Analyse génétique et moléculaire de l'immunité des hydathodes et du système vasculaire des Brassicacées

Les hydathodes sont décrits pour la première fois à la fin du XIXe siècle, par le botaniste chirurgien microbiologiste Prussien Anton de Bary. Depuis, ces organes, pourtant présents sur les feuilles de la majorité des plantes vasculaires, ne sont étudiés que sporadiquement par la communauté scientifique. Sites de la guttation, les hydathodes se retrouvent à la pointe de la dentelure des feuilles. Constitués de pores dans l'épiderme et d'un parenchyme distinctif lié au système vasculaire, les hydathodes font le lien direct entre le milieu extérieur et les vaisseaux du xylème des feuilles. De façon surprenante, cette voie d'entrée dans les tissus végétaux n'est utilisée que par une poignée d'agents pathogènes. Parmi eux, Xanthomonas campestris pathovar campetris (Xcc) est l'agent responsable de la nervation noire de Brassicacées. Cette bactérie constitue une menace pour l'agriculture, puisqu'elle est capable d'infecter de nombreuses espèces cultivées, telles que les choux et choux-fleurs, le navet, la moutarde, le radis, etc. Si les facteurs de virulence de Xcc sont bien connus, peu d'études se sont attelées à décrypter le rôle des hydathodes dans l'immunité des plantes, alors qu'ils sont le premier lieu de contact entre Xcc et la plante. Au cours de ce projet de thèse, j'ai étudié les spécificités transcriptomiques des hydathodes par rapport au mésophylle et les particularités du métabolome du fluide de guttation en comparaison de celui de la sève brute. J'ai ensuite établi les premières bases génétiques de l'immunité post-invasive des hydathodes de chou-fleur (cultivar Clovis) en comparant leur réponse à une souche virulente et avirulente de Xcc, durant les étapes précoces de l'infection. Dans la deuxième partie du projet, j'ai mis en place un système permettant de cribler un grand nombre de mutants d'Arabidopsis thaliana en réponse à Xcc, qui sera utilisé au sein de l'équipe. Grâce à cette nouvelle méthode, j'ai entamé le criblage d'une collection de mutant d'A. thaliana et identifié plus d'une cinquantaine de lignées dont la sensibilité à Xcc est altérée. Pour finir, dans la troisième partie réalisée dans le cadre d'une collaboration, j'ai exploré le lien entre le nombre d'hydathodes, l'état hydrique des tissus et le comportement infectieux de Xcc. Ce projet apporte des données originales et des outils qui permettront de mieux comprendre le fonctionnement des hydathodes en tant qu'organes ainsi que leur rôle au cours des interactions plantes-pathogènes.Hydathodes were first characterized at the end of the XIXth century by Anton de Bary, a Prussian botanist, surgeon and microbiologist. Since, theses organs are studied sporadically, even if they are present on leaves of most vascular plants. Localized at the leaf serration tips, hydathodes are the sites of guttation. They are composed of pores in the epidermis and of a peculiar parenchyma connected to the vasculature. Hydathodes are thus a link between leaf xylem vessels and the outside world. Surprisingly, only a handful of pathogens can penetrate the plant this way. Xanthomonas campestris pathovar campestris (Xcc), causal agent of black rot of Brassica is one of them. Xcc represent a threat to agriculture, because it can infect many Brassica crops, such as cabbage, cauliflower, turnip, mustard or radish. Xcc virulence factors are well studied, but not much is known about plant immunity inside hydathodes, even if they are the first contact point between Xcc and the plant. During this PhD project, I studied hydathode transcriptomic and guttation fluid metabolomics characteristics. I also established the genetic bases of cauliflower hydathode post-invasive immunity, by comparing hydathodes responses to an Xcc virulent or avirulent strain, during the early stages of infection. In the second part of the project, I set up a method to screen immune defect in many Arabidopsis thaliana mutants in response to Xcc infection. This method will be a future asset for my host team. I also used it to start the screen of a collection of A. thaliana mutants. I identified more than fifty lines with a modified susceptibility to Xcc. Last, I delved into the link between number of hydathodes, water status of tissues and Xcc infectious strategy. This work brings original results and a protocol that will help us to better understand hydathodes biology as plant organs as well as their role during plant-pathogen interactions

