Effect of the Chemical Composition of Building Materials on Algal Biofouling

International audienceThe main cause of aesthetical deterioration of outdoor exposed building materials is the colonization by microorganisms. This phenomenon depends on factors such as geographical situation, environmental conditions and surface state of the substrate. Several researches have been devoted to the study of the effect of porosity, roughness and surface treatment on the biofouling of building materials. However, none of them has addressed the influence of cement composition. The main objective of this study is thus to highlight the influence of the composition of the material on its biocolonization by algae. The green alga Klebsormidium flaccidum was chosen because of its representativeness in France. It is indeed the species the most frequently identified and isolated from samples taken on sites. In order to characterize the influence of the composition of building materials on their biofouling, the behavior of mortars prepared with two types of Portland cement and two types of calcium aluminates cement is studied. The biofouling is followed by measuring the covering rate thanks to image analysis. This work is realized both on samples exposed outdoor and on samples tested in a laboratory bench. Obtained results prove that the composition of cementitious materials is a determining factor

Digestive Symptoms in Healthy People and Subjects With Irritable Bowel Syndrome

Altres ajuts: Supported in full by Danone ResearchThe aim of this study was to validate the ability of symptom frequency questionnaire to differentiate between irritable bowel syndrome (IBS) patients and healthy subjects. A digestive symptom frequency questionnaire (DSFQ) was previously used in a food efficacy trial in a non-IBS population with mild gastrointestinal symptoms. We compared 2 well-defined populations: 100 IBS patients fulfilling Rome III criteria (mean age 32 y; range, 18 to 59 y), and 100 sex-matched and age-matched healthy subjects. Frequency of individual digestive symptoms (abdominal pain/discomfort, bloating, flatulence, borborygmi) was assessed using a 5-point Likert scale (from none to everyday of the week) and the IBS severity with the IBS-SSS questionnaire. Health-Related Quality of life (HRQoL) was assessed with the Food and Benefits Assessment (FBA) and Functional Digestive Disorders Quality of Life (FDDQL) questionnaires. The digestive (dis)comfort dimension of these questionnaires was considered as the main dimension for HRQoL. The DSFQ discriminated IBS from healthy subjects with a significant difference (P <0.001) between groups (estimated mean difference=5.58; 95% CI, 4.91-6.28). On the basis of the ROC curve (AUC=0.9479), a cutoff value of 5 gives a sensitivity of 92% and a specificity of 84%, with a positive likelihood ratio of 5.75. Composite score of symptoms correlated strongly (P <0.0001) with digestive discomfort measured by FDDQL (−0.816), digestive comfort measured by FBA (−0.789), and the IBS-SSS score (0.762). Measurement of digestive symptom frequency by means of the DSFQ can differentiate IBS from healthy subjects, and shows a good correlation with other validated questionnaires (clinical trial #NCT01457378

SCAN domain-containing 2 gene (SCAND2) is a novel nuclear protein derived from the zinc finger family by exon shuffling. Gene 289:1–6

Abstract The SCAN domain is a recently recognized protein domain that characterizes a subfamily of the Krüppel-like zinc finger proteins. We have previously described a novel SCAN domain-containing 2 gene (SCAND2) that does not belong to the zinc finger family. We report structural and sequence analyzes of all known members of the SCAN family and use these data to illustrate a model of gene family evolution. Most of the SCAN containing genes share common gene organization features that support the proposed origin for SCAND2 by disruption of an ancestral SCAN-zinc finger gene by a retroposition event and subsequent exon shuffling.

An in-situ and laboratory study of the effect of the intrinsic properties of mortars on their potential bioreceptivity

International audienceThis study aims to clarify the effect of mortar intrinsic properties (porosity, roughness and carbonation level) on its ability to biofouling. Two scales experimental tests, an accelerated fouling in laboratory and a natural fouling in the real-world, were set-up. The first one was conducted in a closed device allowing a periodic sprinkling of an algal suspension on the samples surface. The outdoor test samples were exposed in a park at Grenoble (France). The colonization rate of the sample surface was evaluated by image analysis. The results show that the impact of each intrinsic parameter is quite different as function of the test. The porosity has no influence on the algal colonization of the samples exposed in indoor whereas a high porosity seems to increase slightly the bioreceptivity of ones exposed outdoor. The roughness, in both tests, promoted the microorganisms attachment and so their colonization. However, the discrimination of roughness grades is higher in the laboratory test than in the in-situ one. The surface pH significantly influences on the accelerated biofouling but not on the in-situ one. These dissimilarities result from the difference in experimental configurations of the two tests. Thus the laboratory test should be adjusted to be more suitable and to allow an extrapolation of results

Influence of the intrinsic characteristics of mortars on their biofouling by pigmented organisms: Comparison between laboratory and field-scale experiments.

