The Novel Chloroplast Outer Membrane Kinase KOC1 Is a Required Component of the Plastid Protein Import Machinery

The biogenesis and maintenance of cell organelles such as mitochondria and chloroplasts require the import of many proteins from the cytosol, a process that is controlled by phosphorylation. In the case of chloroplasts, the import of hundreds of different proteins depends on translocons at the outer and inner chloroplast membrane (TOC and TIC, respectively) complexes. The essential protein TOC159 functions thereby as an import receptor. It has an N-terminal acidic (A-) domain that extends into the cytosol, controls receptor specificity, and is highly phosphorylated in vivo. However, kinases that phosphorylate the TOC159 A-domain to enable protein import have remained elusive. Here, using co-purification with TOC159 from Arabidopsis, we discovered a novel component of the chloroplast import machinery, the regulatory kinase at the outer chloroplast membrane 1 (KOC1). We found that KOC1 is an integral membrane protein facing the cytosol and stably associates with TOC. Moreover, KOC1 phosphorylated the A-domain of TOC159 in vitro, and in mutant koc1 chloroplasts, preprotein import efficiency was diminished. koc1 Arabidopsis seedlings had reduced survival rates after transfer from the dark to the light in which protein import into plastids is required to rapidly complete chloroplast biogenesis. In summary, our data indicate that KOC1 is a functional component of the TOC machinery that phosphorylates import receptors, supports preprotein import, and contributes to efficient chloroplast biogenesis

Promouvoir la dignité auprès des personnes atteintes d'un cancer avancé: travail de Bachelor

Contexte: L’augmentation de la demande en soins palliatifs est aujourd’hui un défi de santé publique. Actuellement, l’espérance de vie s’accroît ce qui conduit à un vieillissement de la population. Ceci amène une élévation de l’incidence des cancers. La situation de fin de vie peut susciter chez le patient un sentiment de perte de dignité et par conséquent une altération de sa qualité de vie. But: Cette revue de littérature a pour objectif de décrire le rôle infirmier dans la promotion de la dignité auprès de l’individu en soins palliatifs. L’identification des besoins de la personne ainsi que la posture et les actions infirmières sont mises en avant pour amplifier le sens de la dignité. Méthode: Les bases de données CINAHL, PubMed et Web of Science ont été utilisées. Les articles trouvés répondent à la question de recherche « Quelles sont les interventions infirmières qui ont été développées pour favoriser la dignité chez des personnes adultes ayant un cancer avancé ? ». L’analyse des articles est réalisée et classée au regard de trois thèmes : les moyens utilisés pour promouvoir la dignité, les ressentis des patients en fin de vie et les actions infirmières. Résultats: Les résultats des 11 articles (3 revues de la littérature, 2 essais contrôlés randomisés, 1 étude quantitative, 3 études qualitatives, 1 étude mixte, 1 étude pilote) mettent en évidence plusieurs moyens fiables afin d’évaluer et de promouvoir la dignité en soins palliatifs. Les ressentis des patients impliquent la détresse physique et psychique, la diminution du sens de la dignité, de la qualité de vie, de l’autodétermination et du bien-être spirituel. Les actions infirmières se basent sur le soulagement des symptômes physiques et psychiques. De plus, les professionnels de la santé proposent un soutien social tout en ayant une posture infirmière adéquate. Il ressort également de cette analyse, la difficulté de l’infirmière à aborder la fin de vie avec le patient. Conclusion / Limites: L’identification des besoins et la mise en place des moyens pour promouvoir la dignité a un effet bénéfique chez la personne en fin de vie. La plupart des articles retenus sont issus de l’Amérique du Nord. Cependant, il serait possible d’adapter les résultats en Suisse pour ainsi développer des moyens, permettant aux professionnels soignants une prise en soins individualisé. Cette revue de la littérature comporte 11 articles scientifiques. C’est pourquoi, elle n’est pas exhaustive

Endophytes and epiphytes from the grapevine leaf microbiome as potential biocontrol agents against phytopathogens

Plants harbor diverse microbial communities that colonize both below-ground and above-ground organs. Some bacterial members of these rhizosphere and phyllosphere microbial communities have been shown to contribute to plant defenses against pathogens. In this study, we characterize the pathogen-inhibiting potential of 78 bacterial isolates retrieved from endophytic and epiphytic communities living in the leaves of three grapevine cultivars. We selected two economically relevant pathogens, the fungus Botrytis cinerea causing gray mold and the oomycete Phytophthora infestans, which we used as a surrogate for Plasmopara viticola causing downy mildew. Our results showed that epiphytic isolates were phylogenetically more diverse than endophytic isolates, the latter mostly consisting of Bacillus and Staphylococcus strains, but that mycelial inhibition of both pathogens through bacterial diffusible metabolites was more widespread among endophytes than among epiphytes. Six closely related Bacillus strains induced strong inhibition (<60%) of Botrytis cinerea mycelial growth. Among these, five led to significant perturbation in spore germination, ranging from full inhibition to reduction in germination rate and germ tube length. Different types of spore developmental anomalies were observed for different strains, suggesting multiple active compounds with different modes of action on this pathogen. Compared with B. cinerea, the oomycete P. infestans was inhibited in its mycelial growth by a higher number and more diverse group of isolates, including many Bacillus but also Variovorax, Pantoea, Staphylococcus, Herbaspirillum, or Sphingomonas strains. Beyond mycelial growth, both zoospore and sporangia germination were strongly perturbed upon exposure to cells or cell-free filtrates of selected isolates. Moreover, three strains (all epiphytes) inhibited the pathogen’s growth via the emission of volatile compounds. The comparison of the volatile profiles of two of these active strains with those of two phylogenetically closely related, inactive strains led to the identification of molecules possibly involved in the observed volatile-mediated pathogen growth inhibition, including trimethylpyrazine, dihydrochalcone, and L-dihydroxanthurenic acid. This work demonstrates that grapevine leaves are a rich source of bacterial antagonists with strong inhibition potential against two pathogens of high economical relevance. It further suggests that combining diffusible metabolite-secreting endophytes with volatile-emitting epiphytes might be a promising multi-layer strategy for biological control of above-ground pathogens