Major mite allergen Der f 1 concentration is reduced in buildings with improved energy performance.

BACKGROUND: Environmental conditions play a crucial role in mite growth, and optimal environmental control is key in the prevention of airway inflammation in chronic allergic rhinoconjunctivitis or asthma. OBJECTIVE: To evaluate the relationship between building energy performance and indoor mite allergen concentration in a cross-sectional study. METHODS: Major allergen concentration (Der f 1, Der p 1, mite group 2, Fel d 1 and Bla g 2) was determined by quantitative dot blot analysis from mattress and carpet dust samples in five buildings designed for low energy use (LEB) and in six control buildings (CB). Inhabitants had received 4 weeks prior to mite measurement a personal validated questionnaire related to the perceived state of health and comfort of living. RESULTS: Cumulative mite allergen concentration (with Der f 1 as the major contributor) was significantly lower in LEB as compared with CB both in mattresses and in carpets. In contrast, the two categories of buildings did not differ in Bla g 2 and Fel d 1 concentration, in the amount of dust and airborne mould collected. Whereas temperature was higher in LEB, relative humidity was significantly lower than in CB. Perceived overall comfort was better in LEB. CONCLUSIONS: Major mite allergen Der f 1 preferentially accumulates in buildings not specifically designed for low energy use, reaching levels at risk for sensitization. We hypothesize that controlled mechanical ventilation present in all audited LEB may favour lower air humidity and hence lower mite growth and allergen concentration, while preserving optimal perceived comfort.

Mechanisms of garnet growth in eclogites of the Zermatt-Saas Fee unit, Western Alps

