Activity of class III peroxydases in the defense of cotton to bacterial blight

International audience

A pro-diabetic diet triggers early functional and structural changes in the rat retina

International audience; Purpose : Diabetic retinopathy (DR) is the leading cause of blindness in industrial countries before the age of 50 years. The early consequences of diabetes on the retina are nevertheless poorly known. We therefore aimed at characterizing the early effects of a high fructose and high fat diet on the function and structure of the rat retina. Methods : Male Brown Norway rats (6 weeks of age) were fed for 8 days (n=16), 4 weeks (n=16) and 12 weeks (n=8) with 60% fructose+10% lipid rich diet (HFHF), or a standard chow (n=8). At each time point, intraperitoneal insulin tolerance test (ITT-0.5 U/ml) and intraperitoneal glucose tolerance test (GTT-2g/kg body weight) were ca…

Cryo-méthodes appliquées à l’étude des interactions entre plantes et Pseudomonas Fluorescents en relation avec le fer dans la rhizosphère

SPEBAPEAIPMBIOmE; Cryo-méthodes appliquées à l’étude des interactions entre plantes et [i]Pseudomonas Fluorescents[/i] en relation avec le fer dans la rhizosphère. 7. Journées Scientifiques et Techniques du Réseau des Microscopistes de l'INRA (RμI)

Protection of living yeast cells by micro-organized shells of natural polyelectrolytes

International audience; Saccharomyces cerevisiae, a eukaryotic model organism, plays a key role in the oxidative stability of fermented products. In order to protect cells against environmental stresses, we report a method of modifying the cell surface architecture while maintaining the internal working properties of the system. The objective was to encapsulate living yeast cells in micro-organized polyelectrolyte shells using layer-by-layer (LbL) assembly. For the first time, the natural polyelectrolytes, β-lactoglobulin and sodium alginate, were alternately deposited on the surface of S. cerevisiae. Transmission electron microscopy coupled with immune-cytochemistry and scanning electron m…

Ultrastructural changes in the outer retina and retinal pigment epithelium of the apob100,LDLR-/- mouse, a murine model of aging of the human retina

Ultrastructural changes in the outer retina and retinal pigment epithelium of the apob100,LDLR-/- mouse, a murine model of aging of the human retina. annual meeting of the association-for-research-in-vision-and-ophthalmology (ARVO)

Induction des mécanismes de défense des plantes : Les acquis du modèle tabac/cryptogéine

Cryptogein is a small protein secreted by the oomycete Phytophthora cryptogea, able to trigger on tobacco plants both the developmenl of an hypersensitive response and the induction of resistance against a wide range of pathogens. The deciphering of molecular events associated with this process, using tobacco as a model plant, gave significant informations about the set up of defense mechanisms. The role of plasma membrane dynamics in such a signal transduction has been evidenced. ln particular; the presence of plasma membrane microdomains concentrating signaling proteins, and the modification of the proteic content of these domains upon cryptogein treatment have been demonstrated. Moreover…

Rôle de la dynamique de la membrane plasmique dans la mise en place des réactions de défense chez le tabac

The binding of cryptogein, a plant defense elicitor secreted by an oomycete, to an unknown receptor triggers well-known biochemical events of early signal transduction at the plasma membrane of tobacco cells. One of these early events is the transient production of Reactive Oxygen Species (ROS) by an NADPH oxidase, NtrbohD. We were thus interested to analyze the dynamic of the plasma membrane during these early stages. We determined that internalization of the endocytotic marker FM4-64 is stimulated a few minutes after addition of cryptogein to tobacco BY-2 cells. This stimulation is specific to the signal transduction pathway elicited by cryptogein since a lipid transfer protein, which bin…

Metabolism of fatty acid in yeast: Characterisation of beta-oxidation and ultrastructural changes in the genus Sporidiobolus sp cultivated on ricinoleic acid methyl ester

International audience; Cell structure modifications and b-oxidation induction were monitored in two strains of Sporidiobolus, Sp. Ruinenii and Sp. pararoseus after cultivation on ricinoleic acid methyl ester. Ultrastructural observations of the yeast before and after cultivation on fatty acid esters did not reveal major modifications in Sp. ruinenii. Unexpectedly, in Sp. pararoseus a proliferation of the mitochondrion was observed. After induction, Sp. ruinenii principally exhibited an increase in the activities of acyl-CoA oxidase (ACO), hydroxyacyl- CoA deshydrogenase (HAD), thiolase and catalase. In contrast, Sp. pararoseus lacked ACO and catalase activities, but an increase in acyl-CoA…

