Social Mix Policies in Paris: Discourses, Policies and Social Effects

International audienceSince the 1980s, the issue of social mix has become a public policy category in France. Enshrined in legislation, yet remaining controversial, it represents a major premise on which housing policies have been reconfigured. The concept of social mix is essentially based on who lives where, but it is also evoked in the context of urban renewal schemes for social housing estates, as well as in relation to new-build developments. A study of the bases of social mix policies conducted in Paris since 2001 in the context of the embourgeoisement of the capital shows the fundamental role of social housing stock. The City Council has become involved in policy decisions about both the location and the allocation of social housing. Particular attention has been paid to the middle classes in the name of the principle of 'balancing the population'. In order to measure the effects of the policy, this article relies on an analysis of two City of Paris schemes that have the stated intent of creating social mix. One of these schemes consists of redeveloping a working-class neighbourhood, Goutte d'Or, while the other involves the new acquisition of social housing in various more affluent neighbourhoods in the capital. This comparative study of the population shows that, whether in a neighbourhood poised for gentrification or in a more affluent neighbourhood, this policy has major effects on forms of local social cohesion, setting in motion individual trajectories and reshaping social and/or ethnic identities

Regulation of carbon metabolism by environmental conditions: a perspective from diatoms and other chromalveolates

Diatoms belong to a major, diverse and species-rich eukaryotic clade, the Heterokonta, within the polyphyletic chromalveolates. They evolved as a result of secondary endosymbiosis with one or more Plantae ancestors, but their precise evolutionary history is enigmatic. Nevertheless, this has conferred them with unique structural and biochemical properties that have allowed them to flourish in a wide range of different environments and cope with highly variable conditions. We review the effect of pH, light and dark, and CO2 concentration on the regulation of carbon uptake and assimilation. We discuss the regulation of the Calvin-Benson-Bassham cycle, glycolysis, lipid synthesis, and carbohydrate synthesis at the level of gene transcripts (transcriptomics), proteins (proteomics) and enzyme activity. In contrast to Viridiplantae where redox regulation of metabolic enzymes is important, it appears to be less common in diatoms, based on the current evidence, but regulation at the transcriptional level seems to be widespread. The role of post-translational modifications such as phosphorylation, glutathionylation, etc., and of protein-protein interactions, has been overlooked and should be investigated further. Diatoms and other chromalveolates are understudied compared to the Viridiplantae, especially given their ecological importance, but we believe that the ever-growing number of sequenced genomes combined with proteomics, metabolomics, enzyme measurements, and the application of novel techniques will provide a better understanding of how this important group of algae maintain their productivity under changing conditions

Graphene in silicon photovoltaic cells

Graphene is an allotrope of carbon. Its structure is one-atom-thick planar sheets of carbon atoms that are densely packed in a honeycomb crystal lattice [1]. The richness of optical and electronic properties of graphene attracts enormous interest. Its true potential seems to be in photonics and optoelectronics, where the combination of its unique optical and electronic properties can be fully exploited. The optical absorption of graphene layers is proportional to the number of layers, each absorbing A=1-T=πα=2.3% over the visible spectrum [2].The rise of graphene in photonics and optoelectronics is shown by several recent results, ranging from solar cells and light emitting devices, to touch screens, photodetectors and ultrafast lasers. Current photovoltaic (PV) technology is dominated by Si cells, with an energy conversion coefficient up to 25% [3]. Such an inorganic PV consists in a current transparent conductor (TC) replacing one of the electrodes of a PIN photodiode. The standard material used so far for these electrodes is indium-tinoxide, or ITO. But indium is expensive and relatively rare, so the search has been on for a suitable replacement. A possible substitute made from inexpensive and ubiquitous carbon is graphene. Being only constituted of carbon, it will become cheap and easily recyclable. But at the moment, the major difficulty consists in its fabrication and/or transfer. Our project consists in synthetizing graphene by CVD (Chemical Vapor Deposition) on Cu and in transferring the obtained layer on silicon PV cells, and then in testing their energy conversion efficiency

A new type of flexible CP12 protein in the marine diatom <i>Thalassiosira pseudonana</i>

