Compounding and processing of biodegradable materials based on PLA for packaging applications: In greening the 21st century materials world.

Poly(lactic acid) is a well known polymer for more than 20 years in the biomedical fieldsapplications. Today, according to rising prices of oil and massive consumption of fossil resource,this biodegradable aliphatic polyester is on the way to be a wide used commodity polymer.Moreover PLA is as a “green plastic” because it is synthesized from annually renewable resources.In many ways similar to poly(ethylene terephtalate) such as rigidity, transparency, crystallizationkinetics and food contact ability, it fulfills the packaging industry requirements for most of the rigidobjects. But for applications like hot food packages, soft films and stretch blow bottles for examplesome properties of PLA have to be improved like heat deflection temperature (HDT), impactstiffness and gas barrier properties. There are many ways reported in literature today to improvethese properties. In order to compare it with other well known polymers, figure 1 representsthermal properties of PLA and these polymers. The aim of the work deals to identify actualweaknesses of commercial grades of PLA. Secondly, to present pertinent ways to improve PLA‟sproperties have been identified according to chosen process and final properties wished. This studyis composed of three main items. In a first time, a bibliographical study is necessary to identify thedifferent ways to improve PLA‟s properties used by researchers and industrials in literature. Themost significant ways will be describe here. Then PLA compound (PLA with additives or PLAcopolymers for examples) will be synthesized in conditions closed to industrial conditions studyingcrystallisation kinetic and rheological properties. In this step thermal, physico-chemical andmechanical properties of products synthesized will be characterized. At the end of this study thebest ways of improving PLA‟s behavior will be presented and describe

Rôle des facteurs écologiques dans le processus de spéciation en milieu insulaire. Effet de l'habitat et des pollinisateurs sur la diversification du faham (Jumellea spp., Orchidaceae) aux Mascareignes

Mechanisms responsible for the establishment of reproductive isolation are little studied in island adaptive radiations. According to the theory of ecological speciation, reproductive isolation results from the ecologically-based divergent selection. By their unique characteristics, oceanic islands are ideal systems to study the role of ecological factors in the diversification of endemic lineages. This study focuses on the role of habitat and pollinators in restricting inter and intraspecific gene flow between populations of faham (Jumellea spp.), an orchid endemic to Mascarene Islands. To do this, patterns of phenotypic differentiation (floral traits), environmental differentiation (habitat, altitude, climate) and genetic differentiation (nuclear microsatellites) were compared. At the intraspecific level, the results show that gene flow restriction is mainly due to the colonization of different habitat types with no obvious role of pollinators. At the interspecific level, in addition to the role of habitat, pollinator shift seems to explain effective complete reproductive isolation. By placing these results into the continuum of speciation, it appears that reproductive isolation evolve initially in response to adaptation to different habitats and, in a second phase, would be enhanced by pollinator-driven divergent selection. Operationally, this study reviews the taxonomy of faham and proposes to define management units and priorities in terms of conservation.Les mécanismes à l'origine de la mise en place de l'isolement reproducteur sont relativement peu étudiés dans les radiations adaptatives insulaires. Selon la théorie de la spéciation écologique, l'isolement reproducteur résulte de la sélection divergente agissant sur des populations écologiquement différentes. Par leurs caractéristiques uniques, les îles océaniques constituent des systèmes idéals pour étudier le rôle des facteurs écologiques dans la diversification des lignées endémiques. Le rôle de l'habitat et des pollinisateurs dans la restriction des flux géniques inter et intraspécifique est examiné chez le faham (Jumellea rossii et J. fragrans), une orchidée endémique des Mascareignes. Pour ce faire, les patrons de différenciation phénotypique (traits floraux morphologiques et chimiques), environnementale (habitat, altitude, climat) et génétique (microsatellites nucléaires) ont été confrontés. À l'échelle intraspécifique, les résultats montrent que les flux de gènes sont principalement limités par les différences environnementales entre habitats sans rôle évident des pollinisateurs. A l'échelle interspécifique, outre les variations d'habitat, le changement de pollinisateur semble expliquer l'absence de flux de gènes. Dans le cadre du continuum de spéciation chez le faham, l'isolement reproducteur évoluerait en premier lieu en réponse à l'adaptation aux différents habitats, puis serait renforcé par l'adaptation à différents pollinisateurs. La révision de la taxinomie du clade et les priorités en terme de conservation sont également discutées