La microscopie électronique à balayage au sein d’une Plate-Forme : applications «trans-règnes» en synergie avec d’autres techniques d’imagerie

5èmes Journées Scientifiques et Techniques du Réseau des Microscopistes INRA. « Imagerie cellulaire en science du vivant : Cryo-microscopies, Dynamiques in vivo et Interactions moléculaires »

National audience; L’imagerie cellulaire, dans le domaine des sciences du vivant, est essentielle à la compréhension des phénomènes cellulaires subcellulaires régulant le fonctionnement des cellules et tissus. En microscopie électronique, la mise en oeuvre de cryo-méthodes permet de préserver l’intégrité moléculaire et spatiale des protéines et lipides intracellulaires ou membranaires (de faible poids moléculaire, présentes en faible quantité ou très labiles) dont la localisation in situ est recherchée afin de caractériser leur organisation, participer à la détermination de leur fonction au sein de la cellule et d’analyser leur distribution. Ces techniques, en pleine évolution, seront abord…

Vector Transmission of a Plant-Pathogenic Bacterium in the Arsenophonus Clade Sharing Ecological Traits with Facultative Insect Endosymbionts

Bressan, A., Semetey, O., Arneodo, J., Lherminier, J., and BoudonPadieu, E. 2009. Vector transmission of a plant-pathogenic bacterium in the Arsenophonus clade sharing ecological traits with facultative insect endosymbionts. Phytopathology 99:1289-1296. The planthopper Pentastiridius leporinus (Hemiptera: Cixiidae) is the major vector of a nonculturable plant-pathogenic γ-3 proteobacterium associated with a disease of sugar beet called syndrome “basses richesses” (SBR). The bacterium, here called SBR bacterium, belongs to the Arsenophonous clade, which includes mostly insect-associated facultative symbionts. Assays using field-collected planthopper nymphs and adults were carried out to inve…

Plasma membrane sterol complexation, generated by filipin, triggers signaling responses in tobacco cells

International audience; The effects of changes in plasma membrane (PM) sterol lateral organization and availability on the control of signaling pathways have been reported in various animal systems, but rarely assessed in plant cells. In the present study, the pentaene macrolide antibiotic filipin III, commonly used in animal systems as a sterol sequestrating agent, was applied to tobacco cells. We show that filipin can be used at a non-lethal concentration that still allows an homogeneous labeling of the plasma membrane and the formation of filipin-sterol complexes at the ultrastructural level. This filipin concentration triggers a rapid and transient NADPH oxidase-dependent production of …

The membrane-associated MUC1 improves adhesion of salivary MUC5B on buccal cells. Application to development of an in vitro cellular model of oral epithelium

Objectives: The mucosal pellicle is a thin layer of salivary proteins, mostly MUC5B mucins, anchored to epithelial oral cells. This pellicle is involved in protection of oral mucosae against abrasion, pathogenic microorganisms or chemical xenobiotics. The present study aimed at studying the involvement of MUC1 in mucosal pellicle formation and more specifically in salivary MUC5B binding using a cell-based model of oral epithelium. DESIGN: MUC1 mRNAs were not detected in TR146 cells, and therefore a stable cell line named TR146/MUC1 expressing this protein was developed by transfection. TR146 and TR146/MUC1 were incubated with human saliva in order to evaluate retention of MUC5B by epithelia…

Mode of action of the herbicide siduron on wheat

International audience

Lateral reorganization of plasma membrane is involved in the yeast resistance to severe dehydration

International audience; In this study, we investigated the kinetic and the magnitude of dehydrations on yeast plasma membrane (PM) modifications because this parameter is crucial to cell survival. Functional (permeability) and structural (morphology, ultrastructure, and distribution of the protein Sur7-GFP contained in sterol-rich membrane microdomains) PM modifications were investigated by confocal and electron microscopy after progressive (non-lethal) and rapid (lethal) hyperosmotic perturbations. Rapid cell dehydration induced the formation of many PM invaginations followed by membrane internalization of low sterol content PM regions with time. Permeabilization of the plasma membrane occ…

Seed coat structure in Medicago truncatula : histological changes associated with seed development.

