Amélioration de l’attractivité et de la compétitivité du territoire wallon pour le secteur des services supérieurs. Étude stratégique exploratoire

Rapport de recherche de l'IWEPS n°1

Lexical Recount between Factor Analysis and Kohonen Map: Mathematical Vocabulary of Arithmetic in the Vernacular Language of the Late Middle Ages

International audienceIn this paper we present a combination of factorial projections and of SOM algorithm applied to a text mining problem. The corpus consists of 8 medieval texts which were used to teach arithmetic techniques to merchants. Classical Factorial Component Analysis (FCA) gives nice representations of the selected words in association with the texts, but the quality of the representation is poor in the center of the graphs and it is not easy to look for the successive projections to conclude. So using the nice properties of Kohonen maps, we can highlight the words which seems to play a special role in the vocabulary since they are associated with very different words from a map to another. Finally we show that combination of both representations is a powerful help to text analysis

Structure-fonction de MARCH1, une E3 ubiquitine ligase régulant la présentation antigénique par le CMH II

Les molécules classiques du CMH de classe II sont responsables de la présentation de peptides exogènes par les cellules présentatrices d’antigène aux lymphocytes T CD4+. Cette présentation antigénique est essentielle à l’établissement d’une réponse immunitaire adaptative. Cependant, la reconnaissance d’auto-antigènes ainsi que l’élimination des cellules du Soi sont des problèmes à l’origine de nombreuses maladies auto-immunes. Notamment, le diabète et la sclérose en plaque. D’éventuels traitements de ces maladies pourraient impliquer la manipulation de la présentation antigénique chez les cellules dont la reconnaissance et l’élimination engendrent ces maladies. Il est donc primordial d’approfondir nos connaissances en ce qui concerne les mécanismes de régulation de la présentation antigénique. La présentation antigénique est régulée tant au niveau transcriptionnel que post-traductionnel. Au niveau post-traductionnel, diverses cytokines affectent le processus. Parmi celles-ci, l’IL-10, une cytokine anti-inflammatoire, cause une rétention intracellulaire des molécules du CMH II. Son mécanisme d’action consiste en l’ubiquitination de la queue cytoplasmique de la chaîne bêta des molécules de CMH II. Cette modification protéique est effectuée par MARCH1, une E3 ubiquitine ligase dont l’expression est restreinte aux organes lymphoïdes secondaires. Jusqu’à tout récemment, il y avait très peu de connaissance concernant la structure et les cibles de MARCH1. Considérant son impact majeur sur la présentation antigénique, nous nous sommes intéressé à la structure-fonction de cette molécule afin de mieux caractériser sa régulation ainsi que les diverses conditions nécessaires à son fonctionnement. Dans un premier article, nous avons étudié la régulation de l’expression de MARCH1 au niveau protéique. Nos résultats ont révélé l’autorégulation de la molécule par formation de dimères et son autoubiquitination. Nous avons également démontré l’importance des domaines transmembranaires de MARCH1 dans la formation de dimères et l’interaction avec le CMH II. Dans un second article, nous avons investigué l’importance de la localisation de MARCH1 pour sa fonction. Les résultats obtenus montrent la fonctionnalité des motifs de localisation de la portion C-terminale de MARCH1 ainsi que la présence d’autres éléments de localisation dans la portion N-terminale de la protéine. Les nombreux mutants utilisés pour ce projet nous ont permis d’identifier un motif ‘‘VQNC’’, situé dans la portion cytoplasmique C-terminale de MARCH1, dont la valine est requise au fonctionnement optimal de la molécule. En effet, la mutation de la valine engendre une diminution de la fonction de la molécule et des expériences de BRET ont démontré une modification de l’orientation spatiale des queues cytoplasmiques. De plus, une recherche d’homologie de séquence a révélé la présence de ce même motif dans d’autres ubiquitines ligases, dont Parkin. Parkin est fortement exprimée dans le cerveau et agirait, entre autre, sur la dégradation des agrégats protéiques. La dysfonction de Parkin cause l’accumulation de ces agrégats, nommés corps de Lewy, qui entraînent des déficiences au niveau du fonctionnement neural observé chez les patients atteints de la maladie de Parkinson. La valine comprise dans le motif ‘’VQNC’’ a d’ailleurs été identifiée comme étant mutée au sein d’une famille où cette maladie est génétiquement transmise. Nous croyons que l’importance de ce motif ne se restreint pas à MARCH1, mais serait généralisée à d’autres E3 ligases. Ce projet de recherche a permis de caractériser des mécanismes de régulation de MARCH1 ainsi que de découvrir divers éléments structuraux requis à sa fonction. Nos travaux ont permis de mieux comprendre les mécanismes de contrôle de la présentation antigénique par les molécules de CMH II.Classical MHC class II molecules are responsible for the presentation of exogenous peptides to CD4+ T cells, which is essential for the establishment of the adaptive immune response. However, problems with recognition of auto-antigens and the subsequent cell elimination are at the root of numerous autoimmune diseases. Manipulation of the antigen presentation pathway in order to eliminate cells that present self-antigens could serve as potential treatments of many autoimmune disorders. It is therefore essential to deepen our knowledge regarding the mechanisms regulating antigen presentation. Antigen presentation is regulated both transcriptionally and post-translationally. Whereas many cytokines affect the latter, IL-10, an anti-inflammatory cytokine, causes the intracellular retention of MHC II molecules. This phenotype is the result of the ubiquitination of MHC II -chain cytoplasmic tail by MARCH1. MARCH1 is an E3 ubiquitin ligase expressed in secondary lymphoid organs. Until recently, little was known about the structure-function and the targets of MARCH1. Considering its major impact on antigen presentation, we were interested to study this E3 ligase in order to reveal how it is regulated and what are the required conditions for its function. In a first report, we have investigated the regulation of MARCH1’s protein expression. Our results revealed its autoregulation via dimer formation and autoubiquitination. In addition, we have demonstrated the involvement of MARCH1’s transmembrane domains for dimerization and MHC II interaction. In a second article, we highlighted the importance of MARCH1 localization for its function. Our results indicated that localization motifs in the C-terminal portion of MARCH1 were functional and revealed the presence of some sorting elements in the N-terminal portion of the molecule. A panel of mutant were used and allowed us to identify a ‘’VQNC’’ motif, located in the C-terminal cytoplasmic portion of MARCH1, in which the valine is central for the molecule’s function. Indeed, point-mutation of the valine led to a decrease in MARCH1 ability to relocate MHC II whereas BRET experiments revealed a modification in the spatial organization of the cytoplasmic tails. Moreover, a blast of sequence homology showed the presence or that same motif in others ubiquitine ligases, one of which is Parkin. Parkin is highly expressed in the brain and seems to be implicated in protein aggregates’ degradation. It was reported that malfunction of Parkin leads to the accumulation of aggregates, called Lewy bodies, responsible for the neural functions deficiencies observed in patients with Parkinson disease. Interestingly, a family for which the sickness was genetically transmitted has a mutated valine in the VQNC motif. We believe that the importance of this motif is not restricted to MARCH1 and could be generalized to others E3 ubiquitin ligases. This project enabled us to characterize the regulation mechanisms of MARCH1. In addition, we discovered various structural elements required for its function. Altogether, our data allows for a better understanding of the mechanisms controlling MHC II molecules antigen presentation

