Activation of plasma membrane H + -ATPases participates in dormancy alleviation in sunflower seeds

International audienceUsing various inhibitors and scavengers we took advantage of the size of sunflower (Helianthus annuus) seeds to investigate in vivo the effects of hormones, namely abscisic acid (ABA) and ethylene (ET), and reactive oxygen species (ROS) on the polarization of dormant (D) and non-dormant (ND) embryonic seed cells using microelectrodes. Our data show that D and ND seed cells present different polarization likely due to the regulation of plasma membrane (PM) H+-ATPase activity. The data obtained after addition of hormones or ROS scavengers further suggest that ABA dependent inhibition of PM H+-ATPases could participate in dormancy maintenance and that ET-and ROS-dependent PM H+-ATPase stimulation could participate in dormancy release in sunflower seeds

Arabidopsis thaliana cells: a model to evaluate the virulence of Pectobacterium carotovorum.

Pectobacterium carotovorum are economically important plant pathogens that cause plant soft rot. These enterobacteria display high diversity world-wide. Their pathogenesis depends on production and secretion of virulence factors such as plant cell wall-degrading enzymes, type III effectors, a necrosis-inducing protein, and a secreted virulence factor from Xanthomonas spp., which are tightly regulated by quorum sensing. Pectobacterium carotovorum also present pathogen-associated molecular patterns that could participate in their pathogenicity. In this study, by using suspension cells of Arabidopsis thaliana, we correlate plant cell death and pectate lyase activities during coinfection with different P. carotovorum strains. When comparing soft rot symptoms induced on potato slices with pectate lyase activities and plant cell death observed during coculture with Arabidopsis thaliana cells, the order of strain virulence was found to be the same. Therefore, Arabidopsis thaliana cells could be an alternative tool to evaluate rapidly and efficiently the virulence of different P. carotovorum strains

Calcium and the control of C4 photosynthesis

http://www.sherpa.ac.uk/romeo/search.ph

Increased Anion Channel Activity Is an Unavoidable Event in Ozone-Induced Programmed Cell Death

Ozone is a major secondary air pollutant often reaching high concentrations in urban areas under strong daylight, high temperature and stagnant high-pressure systems. Ozone in the troposphere is a pollutant that is harmful to the plant. generation by salicylic and abscisic acids. Anion channel activation was also shown to promote the accumulation of transcripts encoding vacuolar processing enzymes, a family of proteases previously reported to contribute to the disruption of vacuole integrity observed during programmed cell death.-induced programmed cell death. Because ion channels and more specifically anion channels assume a crucial position in cells, an understanding about the underlying role(s) for ion channels in the signalling pathway leading to programmed cell death is a subject that warrants future investigation

Analyses des phosphoprotéines et du phosphoprotéome ( application à l étude de la phosphoénolpyruvate carboxylase kinase et à la carence en azote chez Arabidopsis thaliana )

ORSAY-PARIS 11-BU Sciences (914712101) / SudocSudocFranceF

Rôle de l’acide oxalique, facteur de pathogénie de différents champignons nécrotrophes dans l’induction de réponses de défense chez Arabidopsis thaliana

International audienc

Rôle de l’acide oxalique, facteur de pathogénie de différents champignons nécrotrophes dans l’induction de réponses de défense chez Arabidopsis thaliana

International audienc

Rôle de l’acide oxalique, facteur de pathogénie de différents champignons nécrotrophes dans l’induction de réponses de défense chez Arabidopsis thaliana

International audienc

Are Methionine Sulfoxide-Containing Proteins Related to Seed Longevity? A Case Study of Arabidopsis thaliana Dry Mature Seeds Using Cyanogen Bromide Attack and Two-Dimensional-Diagonal Electrophoresis

International audienceIn recent years, several reports pointed out the role of protein oxidation in seed longevity, notably regarding the oxidation of methionine (Met) residues to methionine sulfoxide (MetO) in proteins. To further consider this question, we present a handy proteomic method based on the use of two-dimensional diagonal electrophoresis (2Dd) and cyanogen bromide (CNBr) cleavage, which we refer to as 2Dd-CNBr. CNBr treatment of proteins causes the non-enzymatic hydrolysis of peptide bonds on the carboxyl side of reduced Met residues. However, Met oxidation causes a lack of cleavage, thus modifying the electrophoretic mobility of CNBr-induced peptides. This approach was first validated using bovine serum albumin as a model protein, which confirmed the possibility of distinguishing between oxidized and non-oxidized forms of Met-containing peptides in gels. Then, the 2Dd-CNBr method was applied to the Arabidopsis thaliana seed protein extract in a control (non-oxidized) condition and in an oxidized one (as obtained following hypochlorous acid treatment). Twenty-four oxidized Met residues in 19 proteins identified by mass spectrometry were found to be surface exposed in these proteins. In the three-dimensional environment of the oxidized Met, we detected amino acid residues that could be converted by oxidation (carbonylation) or by phosphorylation, suggesting a possible interplay between Met oxidation and the other protein modifications. The identification of the proteins oxidatively modified in Met residues revealed the finding that MetO-containing proteins are related to seed longevity. Based on these results, we suggest that the method presently described also has the potential for wider applications

Hypopituitarism consecutive to the brain damage: a widely unexpected prevalence

Alors que la prévalence de l’hypopituitarisme est largement sous-estimée, son étiologie est souvent méconnue. Des données récentes indiquent que le traumatisme crânien constitue actuellement une cause importante d’hypopituitarisme acquis chez l’adulte. Les traumatismes crâniens représentent un problème majeur de santé publique, avec une incidence annuelle en Belgique de 30.000 patients par an. Plusieurs séries rétrospectives et prospectives ont identifié plus de 5.000 patients avec un traumatisme crânien et souffrant d’un déficit isolé ou combiné en hormone de croissance, gonadotrophines, adrénocorticotrophine, thyrotrophine et, occasionnellement, de prolactine et d’hormone antidiurétique. Nous faisons le point sur ces données récentes et discutons du diagnostic et de la prise en charge de l’hypopituitarisme secondaire au traumatisme crânien.While the prevalence of Hypopituitarism is widely underestimated, its etiology is often misunderstood. Recent data indicate that head trauma is currently a major cause of acquired Hypopituitarism in adulthood. Injuries are a major public health problem, with an annual incidence in Belgium of 30,000 patients per year. Several retrospective and prospective series have identified more than 5,000 patients with trauma injury and suffering from an isolated or in combination hormone growth deficiency, gonadotrophins, adrenocorticotrophin, thyrotrophin and, less frequently prolactin and antidiuretic hormone deficiency. In this presentation , we make the point on these recent data and discuss the diagnosis and management of the secondary Hypopituitarism injury, according to our experience and the review of the litterature