THESIS ABSTRACT Garnets are one of the key metamorphic minerals used to study peak metamorphic conditions or crystallization ages. Equilibrium is typically assumed between the garnet and the matrix. This thesis attempts to understand garnet growth in the Zermatt-Saas Fee (ZSF) eclogites, and discusses consequences for Sm/Nd and Lu/Hf dating and the equilibrium assumption. All studied garnets from the ZSF eclogites are strongly zoned in Mn, Fe, Mg, and Ca. Methods based on chemical zoning patterns and on 3D spatial statistics indicate different growth mechanisms depending on the sample studied. Garnets from the Pfulwe area are grown in a system where surface kinetics likely dominated over intergranular diffusion kinetics. Garnets fram two other localities, Nuarsax and Lago di Cignana, seem to have grown in a system where intergranular diffusion kinetics were dominating over surface kinetics, at least during initial growth. Garnets reveal strong prograde REE+Y zoning. They contain narrow central peaks for Lu + Yb + Tm ± Er and at least one additional small peak towards the rim. The REE Sm + Eu + Gd + Tb ± Dy are depleted in the cores but show one prominent peak close to the rim. It is shown that these patterns cam be explained using a transient matrix diffusion model where REE uptake is limited by diffusion in the matrix surrounding the porphyroblast. The secondary peaks in the garnet profiles are interpreted to reflect thermally activated diffusion due to a temperature increase during prograde metamorphism. The model predicts anomalously low 176Lu/177Hf and 147Sm/144Nd ratios in garnets where growth rates are fast compared to diffusion of the REE, which decreases garnet isochron precisions. The sharp Lu zoning was further used to constrain maximum Lu volume diffusion rates in garnet. The modeled minimum pre-exponential diffusion coefficient which fits the measured central peak is in the order of Do = 5.7* 106 m2/s, taking an activation energy of 270 kJ/mol. The latter was chosen in agreement with experimentally determined values. This can be used to estimate a minimum closure temperature of around 630°C for the ZSF zone. Zoning of REE was combined with published Lu/Hf and Sm/Nd age information to redefine the prograde crystallization interval for Lago di Cignana UHP eclogites. Modeling revealed that a prograde growth interval in the order of 25 m.y. is needed to produce the measured spread in ages. RÉSUMÉ Le grenat est un minéral métamorphique clé pour déterminer les conditions du pic de métamorphisme ainsi que l'âge de cristallisation. L'équilibre entre le grenat et la matrice est requis. Cette étude a pour but de comprendre la croissance du grenat dans les éclogites de la zone de Zermatt-Saas Fee (ZSF) et d'examiner quelques conséquences sur les datations Sm/Nd et Lu/Hf. Tous les grenats des éclogites de ZSF étudiés sont fortement zonés en Mn, Fe, Mg et partiellement en Ca. Les différentes méthodes basées sur le modèle de zonation chimique ainsi que sur les statistiques de répartition spatiale en 3D indiquent un mécanisme de croissance différent en fonction de la localité d'échantillonnage. Les grenats provenant de la zone de Pfulwe ont probablement crû dans un système principalement dominé par la cinétique de surface au détriment de 1a cinétique de diffusion intergranulaire. Les grenats provenant de deux autres localités, Nuarsax et Lago di Cignana, semblent avoir cristallisé dans un système dominé par la diffusion intergranulaire, au moins durant les premiers stades de croissance. Les grenats montrent une forte zonation prograde en Terres Rares (REE) ainsi qu'en Y. Les profils présentent au coeur un pic étroit en Lu + Yb+ Tm ± Er et au moins un petit pic supplémentaire vers le bord. Les coeurs des grenats sont appauvris en Sm + Eu + Gd + Tb ± Dy, mais les bords sont marqués par un pic important de ces REE. Ces profils s'expliquent par un modèle de diffusion matricielle dans lequel l'apport en REE est limité par la diffusion dans la matrice environnant les porphyroblastes. Les pics secondaires en bordure de grain reflètent la diffusion activée par l'augmentation de la température lors du métamorphisme prograde. Ce modèle prédit des rapports 176Lu/177Hf et 147Sm/144Nd anormalement bas lorsque les taux de croissance sont plus rapides que la diffusion des REE, ce qui diminue la précision des isochrones impliquant le grenat. La zonation nette en Lu a permis de contraindre le maximum de diffusion volumique par une approche numérique. Le coefficient de diffusion minimum modélisé en adéquation avec les pics mesurés est de l'ordre de Do = 5.7*10-6 m2/s, en prenant une énergie d'activation ~270 kJ/mol déterminée expérimentalement. Ainsi, la température de clôture minimale est estimée aux alentours de 630°C pour la zone ZSF. Des nouvelles données de zonation de REE sont combinées aux âges obtenus avec les rapports Lu/Hf et Sm/Nd qui redéfissent l'intervalle de cristallisation prograde pour les éclogites UHP de Lago di Cignana. La modélisation permet d'attribuer au minimum un intervalle de croissance prograde de 25 Ma afin d'obtenir les âges préalablement mesurés. RESUME GRAND PUBLIC L'un des principaux buts du pétrologue .métamorphique est d'extraire des roches les informations sur l'évolution temporelle, thermique et barométrique qu'elles ont subi au cours de la formation d'une chaîne de montagne. Le grenat est l'un des minéraux clés dans une grande variété de roches métamorphiques. Il a fait l'objet de nombreuses études dans des terrains d'origines variées ou lors d'études expérimentales afin de comprendre ses domaines de stabilité, ses réactions et sa coexistence avec d'autres minéraux. Cela fait du grenat l'un des minéraux les plus attractifs pour la datation des roches. Cependant, lorsqu'on l'utilise pour la datation et/ou pour la géothermobarométrie, on suppose toujours que le grenat croît en équilibre avec les phases coexistantes de la matrice. Pourtant, la croissance d'un minéral est en général liée au processus de déséquilibre. Cette étude a pour but de comprendre comment croît le grenat dans les éclogites de Zermatt - Saas Fee et donc d'évaluer le degré de déséquilibre. Il s'agit aussi d'expliquer les différences d'âges obtenues grâce aux grenats dans les différentes localités de l'unité de Zermatt-Saas Fee. La principale question posée lors de l'étude des mécanismes de croissance du grenat est: Parmi les processus en jeu lors de la croissance du grenat (dissolution des anciens minéraux, transport des éléments vers le nouveau grenat, précipitation d'une nouvelle couche en surface du minéral), lequel est le plus lent et ainsi détermine le degré de déséquilibre? En effet, les grenats d'une des localités (Pfulwe) indiquent que le phénomène d'adhérence en surface est le plus lent, contrairement aux grenats des autres localités (Lago di Cignana, Nuarsax) dans lesquels ce sont les processus de transport qui sont les plus lents. Cela montre que les processus dominants sont variables, même dans des roches similaires de la même unité tectonique. Ceci implique que les processus doivent être déterminés individuellement pour chaque roche afin d'évaluer le degré de déséquilibre du grenat dans la roche. Tous les grenats analysés présentent au coeur une forte concentration de Terres Rares: Lu + Yb + Tm ± Er qui décroît vers le bord du grain. Inversement, les Terres Rares Sm + Eu + Gd + Tb ± Dy sont appauvries au coeur et se concentrent en bordure du grain. La modélisation révèle que ces profils sont-dus à des cinétiques lentes de transport des Terres Rares. De plus, les modèles prédisent des concentrations basses en éléments radiogéniques pères dans certaines roches, ce qui influence fortement sur la précision des âges obtenus par la méthode d'isochrone. Ceci signifie que les roches les plus adaptées pour les datations ne doivent contenir ni beaucoup de grenat ni de très gros cristaux, car dans ce cas, la compétition des éléments entre les cristaux limite à de faibles concentrations la quantité d'éléments pères dans chaque cristal.