Potential of extracts from Saponaria officinalis and Calendula officinalis to modulate in vitro rumen fermentation with respect to their content in saponins

Saponins have the potential to favorably modulate rumen fermentation, but there is generally a lack of the chemical structures associated with the described effects. The activity of extracts from Calendula officinalisand Saponaria officinalis in the rumen was evaluated in vitro. The S. officinalis root extract, reduced CH4production by 8.5% and increased total VFA concentration by 25.2%. C. officinalis and S. officinalis root extracts and the S. officinalis aerial part extract decreased the acetate to propionate ratio from 8.6 to 17.4%, according to the extract. An HPLC-ELSD analysis indicated that the saponin content ranged from 43.6 to 57.6 mg/g of dry matter (DM) in the C. officinalis extracts and from 224.0 to 693.8 mg/g of DM in the S. officinalis extracts, expressed as the hederacoside C equivalent. Identification of the saponin compounds present in the extracts by HPLC–MSn suggested that the saponin profile modulated the biological activities, showing the importance of determining the structure of saponins when evaluating extracts

ROOT - A C++ Framework for Petabyte Data Storage, Statistical Analysis and Visualization

ROOT is an object-oriented C++ framework conceived in the high-energy physics (HEP) community, designed for storing and analyzing petabytes of data in an efficient way. Any instance of a C++ class can be stored into a ROOT file in a machine-independent compressed binary format. In ROOT the TTree object container is optimized for statistical data analysis over very large data sets by using vertical data storage techniques. These containers can span a large number of files on local disks, the web, or a number of different shared file systems. In order to analyze this data, the user can chose out of a wide set of mathematical and statistical functions, including linear algebra classes, numerical algorithms such as integration and minimization, and various methods for performing regression analysis (fitting). In particular, ROOT offers packages for complex data modeling and fitting, as well as multivariate classification based on machine learning techniques. A central piece in these analysis tools are the histogram classes which provide binning of one- and multi-dimensional data. Results can be saved in high-quality graphical formats like Postscript and PDF or in bitmap formats like JPG or GIF. The result can also be stored into ROOT macros that allow a full recreation and rework of the graphics. Users typically create their analysis macros step by step, making use of the interactive C++ interpreter CINT, while running over small data samples. Once the development is finished, they can run these macros at full compiled speed over large data sets, using on-the-fly compilation, or by creating a stand-alone batch program. Finally, if processing farms are available, the user can reduce the execution time of intrinsically parallel tasks - e.g. data mining in HEP - by using PROOF, which will take care of optimally distributing the work over the available resources in a transparent way

Software Challenges For HL-LHC Data Analysis

The high energy physics community is discussing where investment is needed to prepare software for the HL-LHC and its unprecedented challenges. The ROOT project is one of the central software players in high energy physics since decades. From its experience and expectations, the ROOT team has distilled a comprehensive set of areas that should see research and development in the context of data analysis software, for making best use of HL-LHC's physics potential. This work shows what these areas could be, why the ROOT team believes investing in them is needed, which gains are expected, and where related work is ongoing. It can serve as an indication for future research proposals and cooperations

Activities of extracts from saponin-containing plants on sheep erythrocytes, Tetrahymena pyriformis and Rumen protozoa

As the effects of saponins in the rumen are due to their membrane-disrupting ability on protozoa, the activities of extracts from saponin containing plants were determined on erythrocytes, Tetrahymena pyriformis and rumen protozoa. Inhibition of Tetrahymena pyriformis were found to be correlated (R2=0.54) with 50% hemolysis. The extracts supplemented to a standard feed, showed null to remarkable in vitro activity on rumen protozoa. With -51% and -41% protozoa inhibition, Primula veris and Chenopodium quinoa might have the potential to improve ammonia utilization in ruminants, meaning less excreted nitrogen and less environmental impact