Multiplex degenerate PCR coupled with an oligo sorbent array for human endogenous retrovirus expression profiling

Human endogenous retroviruses (HERVs) can be divided into distinct families of tens to thousands of paralogous loci. The expression of HERV elements has been detected in all tissues tested to date, particularly germ cells, embryonic tissues and neoplastic tissues. Hence, the study of HERV expression could represent added value in cancer diagnosis. We developed a quantitative assay combining a multiplex degenerate PCR (MD-PCR) amplification, based on the relative conservation of the pol genes, and a colorimetric Oligo Sorbent Array (OLISA(®)). Nine HERV families were selected and amplification primers and capture probes were designed for each family. The features required to achieve efficient amplification of most of the elements of each HERV family and balanced co-amplification of all HERV families were analyzed. We found that MD-PCR reliability, i.e. equivalence of amplification and dose-effect relationship, relied on the adjustment of three critical parameters: the primer degeneracy, the relative concentration of each primer and the total amount of primers in the amplification mixture. The analysis of tumoral versus normal tissues suggests that this assay could prove useful in tumor phenotyping

Natural history of the ERVWE1 endogenous retroviral locus

BACKGROUND: The human HERV-W multicopy family includes a unique proviral locus, termed ERVWE1, whose full-length envelope ORF was preserved through evolution by the action of a selective pressure. The encoded Env protein (Syncytin) is involved in hominoid placental physiology. RESULTS: In order to infer the natural history of this domestication process, a comparative genomic analysis of the human 7q21.2 syntenic regions in eutherians was performed. In primates, this region was progressively colonized by LTR-elements, leading to two different evolutionary pathways in Cercopithecidae and Hominidae, a genetic drift versus a domestication, respectively. CONCLUSION: The preservation in Hominoids of a genomic structure consisting in the juxtaposition of a retrotransposon-derived MaLR LTR and the ERVWE1 provirus suggests a functional link between both elements

Morphological differences and identification of Jumellea rossii and Jumellea fragrans (Orchidaceae) in Reunion Island: implications for conservation

