well as gene families that have a more constrained spatio-temporal expression and are involved in development, immunity and olfaction. We also provide a time-course of expression that we used to characterize the transcriptional regulation of the gene families studied.ConclusionWe conclude that the Sf_TR2012b transcriptome is a valid reference transcriptome. While its reliability decreases for the detection and annotation of genes under strong transcriptional constraint we still recover a fair percentage of tissue-specific transcripts. That allowed us to explore the spatial and temporal expression of genes and to observe that some olfactory receptors are expressed in antennae and palps but also in other non related tissues such as fat bodies. Similarly, we observed an interesting interplay of gene families involved in immunity between fat bodies and antennae

Etudes électrochimiques d'espèces organiques et inorganiques sous champ magnétique intense (1,74 TESLA)

L'étude de l'influence du champ magnétique sur les réactions électrochimiques a fait l'objet de nombreux travaux depuis plus d'un siècle. Il est aujourd'hui bien établi qu'un champ magnétique exerce une influence importante sur les processus ayant lieu au sein de la solution et à l'interface électrode/électrolyte, appelée effet magnétohydrodynamique (MHD). Cependant, les résultats publiés étant souvent contradictoires, nous avons réalisé une étude systématique des paramètres susceptibles de révéler l'effet d'un champ magnétique intense (1,74 tesla) à l'aide de plusieurs techniques : la voltampérométrie cyclique, la chronoampérométrie, la voltampérométrie impulsionnelle différentielle et la spectroscopie d'impédance. Nous nous sommes intéressés à différents systèmes électrochimiques : réversibles et irréversibles, minéraux et organiques, espèces neutres ou chargées. Les mesures voltampérométriques et chronoampérométriques ont révélé pour tous les systèmes une augmentation importante du courant d'électrolyse sous champ magnétique. Nous avons pu quantifier la dépendance du courant limite obtenu vis à vis de la concentration en réactif, du coefficient de diffusion de l'espèce étudiée et de la géométrie de l'électrode de travail. Les mesures d'impédance ont ensuite permis de déterminer l'origine de l'effet MHD : le champ magnétique agit sur le transport diffusionnel des espèces, entraînant la mise en place d'un régime de diffusion-convection. En revanche, aucune influence n'a été observée sur le processus de transfert de charge. Par ailleurs, les résultats obtenus par voltampérométrie impulsionnelle différentielle ont montré que l'effet MHD était un phénomène lent à s'établir en solution. Enfin, l'étude des isomères du nitrobenzaldéhyde et des isomères du dihydroxybenzène a révélé une différence de comportement en présence du champ magnétique, probablement liée aux différences de stabilité des intermédiaires impliqués dans les réactions mises en jeu.LYON1-BU.Sciences (692662101) / SudocSudocFranceF

Determination of iron in calf serum using bathophenanthroline and thermal lens spectrometry

International audienceThermal lens spectrometry has been used for the determination of iron in calf serum. The method is based on dissociation of Fe3+ from proteins, reduction of Fe3+ to Fe2+ and formation of a coloured complex between Fe2+ and bathophenanthroline. Contrary to the spectrophotometric method, it is shown that thermal lens spectrometry is less sensitive to scattering caused by the presence of small particles remaining in the test solution after the deproteinization step. The background signal is very small and the response is only slightly dependent on the amount of scattering particles. The method is reliable, sensitive and reproducible. The limit of detection for iron is 4 ppb and the relative standard deviation is around 2%. It is expected that the volume of serum sample necessary for an analysis can be reduced to less than 100 mul

Electrodeposition of Te nanostructures in ionic liquid

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Synthèse par électrodéposition en milieu liquide ionique de nanostructures de tellure autosupportées

International audienc

Contribution à l'électrodéposition en milieu liquide ionique de tellurure de bismuth en vue de son dopage