ROOT for the HL-LHC: data format

This document discusses the state, roadmap, and risks of the foundational components of ROOT with respect to the experiments at the HL-LHC (Run 4 and beyond). As foundational components, the document considers in particular the ROOT input/output (I/O) subsystem. The current HEP I/O is based on the TFile container file format and the TTree binary event data format. The work going into the new RNTuple event data format aims at superseding TTree, to make RNTuple the production ROOT event data I/O that meets the requirements of Run 4 and beyond

Convergence of arithmetic means of operators in Fréchet spaces

Every Köthe echelon Fréchet space XX that is Montel and not isomorphic to a countable product of copies of the scalar field admits a power bounded continuous linear operator TT such that I−TI−T does not have closed range, but the sequence of arithmetic means of the iterates of TT converges to 0 uniformly on the bounded sets in XX. On the other hand, if XX is a Fréchet space which does not have a quotient isomorphic to a nuclear Köthe echelon space with a continuous norm, then the sequence of arithmetic means of the iterates of any continuous linear operator TT (for which (1/n)Tn(1/n)Tn converges to 0 on the bounded sets) converges uniformly on the bounded subsets of XX, i.e., TT is uniformly mean ergodic, if and only if the range of I−TI−T is closed. This result extends a theorem due to Lin for such operators on Banach spaces. The connection of Browder’s equality for power bounded operators on Fréchet spaces to their uniform mean ergodicity is exposed. An analysis of the mean ergodic properties of the classical Cesàro operator on Banach sequence spaces is also given. © 2012 Elsevier Ltd. All rights reserved.The research of Jose Bonet was partially supported by MEC and FEDER Project MTM 2007-62643, GV Project Prometeo/2008/101 (Spain) and ACOMP/2012/090.Albanese, AA.; Bonet Solves, JA.; Ricker, WJ. (2013). Convergence of arithmetic means of operators in Fréchet spaces. Journal of Mathematical Analysis and Applications. 401(1):160-173. https://doi.org/10.1016/j.jmaa.2012.11.060S160173401

