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991.
Jean-Michel Harmand Hector Ávila Etienne Dambrine Ute Skiba Sergio de Miguel Reina Vanessa Renderos Robert Oliver Francisco Jiménez John Beer 《Biogeochemistry》2007,85(2):125-139
Nitrogen fertilization is a key factor for coffee production but creates a risk of water contamination through nitrate (NO3−) leaching in heavily fertilized plantations under high rainfall. The inclusion of fast growing timber trees in these coffee
plantations may increase total biomass and reduce nutrient leaching. Potential controls of N loss were measured in an unshaded
coffee (Coffea arabica L.) plot and in an adjacent coffee plot shaded with the timber species Eucalyptus deglupta Blume (110 trees ha−1), established on an Acrisol that received 180 kg N ha−1 as ammonium-nitrate and 2,700 mm yr−1 rainfall. Results of the one year study showed that these trees had little effect on the N budget although some N fluxes
were modified. Soil N mineralization and nitrification rates in the 0–20 cm soil layer were similar in both systems (≈280 kg N ha−1 yr−1). N export in coffee harvest (2002) was 34 and 25 kg N ha−1 yr−1 in unshaded and shaded coffee, and N accumulation in permanent biomass and litter was 25 and 45 kg N ha−1 yr−1, respectively. The losses in surface runoff (≈0.8 kg mineral N ha−1 yr−1) and N2O emissions (1.9 kg N ha−1 yr−1) were low in both cases. Lysimeters located at 60, 120, and 200 cm depths in shaded coffee, detected average concentrations
of 12.9, 6.1 and 1.2 mg NO3−-N l−1, respectively. Drainage was slightly reduced in the coffee-timber plantation. NO3− leaching at 200 cm depth was about 27 ± 10 and 16 ± 7 kg N ha−1 yr−1 in unshaded and shaded coffee, respectively. In both plots, very low NO3− concentrations in soil solution at 200 cm depth (and in groundwater) were apparently due to NO3− adsorption in the subsoil but the duration of this process is not presently known. In these conventional coffee plantations,
fertilization and agroforestry practices must be refined to match plant needs and limit potential NO3− contamination of subsoil and shallow soil water. 相似文献
992.
993.
Philippe Castagnone‐Sereno Karine Mulet Etienne G. J. Danchin Georgios D. Koutsovoulos Mgane Karaulic Martine Da Rocha Marc Bailly‐Bechet Loris Pratx Laetitia Perfus‐Barbeoch Pierre Abad 《Molecular ecology》2019,28(10):2559-2572
Adaptation to changing environmental conditions represents a challenge to parthenogenetic organisms, and until now, how phenotypic variants are generated in clones in response to the selection pressure of their environment remains poorly known. The obligatory parthenogenetic root‐knot nematode species Meloidogyne incognita has a worldwide distribution and is the most devastating plant‐parasitic nematode. Despite its asexual reproduction, this species exhibits an unexpected capacity of adaptation to environmental constraints, for example, resistant hosts. Here, we used a genomewide comparative hybridization strategy to evaluate variations in gene copy numbers between genotypes of M. incognita resulting from two parallel experimental evolution assays on a susceptible vs. resistant host plant. We detected gene copy number variations (CNVs) associated with the ability of the nematodes to overcome resistance of the host plant, and this genetic variation may reflect an adaptive response to host resistance in this parthenogenetic species. The CNV distribution throughout the nematode genome is not random and suggests the occurrence of genomic regions more prone to undergo duplications and losses in response to the selection pressure of the host resistance. Furthermore, our analysis revealed an outstanding level of gene loss events in nematode genotypes that have overcome the resistance. Overall, our results support the view that gene loss could be a common class of adaptive genetic mechanism in response to a challenging new biotic environment in clonal animals. 相似文献
994.
