Adaptation à la sécheresse et création variétale : le cas de l'arachide en zone sahélienne, 1ère partie revue bibliographique

Drought is a multiform constraint expressing at different plant organisation levels. It is recognised as the first factor limiting the agriculture production in the world. The Sahel subtropical regions were the most exposed to the devasting effects of the recent climate change. A state of knowledge referring to the plant responses to drought is a fundamental initial step to any program of selection. This review concerns more particularly groundnut (Arachis hypogaea L.), which is a very common legume in the Sahel areas. Critical evaluations of traits as relevant selection criteria for a breeding program aiming at improving yield and yield stability under drought constraint were made. The genetic specificities of the species are exposed in the first part. Then a detailed description of the grain-legume traits related to drought adaptation is presented. The review was widened to other plants for the molecular responses to water deficit, supposed to be more general. Finally, the last part supplied an updated synthesis of the recent advances in biotechnology on groundnut with special focus on drought tolerance. (Résumé d'auteur

Dual requirement of cytokine and activation receptor triggering for cytotoxic control of murine cytomegalovirus by NK cells

Natural killer (NK) cells play a critical role in controlling murine cytomegalovirus (MCMV) and can mediate both cytokine production and direct cytotoxicity. The NK cell activation receptor, Ly49H, is responsible for genetic resistance to MCMV in C57BL/6 mice. Recognition of the viral m157 protein by Ly49H is sufficient for effective control of MCMV infection. Additionally, during the host response to infection, distinct immune and non-immune cells elaborate a variety of pleiotropic cytokines which have the potential to impact viral pathogenesis, NK cells, and other immune functions, both directly and indirectly. While the effects of various immune deficiencies have been examined for general antiviral phenotypes, their direct effects on Ly49H-dependent MCMV control are poorly understood. To specifically interrogate Ly49H-dependent functions, herein we employed an in vivo viral competition approach to show Ly49H-dependent MCMV control is specifically mediated through cytotoxicity but not IFNγ production. Whereas m157 induced Ly49H-dependent degranulation, efficient cytotoxicity also required either IL-12 or type I interferon (IFN-I) which acted directly on NK cells to produce granzyme B. These studies demonstrate that both of these distinct NK cell-intrinsic mechanisms are integrated for optimal viral control by NK cells

Positive regulation of plasmacytoid dendritic cell function via Ly49Q recognition of class I MHC

Plasmacytoid dendritic cells (pDCs) are an important source of type I interferon (IFN) during initial immune responses to viral infections. In mice, pDCs are uniquely characterized by high-level expression of Ly49Q, a C-type lectin-like receptor specific for class I major histocompatibility complex (MHC) molecules. Despite having a cytoplasmic immunoreceptor tyrosine-based inhibitory motif, Ly49Q was found to enhance pDC function in vitro, as pDC cytokine production in response to the Toll-like receptor (TLR) 9 agonist CpG-oligonucleotide (ODN) could be blocked using soluble monoclonal antibody (mAb) to Ly49Q or H-2Kb. Conversely, CpG-ODN–dependent IFN-α production by pDCs was greatly augmented upon receptor cross-linking using immobilized anti-Ly49Q mAb or recombinant H-2Kb ligand. Accordingly, Ly49Q-deficient pDCs displayed a severely reduced capacity to produce cytokines in response to TLR7 and TLR9 stimulation both in vitro and in vivo. Finally, TLR9-dependent antiviral responses were compromised in Ly49Q-null mice infected with mouse cytomegalovirus. Thus, class I MHC recognition by Ly49Q on pDCs is necessary for optimal activation of innate immune responses in vivo

Application of Ultrasonic Coda Wave Interferometry for Micro-cracks Monitoring in Woven Fabric Composites

The consequences of a four-point bending test, up to 12 mm, are examined by emitting 1 MHz ultrasonic guided waves in woven carbon fiber reinforced polymer specimens, using coda wave interferometry (CWI), revealing a potential use for nondestructive evaluation. It is known that CWI is more sensitive to realistic damage than the conventional method based on the first arriving time of flight in geophysical, or in civil engineering applications such as concrete structures. However, in composite materials CWI is not well established because of the involved structural complexity. In this paper, CWI is investigated for monitoring the occurrence of realistic defects such as micro-cracks in a woven carbon fiber composite plate. The micro-cracks are generated by a four-point bending test. The damage state is stepwise enhanced by gradually increasing the load level, until failure initiation. The damage is monitored, after each loading, using ultrasound. It is demonstrated that CWI is a powerful tool to detect damage, even low levels, in the sample. Two damage indicators based on CWI, i.e. signals correlation coefficient and relative velocity change, are investigated and appear to be complimentary. Under significant loading levels, the normalized cross-correlation coefficient between the waveforms recorded in the damaged and in the healthy sample (reference at 0 mm), decreases sharply; this first indicator is therefore useful for severe damage detection. It is also demonstrated, by means of a second indicator, that the relative velocity change between a baseline signal taken at zero loading, and the signals taken at various loadings, is linear as a function of the loading, until a critical level is reached; therefore this second indicator, is useful for low damage level detection. The obtained evolution of the relative velocity measurement is supported by relative comparison to the evolution of the bending modulus in function of displacement. The relative velocity change exhibits the same evolution as the bending modulus with loading. It could be used to indicate when the material stiffness has decreased significantly. The research is done in the framework of composite manufacturing quality control and appears to be a promising inspection technique.This work is supported by the Région Grand Est

