NobleBlocks

CEA Cadarache

governmentSaint-Paul-lès-Durance, Provence-Alpes-Côte d'Azur, France

Research output, citation impact, and the most-cited recent papers from CEA Cadarache (France). Aggregated across the NobleBlocks index of 300M+ scholarly works.

Total works
14.2K
Citations
1.1M
h-index
306
i10-index
20.8K
Also known as
CEA CadaracheCentre de CadaracheCommissariat à l'Énergie Atomique et aux Énergies Alternatives centre de Cadarache

Top-cited papers from CEA Cadarache

ENDF/B-VIII.0: The 8 th Major Release of the Nuclear Reaction Data Library with CIELO-project Cross Sections, New Standards and Thermal Scattering Data
David A. Brown, M. B. Chadwick, R. Capote, Albert C. Kahler +4 more
2018· Nuclear Data Sheets2.3Kdoi:10.1016/j.nds.2018.02.001

We describe the new ENDF/B-VIII.0 evaluated nuclear reaction data library. ENDF/B-VIII.0 fully incorporates the new IAEA standards, includes improved thermal neutron scattering data and uses new evaluated data from the CIELO project for neutron reactions on 1 H, 16 O, 56 Fe, 235 U, 238 U and 239 Pu described in companion papers in the present issue of Nuclear Data Sheets . The evaluations benefit from recent experimental data obtained in the U.S. and Europe, and improvements in theory and simulation. Notable advances include updated evaluated data for light nuclei, structural materials, actinides, fission energy release, prompt fission neutron and γ -ray spectra, thermal neutron scattering data, and charged-particle reactions. Integral validation testing is shown for a wide range of criticality, reaction rate, and neutron transmission benchmarks. In general, integral validation performance of the library is improved relative to the previous ENDF/B-VII.1 library.

The Galaxy platform for accessible, reproducible and collaborative biomedical analyses: 2022 update
The Galaxy Community, Enis Afgan, Anton Nekrutenko, Björn Andreas Grüning +4 more
2022· Nucleic Acids Research1.4Kdoi:10.1093/nar/gkac247

Galaxy is a mature, browser accessible workbench for scientific computing. It enables scientists to share, analyze and visualize their own data, with minimal technical impediments. A thriving global community continues to use, maintain and contribute to the project, with support from multiple national infrastructure providers that enable freely accessible analysis and training services. The Galaxy Training Network supports free, self-directed, virtual training with >230 integrated tutorials. Project engagement metrics have continued to grow over the last 2 years, including source code contributions, publications, software packages wrapped as tools, registered users and their daily analysis jobs, and new independent specialized servers. Key Galaxy technical developments include an improved user interface for launching large-scale analyses with many files, interactive tools for exploratory data analysis, and a complete suite of machine learning tools. Important scientific developments enabled by Galaxy include Vertebrate Genome Project (VGP) assembly workflows and global SARS-CoV-2 collaborations.

Plasma-material interactions in current tokamaks and their implications for next step fusion reactors
G. Federici, Charles H. Skinner, J.N. Brooks, J.P. Coad +4 more
2001· Nuclear Fusion1.4Kdoi:10.1088/0029-5515/41/12/218

View the article online for updates and enhancements.You may also like Plasma-wall interaction, a key issue on the way to a steady state burning fusion device V Philipps - Latest results of Eurofusion plasma-facing components research in the areas of power loading, material erosion and fuel retention M. Reinhart, S. Brezinsek, A.

Plant host habitat and root exudates shape soil bacterial community structure
Feth el Zahar Haichar, C. Marol, Odile Berge, J. Ignacio Rangel‐Castro +4 more
2008· The ISME Journal1.2Kdoi:10.1038/ismej.2008.80

