Search results for " proteins"
showing 10 items of 9071 documents
The fungal elicitor cryptogein induces cell wall modifications on tobacco cell suspension
2000
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…
In vivoanalysis of the lumenal binding protein (BiP) reveals multiple functions of its ATPase domain
2007
International audience; The endoplasmic reticulum (ER) chaperone binding protein (BiP) binds exposed hydrophobic regions of misfolded proteins. Cycles of ATP hydrolysis and nucleotide exchange on the ATPase domain were shown to regulate the function of the ligand-binding domain in vitro. Here we show that ATPase mutants of BiP with defective ATP-hydrolysis (T46G) or ATP-binding (G235D) caused permanent association with a model ligand, but also interfered with the production of secretory, but not cytosolic, proteins in vivo. Furthermore, the negative effect of BiP(T46G) on secretory protein synthesis was rescued by increased levels of wild-type BiP, whereas the G235D mutation was dominant. U…
Sterol and ecdysteroids profiles of Serratula tinctoria (L.) : plant and cell cultures producing steroids
1993
Abstract Cell suspension cultures have been obtained from Serratula tinctoria, a plant producing ecdysteroids. Sterol profiles and ecdysteroid contents have been analysed and compared in plants and cell cultures. In particular, the composition of free and esterified sterols was investigated using appropriate analytical techniques. In plants, esterified sterols were more abundant (50–70% of the total sterol) than in cell cultures (13–36%). A selectivity for sterol esterification was noted: in plants, the triterpenes (as amyrins) were esterified, whereas it was the 4-desmethylsterols (sitosterol and cholesterol) in cell cultures. Ecdysteroids were present in higher quantities in plant (0.1–1.…
Nitric oxide and glutathione impact the expression of iron uptake- and iron transport-related genes as well as the content of metals in A. thaliana p…
2012
International audience; Mounting evidence indicate that nitric oxide (NO) acts as a signaling molecule mediating iron deficiency responses through the upregulation of the expression of iron uptake-related genes. Accordingly, NO donors such as nitrosoglutathione (GSNO) were reported to improve the fitness of plants grown under iron deficiency. Here, we showed that glutathione, a by-product of GSNO, triggered the upregulation of the expression of iron uptake- and transport-related gene and an increase of iron concentration in Arabidopsis thaliana seedlings facing iron deficiency. Furthermore, we provided evidence that under iron deficiency, NO released by GSNO did not improve the root iron co…
Plasma membrane protein trafficking in plant-microbe interactions: a plant cell point of view
2014
International audience; In order to ensure their physiological and cellular functions, plasma membrane (PM) proteins must be properly conveyed from their site of synthesis, i.e., the endoplasmic reticulum, to their final destination, the PM, through the secretory pathway. PM protein homeostasis also relies on recycling and/or degradation, two processes that are initiated by endocytosis. Vesicular membrane trafficking events to and from the PM have been shown to be altered when plant cells are exposed to mutualistic or pathogenic microbes. In this review, we will describe the fine-tune regulation of such alterations, and their consequence in PM protein activity. We will consider the formatio…
Early signaling events induced by elicitors of plant defenses
2006
International audience; Plant pathogen attacks are perceived through pathogenissued compounds or plant-derived molecules that elicit defense reactions. Despite the large variety of elicitors, general schemes for cellular elicitor signaling leading to plant resistance can be drawn. In this article, we review early signaling events that happen after elicitor perception, including reversible protein phosphorylations, changes in the activities of plasma membrane proteins, variations in free calcium concentrations in cytosol and nucleus, and production of nitric oxide and active oxygen species. These events occur within the first minutes to a few hours after elicitor perception. One specific eli…
Functionalized halloysite nanotubes: Efficient carrier systems for antifungine drugs
2018
Abstract Halloysite-cyclodextrin hybrid was employed as carrier for sustained release of clotrimazole for vaginal or buccal treatment of Candidiasis. The nanocarrier was obtained by functionalization of halloysite surface with cyclodextrin moieties by means of microwave irradiation, with the final goal to obtain a scaffold for the covalent linkage of cysteamine hydrochloride. The interaction between clotrimazole and the pristine components, namely cyclodextrin and halloysite, was thoroughly investigated by several techniques such as DSC, TGA, UV–vis spectroscopy and some adsorption studies were, also, carried out. The release of the antifungine molecule was finally investigated in a medium …
Physiopathologie de la dyslipidémie du diabète de type 2 : nouvelles perspectives
2019
Resume La dyslipidemie du diabete de type 2 (DT2) est un facteur en cause dans l’augmentation du risque cardiovasculaire au cours du DT2. La dyslipidemie du DT2 est caracterisee non seulement par des anomalies quantitatives des lipoproteines, mais aussi par des anomalies qualitatives et cinetiques a potentiel atherogene. Les anomalies quantitatives caracteristiques sont l’hypertriglyceridemie et la diminution du HDL-cholesterol. Les anomalies qualitatives comprennent une augmentation des VLDL de grande taille enrichies en cholesterol esterifie et triglycerides (VLDL1) et des LDL petites et denses, ainsi qu’une augmentation des triglycerides au sein des LDL et des HDL, une glycation des apol…
Generation of oxysterols formed by free radicals and enzymes by electrochemical oxidation
2016
International audience; It is commonly accepted that cholesterol oxide derivatives, also named oxysterols, are 27 carbon-atom molecules deriving either from enzymatic and non-enzymatic oxidation of cholesterol. Most of these compounds can be synthesized by more or less difficult and time consuming chemical reactions, and some of them have been discovered before the identification of the enzymes [mainly cytochrome P450 enzymes (CYP enzymes)] involved in their biosynthesis. A wide range of biological activities depends on oxysterols. Some oxysterols are also involved in the synthesis of cholesterol metabolites which have various properties. The paper by Weber et al. in this issue of European …
Roles for RpoS in survival of Escherichia coli during protozoan predation and in reduced moisture conditions highlight its importance in soil environ…
2017
The soil is a complex ecosystem where interactions between biotic and abiotic factors determine the survival and fate of microbial inhabitants of the system. Having previously shown that Escherichia coli requires the general stress response regulator, RpoS, to survive long term in soil, it was important to determine what specific conditions in this environment necessitate a functional RpoS. This study investigated the susceptibility of soil-persistent E. coli to predation by the single-celled eukaryotes Acanthamoeba polyphaga and Tetrahymena pyriformis, and the role RpoS plays in resisting this predation. Strain-specific differences were observed in the predation of E. coli strains, with so…