On the continuous Cesàro operator in certain function spaces

“The final publication is available at Springer via http://dx.doi.org/10.1007/s11117-014-0321-5"Various properties of the (continuous) Cesàro operator C, acting on Banach and Fréchet spaces of continuous functions and L p-spaces, are investigated. For instance, the spectrum and point spectrum of C are completely determined and a study of certain dynamics of C is undertaken (eg. hyper- and supercyclicity, chaotic behaviour). In addition, the mean (and uniform mean) ergodic nature of C acting in the various spaces is identified.The research of the first two authors was partially supported by the projects MTM2010-15200 and GVA Prometeo II/2013/013 (Spain). The second author gratefully acknowledges the support of the Alexander von Humboldt Foundation.Albanese, AA.; Bonet Solves, JA.; Ricker, WJ. (2015). On the continuous Cesàro operator in certain function spaces. Positivity. 19:659-679. https://doi.org/10.1007/s11117-014-0321-5S65967919Albanese, A.A.: Primary products of Banach spaces. Arch. Math. 66, 397–405 (1996)Albanese, A.A.: On subspaces of the spaces $$L^p_{\rm loc}$$ L loc p and of their strong duals. Math. Nachr. 197, 5–18 (1999)Albanese, A.A., Moscatelli, V.B.: Complemented subspaces of sums and products of copies of $$L^1 [0,1]$$ L 1 [ 0 , 1 ] . Rev. Mat. Univ. Complut. Madr. 9, 275–287 (1996)Albanese, A.A., Bonet, J., Ricker, W.J.: Mean ergodic operators in Fréchet spaces. Ann. Acad. Sci. Fenn. Math. 34, 401–436 (2009)Albanese, A.A., Bonet, J., Ricker, W.J.: On mean ergodic operators. In: Curbera, G.P. (eds.) Vector Measures, Integration and Related Topics. Operator Theory: Advances and Applications, vol. 201, pp. 1–20. Birkhäuser, Basel (2010)Albanese, A.A., Bonet, J., Ricker, W.J.: $$C_0$$ C 0 -semigroups and mean ergodic operators in a class of Fréchet spaces. J. Math. Anal. Appl. 365, 142–157 (2010)Albanese, A.A., Bonet, J., Ricker, W.J.: Convergence of arithmetic means of operators in Fréchet spaces. J. Math. Anal. Appl. 401, 160–173 (2013)Bayart, F., Matheron, E.: Dynamics of linear operators. Cambridge Tracts in Mathematics, vol. 179. Cambridge University Press, Cambridge (2009)Bellenot, S.F., Dubinsky, E.: Fréchet spaces with nuclear Köthe quotients. Trans. Am. Math. Soc. 273, 579–594 (1982)Bonet, J., Frerick, L., Peris, A., Wengenroth, J.: Transitive and hypercyclic operators on locally convex spaces. Bull. Lond. Math. Soc. 37, 254–264 (2005)Boyd, D.W.: The spectrum of the Cesàro operator. Acta Sci. Math. (Szeged) 29, 31–34 (1968)Brown, A., Halmos, P.R., Shields, A.L.: Cesàro operators. Acta Sci. Math. (Szeged) 26, 125–137 (1965)Dierolf, S., Zarnadze, D.N.: A note on strictly regular Fréchet spaces. Arch. Math. 42, 549–556 (1984)Dunford, N., Schwartz, J.T.: Linear Operators I: General Theory (2nd Printing). Wiley-Interscience, New York (1964)Galaz Fontes, F., Solís, F.J.: Iterating the Cesàro operators. Proc. Am. Math. Soc. 136, 2147–2153 (2008)Galaz Fontes, F., Ruiz-Aguilar, R.W.: Grados de ciclicidad de los operadores de Cesàro–Hardy. Misc. Mat. 57, 103–117 (2013)González, M., León-Saavedra, F.: Cyclic behaviour of the Cesàro operator on $$L_2(0,+\infty )$$ L 2 ( 0 , + ∞ ) . Proc. Am. Math. Soc. 137, 2049–2055 (2009)Grosse-Erdmann, K.G., Peris Manguillot, A.: Linear chaos. In: Universitext. Springer, London (2011)Hardy, G.H., Littlewood, J.E., Pólya, G.: Inequalities. In: Reprint of the 1952 Edition. Cambridge Mathematical Library. Cambridge University Press, Cambridge (1988)Krengel, U.: Ergodic theorems. In: De Gruyter Studies in Mathematics, vol. 6. Walter de Gruyter Co., Berlin (1985)Leibowitz, G.M.: Spectra of finite range Cesàro operators. Acta Sci. Math. (Szeged) 35, 27–28 (1973)Leibowitz, G.M.: The Cesàro operators and their generalizations: examples in infinite-dimensional linear analysis. Am. Math. Mon. 80, 654–661 (1973)León-Saavedra, F., Piqueras-Lerena, A., Seoane-Sepúlveda, J.B.: Orbits of Cesàro type operators. Math. Nachr. 282, 764–773 (2009)Lin, M.: On the uniform ergodic theorem. Proc. Am. Math. Soc. 43, 337–340 (1974)Meise, R., Vogt, D.: Introduction to functional analysis. In: Oxford Graduate Texts in Mathematics, vol. 2. The Clarendon Press; Oxford University Press, New York (1997)Metafune, G., Moscatelli, V.B.: Quojections and prequojections. In: Terzioğlu, T. (ed.) Advances in the Theory of Fréchet spaces. NATO ASI Series, vol. 287, pp. 235–254. Kluwer Academic Publishers, Dordrecht (1989)Moscatelli, V.B.: Fréchet spaces without norms and without bases. Bull. Lond. Math. Soc. 12, 63–66 (1980)Piszczek, K.: Quasi-reflexive Fréchet spaces and mean ergodicity. J. Math. Anal. Appl. 361, 224–233 (2010)Piszczek, K.: Barrelled spaces and mean ergodicity. Rev R. Acad. Cienc. Exactas Fis. Nat. Ser. A Math. RACSAM 104, 5–11 (2010)Yosida, K.: Functional Analysis, 6th edn. Springer, Berlin (1980