Metallogenic implications of a new geodynamic model for the Eglab, Algeria

The Reguibat Shield is the northern part of the Archean-Proterozoic West African Craton. The Algerian portion of the Reguibat Shield is an extensive (~125,000 km2), long-lived Paleoproterozoic volcanic-plutonic tract. Previous workers (e.g., Lasserre et al., 1970; Sabate, 1973) have subdivided this basement into the Yetti domain to the west and the Eglab domain to the east, separated by a postulated terrane boundary called the “Yetti-Eglab shear zone.” Our Algerian Geological Survey Agency (ASGA) – U.S. Geological Survey (USGS) study area includes these domains and is known as the Eglab region. Magmatism in the Eglab region spanned more than 150 million years of Paleoproterozoic time during the Birimian (or Eburnian; ca. 2250-1900 Ma; Peucat et al., 2005) orogeny. Latest Birimian to possibly Mesoproterozoic dikes were the last major event in the region until onset of the Neoproterozoic Pan-African orogeny, which resulted in deformation in the Eglab region in the form of faulting and folding but little magmatism and no metamorphism. The youngest widespread magmatic event recorded in the Eglab region was the emplacement of Central Atlantic Magmatic Province (CAMP) mafic dikes and sills at ca. 200 Ma. Within the study area, the Tindouf (Cambrian or Ordovician to Devonian), Reggane (probably late Mesoproterozoic to Devonian), and Taoudeni (Mesoproterozoic to Cambrian or Ordovician) basins form the margins of the Eglab region on the north, east, and south flanks, respectively. The most widely accepted tectonic model for the Eglab region (Peucat et al., 2005) proposes that a 2.73 Ga relict of oceanic crust formed a cratonal core against which an eastward-dipping subduction zone developed, producing arc magmatism in the Eglab domain from 2.21-2.18 Ga. Closure of an intervening ocean and collision of the Yetti and Eglab domains at 2.09 Ga produced a second active margin magmatic event and deformation along the supposed Yetti-Eglab terrane boundary. Both domains were then intruded by large volumes of high-K, post-orogenic magmas triggered by slab roll-back and asthenospheric upwelling. Our work defines magmatic episodes at about 2210, 2150, 2090, and 2075 Ma. From ca. 2240 to 2100 Ma, magmatism was the product of east-dipping subduction, with the axis of magmatism migrating from east to west. The composite Paleoproterozoic arcs collided with the Archean craton in Mauritania at ca. 2090 Ma. The Paleoproterozoic Yetti, Akilet Deilel, and Oued Souss basins are intra-arc basins comprising continentally derived sedimentary rocks and dacite-rhyolite volcanic rocks. Oceanic sedimentary and basaltic volcanic rocks are rare to absent. Similarity of detrital zircon age populations and composition suggests absence of a major terrane boundary along the postulated Yetti-Eglab shear zone. Late collisional slab break-off resulted in a voluminous post-collisional igneous flareup and emplacement of early high-K calc-alkaline and later alkaline magmas throughout the Reguibat Shield at 2080-2060 Ma. Our preferred model for the geodynamic evolution of the Eglab region is shown in Figure 1. Our field observations, as well as igneous and detrital zircon geochronologic studies, do not support the presence of an Archean continental nucleus in the Eglab region. The absence of a significant Archean remnant in the Eglab region is also shown by neodymium model ages (TDM, “mantle separation ages”, 2.5 to 2.2 Ga; Peucat et al., 2005) that decrease from east to west, consistent with our igneous zircon data. All igneous rocks are overwhelmingly calc-alkaline, suggesting formation in an arc-subduction zone environment—probably as a series of continental margin arcs. The majority of the intrusive rocks are mixtures of metaluminous to peraluminous (I- and S-type) granites with a minor component of alkaline rocks; few igneous rocks exhibit A-type or peralkaline compositions, i.e., they are post-collision granites, not within-plate granites. Geophysical data do not show the presence of a major terrane boundary along the postulated Yetti-Eglab shear zone. The observed magnetic low over the Yetti granitic rocks is likely due to lower magnetite content in rocks with a higher component of metasedimentary protolith. This is supported by the slightly more peraluminous character of the Yetti basement compared to the Eglab basement. Based on our tectonic and metallogenic interpretations of the new data, a wide variety of mineral deposit types are permissible to occur in the Eglab. The most likely deposits include Mo-Cu porphyry deposits in arc magmatic rocks, epithermal base and precious metal vein deposits related to porphyry intrusions, and orogenic Au and Cu-Mo vein deposits in the Birimian volcano-sedimentary sequences. Also likely are U-Th-Nb-Ta-REE and possibly Au deposits related to alkaline/peralkaline granites, granite-hosted (shear) and calcrete-hosted (Hamada-type) uranium deposits, and Phanerozoic oolitic ironstones. Deposit types that are permissive, but less likely to occur, include PGE-Cr in layered gabbroic intrusions (sulfide-poor reef-type), Cu-Ni-PGE in unlayered mafic-ultramafic dikes/sills (sulfide-rich conduit-type), and iron/magnetite skarn and sedimentary rock-hosted U and Cu deposits in the marginal basins flanking the Eglab. The absence of a thick cratonic core in the Eglab region has important implications for diamond exploration. Previous studies have suggested that the Eglab may be a source region for headless diamond placers in Reggane, and several studies have noted the presence of a few harzburgitic “G9” and eclogitic garnets (Zerrouki, 2000; Kahoui et al., 2008). During the ASGA-USGS project, 74 regolith samples were collected and processed for kimberlite indicator minerals. Electron microprobe data for ~800 garnets were evaluated using the classification scheme of Schulze (2003). Our samples contained no peridotitic garnets; however, 74 eclogitic and 3 Cr-poor megacrystic garnets were detected. The majority of the eclogitic garnets are “group B”-type; of the remainder, a few are “group-C”-type and grospydite garnets. While eclogitic garnets are not as prospective for diamond potential as the presence of peridotitic garnets, the Eglab region remains permissive for primary diamonds in “off-craton” kimberlit

