The molecular basis and biologic significance of the β-dystroglycan-emerin interaction

β-dystroglycan (β-DG) assembles with lamins A/C and B1 and emerin at the nuclear envelope (NE) to maintain proper nuclear architecture and function. To provide insight into the nuclear function of β-DG, we characterized the interaction between β-DG and emerin at the molecular level. Emerin is a major NE protein that regulates multiple nuclear processes and whose deficiency results in Emery–Dreifuss muscular dystrophy (EDMD). Using truncated variants of β-DG and emerin, via a series of in vitro and in vivo binding experiments and a tailored computational analysis, we determined that the β-DG–emerin interaction is mediated at least in part by their respective transmembrane domains (TM). Using surface plasmon resonance assays we showed that emerin binds to β-DG with high affinity (KD in the nanomolar range). Remarkably, the analysis of cells in which DG was knocked out demonstrated that loss of β-DG resulted in a decreased emerin stability and impairment of emerin-mediated processes. β-DG and emerin are reciprocally required for their optimal targeting within the NE, as shown by immunofluorescence, western blotting and immunoprecipitation assays using emerin variants with mutations in the TM domain and B-lymphocytes of a patient with EDMD. In summary, we demonstrated that β-DG plays a role as an emerin interacting partner modulating its stability and function

Biotecnología de plantas superiores y algas verdes

Los ureidos, alantoína y alantoato, son los principales compuestos sintetizados a partir del nitrógeno fijado en los nódulos de las leguminosas que se exportan a las partes aéreas en leguminosas tropicales como la judía. Los ureidos se producen por la oxidación de las purinas sintetizadas de novo en los nódulos radicales y también como parte de un proceso de recuperación de los compuestos nitrogenados en tejidos senescentes. Los ureidos se acumulan en varios tejidos vegetales en respuesta al estrés hídrico, y se ha sugerido que la acumulación de estos compuestos nitrogenados es la responsable de la inhibición de la fijación de nitrógeno que tiene lugar en condiciones ambientales adversas. A pesar de la importancia crucial de los ureidos como compuestos de reserva y transporte de nitrógeno, hasta el momento no se llevado a cabo la caracterización de las rutas de síntesis y degradación de ureidos en plantas. En particular, parece que existen dos posibles rutas de degradación de alantoato, y que el que determinadas leguminosas usen una u otra ruta puede afectar a la sensibilidad o tolerancia de esas plantas a la sequía. Por tanto la determinación de la ruta que opera en leguminosas de gran interés agronómico como la judía y el garbanzo, puede a la larga tener utilidad biotecnológica con la obtención de plantas que sean capaces de mantener la fijación de nitrógeno en condiciones ambientales adversas, como la sequía. Además de en la caracterización, con fines biotecnológicos del metabolismo de ureidos en leguminosas, se está trabajando obtención de algas superproductoras de γ-tocoferol (vitamina E) mediante ingeniería metabólica, así como en el análisis del contenido en antioxidantes del aceite de oliv

Towards the identification of host factors involved in the Plum pox virus infection cycle in Arabidopsis thaliana

International audienc

Multiple resistance traits control Plum pox virus infection in Arabidopsis thaliana

Publication Inra prise en compte dans l'analyse bibliométrique des publications scientifiques mondiales sur les Fruits, les Légumes et la Pomme de terre. Période 2000-2012. http://prodinra.inra.fr/record/256699International audienc

Analysis and regulation of gene expression in the resurrection plant Craterostigma plantagineum

Analysis of genes induced by water stres

Gene expression during water stress

Analysis of gene expression under water stress condition on resurrection plant

Extraction, partial characterization and susceptibility to Hg2+ of acid phosphatase from the microalgae Pseudokirchneriella subcapitata Extração, caracterização parcial e susceptibilidade ao Hg2+ da fosfatase ácida da microalga Pseudokirchneriella subcapitata

Pseudokirchneriella subcapitata is a unicellular green algae widely distributed in freshwater and soils. Due to its cosmopolitan characteristic, its use is recommended by national and international protocols in ecotoxicity studies. The alteration of phosphatase activities by agriculture pollutants like heavy metals has been extensively used as a biomarker in risk assessment and biomonitoring. In this study, we compared the extraction of acid phosphatase from P. subcapitata by different procedures and we studied the stability, substrates specificity, kinetics and the effect of Hg2+ in the crude extract. The freezing and thawing technique associated with probe sonication was the most suitable method of extraction. The enzyme was stable when frozen at -20ºC for at least six months, showed an optimum pH of 5 and a Km value of 0.27 mM for p-nitrophenylphosphate (pNPP) as substrate. Some natural organic substrates were cleaved by a similar extent as the synthetic substrate pNPP. Short term exposure (24 hours) to Hg2+ had little effect but inhibition of the specific activity was observed after 7 days with EC50 (concentration of Hg2+ that promotes 50% decrease of specific activity) value of 12.63 &#956;M Hg2+.<br>Pseudokirchneriella subcapitata é uma alga verde unicelular amplamente distribuída em corpos d´agua e solos. Devido a sua natureza cosmopolita, seu uso é recomendado por protocolos nacionais e internacionais na realização de estudos de ecotoxicidade. A alteração da atividade de fosfatases por agentes poluentes de origem agrícola, como metais pesados, tem sido largamente usada como um biomarcador na avaliação de risco e biomonitoramento. No presente trabalho foi comparada a extração da fosfatase ácida de P. subcapitata por diferentes métodos e estudada a sua estabilidade, especificidade por substratos, cinética e efeito do Hg2+ no extrato bruto. O congelamento e descongelamento, associado com ultrassom, foi o método que proporcionou maior rendimento de extração. A enzima, praticamente estável por armazenamento a -20ºC, durante aproximadamente seis meses, demonstrou uma atividade ótima em pH 5 e um valor de Km para o p-nitrofenilfostato (pNPP) de 0,27 mM. Alguns substratos naturais foram hidrolisados com uma intensidade semelhante à do substrato sintético pNPP. Diferentemente dos estudos de exposição a curto prazo (24 horas), observou-se inibição da atividade específica nas culturas expostas durante 7 dias, com um valor de CE50 (concentração de Hg2+ que promove 50% de decréscimo da atividade específica) equivalente a 12,63 &#956;M Hg2+

The Functions of RNA-Dependent RNA Polymerases in Arabidopsis

One recently identified mechanism that regulates mRNA abundance is RNA silencing, and pioneering work in Arabidopsis thaliana and other genetic model organisms helped define this process. RNA silencing pathways are triggered by either self-complementary fold-back structures or the production of double-stranded RNA (dsRNA) that gives rise to small RNAs (smRNAs) known as microRNAs (miRNAs) or small-interfering RNAs (siRNAs). These smRNAs direct sequence-specific regulation of various gene transcripts, repetitive sequences, viruses, and mobile elements via RNA cleavage, translational inhibition, or transcriptional silencing through DNA methylation and heterochromatin formation. Early genetic screens in Arabidopsis were instrumental in uncovering numerous proteins required for these important regulatory pathways. Among the factors identified by these studies were RNA-dependent RNA polymerases (RDRs), which are proteins that synthesize siRNA-producing dsRNA molecules using a single-stranded RNA (ssRNA) molecule as a template. Recently, a growing body of evidence has implicated RDR-dependent RNA silencing in many different aspects of plant biology ranging from reproductive development to pathogen resistance. Here, we focus on the specific functions of the six Arabidopsis RDRs in RNA silencing, their ssRNA substrates and resulting RDR-dependent smRNAs, and the numerous biological functions of these proteins in plant development and stress responses