Morphological and Molecular Characterization of Retinoic Acid-Induced Limb Duplications in Mice

AbstractThis study reports a morphological, skeletal, and molecular characterization of the supernumerary limbs induced by systemic administration of all-transretinoic acid to egg-cylinder stage mouse embryos. As initially described by Rutledgeet al.(Proc. Natl. Acad. Sci. USA91, 5436, 1994), we have found that oral administration of all-transretinoic acid (70 mg/kg body weight) at 5.5 days postcoitum induced the formation of supernumerary limbs. Most often, these arose as a pair of extra buds located caudally and ventrally to the normal (orthotopic) hindlimb buds without duplication of the lower body axis. The resulting one or two supernumerary hindlimbs were connected to an imperfectly mirror-image-duplicated pelvic girdle. Variable truncations of the stylopodium and zeugopodium skeleton, as well as abnormal splitting of the distal skeleton, were frequently observed. The apical ectodermal ridge of the extra limb buds expressed expected growth factor genes. However, an ectopic anterior expression ofSonic hedgehogandHoxd-13was seen in the supernumerary buds, suggesting that these buds would incorporate potential polarizing cells of the hindlimb or genital field and generate an ectopic polarizing zone. This is consistent with the reverse orientation of most supernumerary limbs at later stages. Some of the buds did not express limb-specific markers and were thus expected to degenerate or form nonlimb structures, as observed in an adult specimen. Less frequently, extra limb buds with normal polarity were associated to a duplicated lower body axis. Retinoic acid also generated a novel type of duplication in which “twin” hindlimbs with two parallel apical ectodermal ridges and zones of polarizing activity arose on one side of the embryo

Vivants puis morts : des victimes de violence intégrées au cimetière néolithique de Kadruka 23, Haute- Nubie (Soudan, 1re moitié du 5e millénaire av. J.-C.)

La butte funéraire de Kadruka 23 (Soudan, Northern State, Haute-Nubie), dans la zone multi-sites de Kadruka, à une dizaine de km à l’est du Nil (un peu au nord de Dongola, la capitale de l’état), est fouillée depuis 2014 par une équipe franco-soudanaise et a livré, au fil des campagnes de fouille, un véritable cimetière, daté de la première moitié du 5e millénaire av. J.-C. (par le matériel funéraire). Jusqu’à présent, 140 individus, inhumés de façon organisée sur moins de 110 m2, ont pu être..

The Expression Pattern of the Mouse Receptor Tyrosine Kinase GeneMDK1Is Conserved through Evolution and RequiresHoxa-2for Rhombomere-Specific Expression in Mouse Embryos

AbstractSegmentation of the hindbrain has been conserved throughout the vertebrate species and results in the transient formation of rhombomeres, which are lineage-restricted compartments. Studies on the molecular mechanisms underlying the segmentation process have revealed that rhombomeric boundaries coincide with the expression limits of several evolutionary conserved genes such as the zinc-finger transcription factorKrox-20and homeobox genes which are expressed in a specific spatial and temporal order and have been shown to be important regulators of segmental identity. In addition toKrox-20and Hox genes, several members of the Eph subfamily of receptor protein tyrosine kinase (RTK) genes are also expressed in a segment-restricted manner in the hindbrain, suggesting that these receptors may act in concert with Hox genes to establish regional identity. In the cascade of regulatory interactions leading to segmental identity,Krox-20appears to act “upstream” of Hox genes, but the identity of the “downstream” effectors has not yet been identified. We report here the isolation of the zebrafish orthologue of the mouse RTK geneMDK1which belongs to the Eph receptor subfamily and show that the major expression domains of the mouse and the zebrafish genes have been conserved through evolution. Since the coincident spatial and temporal expression ofHoxa-2andMDK1in the mouse hindbrain suggested a possible regulatory link between them, we analyzed the expression of theMDK1inHoxa-2null mutant embryos. A selective lack ofMDK1expression in rhombomere 3 ofHoxa-2mutant hindbrains together with an overall altered expression pattern in the other rhombomeres was observed, thus demonstrating thatMDK1lies downstream ofHoxa-2in the morphogenetic signaling cascade

SAW RFID devices using connected IDTs as an alternative to conventional reflectors for harsh environments

International audienceRemote interrogation of surface acoustic wave ID-tags imposes a high signal amplitude which is related to a high coupling coefficient value (K 2) and low propagation losses (α). In this paper, we propose and discuss an alternative configuration to the standard one. Here, we replaced the conventional configuration, i.e. one interdigital transducer (IDT) and several reflectors, by a series of electrically connected IDTs. The goal is to increase the amplitude of the detected signal using direct transmission between IDTs instead of the reflection from passive reflectors. This concept can therefore increase the interrogation scope of ID-tags made on conventional substrate with high K 2 value. Moreover, it can also be extended to suitable substrates for harsh environments such as high temperature environments: the materials used exhibit limited performances (low K 2 value and relatively high propagation losses) and are therefore rarely used for identification applications. The concept was first tested and validated using the lithium niobate 128°Y-X cut substrate, which is commonly used in ID-tags. A good agreement between experimental and numerical results was obtained for the promising concept of connected IDTs. The interesting features of the structure were also validated using a langasite substrate, which is well-known to operate at very high temperatures. Performances of both substrates (lithium niobate and langasite) were tested with an in-situ RF characterization up to 600°C. Unexpected results regarding the resilience of devices based on congruent lithium niobate were obtained. Index Terms-high temperature, lithium niobate, radio frequency identification (RFID), surface acoustic wave (SAW

