Coupling of importin beta binding peptide on plasmid DNA: transfection efficiency is increased by modification of lipoplex's physico-chemical properties

BACKGROUND: Non-viral vectors for gene transfer are less immunogenic than viral vectors but also less efficient. Significant effort has focused on enhancing non-viral gene transfer efficiency by increasing nuclear import of plasmid DNA, particularly by coupling nuclear localization peptidic sequences to plasmid DNA. RESULTS: We have coupled a 62-aminoacid peptide derived from hSRP1α importin beta binding domain, called the IBB peptide to plasmid DNA by using the heterobifunctional linker N-(4-azido-2,3,5,6 tetrafluorobenzyl)-6-maleimidyl hexanamide (TFPAM-6). When covalently coupled to plasmid DNA, IBB peptide did not increase the efficiency of cationic lipid mediated transfection. The IBB peptide was still able to interact with its nuclear import receptor, importin β, but non-specifically. However, we observed a 20-fold increase in reporter gene expression with plasmid DNA / IBB peptide complexes under conditions of inefficient transfection. In which case, IBB was associated with plasmid DNA through self assembling ionic interaction. CONCLUSIONS: The improvement of transfection activity was not due to an improved nuclear import of DNA, but rather by the modification of physicochemical properties of IBB peptide / plasmid complexes. IBB peptide increased lipoplex size and these larger complexes were more efficient for gene transfer

Growth and organization of (3-Trimethoxysilylpropyl) diethylenetriamine within reactive amino-terminated self-assembled monolayer on silica

Alkane chains are the most commonly used molecules for monolayer fabrication. Long chains are used for their strong van der Waals interactions inducing good layer organization. Amine function-terminated alkyl chains are of great interest and are widely used for further surface functionalization. Since it is mandatory that such layers be organized to provide amine moieties at the surface, the present study deals with exploring amine-terminated SAM formation as an alternative to the usual aminopropylalkylsilane SAM. Additionally, using a long NH2terminated alkyl chain allows the formation of hydrogen bonding thanks to the two NH moieties born along the chain. Furthermore, such hydrogen bonding makes possible to shorten the molecule length while preserving a well-organized monolayer. For this purpose we performed a complete study of the grafting of (3-Trimethoxysilylpropyl) diethylenetriamine (DETAS) on native silicon oxide using various solvents, relative humidity and temperature values. Grafting kinetics was monitored by ellipsometry and goniometry, and SAM structure and organization using AFM and ATR-FTIR spectroscopy. Hydrogen bonding was evidenced within the SAM growth process and in the final complete SAM. We believe such study enables a better control of good quality DETAS SAM in order to improve their efficiency in further surface functionalization applications

L’épave de Port Berteau II (Charente-Maritime)

Découverte en 1973 dans la Charente, en aval de Saintes et par 7 m de fond, l’épave de Port Berteau II a été fouillée de 1992 à 1997 avec une double problématique reposant sur la mise en relation des vestiges de la coque avec son environnement.Conduite selon les techniques classiques de l’archéologie subaquatique, l’étude de l’épave, de l’étrave à l’étambot, a permis de dresser le -portrait architectural » d’un caboteur du début du Vile s. Long de 1430 m et bâti à franc-bord embrure première », ce bateau a été construit pour la navigation fluvio-maritime et pouvait transporter une cargaison d’une dizaine de tonnes. L’analyse du milieu fluvial, relevant de ce que l’on pourrait qualifier d’archéologie nautique, a abouti quant à elle à une restitution du paysage naturel contemporain de l’épave. Le caboteur de Port Berteau II est désormais une référence pour l’histoire de la construction à carvel dans le Ponant uniquement attestée jusqu’alors par des textes du XVe s.Discovered in 1973, the Port Berteau wreck lies at a depth of 7 metres in the Charente river below Samtes. Excavations (1992-1997) were carried out with the dual objective of studying both the hull’s remains and its natural environment.Using the traditional techniques of ship archaeology to examine the wreck from the stem to the stern-post has enabled archaeologists to draw an ‘architectural portrait" of an early 7th century coaster. The 14.30 metre carvel built "frame-first" boat was intended for river navigation and built to carry a cargo of up to ten tonnes. Using what could be called a naval archaeology approach, researchers have analysed the nver environment to reconstruct the natural landscape of the period. The Port Berteau II coaster thus provides a reference for carvel construction history in the Ponant, reviously attested only in 15th century texts

Influence of Uranium on Bacterial Communities: A Comparison of Natural Uranium-Rich Soils with Controls

This study investigated the influence of uranium on the indigenous bacterial community structure in natural soils with high uranium content. Radioactive soil samples exhibiting 0.26% - 25.5% U in mass were analyzed and compared with nearby control soils containing trace uranium. EXAFS and XRD analyses of soils revealed the presence of U(VI) and uranium-phosphate mineral phases, identified as sabugalite and meta-autunite. A comparative analysis of bacterial community fingerprints using denaturing gradient gel electrophoresis (DGGE) revealed the presence of a complex population in both control and uranium-rich samples. However, bacterial communities inhabiting uraniferous soils exhibited specific fingerprints that were remarkably stable over time, in contrast to populations from nearby control samples. Representatives of Acidobacteria, Proteobacteria, and seven others phyla were detected in DGGE bands specific to uraniferous samples. In particular, sequences related to iron-reducing bacteria such as Geobacter and Geothrix were identified concomitantly with iron-oxidizing species such as Gallionella and Sideroxydans. All together, our results demonstrate that uranium exerts a permanent high pressure on soil bacterial communities and suggest the existence of a uranium redox cycle mediated by bacteria in the soil

Polarized Cdc42 activation promotes polar body protrusion and asymmetric division in mouse oocytes.