The rhizosphere is active and dynamic in which newly generated carbon, derived from root exudates, and ancient carbon, in soil organic matter (SOM), are available for microbial growth. Stable isotope probing (SIP) was used to determine bacterial communities assimilating each carbon source in the rhizosphere of four plant species. Wheat, maize, rape and barrel clover (Medicago truncatula) were grown separately in the same soil under (13)CO(2) (99% of atom (13)C) and DNA extracted from rhizosphere soil was fractionated by isopycnic centrifugation. Bacteria-assimilating root exudates were characterized by denaturing gradient gel electrophoresis (DGGE) analysis of (13)C-DNA and root DNA, whereas those assimilating SOM were identified from (12)C-DNA. Plant species root exudates significantly shaped rhizosphere bacterial community structure. Bacteria related to Sphingobacteriales and Myxococcus assimilated root exudates in colonizing roots of all four plants, whwereas bacteria related to Sphingomonadales utilized both carbon sources, and were identified in light, heavy and root compartment DNA. Sphingomonadales were specific to monocotyledons, whereas bacteria related to Enterobacter and Rhizobiales colonized all compartments of all four plants, used both fresh and ancient carbon and were considered as generalists. There was also evidence for an indirect important impact of root exudates, through stimulation of SOM assimilation by a diverse bacterial community.

Chapter 3: MHD stability, operational limits and disruptions
T. C. Hender, John C. Wesley, J. Bialek, A. Bondeson +4 more
2007· Nuclear Fusion1.2Kdoi:10.1088/0029-5515/47/6/s03

Chapter 3: MHD stability, operational limits and disruptions, Hender, T.C., Wesley, J.C, Bialek, J., Bondeson, A., Boozer, A.H., Buttery, R.J., Garofalo, A., Goodman, T.P, Granetz, R.S., Gribov, Y., Gruber, O., Gryaznevich, M., Giruzzi, G., Günter, S., Hayashi, N., Helander, P., Hegna, C.C., Howell, D.F., Humphreys, D.A., Huysmans, G.T.A., Hyatt, A.W., Isayama, A., Jardin, S.C., Kawano, Y., Kellman, A., Kessel, C., Koslowski, H.R., La Haye, R.J., Lazzaro, E., Liu, Y.Q., Lukash, V., Manickam, J., Medvedev, S., Mertens, V., Mirnov, S.V., Nakamura, Y., Navratil, G., Okabayashi, M., Ozeki, T., Paccagnella, R., Pautasso, G., Porcelli, F., Pustovitov, V.D., Riccardo, V., Sato, M., Sauter, O., Schaffer, M.J., Shimada, M., Sonato, P., Strait, E.J., Sugihara, M., Takechi, M., Turnbull, A.D., Westerhof, E., Whyte, D.G., Yoshino, R., Zohm, H., the ITPA MHD, Disruption and Magnetic Control Topical Group

Chapter 4: Power and particle control
Alberto Loarte, B. Lipschultz, A.S. Kukushkin, G.F. Matthews +4 more
2007· Nuclear Fusion1.1Kdoi:10.1088/0029-5515/47/6/s04

Chapter 4: Power and particle control, Loarte, A., Lipschultz, B., Kukushkin, A.S., Matthews, G.F., Stangeby, P.C., Asakura, N., Counsell, G.F., Federici, G., Kallenbach, A., Krieger, K., Mahdavi, A., Philipps, V., Reiter, D., Roth, J., Strachan, J., Whyte, D., Doerner, R., Eich, T., Fundamenski, W., Herrmann, A., Fenstermacher, M., Ghendrih, P., Groth, M., Kirschner, A., Konoshima, S., LaBombard, B., Lang, P., Leonard, A.W., Monier-Garbet, P., Neu, R., Pacher, H., Pegourie, B., Pitts, R.A., Takamura, S., Terry, J., Tsitrone, E., the ITPA Scrape-off Layer and Divertor Physics Topical Group

Suppression of Large Edge-Localized Modes in High-Confinement DIII-D Plasmas with a Stochastic Magnetic Boundary
T.E. Evans, Richard A. Moyer, Paul Thomas, J.G. Watkins +4 more
2004· Physical Review Letters866doi:10.1103/physrevlett.92.235003

A stochastic magnetic boundary, produced by an applied edge resonant magnetic perturbation, is used to suppress most large edge-localized modes (ELMs) in high confinement (H-mode) plasmas. The resulting H mode displays rapid, small oscillations with a bursty character modulated by a coherent 130 Hz envelope. The H mode transport barrier and core confinement are unaffected by the stochastic boundary, despite a threefold drop in the toroidal rotation. These results demonstrate that stochastic boundaries are compatible with H modes and may be attractive for ELM control in next-step fusion tokamaks.

