Foundations of aeroelastic optimization and some applications to continuous systems

Static and dynamic aeroelastic problems in optimization of continuous system

Intracellular delivery of peptides via association with ubiquitin or SUMO-1 coupled to protein transduction domains

<p>Abstract</p> <p>Background</p> <p>We previously developed small hybrid proteins consisting of SUMO-1 linked to an heptapeptide fused to the Tat protein transduction domain (PTD). The heptapeptide motif was selected from a library of random sequences to specifically bind HIV-1 regulatory proteins Tat or Rev. These constructs, named SHP, are able to enter primary lymphocytes and some of them inhibit HIV-1 replication. Considering these positive results and other data from the literature, we further tested the ability of ubiquitin or SUMO-1 linked to various PTD at their N-terminus to deliver within cells proteins or peptides fused downstream of their diglycine motif. In this system it is expected that the intracellular ubiquitin or SUMO-1 hydrolases cleave the PTD-Ub or PTD-SUMO-1 modules from the cargo polypeptide, thereby allowing its delivery under an unmodified form.</p> <p>Results</p> <p>Several bacterial expression vectors have been constructed to produce modular proteins containing from the N- to the C-terminus: the FLAG epitope, a cleavage site for a protease, a PTD, human ubiquitin or SUMO-1, and either GFP or the HA epitope. Nine different PTDs were tested, including the Tat basic domain, wild type or with various mutations, and stretches of arginine or lysine. It was observed that some of these PTDs, mainly the Tat PTD and seven or nine residues long polyarginine motifs, caused association of the hybrid proteins with cells, but none of these constructs were delivered to the cytosol. This conclusion was derived from biochemical and immunofluorescence studies, and also from the fact that free cargo protein resulting from cleavage by proteases after ubiquitin or SUMO-1 was never observed. However, in agreement with our previous observations, mutation of the diglycine motif into alanine-arginine, as in the SHP constructs, allows cytosol entry demonstrated by immunofluorescence observations on living cells and by cell fractionation analyses. This process results from a non-endocytic pathway.</p> <p>Conclusion</p> <p>Our observations indicate that fusion of SUMO-1 to a peptide-PTD module allows generation of a stable hybrid protein that is easily produced in bacteria and which efficiently enters into cells but this property necessitates mutation of the diglycine motif at the end of SUMO-1, thereby impairing delivery of the peptide alone.</p

LTR retrotransposons in rice (Oryza sativa, L.): recent burst amplifications followed by rapid DNA loss

Background: LTR retrotransposons are one of the main causes for plant genome size and structure evolution, along with polyploidy. The characterization of their amplification and subsequent elimination of the genomes is therefore a major goal in plant evolutionary genomics. To address the extent and timing of these forces, we performed a detailed analysis of 41 LTR retrotransposon families in rice. Results: Using a new method to estimate the insertion date of both truncated and complete copies, we estimated these two forces more accurately than previous studies based on other methods. We show that LTR retrotransposons have undergone bursts of amplification within the past 5 My. These bursts vary both in date and copy number among families, revealing that each family has a particular amplification history. The number of solo LTR varies among families and seems to correlate with LTR size, suggesting that solo LTR formation is a family-dependent process. The deletion rate estimate leads to the prediction that the half-life of LTR retrotransposon sequences evolving neutrally is about 19 My in rice, suggesting that other processes than the formation of small deletions are prevalent in rice DNA removal. Conclusion: Our work provides insights into the dynamics of LTR retrotransposons in the rice genome. We show that transposable element families have distinct amplification patterns, and that the turn-over of LTR retrotransposons sequences is rapid in the rice genome

Modulation of HIV-1 Rev protein abundance and activity by polyubiquitination with unconventional Lys-33 branching

AbstractThe HIV-1 Rev protein plays a key role in virus replication by allowing export to the cytoplasm of unspliced or singly-spliced RNAs. In this report, we investigated whether Rev is modified by ubiquitination or sumoylation. Whereas no evidence of sumoylation was obtained, transient expression experiments showed that ubiquitin conjugates to Rev as high molecular weight polyubiquitin chains. Mutation of the three lysine residues of Rev showed that the site of ubiquitin conjugation is Lys-115. Experiments with ubiquitin mutants including a single lysine at every seven possible position indicated that branching of the polyubiquitin chains mainly involves Lys-33. Mutation of Rev Lys-115 to arginine reduces markedly the steady state amount of the protein, but does not impair its ability to export RNA via the Rev response element. These observations support the notion that polyubiquitination of Rev stabilizes the viral protein but hinders its activity

