Nanodevices for correlated electrical transport and structural investigation of individual carbon nanotubes

We report a new approach to the correlation of the structural properties and the transport properties of carbon nanotubes. Through an original combination of UV lithography, custom-made photosensitive sol–gel resist and deep reactive ion etching (RIE), we have successfully integrated membrane technology and nanodevice fabrication for the electrical connection of individual carbon nanotubes. After single wall nanotube (SWNT) deposition by molecular combing and contacting using high resolution electron beam lithography, we obtain a device that allows both the investigation of the nanotubes and the contact regions by transmission electron microscopy (TEM) and the measurement of the electronic transport properties of the same individual nano-object. The whole fabrication process is detailed and the demonstration that the micro membranes are suitable for both TEM inspection and nanoelectrode fabrication is given

Midbody and primary cilium of neural progenitors release extracellular membrane particles enriched in the stem cell marker prominin-1

Expansion of the neocortex requires symmetric divisions of neuroepithelial cells, the primary progenitor cells of the developing mammalian central nervous system. Symmetrically dividing neuroepithelial cells are known to form a midbody at their apical (rather than lateral) surface. We show that apical midbodies of neuroepithelial cells concentrate prominin-1 (CD133), a somatic stem cell marker and defining constituent of a specific plasma membrane microdomain. Moreover, these apical midbodies are released, as a whole or in part, into the extracellular space, yielding the prominin-1–enriched membrane particles found in the neural tube fluid. The primary cilium of neuroepithelial cells also concentrates prominin-1 and appears to be a second source of the prominin-1–bearing extracellular membrane particles. Our data reveal novel origins of extracellular membrane traffic that enable neural stem and progenitor cells to avoid the asymmetric inheritance of the midbody observed for other cells and, by releasing a stem cell membrane microdomain, to potentially influence the balance of their proliferation versus differentiation

Release of extracellular membrane vesicles from microvilli of epithelial cells is enhanced by depleting membrane cholesterol

AbstractWe previously reported on the occurrence of prominin-1-carrying membrane vesicles that are released into body fluids from microvilli of epithelial cells. This release has been implicated in cell differentiation. Here we have characterized these vesicles released from the differentiated Caco-2 cells. We find that in these vesicles, prominin-1 directly interacts with membrane cholesterol and is associated with a membrane microdomain. The cholesterol depletion using methyl-β-cyclodextrin resulted in a marked increase in their release, and a dramatic change in the microvillar ultrastructure from a tubular shape to a “pearling” state, with multiple membrane constrictions, suggesting a role of membrane cholesterol in vesicle release from microvilli

MoccaDB - an integrative database for functional, comparative and diversity studies in the Rubiaceae family

<p>Abstract</p> <p>Background</p> <p>In the past few years, functional genomics information has been rapidly accumulating on Rubiaceae species and especially on those belonging to the <it>Coffea </it>genus (coffee trees). An increasing number of expressed sequence tag (EST) data and EST- or genomic-derived microsatellite markers have been generated, together with Conserved Ortholog Set (COS) markers. This considerably facilitates comparative genomics or map-based genetic studies through the common use of orthologous loci across different species. Similar genomic information is available for e.g. tomato or potato, members of the Solanaceae family. Since both Rubiaceae and Solanaceae belong to the Euasterids I (lamiids) integration of information on genetic markers would be possible and lead to more efficient analyses and discovery of key loci involved in important traits such as fruit development, quality, and maturation, or adaptation. Our goal was to develop a comprehensive web data source for integrated information on validated orthologous markers in Rubiaceae.</p> <p>Description</p> <p>MoccaDB is an online MySQL-PHP driven relational database that houses annotated and/or mapped microsatellite markers in Rubiaceae. In its current release, the database stores 638 markers that have been defined on 259 ESTs and 379 genomic sequences. Marker information was retrieved from 11 published works, and completed with original data on 132 microsatellite markers validated in our laboratory. DNA sequences were derived from three <it>Coffea </it>species/hybrids. Microsatellite markers were checked for similarity, <it>in vitro </it>tested for cross-amplification and diversity/polymorphism status in up to 38 Rubiaceae species belonging to the Cinchonoideae and Rubioideae subfamilies. Functional annotation was provided and some markers associated with described metabolic pathways were also integrated. Users can search the database for marker, sequence, map or diversity information through multi-option query forms. The retrieved data can be browsed and downloaded, along with protocols used, using a standard web browser. MoccaDB also integrates bioinformatics tools (CMap viewer and local BLAST) and hyperlinks to related external data sources (NCBI GenBank and PubMed, SOL Genomic Network database).</p> <p>Conclusion</p> <p>We believe that MoccaDB will be extremely useful for all researchers working in the areas of comparative and functional genomics and molecular evolution, in general, and population analysis and association mapping of Rubiaceae and Solanaceae species, in particular.</p

Methylation-associated PHOX2B gene silencing is a rare event in human neuroblastoma.