Fabien Pifferi Olène Dorieux Christian-Alexandre Castellano Etienne Croteau Marie Masson Martine Guillermier Nadja Van Camp Philippe Guesnet Jean-Marc Alessandri Stephen Cunnane Marc Dhenain Fabienne Aujard 《Journal of lipid research》2015,56(8):1511-1518
Decreased brain content of DHA, the most abundant long-chain n-3 polyunsaturated fatty acid (n-3 LCPUFA) in the brain, is accompanied by severe neurosensorial impairments linked to impaired neurotransmission and impaired brain glucose utilization. In the present study, we hypothesized that increasing n-3 LCPUFA intake at an early age may help to prevent or correct the glucose hypometabolism observed during aging and age-related cognitive decline. The effects of 12 months’ supplementation with n-3 LCPUFA on brain glucose utilization assessed by positron emission tomography was tested in young adult mouse lemurs (Microcebus murinus). Cognitive function was tested in parallel in the same animals. Lemurs supplemented with n-3 LCPUFA had higher brain glucose uptake and cerebral metabolic rate of glucose compared with controls in all brain regions. The n-3 LCPUFA-supplemented animals also had higher exploratory activity in an open-field task and lower evidence of anxiety in the Barnes maze.jlr Our results demonstrate for the first time in a nonhuman primate that n-3 LCPUFA supplementation increases brain glucose uptake and metabolism and concomitantly reduces anxiety. 相似文献
995.
996.
Thymus‐derived regulatory T cells restrain pro‐inflammatory Th1 responses by downregulating CD70 on dendritic cells 下载免费PDF全文
Sophie Uzureau Julie Denoeud Valérie Acolty Guillaume Oldenhove Adrien Galuppo Tim Sparwasser Kris Thielemans Etienne Pays Hideo Yagita Jannie Borst Muriel Moser 《The EMBO journal》2015,34(10):1336-1348
The severity and intensity of autoimmune disease in immune dysregulation, polyendocrinopathy, enteropathy, X‐linked (IPEX) patients and in scurfy mice emphasize the critical role played by thymus‐derived regulatory T cells (tTregs) in maintaining peripheral immune tolerance. However, although tTregs are critical to prevent lethal autoimmunity and excessive inflammatory responses, their suppressive mechanism remains elusive. Here, we demonstrate that tTregs selectively inhibit CD27/CD70‐dependent Th1 priming, while leaving the IL‐12‐dependent pathway unaffected. Immunized mice depleted of tTregs showed an increased response of IFN‐γ‐secreting CD4+ T cells that was strictly reliant on a functional CD27/CD70 pathway. In vitro studies revealed that tTregs downregulate CD70 from the plasma membrane of dendritic cells (DCs) in a CD27‐dependent manner. CD70 downregulation required contact between Tregs and DCs and resulted in endocytosis of CD27 and CD70 into the DC. These findings reveal a novel mechanism by which tTregs can maintain tolerance or prevent excessive, proinflammatory Th1 responses. 相似文献
997.
Etienne Loiseau Gladys Massiera Simon Mendez Patricia?Aguilar Martinez Manouk Abkarian 《Biophysical journal》2015,108(11):2623-2632
Sickle cell anemia is a blood disorder, known to affect the microcirculation and is characterized by painful vaso-occlusive crises in deep tissues. During the last three decades, many scenarios based on the enhanced adhesive properties of the membrane of sickle red blood cells have been proposed, all related to a final decrease in vessels lumen by cells accumulation on the vascular walls. Up to now, none of these scenarios considered the possible role played by the geometry of the flow on deposition. The question of the exact locations of occlusive events at the microcirculatory scale remains open. Here, using microfluidic devices where both geometry and oxygen levels can be controlled, we show that the flow of a suspension of sickle red blood cells around an acute corner of a triangular pillar or of a bifurcation, leads to the enhanced deposition and aggregation of cells. Thanks to our devices, we follow the growth of these aggregates in time and show that their length does not depend on oxygenation levels; instead, we find that their morphology changes dramatically to filamentous structures when using autologous plasma as a suspending fluid. We finally discuss the possible role played by such aggregates in vaso-occlusive events. 相似文献
998.
