Analysis of the Plant bos1 Mutant Highlights Necrosis as an Efficient Defence Mechanism during D. dadantii/Arabidospis thaliana Interaction

Dickeya dadantii is a broad host range phytopathogenic bacterium provoking soft rot disease on many plants including Arabidopsis. We showed that, after D. dadantii infection, the expression of the Arabidopsis BOS1 gene was specifically induced by the production of the bacterial PelB/C pectinases able to degrade pectin. This prompted us to analyze the interaction between the bos1 mutant and D. dadantii. The phenotype of the infected bos1 mutant is complex. Indeed, maceration symptoms occurred more rapidly in the bos1 mutant than in the wild type parent but at a later stage of infection, a necrosis developed around the inoculation site that provoked a halt in the progression of the maceration. This necrosis became systemic and spread throughout the whole plant, a phenotype reminiscent of that observed in some lesion mimic mutants. In accordance with the progression of maceration symptoms, bacterial population began to grow more rapidly in the bos1 mutant than in the wild type plant but, when necrosis appeared in the bos1 mutant, a reduction in bacterial population was observed. From the plant side, this complex interaction between D. dadantii and its host includes an early plant defence response that comprises reactive oxygen species (ROS) production accompanied by the reinforcement of the plant cell wall by protein cross-linking. At later timepoints, another plant defence is raised by the death of the plant cells surrounding the inoculation site. This plant cell death appears to constitute an efficient defence mechanism induced by D. dadantii during Arabidopsis infection

PlantPhos: using maximal dependence decomposition to identify plant phosphorylation sites with substrate site specificity

<p>Abstract</p> <p>Background</p> <p>Protein phosphorylation catalyzed by kinases plays crucial regulatory roles in intracellular signal transduction. Due to the difficulty in performing high-throughput mass spectrometry-based experiment, there is a desire to predict phosphorylation sites using computational methods. However, previous studies regarding <it>in silico </it>prediction of plant phosphorylation sites lack the consideration of kinase-specific phosphorylation data. Thus, we are motivated to propose a new method that investigates different substrate specificities in plant phosphorylation sites.</p> <p>Results</p> <p>Experimentally verified phosphorylation data were extracted from TAIR9-a protein database containing 3006 phosphorylation data from the plant species <it>Arabidopsis thaliana</it>. In an attempt to investigate the various substrate motifs in plant phosphorylation, maximal dependence decomposition (MDD) is employed to cluster a large set of phosphorylation data into subgroups containing significantly conserved motifs. Profile hidden Markov model (HMM) is then applied to learn a predictive model for each subgroup. Cross-validation evaluation on the MDD-clustered HMMs yields an average accuracy of 82.4% for serine, 78.6% for threonine, and 89.0% for tyrosine models. Moreover, independent test results using <it>Arabidopsis thaliana </it>phosphorylation data from UniProtKB/Swiss-Prot show that the proposed models are able to correctly predict 81.4% phosphoserine, 77.1% phosphothreonine, and 83.7% phosphotyrosine sites. Interestingly, several MDD-clustered subgroups are observed to have similar amino acid conservation with the substrate motifs of well-known kinases from Phospho.ELM-a database containing kinase-specific phosphorylation data from multiple organisms.</p> <p>Conclusions</p> <p>This work presents a novel method for identifying plant phosphorylation sites with various substrate motifs. Based on cross-validation and independent testing, results show that the MDD-clustered models outperform models trained without using MDD. The proposed method has been implemented as a web-based plant phosphorylation prediction tool, PlantPhos <url>http://csb.cse.yzu.edu.tw/PlantPhos/</url>. Additionally, two case studies have been demonstrated to further evaluate the effectiveness of PlantPhos.</p

Systemic virulence of Erwinia chrysanthemi 3937 requires a functional iron assimilation system.

In Erwinia chrysanthemi, conditions of iron starvation initiate production of a catechol-type siderophore and enhance production of three outer membrane polypeptides. Twenty-two mutants affected in the different stages of this iron assimilation system were isolated by mini-Mu insertion mutagenesis. All of them failed to induce systemic soft rot on axenically grown Saintpaulia plants. From the siderophore auxotrophs and the iron uptake mutants, clones having recovered the missing function(s) were isolated by using the in vivo cloning vector pULB113 (RP4::mini-Mu). An R-prime plasmid containing a ca. 35.5-kilobase-pair DNA insert was identified. Restoration of the iron functions restored partially, if not completely, the virulence of the parental strain

Chromosomal mapping of the pel and cel genes in Erwinia chrysanthemi strain B374

Using the RP4:mini-Mu in vivo cloning technique, van Gijsegem et al. (1985) isolated several pel and cel genes of Erwinia chrysanthemi (Ech) B374 strain. We have localized these genes on the Ech chromosome by co-transfer mapping of Mud11734 insertion mutants and refined the map by co-transposition analysis. This analysis has enabled us to identify another cel gene.SCOPUS: ar.jFLWNAinfo:eu-repo/semantics/publishe

Effects of exercise programs to prevent decline in health-related quality of life in highly deconditioned institutionalized elderly persons: a randomized controlled trial.

Contains fulltext : 88758.pdf (publisher's version ) (Closed access)BACKGROUND: Our objective was to assess the effects of targeted exercise programs on health-related quality of life compared with usual care based on the ability to perform activities of daily living (ADL) and the Neuropsychiatric Inventory scores in geriatric institutionalized persons. METHODS: A randomized controlled trial of 2 exercise programs vs usual care was conducted in 160 institutionalized persons 65 years or older who were able to understand basic motor commands and to move from one position to another. Interventions were performed over 6 months and were either an adapted tai chi program (4 times 30 min/wk) or a cognition-action program (2 times 30-45 min/wk) that focused primarily on an adapted guidance of patient-centered communication skills. The control group received usual care. The study was conducted at 4 settings. The main outcomes were changes in health-related quality of life based on ADL and Neuropsychiatric Inventory scores after 12 months. RESULTS: The control group experienced a decline in ADL over the 12-month period compared with the adapted tai chi and cognition-action groups, but the differences were not significant (P = .24 and P = .15, respectively). Also, the components of ADL, eg, ability to walk, continence, and nutrition, were maintained better in the intervention groups than in the control group. The total Neuropsychiatric Inventory score also worsened significantly in the control group, while it was unchanged or improved in the intervention groups. The differences between the cognition-action group and the control group were significant (P > .001). Neuropsychiatric diagnosis subgroups (such as dementia and psychosis) did not show a specific response from any intervention. CONCLUSION: Adapted exercise programs can slow down the decline in health-related quality of life among heterogeneous, institutionalized elderly persons. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00623532

Physical transformations of the active pharmaceutical ingredient BN83495: enantiotropic and monotropic relationships. Access to several polymorphic forms by using various solvation–desolvation processes

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