Effect of precipitated extracellular marennine on angiogenesis and tumour cell proliferation

Angiogenesis is a fundamental biological process involved in the formation of new blood vessels from the pre-existing vascular network. In addition to physiological processes, angiogenesis is also implicated in pathological conditions such as tumour growth and metastatic progression. Research on marennine, a water-soluble blue-green pigment produced by the marine diatom Haslea ostrearia, has highlighted various promising biological activities. In vivo studies have suggested the potential of marennine in cancer treatment. However, these studies were conducted with crude extracts, the exact composition of which remained poorly defined. In this context, our study aimed to explore the effects of marennine on angiogenesis and tumour proliferation by using a Precipitated Extracellular Marennine (PEMn) extract. Our results confirmed the antiproliferative properties of PEMn on several cancer cell lines associated with angiogenic tumours. We then analysed its impact on the key steps of the angiogenic process, including Endothelial Colony-Forming Cells (ECFCs) proliferation, migration, and tubulogenesis. In parallel, we investigated the underlying mechanisms of its action, notably by assessing its effects on cell cycle regulation, senescence, and apoptosis. PEMn significantly inhibited tumour cell proliferation, induced ECFC senescence and apoptosis, impaired migration and tubulogenesis, and downregulated VEGFR-1 expression, highlighting its potential as a novel marine-derived antiangiogenic compound. These findings provide deeper insights into the mechanisms of action of marennine, identifying this bioactive natural compound as a novel bioactive compound in cancer treatment

In Vivo Expression Pattern of MICA and MICB and Its Relevance to Auto-Immunity and Cancer

Non-conventional MHC class I MIC molecules interact not with the TCR, but with NKG2D, a C-type lectin activatory receptor present on most NK, γδ and CD8+ αβ T cells. While this interaction is critical in triggering/calibrating the cytotoxic activity of these cells, the actual extent of its in vivo involvement, in man, in infection, cancer or autoimmunity, needs further assessment. The latter has gained momentum along with the reported expansion of peripheral CD4+CD28−NKG2D+ T cells in rheumatoid arthritis (RA). We first initiated to extend this report to a larger cohort of not only RA patients, but also those affected by systemic lupus erythematosus (SLE) and Sjögren's syndrome (SS). In RA and SS, this initial observation was further tested in target tissues: the joint and the salivary glands, respectively. In conclusion and despite occasional and indiscriminate expansion of the previously incriminated T cell subpopulation, no correlation could be observed between the CD4+CD28−NKG2D+ and auto-immunity. Moreover, in situ, the presence of NKG2D matched that of CD8+, but not that of CD4+ T cells. In parallel, a total body tissue scan of both MICA and MICB transcription clearly shows that despite original presumptions, and with the exception of the central nervous system, both genes are widely transcribed and therefore possibly translated and membrane-bound. Extending this analysis to a number of human tumors did not reveal a coherent pattern of expression vs. normal tissues. Collectively these data question previous assumptions, correlating a tissue-specific expression/induction of MIC in relevance to auto-immune or tumor processes

Year in review in Intensive Care Medicine 2011: III. ARDS and ECMO, weaning, mechanical ventilation, noninvasive ventilation, pediatrics and miscellanea

SCOPUS: re.jinfo:eu-repo/semantics/publishe