International audienceBackground: CP12 is a small chloroplast protein that is widespread in various photosynthetic organisms and is an actor of the redox signaling pathway involved in the regulation of the Calvin Benson Bassham (CBB) cycle. The gene encoding this protein is conserved in many diatoms, but the protein has been overlooked in these organisms, despite their ecological importance and their complex and still enigmatic evolutionary background. Methods: A combination of biochemical, bioinformatics and biophysical methods including electrospray ionizationmass spectrometry, circular dichroism, nuclear magnetic resonance spectroscopy and small X ray scattering, was used to characterize a diatom CP12. Results: Here, we demonstrate that CP12 is expressed in the marine diatom Thalassiosira pseudonana constitutively in dark-treated and in continuous light-treated cells as well as in all growth phases. This CP12 similarly to its homologues in other species has some features of intrinsically disorder protein family: it behaves abnormally under gel electrophoresis and size exclusion chromatography, has a high net charge and a bias amino acid composition. By contrast, unlike other known CP12 proteins that are monomers, this protein is a dimer as suggested by native electrospray ionization-mass spectrometry and small angle X-ray scattering. In addition, small angle X-ray scattering revealed that this CP12 is an elongated cylinder with kinks. Circular dichroism spectra indicated that CP12 has a high content of α-helices, and nuclear magnetic resonance spectroscopy suggested that these helices are unstable and dynamic within a millisecond timescale. Together with in silico predictions, these results suggest that T. pseudonana CP12 has both coiled coil and disordered regions. Conclusions: These findings bring new insights into the large family of dynamic proteins containing disordered regions, thus increasing the diversity of known CP12 proteins. As it is a protein that is more abundant in many stresses, it is not devoted to one metabolism and in particular, it is not specific to carbon metabolism. This raises questions about the role of this protein in addition to the well-established regulation of the CBB cycle

Probing the dynamic stalk region of the ribosome using solution NMR

Abstract: We describe an NMR approach based on the measurement of residual dipolar couplings (RDCs) to probe the structural and motional properties of the dynamic regions of the ribosome. Alignment of intact 70S ribosomes in filamentous bacteriophage enabled measurement of RDCs in the mobile C-terminal domain (CTD) of the stalk protein bL12. A structural refinement of this domain using the observed RDCs did not show large changes relative to the isolated protein in the absence of the ribosome, and we also found that alignment of the CTD was almost independent of the presence of the core ribosome particle, indicating that the inter-domain linker has significant flexibility. The nature of this linker was subsequently probed in more detail using a paramagnetic alignment strategy, which revealed partial propagation of alignment between neighbouring domains, providing direct experimental validation of a structural ensemble previously derived from SAXS and NMR relaxation measurements. Our results demonstrate the prospect of better characterising dynamical and functional regions of more challenging macromolecular machines and systems, for example ribosome–nascent chain complexes

Protein folding on the ribosome studied using NMR spectroscopy

NMR spectroscopy is a powerful tool for the investigation of protein folding and misfolding, providing a characterization of molecular structure, dynamics and exchange processes, across a very wide range of timescales and with near atomic resolution. In recent years NMR methods have also been developed to study protein folding as it might occur within the cell, in a de novo manner, by observing the folding of nascent polypeptides in the process of emerging from the ribosome during synthesis. Despite the 2.3 MDa molecular weight of the bacterial 70S ribosome, many nascent polypeptides, and some ribosomal proteins, have sufficient local flexibility that sharp resonances may be observed in solution-state NMR spectra. In providing information on dynamic regions of the structure, NMR spectroscopy is therefore highly complementary to alternative methods such as X-ray crystallography and cryo-electron microscopy, which have successfully characterized the rigid core of the ribosome particle. However, the low working concentrations and limited sample stability associated with ribosome-nascent chain complexes means that such studies still present significant technical challenges to the NMR spectroscopist. This review will discuss the progress that has been made in this area, surveying all NMR studies that have been published to date, and with a particular focus on strategies for improving experimental sensitivity

Fatal Enterovirus-related Myocarditis in a Patient with Devic’s Syndrome Treated with Rituximab

Enteroviruses are a frequent source of infection and among the most common central nervous system viral pathogens. Enteroviruses – in particular, the Coxsackie B viruses – are a known cause of myocarditis. Rituximab is a genetically engineered chimeric anti-CD20 monoclonal antibody. Many reports in the literature suggest a higher risk of infection following repeated rituximab therapy, including viral infection. However, observations of enterovirus-related myocarditis in the context of rituximab treatment are scarce. The authors describe the case of a patient with neuromyelitis optica spectrum disorder who developed severe and fatal enterovirus-related myocarditis after rituximab therapy with a difficult differential diagnosis of autoimmune or giant-cell myocarditis. This case highlights the importance of complete diagnostic workup in difficult cases of myocarditis, including endomyocardial biopsies