International audienceNeuroblastoma (NB), an embryonic tumour originating from neural crest cells, is one of the most common solid tumours in childhood. Although NB is characterised by numerous recurrent, large-scale chromosome rearrangements, the genes targeted by these imbalances have remained elusive. We recently identified the paired-like homeobox 2B (PHOX2B, MIM 603851) gene as disease-causing in dysautonomic disorders including Congenital Central Hypoventilation Syndrome (CCHS), Hirschsprung disease (HSCR) and NB in various combinations. Most patients with NB due to a germline heterozygous PHOX2B gene mutation are familial and/or syndromic. PHOX2B, at chromosome 4p12, does not lie in a commonly rearranged locus in NB. To evaluate the role of PHOX2B in sporadic, isolated NB, we analysed 13 NB cell lines and 45 tumours for expression, mutations of coding and promoter sequences, loss of heterozygosity (LOH), or aberrant hypermethylation of PHOX2B (13 cell lines and 18 tumours). We didn't identify any mutation but LOH in about 10% of the cases and aberrant CpG dinucleotide methylation of the 500 bp PHOX2B promoter region in 4/31 tumours and cell lines (12.9%). Altogether, both germinal and somatic anomalies at the PHOX2B locus are found in NB

Rejets médicamenteux dans les eaux

La pollution de l'environnement, et plus particulièrement des eaux, par les micropolluants d'origine pharmaceutique n'est pas un phénomène récent. Chaque année, des milliers de tonnes de substances pharmacologiquement actives sont utilisées afin de traiter les maladies humaines et animales. Ce sont les rejets de ces substances qui penvent se retrouver, sous des formes plus ou moins actives dans les eaux. Il devient urgent d'évaluer les risques dont ils peuvent être responsables, sur la faune et la flore aquatiques, mais également sur l'homme. Il est nécessaire de mettre au point des méthodes d'évaluation qualitative et quantitative des différentes substances. Les résidus médicamenteux ont été incriminés dans des phénomènes d'antibio-résistance ou encore de modulations endocriniennes sur des espèces aquatiques. De tels efforts doivent être pris en charge rapidement afin de préserver notre environnement. L'évaluation des impacts écologiques des substances présentes à faibles concentrations est en plein développement et représente un enjeu majeur à l'échelle nationale et internationale. En effet, de nombreux programmes d'évaluation ont été initiés durant cette dernière décennie, notamment au niveau européen. En novembre 2009, le gouvernement français intégrait le Plan National sur les Résidus Médicamenteux (PNRM) à son projet de Plan National Santé Environnement 2(PNSE 2) lancé en juin 2009.ANGERS-BU Médecine-Pharmacie (490072105) / SudocSudocFranceF

Monitoring Rainfall Patterns in the Southern Amazon with PERSIANN-CDR Data: Long-Term Characteristics and Trends

Satellite-derived estimates of precipitation are essential to compensate for missing rainfall measurements in regions where the homogeneous and continuous monitoring of rainfall remains challenging due to low density rain gauge networks. The Precipitation Estimation from Remotely Sensed Information using Artificial Neural Networks—Climate Data Record (PERSIANN-CDR) is a relatively new product (released in 2013) but that contains data since 1983, thus enabling long-term rainfall analysis. In this work, we used three decades (1983–2014) of PERSIANN-CDR daily rainfall data to characterize precipitation patterns in the southern part of the Amazon basin, which has been drastically impacted in recent decades by anthropogenic activities that exacerbate the spatio-temporal variability of rainfall regimes. We computed metrics for the rainy season (onset date, demise date and duration) on a pixel-to-pixel basis for each year in the time series. We identified significant trends toward a shortening of the rainy season in the southern Amazon, mainly linked to earlier demise dates. This work thus contributes to monitoring possible signs of climate change in the region and to assessing uncertainties in rainfall trends and their potential impacts on human activities and natural ecosystems

Padrões de precipitação no Sul da Amazônia baseado no PERSIANN-CDR: Características e tendências

International audiencePrecipitation is a key climatic parameter for many anthropogenic activities, especially agriculture. Yet, its homogeneous and continuous monitoring remains challenging. That is particularly true for the Amazon region, which is sparsely inhabited and has a low density of ground-based rain gauge network. Satellite-derived estimates of precipitation are thus essential to fill up the gap of rainfall measurements in the region. The PERSIANN-CDR is a relatively new product (released in 2013), available for the period 1983-delayed present, which provides a renewed opportunity to analyse and estimate precipitation in the Amazon region, based on a long-term record. In this work, we use three decades (1983-2013) of PERSIANN-CDR daily rainfall data to characterize precipitation patterns in the southern region of the Amazon basin-which has been heavily deforested and transformed in the past decades-, and to assess trends. Our analyses confirm the potential of PERSIANN-CDR estimates to monitor rainfall in the Amazon. We also computed metrics of the rain season (onset, demise and duration) and highlighted significant trends toward a reduction of the rainy season in the Southern Amazon, mainly related to earlier demise dates. This work thus contributes to monitor possible signs of climate change in the region, and to the assessment of uncertainties in rainfall trends

Padrões de precipitação no Sul da Amazônia baseado no PERSIANN-CDR: Características e tendências

International audiencePrecipitation is a key climatic parameter for many anthropogenic activities, especially agriculture. Yet, its homogeneous and continuous monitoring remains challenging. That is particularly true for the Amazon region, which is sparsely inhabited and has a low density of ground-based rain gauge network. Satellite-derived estimates of precipitation are thus essential to fill up the gap of rainfall measurements in the region. The PERSIANN-CDR is a relatively new product (released in 2013), available for the period 1983-delayed present, which provides a renewed opportunity to analyse and estimate precipitation in the Amazon region, based on a long-term record. In this work, we use three decades (1983-2013) of PERSIANN-CDR daily rainfall data to characterize precipitation patterns in the southern region of the Amazon basin-which has been heavily deforested and transformed in the past decades-, and to assess trends. Our analyses confirm the potential of PERSIANN-CDR estimates to monitor rainfall in the Amazon. We also computed metrics of the rain season (onset, demise and duration) and highlighted significant trends toward a reduction of the rainy season in the Southern Amazon, mainly related to earlier demise dates. This work thus contributes to monitor possible signs of climate change in the region, and to the assessment of uncertainties in rainfall trends