Prion Strain Discrimination Based on Rapid In Vivo Amplification and Analysis by the Cell Panel Assay

Prion strain identification has been hitherto achieved using time-consuming incubation time determinations in one or more mouse lines and elaborate neuropathological assessment. In the present work, we make a detailed study of the properties of PrP-overproducing Tga20 mice. We show that in these mice the four prion strains examined are rapidly and faithfully amplified and can subsequently be discriminated by a cell-based procedure, the Cell Panel Assay

In Vitro and In Vivo Neurotoxicity of Prion Protein Oligomers

The mechanisms underlying prion-linked neurodegeneration remain to be elucidated, despite several recent advances in this field. Herein, we show that soluble, low molecular weight oligomers of the full-length prion protein (PrP), which possess characteristics of PrP to PrPsc conversion intermediates such as partial protease resistance, are neurotoxic in vitro on primary cultures of neurons and in vivo after subcortical stereotaxic injection. Monomeric PrP was not toxic. Insoluble, fibrillar forms of PrP exhibited no toxicity in vitro and were less toxic than their oligomeric counterparts in vivo. The toxicity was independent of PrP expression in the neurons both in vitro and in vivo for the PrP oligomers and in vivo for the PrP fibrils. Rescue experiments with antibodies showed that the exposure of the hydrophobic stretch of PrP at the oligomeric surface was necessary for toxicity. This study identifies toxic PrP species in vivo. It shows that PrP-induced neurodegeneration shares common mechanisms with other brain amyloidoses like Alzheimer disease and opens new avenues for neuroprotective intervention strategies of prion diseases targeting PrP oligomers

Atypical BSE (BASE) Transmitted from Asymptomatic Aging Cattle to a Primate

BACKGROUND: Human variant Creutzfeldt-Jakob Disease (vCJD) results from foodborne transmission of prions from slaughtered cattle with classical Bovine Spongiform Encephalopathy (cBSE). Atypical forms of BSE, which remain mostly asymptomatic in aging cattle, were recently identified at slaughterhouses throughout Europe and North America, raising a question about human susceptibility to these new prion strains. METHODOLOGY/PRINCIPAL FINDINGS: Brain homogenates from cattle with classical BSE and atypical (BASE) infections were inoculated intracerebrally into cynomolgus monkeys (Macacca fascicularis), a non-human primate model previously demonstrated to be susceptible to the original strain of cBSE. The resulting diseases were compared in terms of clinical signs, histology and biochemistry of the abnormal prion protein (PrPres). The single monkey infected with BASE had a shorter survival, and a different clinical evolution, histopathology, and prion protein (PrPres) pattern than was observed for either classical BSE or vCJD-inoculated animals. Also, the biochemical signature of PrPres in the BASE-inoculated animal was found to have a higher proteinase K sensitivity of the octa-repeat region. We found the same biochemical signature in three of four human patients with sporadic CJD and an MM type 2 PrP genotype who lived in the same country as the infected bovine. CONCLUSION/SIGNIFICANCE: Our results point to a possibly higher degree of pathogenicity of BASE than classical BSE in primates and also raise a question about a possible link to one uncommon subset of cases of apparently sporadic CJD. Thus, despite the waning epidemic of classical BSE, the occurrence of atypical strains should temper the urge to relax measures currently in place to protect public health from accidental contamination by BSE-contaminated products

Prion Protein Is a Key Determinant of Alcohol Sensitivity through the Modulation of N-Methyl-D-Aspartate Receptor (NMDAR) Activity

The prion protein (PrP) is absolutely required for the development of prion diseases; nevertheless, its physiological functions in the central nervous system remain elusive. Using a combination of behavioral, electrophysiological and biochemical approaches in transgenic mouse models, we provide strong evidence for a crucial role of PrP in alcohol sensitivity. Indeed, PrP knock out (PrP−/−) mice presented a greater sensitivity to the sedative effects of EtOH compared to wild-type (wt) control mice. Conversely, compared to wt mice, those over-expressing mouse, human or hamster PrP genes presented a relative insensitivity to ethanol-induced sedation. An acute tolerance (i.e. reversion) to ethanol inhibition of N-methyl-D-aspartate (NMDA) receptor-mediated excitatory post-synaptic potentials in hippocampal slices developed slower in PrP−/− mice than in wt mice. We show that PrP is required to induce acute tolerance to ethanol by activating a Src-protein tyrosine kinase-dependent intracellular signaling pathway. In an attempt to decipher the molecular mechanisms underlying PrP-dependent ethanol effect, we looked for changes in lipid raft features in hippocampus of ethanol-treated wt mice compared to PrP−/− mice. Ethanol induced rapid and transient changes of buoyancy of lipid raft-associated proteins in hippocampus of wt but not PrP−/− mice suggesting a possible mechanistic link for PrP-dependent signal transduction. Together, our results reveal a hitherto unknown physiological role of PrP on the regulation of NMDAR activity and highlight its crucial role in synaptic functions