Conservation strategies are not possible when there is confusion in the taxonomic status of a group of plants. Such confusion makes difficult for systematic biologists to identify functional biological entities. This is particularly true in the case of species that diversified fast due to adaptive radiation particularly plants from the oceanic islands. It is the case of certain orchids from Reunion Island. Among them, the “Faham” complex includes several taxa whose populations are situated at various elevations with morphological and reproductive variations. These taxa are actually merged into one name: Jumellea fragrans causing confusion in their taxonomic status. This confusion has caused numerous problems of identification and errors hindering the protection status of the species. In this study, we suggest to clarify the systematic position of the taxa composing complex Jumellea fragrans using a biometric approach at population scale. The objective is to identify morphological characters that allow distinguishing the taxa of the J. fragrans complex. Morphological characters (vegetative and floral) are measured on individuals from three natural populations representative of altitudinal range of the complex. Principal component analysis made on the characters show a separation of the individuals in two groups (Mare-Longue vs Basse-Vallée and Cilaos). Nine characters (on 14 measured) are significantly different between Mare-Longue population and the populations of Basse-Vallée and Cilaos and allow identifying both groups. Population of Mare-Longue belongs to the species Jumellea fragrans (Thouars) Schltr. and populations of Basse-Vallée and Cilaos belongs to the species Jumellea rossii Senghas. In terms of conservation, the first recommendation is to recognize two different species: J. rossii and J. fragrans. Moreover, putting J. fragrans into the « vulnerable » IUCN Red List category and the adoption of a protection status are recommended. Concerning J. rossii, more studies on geographical range and population dynamics are necessary to estimate the risk of extinction. In the same way, studies on genetic variability of both species would generate useful data for implementation of conservation strategiesLa clarification du statut taxinomique des espèces constitue un préambule nécessaire à la mise en place de mesures de conservation appropriées et efficaces, particulièrement dans les îles océaniques où la radiation adaptative rend difficile la reconnaissance des entités biologiques fonctionnelles. C’est le cas de certaines orchidées de La Réunion comme le « Faham » (Jumellea spp.) qui regroupe plusieurs taxons dont les populations se situent à différentes altitudes et semblent présenter des variations morphologiques et reproductives. Dans cette étude, nous proposons d’éclaircir la position systématique des taxons composant le complexe d’espèces regroupées sous le nom de « Faham » par le biais d’une approche morphométrique à l’échelle populationnelle et d’identifier des caractères morphologiques permettant de distinguer les différents taxons. Quatorze caractères (végétatifs et floraux) ont été mesurés sur 51 individus issus de trois populations naturelles représentatives de la distribution altitudinale du complexe. Des analyses multivariées effectuées sur ces caractères ont montré une séparation des individus en deux groupes (Mare-Longue d’une part, Basse-Vallée et Cilaos d’autre part). Neuf caractères sont significativement différents entre la population de Mare-Longue et les populations de Basse-Vallée et Cilaos et permettent de distinguer les deux groupes. La population de Mare-Longue appartiendrait à l’espèce Jumellea fragrans (Thouars) Schltr. et les populations de Basse-Vallée et Cilaos à l’espèce Jumellea rossii Senghas. En termes de conservation, la première recommandation est de reconnaître deux espèces bien distinctes : J. rossii et J. fragrans. D’autre part, l’inscription dans la catégorie « vulnérable » de la Liste Rouge de l’UICN et l’adoption d’un statut de protection semblent fortement recommandées pour J. fragrans. Concernant J. rossii, des connaissances approfondies sur la distribution géographique et la dynamique des populations de l’espèce s’avèrent nécessaires afin d’évaluer le risque d’extinction. Parallèlement, l’étude de la diversité génétique des deux espèces fournirait des données utiles pour la mise en oeuvre de plans de conservatio

Liver fibrosis staging using supersonic shear imaging : a clinical study on 142 patients

International audienceI. Background, Motivation and ObjectiveFibrosis staging can be assessed by a rough estimation of the liver stiffness averaged along an ultrasonic A-line. Providing a complete 2D map of liver stiffness would thus be of great clinical interest for the diagnosis of hepatic fibrosis and help prevent upcoming cirrhosis. However, such measurement requires both a quantitative value of shear elasticity and a great precision to discriminate between different fibrosis levels. Beyond the scope of non-invasive fibrosis quantification, it is also envisioned that quantitative elasticity imaging of liver will have potential interest for liver cancer diagnosis. In this work, the Supersonic Shear Imaging technique (SSI) is proposed to map the in vivo viscoelastic parameters of liver on patients with hepatitis C and derive a mean elasticity of liver tissues. The results are compared to biological tests (Fib4, Apri, Forns) and Fibroscan® measurements. II. Statement of Contribution / MethodsThe SSI technique is based on the radiation force induced by a conventional ultrasonic probe to generate a planar shear wave deep into tissues. The shear wave propagation throughout the medium is caught in real time thanks to an ultrafast ultrasound scanner (up to 5000 frames/s). Using modified sequences and post-processing, this technique is implemented on curved arrays in order to get a larger field of view of liver tissues. A study on 150 HCV patients with different fibrosis stages F has been conducted in order to investigate the accuracy of the technique (F ϵ [0;4]). Quantitative maps of liver elasticity are produced for each volunteer with a linear and a curved array. III. ResultsB-mode images of 120x75 mm² and corresponding elasticity maps are obtained using a 2.5 MHz curved ultrasonic probe with a good reproducibility and accuracy. The shear wave phase velocity dispersion is also calculated. This study shows a good correlation between the values obtained by SSI and the fibrosis levels diagnosed by biological tests (p-index 0.9 for F>3 and Y> 0.8 for F>2). Results are also compared (r2 > 0.92) to the Fibroscan® elasticity measurement by fitting the velocity dispersion curves obtained by SSI at 50 Hz.IV. Discussion and ConclusionsThis real-time elasticity mapping using an ultrasonic curved probe offers better signal to noise ratio than linear arrays and a larger area in the patient's liver (13.3±2.8 cm² estimation area). This gives more confidence on the accuracy of the diagnosis of the fibrosis stage. Furthermore, the elasticity parameters obtained with SSI give access to the shear wave group velocity and the phase velocity. As a consequence, the SSI assessment of liver stiffness could potentially give more information on the viscoelasticity properties of the liver