Chapter 2: Plasma confinement and transport
E. J. Doyle, Wayne A. Houlberg, Y. Kamada, V.S. Mukhovatov +4 more
2007· Nuclear Fusion833doi:10.1088/0029-5515/47/6/s02

Chapter 2: Plasma confinement and transport, Doyle, E.J., Houlberg, W.A., Kamada, Y., Mukhovatov, V., Osborne, T.H., Polevoi, A., Bateman, G., Connor, J.W., Cordey, J.G., Fujita, T., Garbet, X., Hahm, T.S., Horton, L.D., Hubbard, A.E., Imbeaux, F., Jenko, F., Kinsey, J.E., Kishimoto, Y., Li, J., Luce, T.C., Martin, Y., Ossipenko, M., Parail, V., Peeters, A., Rhodes, T.L., Rice, J.E., Roach, C.M., Rozhansky, V., Ryter, F., Saibene, G., Sartori, R., Sips, A.C.C., Snipes, J.A., Sugihara, M., Synakowski, E.J., Takenaga, H., Takizuka, T., Thomsen, K., Wade, M.R., Wilson, H.R., ITPA Transport Physics Topical Group, ITPA Confinement Database and Modelling Topical Group, ITPA Pedestal and Edge Topical Group

Heavy metal toxicity: cadmium permeates through calcium channels and disturbs the plant water status
Laetitia Perfus‐Barbeoch, Nathalie Leonhardt, Alain Vavasseur, Cyrille Forestier
2002· The Plant Journal791doi:10.1046/j.1365-313x.2002.01442.x

Because plant wilting has been described as a consequence of cadmium (Cd2+) toxicity, we investigate Cd2+ effects on plant water losses, gas exchanges and stomatal behaviour in Arabidopsis thaliana L. Effects of 1-week Cd2+ application in hydroponic condition (CdCl2 10-100 micro m) were analyzed. A 10- micro m Cd2+ concentration had no significant effect on the plant-water relationship and carbon assimilation. At higher Cd2+ concentrations, a Cd2+ -dependent decrease in leaf conductance and CO2 uptake was observed despite the photosynthetic apparatus appeared not to be affected as probed by fluorescence measurements. In epidermal strip bioassays, nanomolar Cd2+ concentrations reduced stomatal opening under light in A. thaliana, Vicia faba and Commelina communis. Application of 5 micro m ABA limited the root-to-shoot translocation of cadmium. However, the Cd2+-induced stomatal closure was likely ABA-independent, since a 5-day treatment with 50 micro m Cd2+ did not affect the plant relative water content. Additionally, a similar Cd2+-induced stomatal closure was observed in the ABA insensitive mutant abi1-1. Interestingly, this mutant displayed a higher transpiration rate than the wild type but did not accumulate more Cd2+, arguing that Cd2+ uptake is not dependent only on the transpiration flow. Application of putative calcium channels inhibitors suppressed the inhibitory effect of Cd2+ in epidermal strip experiments, suggesting that Cd2+ could enter the guard cell through calcium channels. Patch-clamp studies with V. faba guard cell protoplasts showed that plasma membrane K+ channels were insensitive to external Cd2+ application whereas Ca2+ channels were found permeable to Cd2+. In conclusion, we propose that Cd2+ affects guard cell regulation in an ABA-independent manner by entering the cytosol via Ca2+ channels.

Oil accumulation in the model green alga Chlamydomonas reinhardtii: characterization, variability between common laboratory strains and relationship with starch reserves
Magali Siaut, Stéphan Cuiné, Caroline Cagnon, Boris Fessler +4 more
2011· BMC Biotechnology760doi:10.1186/1472-6750-11-7

