Molecular Characterization of the Gastrula in the Turtle Emys orbicularis: An Evolutionary Perspective on Gastrulation

Due to the presence of a blastopore as in amphibians, the turtle has been suggested to exemplify a transition form from an amphibian- to an avian-type gastrulation pattern. In order to test this hypothesis and gain insight into the emergence of the unique characteristics of amniotes during gastrulation, we have performed the first molecular characterization of the gastrula in a reptile, the turtle Emys orbicularis. The study of Brachyury, Lim1, Otx2 and Otx5 expression patterns points to a highly conserved dynamic of expression with amniote model organisms and makes it possible to identify the site of mesoderm internalization, which is a long-standing issue in reptiles. Analysis of Brachyury expression also highlights the presence of two distinct phases, less easily recognizable in model organisms and respectively characterized by an early ring-shaped and a later bilateral symmetrical territory. Systematic comparisons with tetrapod model organisms lead to new insights into the relationships of the blastopore/blastoporal plate system shared by all reptiles, with the blastopore of amphibians and the primitive streak of birds and mammals. The biphasic Brachyury expression pattern is also consistent with recent models of emergence of bilateral symmetry, which raises the question of its evolutionary significance

The James Webb Space Telescope Mission

Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least $4m$. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the $6.5m$ James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

Les difficultés d'une enquête génétique en Polynésie Française (à propos d'une famille porteuse de la mutation c.1261-10A>=G responsable de la myopathie myotubulaire liée à l'X)

Nous rapportons pour la première fois les cas de deux nouveau-nés cousins germains, décédés en période néo-natale précoce atteints de myopathie myotubulaire liée à l X sur le territoire de la Polynésie Française. Le diagnostic de la maladie a permis la réalisation d un diagnostic prénatal lors d une nouvelle grossesse de la mère de l un des enfants décédés. Cette grave pathologie, dont le site de mutation n a été identifié qu en 1996, doit être évoquée devant la présence d un tableau d hypotonie néonatale sévère conduisant à un décès précoce. La notion familiale de fausse-couche ou de décès en période néonatale de nouveau-nés de sexe masculin, la présence d un hydramnios et la diminution des mouvements fœtaux au troisième trimestre de grossesse, sont les éléments diagnostiques principaux. Le phénotype de la maladie est variable en fonction du génotype et est responsable de tableaux cliniques très hétérogènes. La réalisation d un arbre généalogique est indispensable à l établissement d un diagnostic anténatal. Une meilleure connaissance des aspects anthropologiques spécifiques à la culture polynésienne concernant la conception, la maladie et la mort, nous permettra de tenter d expliquer les difficultés diagnostiques auxquelles nous avons été confrontés.LIMOGES-BU Médecine pharmacie (870852108) / SudocPARIS-BIUM (751062103) / SudocSudocFranceF

La translocation t(12;21)(p13;q22) dans les leucémies aiguës lymphoblastiques de l'enfant (quantification de la maladie résiduelle par Real Time Quantitative PCR et valeur pronostique)

MONTPELLIER-BU Médecine UPM (341722108) / SudocPARIS-BIUM (751062103) / SudocMONTPELLIER-BU Médecine (341722104) / SudocSudocFranceF

Use of thiolysis hyphenated to RP-HPLC-ESI(-)-MS/MS for the analysis of flavanoids in fresh lager beers

Proanthocyanidins are well known for their involvement in haze and colour development during beer ageing. New methodologies are needed, however, to understand what happens to them in the bottled beer. For the first time in the brewing Held, thiolysis was hyphenated to RP-HPLC-ESI(-)-MS/MS to investigate these flavanoids. Thirty minutes at 40 degrees C followed by 10 h at room temperature emerged as the best conditions for complete depolymerisation. NP-HPLC-ESI(-)-MS/MS was used to quantify and isolate fractions from monomers to trimers in a Sephadex LH20 acetone/water (70/30, v/v) beer extract. Unsurprisingly, a lower dimer/monomer ratio was evidenced in PVPP-treated beers than in silica gel-filtered beers. Most beer dimers are procyanidins B3 (two catechin units) whilst most trimers are prodelphinidins (catechin in terminal units and gallocatechins or catechins in extension units). Gallocatechin appeared to come mainly from malt. Despite the absence of chromatographic peaks corresponding to oligomers above trimers, an apparent degree of polymerisation close to six was calculated in the total LH20 extract. Still higher mean degrees of polymerisation (mDPs) were calculated for malt and hop, indicating selective extraction or depolymerisation from raw materials to beer. The main part of beer polyphenols is composed of complex undefined structures not degraded by toluene-alpha-thiol. (C) 2008 Elsevier Ltd. All rights reserved