The SNARE Machinery in Mast Cell Secretion

Mast cells are known as inflammatory cells which exert their functions in allergic and anaphylactic reactions by secretion of numerous inflammatory mediators. During an allergic response, the high-affinity IgE receptor, FcεRI, becomes cross-linked by receptor-bound IgE and antigen resulting in immediate release of pre-synthesized mediators – stored in granules – as well as in de novo synthesis of various mediators like cytokines and chemokines. Soluble N-ethylmaleimide-sensitive factor attachment protein (SNAP) receptors (SNARE) proteins were found to play a central role in regulating membrane fusion events during exocytosis. In addition, several accessory regulators like Munc13, Munc18, Rab GTPases, secretory carrier membrane proteins, complexins, or synaptotagmins were found to be involved in membrane fusion. In this review we summarize our current knowledge about the SNARE machinery and its mechanism of action in mast cell secretion

Enjeux, difficultés et modalités de l’expression sur le travail : point de vue de la clinique médicale du travail de Philippe Davezies« Les dilemmes d’un débat centré sur l’activité »

Introduction à la discussion À partir de sa démarche de médecin du travail, d’ergonome et d’universitaire enclin à ouvrir son savoir au milieu syndical, Philippe Davezies nous amène à renouveler notre prise en charge des questions de conditions de travail. Avec d’autres chercheurs, il nous conduit à envisager qu’au-delà des « conditions de travail », ce sont les « conditions d’accomplissement de soi dans le travail » qu’il importe désormais de saisir si l’on veut contrer Le nouvel esprit du c..

Enjeux, difficultés et modalités de l’expression sur le travail : point de vue de la clinique médicale du travail de Philippe Davezies« Les dilemmes d’un débat centré sur l’activité »

Introduction à la discussion À partir de sa démarche de médecin du travail, d’ergonome et d’universitaire enclin à ouvrir son savoir au milieu syndical, Philippe Davezies nous amène à renouveler notre prise en charge des questions de conditions de travail. Avec d’autres chercheurs, il nous conduit à envisager qu’au-delà des « conditions de travail », ce sont les « conditions d’accomplissement de soi dans le travail » qu’il importe désormais de saisir si l’on veut contrer Le nouvel esprit du c..

La préservation du paysage et la conservation de la nature sous le III Reich

O objetivo do artigo é discutir as políticas de preservação da paisagem e de conversação danatureza durante o regime nazista (1933-1945) na Alemanha, quando o III Reich apropriou-se etransformou ideologicamente o ideário romântico de relações entre a natureza e a cultura. Apolítica de conservação da paisagem e da natureza estava fundamentada na concepçãoautoritária de que a natureza era o lar (Heimat) da civilização germânica. O regime nazistaproduziu uma simbiose entre os conceitos de Landschaft e de Lebensraum, que se manifestava nadivisão regional da própria Alemanha3211

Etchplanação dinâmica e episódica nos trópicos quentes e úmidos

This paper examines the etchplanation theory, a recent approach in geomorphology. This theory is suitable to study landforms in wet and warm tropical regions, since it considers chemical weathering and transformation of systems by pedological processes and levelling landforms. The originality of Etchplanation theory relies on the consideration of geochemical and pedogenetics processes as very important mechanisms, which  are related to morphogenesis and levelling landform. On discusses the Etchplanation theory genesis, the Etchplanation in tropical regions, the chemical weathering as a basic mechanism for levelling landforms and the proposition of work considering Etchplanation.O artigo apresenta a teoria da etchplanação como um referencial teórico e metodológico para os estudos das formas de relevo nas regiões tropicais quentes e úmidas, destacando o papel do intemperismo químico e dos sistemas de transformação da cobertura pedológica. A originalidade da teoria da etchplanação é que ela considera os processos geoquímicos e pedogenéticos como os principais mecanismos da morfogênese e do aplainamento das formas de relevo. Neste trabalho são discutidos a gênese da teoria da etchplanação, o intemperismo químico como mecanismo básico do aplainamento das formas de relevo e uma proposta de trabalho com a etchplanação