BACKGROUND: When cultivated under stress conditions, many microalgae species accumulate both starch and oil (triacylglycerols). The model green microalga Chlamydomonas reinhardtii has recently emerged as a model to test genetic engineering or cultivation strategies aiming at increasing lipid yields for biodiesel production. Blocking starch synthesis has been suggested as a way to boost oil accumulation. Here, we characterize the triacylglycerol (TAG) accumulation process in Chlamydomonas and quantify TAGs in various wild-type and starchless strains. RESULTS: In response to nitrogen deficiency, Chlamydomonas reinhardtii produced TAGs enriched in palmitic, oleic and linoleic acids that accumulated in oil-bodies. Oil synthesis was maximal between 2 and 3 days following nitrogen depletion and reached a plateau around day 5. In the first 48 hours of oil deposition, a ~80% reduction in the major plastidial membrane lipids occurred. Upon nitrogen re-supply, mobilization of TAGs started after starch degradation but was completed within 24 hours. Comparison of oil content in five common laboratory strains (CC124, CC125, cw15, CC1690 and 11-32A) revealed a high variability, from 2 μg TAG per million cell in CC124 to 11 μg in 11-32A. Quantification of TAGs on a cell basis in three mutants affected in starch synthesis (cw15sta1-2, cw15sta6 and cw15sta7-1) showed that blocking starch synthesis did not result in TAG over-accumulation compared to their direct progenitor, the arginine auxotroph strain 330. Moreover, no significant correlation was found between cellular oil and starch levels among the twenty wild-type, mutants and complemented strains tested. By contrast, cellular oil content was found to increase steeply with salt concentration in the growth medium. At 100 mM NaCl, oil level similar to nitrogen depletion conditions could be reached in CC124 strain. CONCLUSION: A reference basis for future genetic studies of oil metabolism in Chlamydomonas is provided. Results highlight the importance of using direct progenitors as control strains when assessing the effect of mutations on oil content. They also suggest the existence in Chlamydomonas of complex interplays between oil synthesis, genetic background and stress conditions. Optimization of such interactions is an alternative to targeted metabolic engineering strategies in the search for high oil yields.

The joint evaluated fission and fusion nuclear data library, JEFF-3.3
Arjan J. M. Plompen, Oscar Cabellos, Cyrille De Saint Jean, Michael Fleming +4 more
2020· The European Physical Journal A710doi:10.1140/epja/s10050-020-00141-9

Abstract The joint evaluated fission and fusion nuclear data library 3.3 is described. New evaluations for neutron-induced interactions with the major actinides $$^{235}\hbox {U}$$ 235U , $$^{238}\hbox {U}$$ 238U and $$^{239}\hbox {Pu}$$ 239Pu , on $$^{241}\hbox {Am}$$ 241Am and $$^{23}\hbox {Na}$$ 23Na , $$^{59}\hbox {Ni}$$ 59Ni , Cr, Cu, Zr, Cd, Hf, W, Au, Pb and Bi are presented. It includes new fission yields, prompt fission neutron spectra and average number of neutrons per fission. In addition, new data for radioactive decay, thermal neutron scattering, gamma-ray emission, neutron activation, delayed neutrons and displacement damage are presented. JEFF-3.3 was complemented by files from the TENDL project. The libraries for photon, proton, deuteron, triton, helion and alpha-particle induced reactions are from TENDL-2017. The demands for uncertainty quantification in modeling led to many new covariance data for the evaluations. A comparison between results from model calculations using the JEFF-3.3 library and those from benchmark experiments for criticality, delayed neutron yields, shielding and decay heat, reveals that JEFF-3.3 performes very well for a wide range of nuclear technology applications, in particular nuclear energy.

The ABI1 and ABI2 protein phosphatases 2C act in a negative feedback regulatory loop of the abscisic acid signalling pathway
Sylvain Merlot, Françoise Gosti, Danièle Guerrier, Alain Vavasseur +1 more
2001· The Plant Journal698doi:10.1046/j.1365-313x.2001.00965.x

The Arabidopsis ABI1 and ABI2 genes encode two protein serine/threonine phosphatases 2C (PP2C). These genes have been originally identified by the dominant mutations abi1--1 and abi2--1, which reduce the plant's responsiveness to the hormone abscisic acid (ABA). However, recessive mutants of ABI1 were recently shown to be supersensitive to ABA, which demonstrated that the ABI1 phosphatase is a negative regulator of ABA signalling. We report here the isolation and characterisation of the first reduction-of-function allele of ABI2, abi2--1R1. The in vitro phosphatase activity of the abi2--1R1 protein is approximately 100-fold lower than that of the wild-type ABI2 protein. Abi2--1R1 plants displayed a wild-type ABA sensitivity. However, doubly mutant plants combining the abi2--1R1 allele and a loss-of-function allele at the ABI1 locus were more responsive to ABA than each of the parental single mutants. These data indicate that the wild-type ABI2 phosphatase is a negative regulator of ABA signalling, and that the ABI1 and ABI2 phosphatases have overlapping roles in controlling ABA action. Measurements of PP2C activity in plant extracts showed that the phosphatase activity of ABI1 and ABI2 increases in response to ABA. These results suggest that ABI1 and ABI2 act in a negative feedback regulatory loop of the ABA signalling pathway.