Changing agricultural practices modify the species and trait composition of the weed flora. A simulation study using a cropping system model

International audienc

Changing agricultural practices modifies the species and trait composition of the weed flora. A simulation study using a cropping system model

International audienceCropping systems change over time to adapt to socio-economical and environmental constraints and to profit from technological innovations. These changes can result in unexpected side-effects which are difficult to determine in fields. The objective of the present study was to use a cropping system model to evaluate the impacts of modified agricultural practices ex ante on weeds. The FLORSYS model quantifies the effect of crop succession, management techniques and climate on multi-specific weed dynamics over the years; it was parameterized with functional relationships predicting model parameters (e.g. pre-emergent seedling mortality) from species traits (e.g. seed mass). Cropping systems typical of three French regions were determined from farm surveys and the Biovigilance data base. These control scenarios as well as various management modifications were simulated in each region, using a weed flora consisting of sixteen major weed species. Each scenario was simulated over 27 years and repeated 10 times, by randomly choosing each year annual climate series measured in the tested region. The control and prospective scenarios were analysed for their total weed density and their species compositions, showing for instance that the weed flora was more diverse in the longer Burgundy (oilseed rape / winter wheat / winter barley, with mouldboard ploughing every three years) and Poitou-Charentes rotations (OSR / winter wheat / sunflower / winter wheat, with ploughing three years out of four) than in the Aquitaine maize monoculture. Modifying management practices modified both weed density and composition. For instance, simplifying or abandoning tillage greatly increased weed infestation. If it was moreover accompanied by earlier sowing, infestations increased even more, but only when autumnal weed species dominated. Introducing temporary crops before spring crops (as required by recent French regulations) reduced densities, particularly in autumnal weeds. Simplifying the three-year Burgundy rotation to a two-year oilseed rape/wheat increased weed densities, particularly when mouldboard ploughing was also abandoned. Conversely, diversifying rotations decreased densities in Burgundy (addition of a spring pea) and, particularly, in Aquitaine (maize monoculture changed to a four-year rotation). Abandoning ploughing though still increased densities. Some cultural changes (e.g. no-till) greatly changed weed flora composition. To understand these changes, the relationships between management practices and weed species traits were studied with RLQ and fourth-corner analyses. Longer rotations were thus shown to select weed species with elongated/flattened seeds (which present little dormancy) and long emergence periods. These species are able to emergence in crops irrespective of their sowing date. Conversely, rotations with late-sown crops (i.e. spring crops or late-sown autumn crops) favoured species with round seeds which are more dormant, thus reducing germination prior to crop sowing. Frequent mouldboard ploughing selected species with thick-coated seeds which are also those least prone to mortality. Ploughing also favoured species with low-lipidic seeds which germinate later and more slowly. Both consequences, low mortality and reduced germination, improve seed survival after burial by ploughing until a further ploughing moves seeds again closer to soil surface where emergence is possible. More generally, frequent tillage favoured monocotyledonous species and species with a late and short emergence period, thus limiting fatal germination triggered by early tillage. Glyphosate before sowing in direct-drilled fields selected seeds with low area/mass ratios which germinate later and can thus avoid the glyphosate application

Naevomatose Basocellulaire : À propos de deux cas

International audienc

Naevomatose Basocellulaire : À propos de deux cas

International audienc

Comparative metabolite profiling and chemical study of Ramalina siliquosa complex using LC–ESI-MS/MS approach

A chemical study of the lichen Ramalina siliquosa complex found in Brittany was conducted. Eight chemotypes were considered and their chemical composition was elucidated for the first time by LC–MS analysis. Ten main compounds were identified: conhypoprotocetraric acid (1), salazinic acid (2), peristictic acid (3), cryptostictic acid (4), protocetraric acid (5), stictic acid (6), norstictic acid (7), hypoprotocetraric acid (8), 4-O-demethylbarbatic acid (9), (+)-usnic acid (10) and 22 minor compounds were reported. The MS/MS fragmentation patterns of each compound of R. siliquosa complex were determined and proposed