Prion Protein Accumulation In Lipid Rafts of Mouse Aging Brain

The cellular form of the prion protein (PrP(C)) is a normal constituent of neuronal cell membranes. The protein misfolding causes rare neurodegenerative disorders known as transmissible spongiform encephalopathies or prion diseases. These maladies can be sporadic, genetic or infectious. Sporadic prion diseases are the most common form mainly affecting aging people. In this work, we investigate the biochemical environment in which sporadic prion diseases may develop, focusing our attention on the cell membrane of neurons in the aging brain. It is well established that with aging the ratio between the most abundant lipid components of rafts undergoes a major change: while cholesterol decreases, sphingomyelin content rises. Our results indicate that the aging process modifies the compartmentalization of PrP(C). In old mice, this change favors PrP(C) accumulation in detergent-resistant membranes, particularly in hippocampi. To confirm the relationship between lipid content changes and PrP(C) translocation into detergent-resistant membranes (DRMs), we looked at PrP(C) compartmentalization in hippocampi from acid sphingomyelinase (ASM) knockout (KO) mice and synaptosomes enriched in sphingomyelin. In the presence of high sphingomyelin content, we observed a significant increase of PrP(C) in DRMS. This process is not due to higher levels of total protein and it could, in turn, favor the onset of sporadic prion diseases during aging as it increases the PrP intermolecular contacts into lipid rafts. We observed that lowering sphingomyelin in scrapie-infected cells by using fumonisin B1 led to a 50% decrease in protease-resistant PrP formation. This may suggest an involvement of PrP lipid environment in prion formation and consequently it may play a role in the onset or development of sporadic forms of prion diseases

La gouvernance des espaces publics à l'épreuve de l'informalité. Conflits, corruption et pratiques du droit dans l'occupation des rues par les vendeurs informels à Mumbai

Since the economic reforms of the 1990’s, street vending plays an important part in everyday life and urban economy in many cities all over India. In Mumbai, street trading allows a large part of urban dwellers to earn a living and provide some essential and affordable goods to the population. However, this activity seems to be “unwanted”, according to urban planning and governance policies and according to a part of “civil society” discourses.Consequently, street vendors are central in the conflicts about public space, which represent a working and living place, a vital spatial resource but also a place for fluent traffic, leisure activities, flânerie or consumption. Moreover, for a large part of official and non-official urban actors, public spaces are a source of informal income through corruption and clientelism practices. Indeed, hawkers, considered as illegal, are victims of a huge extortion process by the municipality and police but also by some informal actors.A new law for the defence of street vendors’ rights (Street vendors Act) has been voted in March 2014 at central level, and recognizes the legitimacy and the legality of these activities through a regularization process. In this context, this article tries to analyse the use of law in public spaces conflicts, as well as concrete practices of law through transgressions and negotiations. Analysing informality seems to be a relevant case to understand the tensions between the normative aspect of public spaces and the diversity of their modalities of appropriation, and the plurality of powers which are ruling public spaces occupation.Depuis les réformes économiques des années 1990, le commerce représente en Inde une part de plus en plus importante des économies urbaines. À Mumbai, ce commerce fait vivre directement et indirectement un très grand nombre de résidents urbains tout en fournissant quotidiennement des services essentiels à une grande partie de la population. Pour autant, dans les discours et les politiques d’aménagement et de gouvernance de l’espace urbain, il apparaît comme une activité indésirable.Dès lors, les vendeurs des rues sont au cœur des conflits portant sur l’espace public, envisagé comme un lieu de travail, un lieu de vie, une ressource économique urbaine essentielle mais également comme un espace de circulation, de récréation, de flânerie et de consommation. Par ailleurs, pour nombre d’acteurs, l’espace public représente une « rente spatiale » informelle, créée par des pratiques corruptives, notamment pour les pouvoirs municipaux qui prélèvent une « taxe » sur les activités des rues rendues illégales, mais également par des pratiques clientélistes et mafieuses pour d’autres types d’acteurs exerçant un contrôle informel sur l’espace.Une nouvelle loi pour la défense des droits des vendeurs des rues (Street Vendors Act) a été adoptée en mars 2014 au niveau fédéral, reconnaissant la légitimité et la légalité de leurs activités par le biais d’un processus de régularisation. Dans ce contexte, il s’agit d’analyser la place du droit dans les situations de conflits portant sur les espaces publics, ainsi que les pratiques concrètes de sa mise en œuvre, à savoir les transgressions, les détournements et les arrangements. L’étude de la notion d’informalité politique constitue ici un prisme pertinent pour analyser la tension entre l’aspect normatif des espaces publics et leurs modes divers d’appropriation ainsi que la pluralité des pouvoirs régissant l’occupation de ces espaces