AtHMA3, a P1B-ATPase Allowing Cd/Zn/Co/Pb Vacuolar Storage in Arabidopsis
Mélanie Morel‐Rouhier, Jérôme Crouzet, Antoine Gravot, Pascaline Auroy +3 more
2008· PLANT PHYSIOLOGY682doi:10.1104/pp.108.130294

The Arabidopsis (Arabidopsis thaliana) Heavy Metal Associated3 (AtHMA3) protein belongs to the P1B-2 subgroup of the P-type ATPase family, which is involved in heavy metal transport. In a previous study, we have shown, using heterologous expression in the yeast Saccharomyces cerevisiae, that in the presence of toxic metals, AtHMA3 was able to phenotypically complement the cadmium/lead (Cd/Pb)-hypersensitive strain ycf1 but not the zinc (Zn)-hypersensitive strain zrc1. In this study, we demonstrate that AtHMA3 in planta is located in the vacuolar membrane, with a high expression level in guard cells, hydathodes, vascular tissues, and the root apex. Confocal imaging in the presence of the Zn/Cd fluorescent probe BTC-5N revealed that AtHMA3 participates in the vacuolar storage of Cd. A T-DNA insertional mutant was found more sensitive to Zn and Cd. Conversely, ectopic overexpression of AtHMA3 improved plant tolerance to Cd, cobalt, Pb, and Zn; Cd accumulation increased by about 2- to 3-fold in plants overexpressing AtHMA3 compared with wild-type plants. Thus, AtHMA3 likely plays a role in the detoxification of biological (Zn) and nonbiological (Cd, cobalt, and Pb) heavy metals by participating in their vacuolar sequestration, an original function for a P1B-2 ATPase in a multicellular eukaryote.

Physics basis for the first ITER tungsten divertor
R.A. Pitts, X. Bonnin, Frederic Escourbiac, H. Frerichs +4 more
2019· Nuclear Materials and Energy668doi:10.1016/j.nme.2019.100696

• Reviews the fundamental physics aspects of the first ITER W divertor and defines the required operational lifetime within the Staged Approach. • Uses the ITER divertor SOLPS simulation database to establish the target peak heat flux and neutral pressure burning plasma operating domain. • Assesses consequences of narrow SOL heat flux channels, fluid drifts, component shaping and 3D magnetic fields for ELM control. • Uses W recrystallization to define an operational budget and shows that heat fluxes ∼50% higher than previously assumed may be acceptable. • Shows that Ne and N should be equally good as seed impurities and suggests that very strong ELM mitigation will be required at high performance. • Provides a list of key outstanding R&D areas to consolidate the divertor physics basis in the period up to ITER operation. On the eve of component procurement, this paper discusses the present physics basis for the first ITER tungsten (W) divertor, beginning with a reminder of the key elements defining the overall design, and outlining relevant aspects of the Research Plan accompanying the new “staged approach” to ITER nuclear operations which fixes the overall divertor lifetime constraint. The principal focus is on the main design driver, steady state power fluxes in the DT phases, obtained from simulations using the 2-D SOLPS-4.3 and SOLPS-ITER plasma boundary codes, assuming the use of the low Z seeding impurities nitrogen (N) and neon (Ne). A new perspective on the simulation database is adopted, concentrating purely on the divertor physics aspects rather than on the core-edge integration, which has been studied extensively in the course of the divertor design evolution and is published elsewhere. Emphasis is placed on factors which may increase the peak steady state loads: divertor target shaping for component misalignment protection, the influence of fluid drifts, and the consequences of narrow scrape-off layer heat flux channels. All tend to push the divertor into an operating space at higher sub-divertor neutral pressure in order to remain at power flux densities acceptable for the target material. However, a revised criterion for the maximum tolerable loads based on avoidance of W recrystallization, sets an upper limit potentially ∼50% higher than the previously accepted value of ∼10 MW m −2 , a consequence both of the choice of material and the finalized component design. Although the simulation database is currently restricted to the 2-D toroidally symmetric situation, considerable progress is now also being made using the EMC3-Eirene 3-D code suite for the assessment of power loading in the presence of magnetic perturbations for ELM control. Some new results for low input power corresponding to the early H-mode operation phases are reported, showing that even if realistic plasma screening is taken into account, significant asymmetric divertor heat fluxes may arise far from the unperturbed strike point. The issue of tolerable limits for transient heat pulses is an open and key question. A new scaling for ELM power deposition has shown that whilst there may be more latitude for operation at higher current without ELM control, the ultimate limit is likely to be set more by material fatigue under large numbers of sub-threshold melting events.