International audienceAsymmetric meiotic divisions in mammalian oocytes rely on the eccentric positioning of the spindle and the remodeling of the overlying cortex, resulting in the formation of small polar bodies. The mechanism of this cortical polarization, exemplified by the formation of a thick F-actin cap, is poorly understood. Cdc42 is a major player in cell polarization in many systems; however, the spatio-temporal dynamics of Cdc42 activation during oocyte meiosis, and its contribution to mammalian oocyte polarization, have remained elusive. In this study, we investigated Cdc42 activation (Cdc42-GTP), dynamics and role during mouse oocyte meiotic divisions. We show that Cdc42-GTP accumulates in restricted cortical regions overlying meiotic chromosomes or chromatids, in a Ran-GTP-dependent manner. This polarized activation of Cdc42 is required for the recruitment of N-WASP and the formation of F-actin-rich protrusions during polar body formation. Cdc42 inhibition in MII oocytes resulted in the release of N-WASP into the cytosol, a loss of the polarized F-actin cap, and a failure to protrude the second polar body. Cdc42 inhibition also resulted in central spindle defects in activated MII oocytes. In contrast, emission of the first polar body during oocyte maturation could occur in the absence of a functional Cdc42/N-WASP pathway. Therefore, Cdc42 is a new protagonist in chromatin-induced cortical polarization in mammalian oocytes, with an essential role in meiosis II completion, through the recruitment and activation of N-WASP, downstream of the chromatin-centered Ran-GTP gradient

Conclusion

Au cours de ces années de recherche, les problématiques ont évolué, passant de l’analyse d’un site particulier –un port fluvial– à celle d’un espace nautique, avec pour objet principal les moyens de transport mais aussi les aménagements du fleuve, le paysage fluvial et, d’une manière plus large, le cadre régional. Ce changement d’orientation est lié bien sûr à la progression des travaux menés dans la Charente, mais aussi à l’influence des recherches conduites à l’étranger, sous la direction n..

Lexique

About (n. m.). Extrémité par laquelle une pièce de charpente se joint à une autre. About d’un bordage. Accore (n. m.). Pièce de bois qui soutient un bateau en construction ou en réparation. Acculement (n. m.). Élévation des extrémités de la varangue par rapport au plan de la face supérieure de la quille. Allège (n. f.). Embarcation servant au chargement et au déchargement des navires. Allonge (n. f.). Élément d’une membrure qui prolonge la varangue. Apotureau (n. m.). Extrémité supérieure d’u..

Introduction

La fouille de l’épave de Port Berteau II, commencée en 1992, s’est achevée au cours du mois d’octobre 1997. Elle marque le terme d’un long programme de recherches subaquatiques, qui a débuté à la fin de l’été 1971 avec les premiers travaux d’évaluation archéologique du site portuaire médiéval et moderne de Port Berteau, à une cinquantaine de mètres en amont de l’épave. De ce fait, l’étude ici présentée ne peut être dissociée des recherches antérieures menées dans les eaux de la Charente sur d..

Apports de la microscopie réalisée

La microscopie intravitale est une technique de développement récent qui permet de visualiser des phénomènes in situ directement chez l’animal vivant. Elle permet d’enregistrer, par l’intermédiaire d’un microscope adapté, des phénomènes fluorescents, cinétiques, dans l’espace et le temps, apparaissant à l’échelle d’un tissu ou d’un organe chez un animal intact, éveillé ou endormi. Appliquée au cancer, elle a surtout été utilisée à l’étude de la vascularisation intratumorale. Cependant, des tentatives récentes et isolées laissent présager qu’elle devrait avoir un intérêt majeur dans l’étude des mouvements des cellules immunitaires au cours du développement d’une tumeur cancéreuse ainsi que dans celui du recrutement des métastases par les vaisseaux des tissus secondairement envahis. Technique réalisée in vivo chez l’animal, la microscopie intravitale est une des étapes ultimes dans le transfert des connaissances acquises lors d’études fondamentales vers l’application à la médecine humaine. Les observations qu’elle a permis ou permettra d’acquérir sur les vaisseaux intratumoraux et les mouvements des cellules impliquées dans les défenses immunitaires de l’organisme contre les tumeurs cancéreuses font espérer qu’elle sera une aide pour l’évaluation des nouveaux axes thérapeutiques anticancéreux (thérapies antivasculaires ou immunothérapie cellulaire anticancéreuse utilisant des cellules dendritiques ou des lymphocytes)