National audience

NADPH Oxidase-Mediated Reactive Oxygen Species Production: Subcellular Localization and Reassessment of Its Role in Plant Defense

International audience; Chemiluminescence detection of reactive oxygen species (ROS) triggered in tobacco BY-2 cells by the fungal elicitor cryptogein was previously demonstrated to be abolished in cells transformed with an antisense construct of the plasma membrane NADPH oxidase, NtrbohD. Here, using electron microscopy, it has been confirmed that the first hydrogen peroxide production occurring a few minutes after challenge of tobacco cells with cryptogein is plasma membrane located and NtrbohD mediated. Furthermore, the presence of NtrbohD in detergent-resistant membrane fractions could be associated with the presence of NtrbohD-mediated hydrogen peroxide patches along the plasma membran…

Internalisation de la cryptogéine dans des cellules de tabac Nicotiana tabacum, cv Bright Yellow 2 (BY-2)

SPEBAPIPMUBINRA; Internalisation de la cryptogéine dans des cellules de tabac [i]Nicotiana tabacum[/i], cv Bright Yellow 2 (BY-2). 7. Journées Scientifiques et Techniques du Réseau des Microscopistes de l'INRA (RμI)

Dynamic changes in the subcellular distribution of the tobacco ROS-producing enzyme RBOHD in response to the oomycete elicitor cryptogein.

Highlight text The oomycete elicitor cryptogein triggers the relocation of RBOHD from intracellular compartments to the plasma membrane in tobacco cells. This suggests that intracellular trafficking is a potential determinant of RBOHD activity.

Cytological characterization of elicitin-induced protection in tobacco plants infected by Phytophthora parasitica or phytoplasma

International audience

A small HSP, Lo18, interacts with the cell membrane and modulates lipid physical state under heat shock conditions in a lactic acid bacterium

International audience; The small heat shock proteins (sHSP) are characterized by a chaperone activity to prevent irreversible protein denaturation. This study deals with the sHSP Lo18 induced by multiple stresses in Oenococcus oeni, a lactic acid bacterium. Using in situ immunocytochemistry and cellular fractionation experiments, we demonstrated the association of Lo18 with the membrane in O. oeni cells submitted to heat shock. The same result was obtained after exposure of cells to ethanol or benzyl alcohol, agents known to have an influence on membranes. For the different stresses, the protein was located on the periphery of the cell at membrane level and was also found within the cytopl…

The Plant Defense Elicitor Cryptogein Stimulates Clathrin-Mediated Endocytosis Correlated with Reactive Oxygen Species Production in Bright Yellow-2 Tobacco Cells  

Abstract The plant defense elicitor cryptogein triggers well-known biochemical events of early signal transduction at the plasma membrane of tobacco (Nicotiana tabacum) cells, but microscopic observations of cell responses related to these early events were lacking. We determined that internalization of the lipophilic dye FM4-64, which is a marker of endocytosis, is stimulated a few minutes after addition of cryptogein to tobacco Bright Yellow-2 (BY-2) cells. This stimulation is specific to the signal transduction pathway elicited by cryptogein because a lipid transfer protein, which binds to the same receptor as cryptogein but without triggering signaling, does not increase endocytosis. To…

The fungal elicitor cryptogein induces cell wall modifications on tobacco cell suspension

Upon addition of the fungal elicitor cryptogein, suspension cells of tobacco (Nicotiana tabacum cv. Xanthi) aggregated in clusters. Cytochemical experiments indicated that elicited cells displayed fibrillar expansions of pectin along the primary cell wall. Immunocytochemical detection of pectin epitopes indicated that the fibrillar material surrounding the treated cells was mostly composed of low methylated galacturonan sequences, but the use of the cationic probe did not reveal the presence of negatively charged carboxyl groups: the presence of important amounts of calcium ions in these pectic fibrillar expansions accounts for these observations. These data indicate that tobacco cells trea…

Proteomic analysis of sub-retinal deposits in age-related macular degeneration

National audience

Effects of dietary oxysterols on coronary arteries in hyperlipidaemic hamster

International audience

Mechanisms of astringency: Structural alteration of the oral mucosal pellicle by dietary tannins and protective effect of bPRPs

International audience; The interaction of tannins with salivary proteins is involved in astringency. This paper focussed on saliva liningoral mucosae, the mucosal pellicle. Using a cell-based model, the impact of two dietary tannins (EgC and EgCG)on the mucosal pellicle structure and properties was investigated by microscopic techniques. The role of basicProline-Rich-Proteins (bPRPs) in protecting the mucosal pellicle was also evaluated.At low (0.05 mM) tannin concentration, below the sensory detection threshold, the distribution of salivarymucins MUC5B on cells remained unaffected. At 0.5 and 1 mM, MUC5B-tannin aggregates were observed andtheir size increased with tannin concentration and…

Association with the syndrome "basses richessses" of sugar beet of aphytoplasma and a bacterium-like organism transmitted by a pentastiridius sp.

