Search results for "Cell biology"
showing 10 items of 8732 documents
Preferential induction of 20S proteasome subunits during elicitation of plant defense reactions: towards the characterization of "plant defense prote…
2003
Plants have evolved efficient mechanisms to resist pathogens. The earliest defense response is the hypersensitive response (HR) considered as the main step leading to plant systemic acquired resistance (SAR) that protects the whole plant against a large spectrum of pathogens. We showed previously that elicitation of defense reactions in tobacco cells by cryptogein, a proteinaceous elicitor of plant defense reactions, leads to a rapid and differential accumulation of transcripts corresponding to genes encoding defense-induced (din) subunits of 20S proteasome: beta1din, alpha3din and alpha6din.Here, expression of these three subunits was investigated by Northern blotting and by Western blotti…
Hydrogen peroxide induces programmed cell death features in cultured tobacco BY-2 cells, in a dose-dependent manner
2001
Active oxygen species (AOS), especially hydrogen peroxide, play a critical role in the defence of plants against invading pathogens and in the hypersensitive response (HR). This is characterized by the induction of a massive production of AOS and the rapid appearance of necrotic lesions is considered as a programmed cell death (PCD) process during which a limited number of cells die at the site of infection. This work was aimed at investigating the mode of cell death observed in cultures of BY-2 tobacco cells exposed to H(2)O(2). It was shown that H(2)O(2) is able to induce various morphological cell death features in cultured tobacco BY-2 cells. The hallmarks of cell death observed with fl…
Retroconversion of docosapentaenoic acid (n-6): an alternative pathway for biosynthesis of arachidonic acid in Daphnia magna.
2013
The aim of this study was to assess metabolic pathways for arachidonic acid (20:4n-6) biosynthesis in Daphnia magna. Neonates of D. magna were maintained on [13C] enriched Scenedesmus obliquus and supplemented with liposomes that contained separate treatments of unlabeled docosapentaenoic acid (22:5n-6), 20:4n-6, linoleic acid (18:2n-6) or oleic acid (18:1n-9). Daphnia in the control treatment, without any supplementary fatty acids (FA) containing only trace amounts of 20:4n-6 (~0.3 % of all FA). As expected, the highest proportion of 20:4n-6 (~6.3 %) was detected in Daphnia that received liposomes supplemented with this FA. Higher availability of 18:2n-6 in the diet increased the proportio…
Activation of a nuclear-localized SIPK in tobacco cells challenged by cryptogein, an elicitor of plant defence reactions.
2009
When a plant cell is challenged by a well-defined stimulus, complex signal transduction pathways are activated to promote the modulation of specific sets of genes and eventually to develop adaptive responses. In this context, protein phosphorylation plays a fundamental role through the activation of multiple protein kinase families. Although the involvement of protein kinases at the plasma membrane and cytosolic levels are now well-documented, their nuclear counterparts are still poorly investigated. In the field of plant defence reactions, no known study has yet reported the activation of a nuclear protein kinase and/or its nuclear activity in plant cells, although some protein kinases, e.…
AM fungal exudates activate MAP kinases in plant cells in dependence from cytosolic Ca2+ increase
2011
International audience; The molecular dialogue occurring prior to direct contact between the fungal and plant partners of arbuscular-mycorrhizal (AM) symbioses begins with the release of fungal elicitors, so far only partially identified chemically, which can activate specific signaling pathways in the host plant. We show here that the activation of MAPK is also induced by exudates of germinating spores of Gigaspora margarita in cultured cells of the non-leguminous species tobacco (Nicotiana tabacum), as well as in those of the model legume Lotus japonicus. MAPK activity peaked about 15 min after the exposure of the host cells to the fungal exudates (FE). FE were also responsible for a rapi…
Spatial monitoring of gene activity in extraradical and intraradical developmental stages of arbuscular mycorrhizal fungi by direct fluorescent in si…
2008
International audience; Gene expression profiling based on tissue extracts gives only limited information about genes associated with complex developmental processes such as those implicated in fungal interactions with plant roots during arbuscular mycorrhiza development and function. To overcome this drawback, a direct fluorescent in situ RT-PCR methodology was developed for spatial mapping of gene expression in different presymbiotic and symbiotic structures of an arbuscular mycorrhizal fungus. Transcript detection was optimized by targeting the LSU rRNA gene of Glomus intraradices and monitoring expression of a stearoyl-CoA-desaturase gene that is consistently expressed at high levels in…
Plasma membrane sterol complexation, generated by filipin, triggers signaling responses in tobacco cells
2010
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 …
Resistance of a recombinant Escherichia coli to dehydration.
2009
International audience; Dehydration of microorganisms, rendering them anhydrobiotic, is often an efficient method for the short and long term conservation of different strain-producers. However, some biotechnologically important recombinant bacterial strains are extremely sensitive to conventional treatment. We describe appropriate conditions during dehydration of the recombinant Escherichia coli strain HB 101 (GAPDH) that can result dry cells having a 88% viability on rehydration. The methods entails air-drying after addition of 100 mM trehalose to the cultivation medium or distilled water (for short term incubation).
Evidence for specific, high-affinity binding sites for a proteinaceous elicitor in tobacco plasma membrane
1995
Abstract Binding of cryptogein, a proteinaceous elicitor, was studied on tobacco plasma membrane. The binding of the [125I]cryptogein was saturable, reversible and specific with an apparent Kd of 2 nM. A single class of cryptogein binding sites was found with a sharp optimum pH for binding at about pH 7.0. The high-affinity correlates with cryptogein concentrations required for biological activity in vivo.
Comparison of the effects of cryptogein and oligogalacturonides on tabacco cells and evidence of different forms of desensitization induced by these …
1998
Abstract The effects of cryptogein and oligogalacturonides (OGs) were compared on tobacco cells by measuring calcium influx and calcium-dependent responses including extracellular alkalinization and H 2 O 2 production. The main difference is the higher calcium influx and the sustained H 2 O 2 production induced by cryptogein compared to OGs. Amplitude and duration of calcium signalling triggered by cryptogein or OGs may explain the necrotic effect of cryptogein, and the absence of necrosis in tobacco plants treated with OGs. We used induction of alkalinization and H 2 O 2 production to investigate cryptogein effects after a first treatment with cryptogein or OGs, and reciprocally. Results s…