Retinoic Acid Controls the Bilateral Symmetry of Somite Formation in the Mouse Embryo

A striking characteristic of vertebrate embryos is their bilaterally symmetric body plan, which is particularly obvious at the level of the somites and their derivatives such as the vertebral column. Segmentation of the presomitic mesoderm must therefore be tightly coordinated along the left and right embryonic sides. We show that mutant mice defective for retinoic acid synthesis exhibit delayed somite formation on the right side. Asymmetric somite formation correlates with a left-right desynchronization of the segmentation clock oscillations. These data implicate retinoic acid as an endogenous signal that maintains the bilateral synchrony of mesoderm segmentation, and therefore controls bilateral symmetry, in vertebrate embryos

MRI investigation of granular interface rheology using a new cylinder shear apparatus

The rheology of granular materials near an interface is investigated through proton magnetic resonance imaging. A new cylinder shear apparatus has been inserted in the MRI device, which allows the control of the radial confining pressure exerted by the outer wall on the grains and the measurement of the torque on the inner shearing cylinder. A multi-layer velocimetry sequence has been developed for the simultaneous measurement of velocity profiles in different sample zones, while the measurement of the solid fraction profile is based on static imaging of the sample. This study describes the influence of the roughness of the shearing interface and of the transverse confining walls on the granular interface rheology

Gestion des appels d'urgence routiers : contexte et perspectives d'évolution

Face à la diversification des moyens d'appels à disposition des usagers de la route en détresse, se pose la question de l'évolution du RAU (réseau d'appels d'urgence), équipement routier dédié aux urgences. Pour l'évaluer ce document présente :Le diagnostic de fonctionnement du RAU et des appels d'urgence au travers des aspects techniques(RAU, téléphonie mobile. . .), de l'organisation des centres d'appels d'urgence, de l'acheminements des appels, d'enquêtes auprès des acteurs et des usagers.Le fonctionnement dans quatre pays européens, synthèse d'une étude faite en Allemagne,Grande-Bretagne, Italie, Hollande.Une corrélation accidents, appels d'urgence : croisement géographique de l'implantation des PAU sur RN avec des données accidents.Des perspectives d'évolutions sur le plan technique, sur l'organisation et l'acheminement des appels.Une synthèse de propositions et de suites à donner

beDNA : un projet visant à la collection systématique d’échantillons humains archéologiques à vocation paléogénétique – une première expérimentation

La paléogénétique occupe désormais une place importante dans les problématiques archéologiques. Toutefois, les analyses d’ADN ancien peuvent être desservies, voire empêchées, par l’état de préservation des échantillons en raison de contamination par de l’ADN moderne ou de mauvaises conditions de stockage. Le projet beDNA, "banque d’échantillons et de Données Nationale Archéogénétique", souhaite donner les moyens d’analyses paléogénétiques futures, en proposant le stockage systématique d’échantillons des squelettes humains tenant compte des contraintes inhérentes à la préservation de l’ADN ancien. Le projet implique (1) un protocole systématique d’échantillonnage "propre" des restes humains sur le terrain commun à toutes les opérations archéologiques, (2) un espace de stockage dédié à ces échantillons adapté à la conservation de l’ADN ancien, (3) une base de données faisant le lien entre les sites et les échantillons conservés dans la banque, (4) l’approbation par l’État des demandes d’analyse d’échantillons après expertise. La phase de test du projet, initiée en septembre 2020 sur la région Île-de-France, nous a permis d’évaluer et d’ajuster le protocole d’échantillonnage sur le terrain et les dispositifs de transfert vers la banque. Cette note présente les étapes envisagées pour chaque échantillon, depuis les terrains jusqu’aux laboratoires d’analyse génétique, ainsi que le déroulement de sa phase test, en cours, et les premiers retours d’expérience.Palaeogenetics is becoming increasingly important in tackling archaeological issues. However, analyses of ancient DNA can be hampered or even prevented by the state of preservation of samples due to poor storage conditions, and because of contamination by modern DNA. The beDNA project for a national archaeological genetic data and sample bank (banque d’échantillons et de Données Nationale Archéogénétique) is developing the means to enable future palaeogenetic analyses by systematically storing human skeletal samples, with the constraints inherent to the preservation of ancient DNA taken into account. This project comprises (1) a systematic protocol for "clean" sampling of human remains to be common to all archaeological operations, (2) a dedicated storage space for samples, suited to aDNA preservation, (3) a database linking sites with the samples stored in the bank, (4) approval of sample analysis requests by authorities, after expert review. The test phase of the project, which began in September 2020 in the Île-de-France region, enabled us to evaluate and adjust both the sampling protocol in the field and the transfer process to the beDNA bank. This note describes the different stages envisaged for each sample, from the archaeological field to the genetics laboratory, as well as the development of the experimental phase and initial feedback from it