International audienceBiodeterioration of mortars by the photosynthetic microorganisms is affected by their intrinsic properties such as porosity, roughness and surface pH. The influence of these parameters was examined using an accelerated fouling test in laboratory and a natural fouling test in the real-world ( in situ). Based on color measurement and image analysis, the impact of each intrinsic parameter was evaluated. The results differed from a scale to the other one. No influence of porosity was measured on the algal colonization rate in the laboratory test whereas, a high porosity seemed to increase slightly the bioreceptivity of the mortars exposed outdoor. The roughness, in both tests, promoted the microbial colonization. However, the discrimination of roughness grades was better in the laboratory test than in the in situ one. The surface pH influenced remarkably on the accelerated biofouling test but not on the in situ one. These dissimilarities resulted from the differences in experimental configurations of the two tests

Anal gas evacuation and colonic microbiota in patients with flatulence : effect of diet

Altres ajuts:This work was supported by the , Fundació La Marató TV3 (MARATV3_072010), the European Community's Seventh Framework Programme (FP7/2007-2013: IHMS, grant agreement HEALTH.2010.2.1.1-2) and a grant from Danone Research (France). Ciberehd is funded by the Instituto de Salud Carlos III.To characterise the influence of diet on abdominal symptoms, anal gas evacuation, intestinal gas distribution and colonic microbiota in patients complaining of flatulence. Patients complaining of flatulence (n=30) and healthy subjects (n=20) were instructed to follow their usual diet for 3 days (basal phase) and to consume a high-flatulogenic diet for another 3 days (challenge phase). During basal phase, patients recorded more abdominal symptoms than healthy subjects in daily questionnaires (5.8±0.3 vs 0.4±0.2 mean discomfort/pain score, respectively; p=<0.0001) and more gas evacuations by an event marker (21.9±2.8 vs 7.4±1.0 daytime evacuations, respectively; p=0.0001), without differences in the volume of gas evacuated after a standard meal (262±22 and 265±25 mL, respectively). On flatulogenic diet, both groups recorded more abdominal symptoms (7.9±0.3 and 2.8±0.4 discomfort/pain, respectively), number of gas evacuations (44.4±5.3 and 21.7±2.9 daytime evacuations, respectively) and had more gas production (656±52 and 673±78 mL, respectively; p<0.05 vs basal diet for all). When challenged with flatulogenic diet, patients' microbiota developed instability in composition, exhibiting variations in the main phyla and reduction of microbial diversity, whereas healthy subjects' microbiota were stable. Taxa from Bacteroides fragilis or Bilophila wadsworthia correlated with number of gas evacuations or volume of gas evacuated, respectively. Patients complaining of flatulence have a poor tolerance of intestinal gas, which is associated with instability of the microbial ecosystem

Mécanismes d’action des composés soufrés des alliacées sur les phases précoces de la cancérogenèse (initiation, promotion)

5 annexes, 20p. Diplôme : Dr. d'UniversitéDifférentes études épidémiologiques ont montré » que la consommation d’ail ou d’oignon est associée à une diminution de l’incidence de plusieurs types de cancers. Par ailleurs, les propriétés anticancérogènes et antimutagènes des composés soufrés de l’ail et de l’oignon ont été mises en évidence expérimentalement. L’objectif de cette thèse est d’explorer les mécanismes impliqués dans les effets anti-initiateurs de certains composés soufrés de l’ail (sulfure de diallyle DAS, disulfure de diallyle DADS ) et de l’oignon (sulfure de dipropyle DPS, disulfure de dipropyle DPDS) et d’évaluer l’influence du DAS et du DADS sur la phase de promotion tumorale. Ces études démontrent que le DADS est le composé les plus intéressant car il exerce des effets protecteurs au niveau des différentes étapes de la cancérogenèse

Ability in biofouling by <i>Klebsormidium flaccidum</i> of mortars: Influence of the intrinsic characteristics

International audienceThe aim of this study was to highlight the influence of the intrinsic properties of mortars (roughness, porosity, and surface pH) on their susceptibility to biodegradation by phototrophic microorganisms. An accelerated fouling test was performed using the green algae Klebsormidium flaccidum. The biofouling was evaluated by means of image analysis. The colonization of samples was not influenced by the porosity because of the specific conditions of testing. However, the increase in roughness and the decreases in surface pH by the means of carbonation, promote algal development significantly. Thus the latency time is shortened and the rate of colonization increases

Influence of the chemical composition of mortars on algal biofouling

ISBN : 978-1-84806-316-7International audienceThe main cause of building-facade biodeterioration is the growth of microorganisms. The state of surface is among parameters which affects the most biofouling kinetics. The main objective of this study was to highlight the influence of mortar chemistry and its physical properties on algal growth. The green algae Klebsormidium flaccidum was chosen for this work because of its representativeness. In order to characterize the influence of the mortar chemistry on biofouling, Portland cement (CEMI) and aluminate cement (CAC) were used. The biofouling kinetics was followed on samples tested in a laboratory bench, where the mortar specimens were exposed to a sprinkling of algal suspension. The algal growth was daily monitored by image analysis. The colonization rate was given by the ratio of colonized area to the total surface. In our case, the surface roughness does not seem to affect the algal colonization. The experimental method highlights that surface pH and chemistry of cement used in mortar formulations have an influence on algal fouling. In fact, the colonization kinetics of CAC mortars is lower than that of CEMI mortar