La thermoélectricité connait un essor important depuis une dizaine d'années. Réservés actuellement à des marchés de niche tels que l'informatique ou l'aérospatiale, les dispositifs à base de matériaux thermoélectriques pourraient trouver de nombreuses applications dans les véhicules afin de récupérer la chaleur dissipée. Les meilleurs matériaux pour une utilisation à des températures proches de l'ambiante sont les composés de la famille du tellurure de bismuth, Bi2Te3. Le but de ce travail de doctorat était la synthèse par voie électrochimique de Bi2Te3 dopé. La réduction des terres rares étant impossible en milieu aqueux, les liquides ioniques possédant une grande stabilité électrochimique, ont été choisis comme électrolytes. La première partie du travail de thèse a consisté à élaborer le liquide ionique le mieux adapté permettant la réduction électrochimique du lanthane(III). Parmi les liquides ioniques testés, le bis(trifluorométhylsulfonyl)imidure d'1-éthyl-1-octylpipéridinium (EOPipTFSI) a été choisi. Nous avons ensuite défini la composition de l'électrolyte permettant d'atteindre une solubilité élevée des sels précurseurs en réalisant un mélange binaire avec EOPipBr. Les comportements électrochimiques de mélanges d'ions Bi(III)/Te(IV) ont été étudiés. Le système électrochimique obtenu est complexe. Cependant, une étude analytique approfondie a permis d'aboutir à la synthèse de Bi2Te3. Dans une dernière partie, nous nous sommes intéressés au système électrochimique Te(IV)/Te(0), l'étude des dépôts de Te(0) ayant révélé qu'ils étaient composés de nanofils monocristallins. L'influence de différents paramètres sur le diamètre et la morphologie des dépôts a été étudiéeThermoelectricity has soared up for few years. Currently reserved to niche markets such as informatics or aerospace, devices based on thermoelectric materials could be used in vehicles in order to harness wasted heat. However, the performance of these materials is insufficient for scale up. Among thermoelectric materials, bismuth telluride (Bi2Te3) compounds are the most efficient at room temperature. The purpose of this work was the electrochemical synthesis of doped-Bi2Te3. Rare earth elements being hardly reducible, aqueous medium is unsuitable for their electrodeposition that's why ionic liquids were chosen as electrolytes because of their large electrochemical window. The first part of this PhD work consisted in elaborating the most suitable ionic liquid allowing lanthanum(III) electrochemical reduction. Among ionic liquids tested, 1-ethyl,1-octylpiperidinium bis(trifluoromethylsulfonyl)imide (EOPipTFSI) was selected. In a second part, we defined a bath composition allows reaching a high solubility of precursor salts by using a binary mixture EOPipTFSI:EOPipBr, EOPipBr being the intermediate product of EOPipTFSI synthesis. Then, electrochemical behaviors of several Bi(III)/Te(IV) mixtures were studied. The electrochemical system is complex. Nevertheless, this detailed analytical study led to Bi2Te3 electrochemical synthesis. Finally, the Te(IV)/Te(0) electrochemical system was more deeply studied, the analysis of Te deposits revealed the coatings were composed of single crystalline nanowires. The influence of experimental on nanowire diameter and coatings morphology was studied. These nanowires could be of great interest to prepare Te-Bi core-shell nanostructuresNANCY-INPL-Bib. électronique (545479901) / SudocSudocFranceF

Differential pulse voltammetry at microdisk electrodes

International audienceExpressions for reversible differential pulse (DP) voltammograms at microdisk electrodes were established from experimental results as a function of pulse electrolysis parameters. Three expressions were computed numerically, depending on the electrode radius and varying the pulse interval, tau. They were compared to theoretical and numerical expressions established previously in literature reports for macrodisk and microcylinder electrodes. The other aim of this work was to determine the minimum value of the pulse interval for which DP voltammograms observed at microdisk electrodes are not distorted. It appeared that no distortion is observed even at very short values of tau, meaning that microdisk electrodes are a good alternative to macroelectrodes in order to reduce time analysis in DPV DP measurements were carried out at platinum electrodes for two reversible reactions: hexacyanoferrate (II) and iodide oxidation reactio

A copper bismuth film electrode for adsorptive cathodic stripping analysis of trace nickel using square wave voltammetry

