Multiple glycerol shocks increase the calcium phosphate transfection of non-synchronized CHO cells

The exposure of CHO DG44 cells to an osmotic shock, after DNA uptake, results in a cellular volume decrease of approx. 55%. Repetitive osmotic shocks targeted different sub-populations of cells as was demonstrated using two different fluorescent reporter genes. Also the exposure of a calcium phosphate-DNA coprecipitate to high osmolarity in vitro caused the release of the DNA from the precipitate. The results demonstrate the importance of the osmotic shock on the efficient delivery of plasmid DNA to the nucleus of CHO cells following calcium phosphate-mediated transfectio

Characterization of Melan-A reactive memory CD8+ T cells in a healthy donor

Melan-A specific CD8+ T cells are thought to play an important role against the development of melanoma. Their in vivo expansion is often observed with advanced disease. In recent years, low levels of Melan-A reactive CD8+ T cells have also been found in HLA-A2 healthy donors, but these cells harbor naive characteristics and are thought to be mostly cross-reactive for the Melan-A antigen. Here, we report on a large population of CD8+ T cells reactive for the Melan-A antigen, identified in one donor with no evidence of melanoma. Interestingly, this population is oligoclonal and displays a clear memory phenotype. However, a detailed study of these cells indicated that they are unlikely to be directly specific for melanoma, so that their in vivo expansion may have been driven by an exogenous antigen. Screening of a Melan-A cross-reactive peptide library suggested that these cells may be specific for an epitope derived from a Mycobacterium protein, which would provide a further example of CD8+ T cell cross-reactivity between a pathogen antigen and a tumor antigen. Finally, we discuss potential perspectives regarding the role of such cells in heterologous immunity, by influencing the balance between protective immunity and pathology, e.g. in the case of melanoma developmen

The CYP71AZ P450 Subfamily: A Driving Factor for the Diversification of Coumarin Biosynthesis in Apiaceous Plants

International audienceThe production of coumarins and furanocoumarins (FCs) in higher plants is widely considered a model illustration of the adaptation of plants to their environment. In this report, we show that the multiplication of cytochrome P450 variants within the CYP71AZ subfamily has contributed to the diversification of these molecules. Multiple copies of genes encoding this enzyme family are found in Apiaceae, and their phylogenetic analysis suggests that they have different functions within these plants. CYP71AZ1 from Ammi majus and CYP71AZ3, 4, and 6 from Pastinaca sativa were functionally characterized. While CYP71AZ3 merely hydroxylated esculetin, the other enzymes accepted both simple coumarins and FCs. Superimposing in silico models of these enzymes led to the identification of different conformations of three regions in the enzyme active site. These sequences were subsequently utilized to mutate CYP71AZ4 to resemble CYP71AZ3. The swapping of these regions lead to significantly modified substrate specificity. Simultaneous mutations of all three regions shifted the specificity of CYP71AZ4 to that of CYP71AZ3, exclusively accepting esculetin. This approach may explain the evolution of this cytochrome P450 family regarding the appearance of FCs in parsnip and possibly in the Apiaceae

New Equipment for Measurement of Soiling and Specular Reflectance on Solar Mirrors

International audienceDuring the life time of Concentrated Solar Power (CSP) plants, optical performance of solar mirrors is affected by soiling phenomena and surface degradation. It is imperative to dissociate soiling that requires cleaning from irreversible degradations which affect the plant performance. In both cases, small degradations or dust deposition cause an optical reflectance loss. In order to provide an adequate cleaning strategy, operators need to determine soiling-induced performance loss. Several commercial instruments already exist to measure optical reflectance, but they are dedicated to a single wavelength range or angle, punctual measurements or to laboratory analyses. CEA has developed a new kind of laboratory sensor to measure separately the loss of reflectance due to the degradation and soiling, thanks to a CCD camera and photodiodes. This equipment allows addressing variable wavelength, incidence and acceptance angles, to compare specular and hemispherical reflectance from other devices. The analysis of the images will quantify the soiling rate in order to optimize the frequency of cleaning water operations. The aim of the present contribution is to distinguish soiling from degradations (abrasion or corrosion of the reflective layer). This paper reviews the different current research works on prototype instruments and a comparison of this new alternative instrument with available commercial ones

TCRgamma silencing during alphabeta T cell development depends upon pre-TCR-induced proliferation.

During thymus development, immature T cells become committed to two distinct lineages based upon expression of alphabeta or gammadelta TCR. In the alphabeta lineage, developing thymocytes progressively extinguish transcription of the TCRgamma genes by a poorly understood process known as gamma silencing. We show that alphabeta lineage thymocytes in mice lacking a functional pre-TCR undergo limited proliferation and fail to silence TCRgamma genes during development. Stimulation of pre-TCR-deficient immature thymocytes with anti-CD3 Abs does not directly down-regulate TCRgamma transcription but restores TCRgamma silencing following proliferation. Collectively our data reveal an important role for pre-TCR induced proliferation in activating the TCRgamma silencer in alphabeta lineage thymocytes, a process that may reinforce alphabeta or gammadelta lineage commitment

Éruptions eczématiformes chroniques du sujet âgé : quelle imputabilité médicamenteuse ?

International audienceLe rôle des médicaments dans la survenue d’éruptions eczématiformes du sujet âgé (EESA) a été suggéré dans une étude cas-témoin française montrant une fréquence de prise des inhibiteurs calciques de 26 % chez les patients ayant une EESA (OR de 2,5 par rapport aux témoins sans eczéma). Ces résultats ont ensuite été confirmés par une étude rétrospective américaine. Des cas isolés d’EESA ont depuis été rapportés avec le clopidogrel, les IEC, les ARAII et les diurétiques. Notre étude initiale ayant été réalisée il y a 15 ans, nous en avons réalisé une nouvelle pour réévaluer l’association entre les prises médicamenteuses et les EESA