Concentration of Airborne Staphylococcus aureus (MRSA and MSSA), Total Bacteria, and Endotoxins in Pig Farms.

Pigs are very often colonized by Staphylococcus aureus and transmission of such pig-associated S. aureus to humans can cause serious medical, hygiene, and economic problems. The transmission route of zoonotic pathogens colonizing farm animals to humans is not well established and bioaerosols could play an important role. The aim of this study was to assess the potential occupational risk of working with S. aureus-colonized pigs in Switzerland. We estimated the airborne contamination by S. aureus in 37 pig farms (20 nursery and 17 fattening units; 25 in summer, 12 in winter). Quantification of total airborne bacterial DNA, airborne Staphylococcus sp. DNA, fungi, and airborne endotoxins was also performed. In this experiment, the presence of cultivable airborne methicillin-resistant S. aureus (MRSA) CC398 in a pig farm in Switzerland was reported for the first time. Airborne methicillin-sensitive S. aureus (MSSA) was found in ~30% of farms. The average airborne concentration of DNA copy number of total bacteria and Staphylococcus sp. measured by quantitative polymerase chain reaction was very high, respectively reaching values of 75 (± 28) × 10(7) and 35 (± 9.8) × 10(5) copy numbers m(-3) in summer and 96 (± 19) × 10(8) and 40 (± 12) × 10(6) copy numbers m(-3) in winter. Total mean airborne concentrations of endotoxins (1298 units of endotoxin m(-3)) and fungi (5707 colony-forming units m(-3)) exceeded the Swiss recommended values and were higher in winter than in summer. In conclusion, Swiss pig farmers will have to tackle a new emerging occupational risk, which could also have a strong impact on public health. The need to inform pig farmers about biological occupational risks is therefore crucial.

Genetic control of iron concentration in Mesoamerican and Andean common bean seeds

The objective of this work was to evaluate the main differences in the genetic control of the iron concentration in Mesoamerican and Andean common bean seeds, in early generations, and to select recombinants with a high iron concentration in the seeds. F1, F1 reciprocal, F2, F2 reciprocal, and backcross (BC11 and BC12) generations were produced by crosses between Mesoamerican (CNFP 10104 x CHC 01-175) and Andean (Cal 96 x Hooter) inbred lines. The expression of significant maternal effect was observed for the Mesoamerican gene pool. Iron concentration was higher in the seed coat of Mesoamerican common bean seeds (54.61 to 67.92%) and in the embryo of Andean common bean seeds (69.40 to 73.44%). High broad-sense heritability was obtained for iron concentration in Mesoamerican and Andean common bean seeds. Gains with the selection of higher magnitude, from 20.39 to 24.58%, are expected in Mesoamerican common bean seeds. Iron concentration in common bean seeds showed a continuous distribution in F2, which is characteristic of quantitative inheritance in Mesoamerican and Andean common bean seeds. Recombinants with high iron concentration in seeds can be selected in both Mesoamerican and Andean common bean hybrids.