International audienceStripping analysis has been widely recognised as a powerful tool for trace metal analysis. Its remarkable sensitivity is attributed to the combination of a preconcentration step coupled with pulse measurements that generates an extremely favourable signal-to-background ratio. Mercury-based electrodes have been traditionally employed for achieving high reproducibility and sensitivity of the stripping technique. However, because of the toxicity of mercury, new alternative electrode materials are highly desired, particularly for on-site monitoring. Recently, the use of bismuth thin films, deposited in situ on platinum or glassy carbon substrates, has been proposed as a possible alternative to mercury: bismuth is 'environmentally-friendly', with a low toxicity and a widespread pharmaceutical use. In this paper, the preparation of bismuth film electrodes by electrodeposition on a copper substrate and their adsorptive stripping performances are presented. Bismuth film electrodes were prepared ex-situ by pulsed potential electrodeposition. The analytical performances of these electrodes for adsorptive cathodic stripping voltammetry of nickel were evaluated in nondeacrated solutions. Well-defined peaks along with low background current were obtained in ammonia buffer by square wave voltammetry, using dimethylglyoxime as complexing agent. Linear calibration curves were obtained for Ni2+ concentrations ranging from 1 x 10(-8) to 1 x 10(-7) mol L-1 and from 1 x 10(-7) to 1 x 10(-6) mol L-1 with relative standard deviations of 5% (n = 15) at 1 x 10(-7) mol L-1 level. The analytical methodology was successfully applied to monitor Ni2+ content in industrial electrolytic baths, ground water and tap water. These results open the possibility to use bismuth film electrodes as an alternative to mercury-based electrodes for nickel analysis

Tuning the morphology of Te 1D nanostructures by template-free electrochemical deposition in an ionic liquid

International audienceTellurium and its alloys are used in many applications such as photoconductors, piezoelectric devices, thermoelectric generators and coolers [1]. For thermoelectric applications, the transport properties (thermal conductivity, electrical resistivity, Seebeck coefficient) of tellurium and its compounds can be improved by nanostructuring [2]. One-dimensional nanostructures like nanowires [3] and core-shell nanowires [4] are particularly promising due to the high phonon interface scattering and the blocking of the phonon conduction along the wire axis which lead to an increase of the thermoelectric conversion efficiency. Te nanowires can represent a base to create core-shell structures, being the core that could be further capped with a shell to get arrays of Te-based thermoelectric nanostructures like BiTe [5], AgTe [6] or LaTe [7]. Template assisted electrodeposition is a low cost technique widely used in literature for the synthesis of nanowires but implies several preparation steps and the removal of the template after the growth of the nanowires. The aim of this work is to develop a template free synthesis route that would be more convenient. For this purpose, Room-Temperature Ionic Liquids (RTILs) appear as promising solvents. Indeed, it has been highlighted that they can act as stabilizing agents for nanoparticles and nanostructured films synthesis [8]. In a previous work ([9]), our laboratory showed that Te nanowires can be obtained in an ionic liquid binary mixture: 1-ethyl-1-octyl-piperidinium bis(trifluoromethylsulfonyl)imide:1-ethyl-1-octyl-piperidinium bromide (EOPipTFSI:EOPipBr). In the present work, several morphologies were obtained by varying the synthesis parameters (applied fixed potential, Te(IV) concentration, electrolyte composition). Under charge transfer control, micrometer faceted grains are formed. Under diffusion control, the deposits are composed of nanowires, which are single crystalline as proven by SAED (Selected Area Electronic Diffraction) and TEM (Transmission Electron Microscopy) analyses. In highest tested overpotential conditions, nanowires turn progressively into crystallized hollow nanostructures (HNs) when the coulometric charge increases. This phenomenon is more accentuated at low concentration and disappears when using a soluble anode, showing that the formation of HNs is due to a limitation by species supply. The geometry of HNs, with a high surface to volume ratio, is particularly interesting to create high performances thermoelectric materials. Indeed, this geometry could further decrease the lattice part of the thermal diffusion coefficient by phonon confinement