A deep learning architecture for temporal sleep stage classification\n using multivariate and multimodal time series
Stanislas Chambon, Mathieu Galtier, Pierrick J. Arnal, Gilles Wainrib +1 more
2017· arXiv (Cornell University)615doi:10.48550/arxiv.1707.03321

Sleep stage classification constitutes an important preliminary exam in the\ndiagnosis of sleep disorders. It is traditionally performed by a sleep expert\nwho assigns to each 30s of signal a sleep stage, based on the visual inspection\nof signals such as electroencephalograms (EEG), electrooculograms (EOG),\nelectrocardiograms (ECG) and electromyograms (EMG). We introduce here the first\ndeep learning approach for sleep stage classification that learns end-to-end\nwithout computing spectrograms or extracting hand-crafted features, that\nexploits all multivariate and multimodal Polysomnography (PSG) signals (EEG,\nEMG and EOG), and that can exploit the temporal context of each 30s window of\ndata. For each modality the first layer learns linear spatial filters that\nexploit the array of sensors to increase the signal-to-noise ratio, and the\nlast layer feeds the learnt representation to a softmax classifier. Our model\nis compared to alternative automatic approaches based on convolutional networks\nor decisions trees. Results obtained on 61 publicly available PSG records with\nup to 20 EEG channels demonstrate that our network architecture yields\nstate-of-the-art performance. Our study reveals a number of insights on the\nspatio-temporal distribution of the signal of interest: a good trade-off for\noptimal classification performance measured with balanced accuracy is to use 6\nEEG with 2 EOG (left and right) and 3 EMG chin channels. Also exploiting one\nminute of data before and after each data segment offers the strongest\nimprovement when a limited number of channels is available. As sleep experts,\nour system exploits the multivariate and multimodal nature of PSG signals in\norder to deliver state-of-the-art classification performance with a small\ncomputational cost.\n

Legumes Symbioses: Absence of Nod Genes in Photosynthetic Bradyrhizobia
Éric Giraud, Lionel Moulin, David Vallenet, Valérie Barbe +4 more
2007· Science608doi:10.1126/science.1139548

Leguminous plants (such as peas and soybeans) and rhizobial soil bacteria are symbiotic partners that communicate through molecular signaling pathways, resulting in the formation of nodules on legume roots and occasionally stems that house nitrogen-fixing bacteria. Nodule formation has been assumed to be exclusively initiated by the binding of bacterial, host-specific lipochito-oligosaccharidic Nod factors, encoded by the nodABC genes, to kinase-like receptors of the plant. Here we show by complete genome sequencing of two symbiotic, photosynthetic, Bradyrhizobium strains, BTAi1 and ORS278, that canonical nodABC genes and typical lipochito-oligosaccharidic Nod factors are not required for symbiosis in some legumes. Mutational analyses indicated that these unique rhizobia use an alternative pathway to initiate symbioses, where a purine derivative may play a key role in triggering nodule formation.

Active Control of Type-I Edge-Localized Modes with n = 1 Perturbation Fields in the JET Tokamak
Y. Liang, Hans Rudolf Koslowski, Paul Thomas, Eric Nardon +4 more
2007· Physical Review Letters600doi:10.1103/physrevlett.98.265004

Type-I edge-localized modes (ELMs) have been mitigated at the JET tokamak using a static external n=1 perturbation field generated by four error field correction coils located far from the plasma. During the application of the n=1 field the ELM frequency increased by a factor of 4 and the amplitude of the D(alpha) signal decreased. The energy loss per ELM normalized to the total stored energy, DeltaW/W, dropped to values below 2%. Transport analyses shows no or only a moderate (up to 20%) degradation of energy confinement time during the ELM mitigation phase.

