310 research outputs found
Excrétion de carbone organique par le phytoplancton lémanique
L'excrétion du carbone organique dissous par le phytoplancton du lac Léman a été évaluée par la méthode du 14C entre mars et novembre 1984. Elle varie entre 0,01 et 0,5 mgC.m-3.h-1 et dépend en premier lieu de la vitesse d'assimilation photosynthétique. L'excrétion carbonée oscille généralement entre 2 et 5% de l'assimilation carbonée et n'excÚde qu'exceptionnellement 6%. Les valeurs sont sous-estimées par la réassimilation hétérotrophe. L'excrétion nocturne représente moins de 10% des pertes liées à la respiration. L'activité hétérotrophe évaluée par assimilation de glucose 14C présente des variations saisonniÚres parallÚlles à celles de l'excrétion phytoplanctonique. Elle ne suffit pas à réassimiler les produits d'excrétion du phytoplancton dans la couche trophogÚne (0-7,5 m). (Résumé d'auteur
Greenhouse Gas Emissions Non-Cattle Confinement Buildings: Monitoring, Emission Factors and Mitigation
Regulation of plant development and defense response by fireman, a new small endogenous peptide
The primary cilium influences interleukin-1 beta-induced NF kappa B signalling by regulating IKK activity
AbstractThe primary cilium is an organelle acting as a master regulator of cellular signalling. We have previously shown that disruption of primary cilia assembly, through targeting intraflagellar transport, is associated with muted nitric oxide and prostaglandin responses to the inflammatory cytokine interleukin-1ÎČ (IL-1ÎČ). Here, we show that loss of the primary cilium disrupts specific molecular signalling events in cytosolic NFÎșB signalling. The induction of cyclooxygenase 2 (COX2) and inducible nitrous oxide synthase (iNOS) protein is abolished. Cells unable to assemble cilia exhibit unaffected activation of IÎșB kinase (IKK), but delayed and reduced degradation of IÎșB, due to diminished phosphorylation of inhibitor of kappa B (IÎșB) by IKK. This results in both delayed and reduced NFÎșB p65 nuclear translocation and nuclear transcript binding. We also demonstrate that heat shock protein 27 (hsp27), an established regulator of IKK, is localized to the ciliary axoneme and cellular levels are dramatically disrupted with loss of the primary cilium. These results suggest that the primary cilia compartment exerts influence over NFÎșB signalling. We propose that the cilium is a locality for regulation of the molecular events defining NFÎșB signalling events, tuning signalling as appropriate
The ROAD MOVIE project - Resistance Of Apple against Diseases : Mechanisms Of Virulence and Identification of Effectors
Inducible NAD overproduction in Arabidopsis alters metabolic pools and gene expression correlated with increased salicylate content and resistance to Pst-AvrRpm1
Plant development and function are underpinned by redox reactions that depend on co-factors such as nicotinamide adenine dinucleotide (NAD). NAD has recently been shown to be involved in several signalling pathways that are associated with stress tolerance or defence responses. However, the mechanisms by which NAD influences plant gene regulation, metabolism and physiology still remain unclear. Here, we took advantage of Arabidopsis thaliana lines that overexpressed the nadC gene from E. coli, which encodes the NAD biosynthesis enzyme quinolinate phosphoribosyltransferase (QPT). Upon incubation with quinolinate, these lines accumulated NAD and were thus used as inducible systems to determine the consequences of an increased NAD content in leaves. Metabolic profiling showed clear changes in several metabolites such as aspartate-derived amino acids and NAD-derived nicotinic acid. Large-scale transcriptomic analyses indicated that NAD promoted the induction of various pathogen-related genes such as the salicylic acid (SA)-responsive defence marker PR1. Extensive comparison with transcriptomic databases further showed that gene expression under high NAD content was similar to that obtained under biotic stress, eliciting conditions or SA treatment. Upon inoculation with the avirulent strain of Pseudomonas syringae pv. tomato Pst-AvrRpm1, the nadC lines showed enhanced resistance to bacteria infection and exhibited an ICS1-dependent build-up of both conjugated and free SA pools. We therefore concluded that higher NAD contents are beneficial for plant immunity by stimulating SA-dependent signalling and pathogen resistance
Optical properties of MgH2 measured in situ in a novel gas cell for ellipsometry/spectrophotometry
The dielectric properties of alpha-MgH2 are investigated in the photon energy
range between 1 and 6.5 eV. For this purpose, a novel sample configuration and
experimental setup are developed that allow both optical transmission and
ellipsometric measurements of a transparent thin film in equilibrium with
hydrogen. We show that alpha-MgH2 is a transparent, colour neutral insulator
with a band gap of 5.6 +/- 0.1 eV. It has an intrinsic transparency of about
80% over the whole visible spectrum. The dielectric function found in this work
confirms very recent band structure calculations using the GW approximation by
Alford and Chou [J.A. Alford and M.Y. Chou (unpublished)]. As Pd is used as a
cap layer we report also the optical properties of PdHx thin films.Comment: REVTeX4, 15 pages, 12 figures, 5 table
The SCOOP 12 peptide regulates defense response and root development in Arabidopsis thaliana
Small secreted peptides are important players in plant development and stress response. Using a targeted in silico approach, we identified a family of 14 Arabidopsis genes encoding precursors of serine-rich endogenous peptides (PROSCOOP). Transcriptomic analyses revealed that one member of this family, PROSCOOP12, is involved in processes linked to biotic and oxidative stress as well as root growth. Plants defective in this gene were less susceptible to Erwinia amylovora infection and showed an enhanced root growth phenotype. In PROSCOOP12 we identified a conserved motif potentially coding for a small secreted peptide. Exogenous application of synthetic SCOOP12 peptide induces various defense responses in Arabidopsis. Our findings show that SCOOP12 has numerous properties of phytocytokines, activates the phospholipid signaling pathway, regulates reactive oxygen species response, and is perceived in a BAK1 co-receptor-dependent manner
Responses to the brassicaceous indolic phytoalexin brassinin in the phytopathogenic fungus Alternaria brassicicola
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