Bert Billen Marijke Brams Sarah Debaveye Alina Remeeva Yeranddy A. Alpizar Etienne Waelkens Mohamed Kreir Andrea Brüggemann Karel Talavera Bernd Nilius Thomas Voets Chris Ulens 《The Journal of biological chemistry》2015,290(20):12964-12974
TRPV3 is a thermosensitive ion channel primarily expressed in epithelial tissues of the skin, nose, and tongue. The channel has been implicated in environmental thermosensation, hyperalgesia in inflamed tissues, skin sensitization, and hair growth. Although transient receptor potential (TRP) channel research has vastly increased our understanding of the physiological mechanisms of nociception and thermosensation, the molecular mechanics of these ion channels are still largely elusive. In order to better comprehend the functional properties and the mechanism of action in TRP channels, high-resolution three-dimensional structures are indispensable, because they will yield the necessary insights into architectural intimacies at the atomic level. However, structural studies of membrane proteins are currently hampered by difficulties in protein purification and in establishing suitable crystallization conditions. In this report, we present a novel protocol for the purification of membrane proteins, which takes advantage of a C-terminal GFP fusion. Using this protocol, we purified human TRPV3. We show that the purified protein is a fully functional ion channel with properties akin to the native channel using planar patch clamp on reconstituted channels and intrinsic tryptophan fluorescence spectroscopy. Using intrinsic tryptophan fluorescence spectroscopy, we reveal clear distinctions in the molecular interaction of different ligands with the channel. Altogether, this study provides powerful tools to broaden our understanding of ligand interaction with TRPV channels, and the availability of purified human TRPV3 opens up perspectives for further structural and functional studies. 相似文献
999.
Jean-Fran?ois Gautier Rapha?l Porcher Charbel Abi Khalil Naima Bellili-Munoz Lila Sabrina Fetita Florence Travert Simeon-Pierre Choukem Jean-Pierre Riveline Samy Hadjadj Etienne Larger Philippe Boudou Bertrand Blondeau Ronan Roussel Pascal Ferré Eric Ravussin Fran?ois Rouzet Michel Marre 《PloS one》2015,10(8)
Background
Fetal exposure to hyperglycemia impacts negatively kidney development and function.Objective
Our objective was to determine whether fetal exposure to moderate hyperglycemia is associated with epigenetic alterations in DNA methylation in peripheral blood cells and whether those alterations are related to impaired kidney function in adult offspring.Design
Twenty nine adult, non-diabetic offspring of mothers with type 1 diabetes (T1D) (case group) were matched with 28 offspring of T1D fathers (control group) for the study of their leukocyte genome-wide DNA methylation profile (27,578 CpG sites, Human Methylation 27 BeadChip, Illumina Infinium). In a subset of 19 cases and 18 controls, we assessed renal vascular development by measuring Glomerular Filtration Rate (GFR) and Effective Renal Plasma Flow (ERPF) at baseline and during vasodilatation produced by amino acid infusion.Results
Globally, DNA was under-methylated in cases vs. controls. Among the 87 CpG sites differently methylated, 74 sites were less methylated and 13 sites more methylated in cases vs. controls. None of these CpG sites were located on a gene known to be directly involved in kidney development and/or function. However, the gene encoding DNA methyltransferase 1 (DNMT1)—a key enzyme involved in gene expression during early development–was under-methylated in cases. The average methylation of the 74 under-methylated sites differently correlated with GFR in cases and controls.Conclusion
Alterations in methylation profile imprinted by the hyperglycemic milieu of T1D mothers during fetal development may impact kidney function in adult offspring. The involved pathways seem to be a nonspecific imprinting process rather than specific to kidney development or function. 相似文献1000.
Marie-France Seronde Mélanie Vausort Etienne Gayat Emeline Goretti Leong L. Ng Iain B. Squire Nicolas Vodovar Malha Sadoune Jane-Lise Samuel Thomas Thum Alain Cohen Solal Said Laribi Patrick Plaisance Daniel R. Wagner Alexandre Mebazaa Yvan Devaux GREAT network 《PloS one》2015,10(11)