Resistances along the CO2 diffusion pathway inside leaves
John R. Evans, Ralf Kaldenhoff, Bernard Genty, Ichiro Terashima
2009· Journal of Experimental Botany594doi:10.1093/jxb/erp117

CO(2) faces a series of resistances while diffusing between the substomatal cavities and the sites of carboxylation within chloroplasts. The absence of techniques to measure the resistance of individual steps makes it difficult to define their relative importance. Resistance to diffusion through intercellular airspace differs between leaves, but is usually of minor importance. Leaves with high photosynthetic capacity per unit leaf area reduce mesophyll resistance by increasing the surface area of chloroplasts exposed to intercellular airspace per unit leaf area, S(c). Cell walls impose a significant resistance. Assuming an effective porosity of the cell wall of 0.1 or 0.05, then cell walls could account for 25% or 50% of the total mesophyll resistance, respectively. Since the fraction of apoplastic water that is unbound and available for unhindered CO(2) diffusion is unknown, it is possible that the effective porosity is <0.05. Effective porosity could also vary in response to changes in pH or cation concentration. Consequently, cell walls could account for >50% of the total resistance and a variable proportion. Most of the remaining resistance is imposed by one or more of the three membranes as mesophyll resistance can be altered by varying the expression of cooporins. The CO(2) permeability of vesicles prepared from chloroplast envelopes has been reduced by RNA interference (RNAi) expression of NtAQP1, but not those prepared from the plasma membrane. Carbonic anhydrase activity also influences mesophyll resistance. Mesophyll resistance is relatively insensitive to the manipulation of any step in the pathway because it represents only part of the total and may also be countered by pleiotropic compensatory changes. The parameters in greatest need of additional measurements are S(c), mesophyll cell wall thickness, and the permeabilities of the plasma membrane and chloroplast envelope.

Chikungunya disease in nonhuman primates involves long-term viral persistence in macrophages
Karine Labadie, Thibaut Larcher, Christophe Joubert, Abdelkrim Mannioui +4 more
2010· Journal of Clinical Investigation590doi:10.1172/jci40104

Chikungunya virus (CHIKV) is a mosquito-borne alphavirus that induces in humans a disease characterized by fever, rash, and pain in muscles and joints. The recent emergence or reemergence of CHIKV in the Indian Ocean Islands and India has stressed the need to better understand the pathogenesis of this disease. Previous CHIKV disease models have used young or immunodeficient mice, but these do not recapitulate human disease patterns and are unsuitable for testing immune-based therapies. Herein, we describe what we believe to be a new model for CHIKV infection in adult, immunocompetent cynomolgus macaques. CHIKV infection in these animals recapitulated the viral, clinical, and pathological features observed in human disease. In the macaques, long-term CHIKV infection was observed in joints, muscles, lymphoid organs, and liver, which could explain the long-lasting CHIKV disease symptoms observed in humans. In addition, the study identified macrophages as the main cellular reservoirs during the late stages of CHIKV infection in vivo. This model of CHIKV physiopathology should allow the development of new therapeutic and/or prophylactic strategies.

Carotenoid oxidation products as stress signals in plants
Michel Havaux
2013· The Plant Journal573doi:10.1111/tpj.12386

Carotenoids are known to play important roles in plants as antioxidants, accessory light-harvesting pigments, and attractants for pollinators and seed dispersers. A new function for carotenoids has recently emerged, which relates to the response of plants to environmental stresses. Reactive oxygen species, especially singlet oxygen, produced in the chloroplasts under stress conditions, can oxidize carotenoids leading to a variety of oxidized products, including aldehydes, ketones, endoperoxides and lactones. Some of those carotenoid derivatives, such as volatile β-cyclocitral, derived from the oxidation of β-carotene, are reactive electrophile species that are bioactive and can induce changes in gene expression leading to acclimation to stress conditions. This review summarizes the current knowledge on the non-enzymatic oxidation of carotenoids, the bioactivity of the resulting cleavage compounds and their functions as stress signals in plants.