Custom human endogenous retroviruses dedicated microarray identifies self-induced HERV-W family elements reactivated in testicular cancer upon methylation control

Endogenous retroviruses (ERVs) are an inherited part of the eukaryotic genomes, and represent ∼400 000 loci in the human genome. Human endogenous retroviruses (HERVs) can be divided into distinct families, composed of phylogenetically related but structurally heterogeneous elements. The majority of HERVs are silent in most physiological contexts, whereas a significant expression is observed in pathological contexts, such as cancers. Owing to their repetitive nature, few of the active HERV elements have been accurately identified. In addition, there are no criteria defining the active promoters among HERV long-terminal repeats (LTRs). Hence, it is difficult to understand the HERV (de)regulation mechanisms and their implication on the physiopathology of the host. We developed a microarray to specifically detect the LTR-containing transcripts from the HERV-H, HERV-E, HERV-W and HERV-K(HML-2) families. HERV transcriptome was analyzed in the placenta and seven normal/tumoral match-pair samples. We identified six HERV-W loci overexpressed in testicular cancer, including a usually placenta-restricted transcript of ERVWE1. For each locus, specific overexpression was confirmed by quantitative RT-PCR, and comparison of the activity of U3 versus U5 regions suggested a U3-promoted transcription coupled with 5′R initiation. The analysis of DNA from tumoral versus normal tissue revealed that hypomethylation of U3 promoters in tumors is a prerequisite for their activation

Neuronal Conduction of Excitation without Action Potentials Based on Ceramide Production

International audienceBACKGROUND: Action potentials are the classic mechanism by which neurons convey a state of excitation throughout their length, leading, after synaptic transmission, to the activation of other neurons and consequently to network functioning. Using an in vitro integrated model, we found previously that peripheral networks in the autonomic nervous system can organise an unconventional regulatory reflex of the digestive tract motility without action potentials. METHODOLOGY/PRINCIPAL FINDINGS: In this report, we used combined neuropharmacological and biochemical approaches to elucidate some steps of the mechanism that conveys excitation along the nerves fibres without action potentials. This mechanism requires the production of ceramide in membrane lipid rafts, which triggers in the cytoplasm an increase in intracellular calcium concentration, followed by activation of a neuronal nitric oxide synthase leading to local production of nitric oxide, and then to guanosine cyclic monophosphate. This sequence of second messengers is activated in cascade from rafts to rafts to ensure conduction of the excitation along the nerve fibres. CONCLUSIONS/SIGNIFICANCE: Our results indicate that second messengers are involved in neuronal conduction of excitation without action potentials. This mechanism represents the first evidence-to our knowledge-that excitation is carried along nerves independently of electrical signals. This unexpected ceramide-based conduction of excitation without action potentials along the autonomic nerve fibres opens up new prospects in our understanding of neuronal functioning