Robustness of Drosophila early embryo and wing imaginal disc development

Within a developing organism, cells require information on where they are in order to differentiate into the correct cell-type. Pattern formation is the process by which cells acquire and process positional cues and thus determine their fate. This can be achieved by the production and release of a diffusible signaling molecule, called a morphogen, which forms a concentration gradient: exposure to different morphogen levels leads to the activation of specific signaling pathways. Thus, in response to the morphogen gradient, cells start to express different sets of genes, forming domains characterized by a unique combination of differentially expressed genes. As a result, a pattern of cell fates and specification emerges.Though morphogens have been known for decades, it is not yet clear how these gradients form and are interpreted in order to yield highly robust patterns of gene expression. During my PhD thesis, I investigated the properties of Bicoid (Bcd) and Decapentaplegic (Dpp), two morphogens involved in the patterning of the anterior-posterior axis of Drosophila embryo and wing primordium, respectively. In particular, I have been interested in understanding how the pattern proportions are maintained across embryos of different sizes or within a growing tissue. This property is commonly referred to as scaling and is essential for yielding functional organs or organisms. In order to tackle these questions, I analysed fluorescence images showing the pattern of gene expression domains in the early embryo and wing imaginal disc. After characterizing the extent of these domains in a quantitative and systematic manner, I introduced and applied a new scaling measure in order to assess how well proportions are maintained. I found that scaling emerged as a universal property both in early embryos (at least far away from the Bcd source) and in wing imaginal discs (across different developmental stages). Since we were also interested in understanding the mechanisms underlying scaling and how it is transmitted from the morphogen to the target genes down in the signaling cascade, I also quantified scaling in mutant flies where this property could be disrupted. While scaling is largely conserved in embryos with altered bcd dosage, my modeling suggests that Bcd trapping by the nuclei as well as pre-steady state decoding of the morphogen gradient are essential to ensure precise and scaled patterning of the Bcd signaling cascade. In the wing imaginal disc, it appears that as the disc grows, the Dpp response expands and scales with the tissue size. Interestingly, scaling is not perfect at all positions in the field. The scaling of the target gene domains is best where they have a function; Spalt, for example, scales best at the position in the anterior compartment where it helps to form one of the anterior veins of the wing. Analysis of mutants for pentagone, a transcriptional target of Dpp that encodes a secreted feedback regulator of the pathway, indicates that Pentagone plays a key role in scaling the Dpp gradient activity.

La Prima Dona ; Le père Reymond / par Édouard Cadol

Collection : Collection Michel Lévy

Ochratoxin A at nanomolar concentration perturbs the homeostasis of neural stem cells in highly differentiated but not in immature three-dimensional brain cell cultures.

Ochratoxin A (OTA), a fungal contaminant of basic food commodities, is known to be highly cytotoxic, but the pathways underlying adverse effects at subcytotoxic concentrations remain to be elucidated. Recent reports indicate that OTA affects cell cycle regulation. Therefore, 3D brain cell cultures were used to study OTA effects on mitotically active neural stem/progenitor cells, comparing highly differentiated cultures with their immature counterparts. Changes in the rate of DNA synthesis were related to early changes in the mRNA expression of neural stem/progenitor cell markers. OTA at 10nM, a concentration below the cytotoxic level, was ineffective in immature cultures, whereas in mature cultures it significantly decreased the rate of DNA synthesis together with the mRNA expression of key transcriptional regulators such as Sox2, Mash1, Hes5, and Gli1; the cell cycle activator cyclin D2; the phenotypic markers nestin, doublecortin, and PDGFRα. These effects were largely prevented by Sonic hedgehog (Shh) peptide (500ngml(-1)) administration, indicating that OTA impaired the Shh pathway and the Sox2 regulatory transcription factor critical for stem cell self-renewal. Similar adverse effects of OTA in vivo might perturb the regulation of stem cell proliferation in the adult brain and in other organs exhibiting homeostatic and/or regenerative cell proliferation.