International audience

Abstracts of papers presented at the 9th meeting of the international council for the study of viruses and virus diseases of the grapevine

Protein storage accumulation at mid-embryogenesis in Medicago truncatula and Pisum sativum

National audience

Effects of isoxaben on sensitive and tolerant plant cell cultures .II. Cellular alterations and inhibition of the synthesis of acid-insoluble cell wall material

International audience

Rôle de la dynamique de la membrane plasmique dans la mise en place des réactions de défense chez le tabac

National audience; Lors des interactions entre les plantes et les microorganismes, des molécules spécifiques élicitent les réponses de défense des cellules végétales. La cryptogéine, une élicitine produite par l’oomycète Phytophtora cryptogea, induit une réponse hypersensible (HR) et une résistance non systémique chez le tabac (1). Aussi bien sur plante entière que sur suspension cellulaire, la reconnaissance au niveau de la membrane plasmique et la fixation de cet éliciteur par un récepteur non identifié déclenche une cascade d’événements au niveau de la membrane plasmique comme un influx rapide de calcium, des efflux d’ions, une alcalinisation extracellulaire. De plus, une NADPH oxydase, …

Characterization of the mode of action of the experimental herbicide LS 82-556 [ (S)3-N-(methylbenzyl) carbamyl-5-propionyl-2,6 lutidine

34 ref.; International audience

Association with the Syndrome "Basses Richesses" of Sugar Beet of a Phytoplasma and a Bacterium-Like Organism Transmitted by a Pentastiridius sp.

The syndrome “basses richesses” of sugar beet (SBR) was first observed in 1991 in Burgundy, France. A cixiid planthopper, Pentastiridius beieri, has been proved to be involved in the transmission to sugar beet of a stolbur phytoplasma, which could be detected in some affected plants. In 2000, periwinkle and sugar beet exposed to field-collected cixiids developed symptoms similar to SBR on sugar beet. Use of 4′-6-diamidino-2-phenylindole (DAPI) staining and transmission electron microscopy confirmed the presence of phytoplasma in some of the plants, which were also positive for this pathogen in a polymerase chain reaction (PCR) analysis. A phloem-restricted gram-negative bacteria was seen i…

Preservation of viability and anti-Listeria activity of lactic acid bacteria, Lactococcus lactis and Lactobacillus paracasei, entrapped in gelling matrices of alginate or alginate/caseinate

In order to control undesirable microorganisms growth in foods, the performance of alginate and alginate-caseinate (an aqueous two-phase system) matrices entrapping lactic acid bacteria (LAB) (Lactobacillus paracasei LAB1 and Lactococcus lactis LAB3) was investigated. Polymeric matrices were initially loaded with Lcells at similar to 10(8-10) or similar to 10(4-6) CFU mL(-1), and were monitored, in liquid and gelled form (beads), for 12 days at 30 degrees C. In the liquid form, maximum cell density (similar to 10(9) CFU mL(-1)) was reached after 24 h whatever the matrix. Then, the Lpopulation decreased but remained higher in alginate-caseinate matrices: 10(7) and 10(6) CFU mL(-1) of LAB3 ce…

Revisiting Plant Plasma Membrane Lipids in Tobacco: A Focus on Sphingolipids

International audience; The lipid composition of plasma membrane (PM) and the corresponding detergent-insoluble membrane (DIM) fraction were analyzed with a specific focus on highly polar sphingolipids, so-called glycosyl inositol phosphorylceramides (GIPCs). Using tobacco (Nicotiana tabacum) 'Bright Yellow 2' cell suspension and leaves, evidence is provided that GIPCs represent up to 40 mol % of the PM lipids. Comparative analysis of DIMs with the PM showed an enrichment of 2-hydroxylated very-long-chain fatty acid-containing GIPCs and polyglycosylated GIPCs in the DIMs. Purified antibodies raised against these GIPCs were further used for immunogold-electron microscopy strategy, revealing …