La compensation écologique : le droit face aux contraintes territoriales et aux dynamiques écologiques : France, Colombie et Pérou

Biodiversity offsetting is a mechanism adopted by a growing number of countries to limit the loss of biodiversity resulting from development projects, with the aim of achieving no net loss. It is the final step in the hierarchy of mitigation measures (avoid-minimize-offset). However, its very principle continues to be decried. Numerous limitations of biodiversity offsets have been highlighted, including its lack of effectiveness and efficiency, which makes it a source of dissatisfaction. This thesis brings together the fields of territorial geography, ecology and law, through an interdisciplinary analysis aimed at answering the following question: could a better interdisciplinary and cognitive integration of biodiversity offsets enable it to be perfected, i.e., to provide solutions to the limitations observed, in order to ensure its success and thus a real protection of biodiversity? The research focused on three different research areas: (i) a comprehensive study (from upstream to downstream phases) of the A79 highway (Route Centre Europe Atlantique) project in the Allier department, (ii) an analysis of court rulings on the A355 highway project (Strasbourg western bypass) and, finally, (iii) an international benchmarking study of Colombia and Peru, countries that could be a source of useful lessons for the French context. This thesis adds to the body of evaluative work on biodiversity offsetting.La compensation écologique est un mécanisme adopté par un nombre croissant de pays pour limiter la perte de biodiversité résultant des projets d’aménagement, à travers un objectif d’absence de perte nette. Elle constitue la dernière étape de la hiérarchie des mesures d’atténuation (éviter-réduire-compenser). Elle demeure toutefois décriée dans son principe même. De nombreuses limites liées à la compensation écologique ont été mises en évidence, parmi lesquelles son manque d’efficacité qui en fait une source d’insatisfaction. Cette thèse croise les regards entre les domaines de la géographie des territoires, de l’écologie et du droit, à travers une analyse interdisciplinaire ayant pour objectif de répondre à la question suivante : une meilleure intégration interdisciplinaire et cognitive de la compensation écologique pourrait-elle permettre de la perfectionner, c’est-à-dire d’apporter des solutions aux limites constatées, afin d’assurer son efficacité et ainsi une réelle protection de la biodiversité ? Les recherches ont porté sur trois terrains : (i) l’étude, dans sa globalité (de la phase amont à la phase aval), du projet d’autoroute A79 (Route Centre Europe Atlantique) dans l’Allier, (ii) l’analyse des décisions juridictionnelles rendues dans le cadre du projet d’autoroute A355 (grand contournement ouest de Strasbourg) et, enfin, (iii) la réalisation d’un benchmark international portant sur la Colombie et le Pérou, pays pouvant être source d’enseignements pour le contexte français. Cette thèse s’ajoute au corpus des travaux à portée évaluative relative à la compensation écologique

L'étude d'impact sur l'environnement : cadre juridique et fonctionnement pratique

Engineering schoo

[Case study] Egyptian Vulture, Cinereous Vulture, Bearded Vulture, Griffon Vulture - France

In the 19 th and 20 th centuries, the population of all four species of vultures declined drastically in France, as a result of intentional persecution and accidental poisoning as a consequence of the use of synthetic pesticides after World War II. Other causes included food shortages due notably to the abandonment of extensive livestock farming and transhumance, and habitat loss and fragmentation. The most common threats now are electrocution and collision with power lines and wind turbines. Recovery has occurred as a result of research into the key threats followed up by the development of European and national action plans (for all four species) that have been implemented through collaboration between authorities, NGOs, livestock farmers, electricity providers and hunters, including through a number of LIFE Nature projects. Key measures to reduce mortality rates have included modification of electricity structures and experimentation with lead-free ammunition. Supplementary feeding, habitat management and the protection of nesting birds from human disturbances has increased breeding productivity. Targeted reintroduction measures have reestablished populations in isolated areas and helped to address the need to increase genetic variability