Virucidal Activity of Chlorine Dioxide Gas for Reduction of Coronavirus on Surfaces and PPE

A coronavirus (SARS-CoV-2) has caused a global pandemic and associated morbidity and mortality resultant from COVID-19. As a result of efforts to control direct (person to person) and indirect (contaminated objects, surfaces, indoor air) transmission of the virus, various interventions have been evaluated. Studies were conducted to evaluate the efficacy of commercially available chlorine dioxide (CD) products to reduce viral loads on PPE (face masks) and surfaces using a novel dry gas release intervention. The efficacy of CD slow release 30-day sachets was tested on N95 face masks inoculated with human coronavirus OC43 in suspension. One sachet was placed with an inoculated mask in plastic resealable bags. Three trials were completed using the original sachet where a mask and sachet were placed into a plastic bag for 13 hours per sachet age of 1 day, 14 days, and 30 days. The amount of CD generated during a 13-hour treatment period was 0.30 mg. The nominal concentration of CD was estimated to be 317 mg/m3. All three tests demonstrated at least a 99.91% reduction of viral loading in the mask versus a non-treated control. Efficacy of CD dry gas fast releasing pods (Ultrashok) for fumigation was also tested in a 1344 ft3 closed room. Two pods were placed in the space and CD surface virucidal efficacy was tested in three locations of the room after 1 hour and 2 hours of dwell time. The estimated nominal peak concentration was 15 ppmv in the room. The one-hour exposure saw a \u3e99.91% OC43 reduction on surfaces and the two-hour exposure resulted in a \u3e99.997% OC43 reduction on surfaces versus a non-treated control. These results indicate dry CD is highly effective against human coronavirus. CD was 99.91% effective for eliminating human coronavirus OC43 in both sachet and capsule fumigant form using both fast and slow release mechanisms. Rapid fumigant application is suitable for contaminated rooms, ambulances, emergency vehicles, and many types of PPE, most particularly porous PPE materials. The gaseous state of CD allows for rapid diffusion and transfer of the virucidal stable free radical to all surfaces of PPE and indoor areas that would favor virus survival. Additionally, this work suggests CD can be effective at levels with significant margins of safety (little to no exposure and rapid degradation of residuals) providing minimal public health risks associated with the use of CD

On the feasibility of retrieving 16O 18O 16O ozone from high resolution ground-based FTIR spectra

We present evidence of the 16O 18O 16O ozone isotope in the 5 micron region from FTIR solar occultation spectra obtained from the Jungfraujoch Solar Observatory (47°N, 8°E, 3580 m) in Switzerland at a spectral resolution of 0,0025 cm-1 (res. = 1/2L). These spectra clearly show numerous unblended lines of the 16O 18O 16O ozone isotope. Laboratory spectra in the 5 micron region of 16O 18O 16O have been measured and have yielded line positions of the nu1 + nu3 isotopic bands which can eventually lead to their retrieval from measured ground-based solar occultation spectra

Specific pattern of cell cycle during limb fetal myogenesis

AbstractTight regulation of cell proliferation and differentiation is required to ensure proper growth during development and post-natal life. The source and nature of signals regulating cell proliferation are not well identified in vivo. We investigated the specific pattern of proliferating cells in mouse limbs, using the Fluorescent ubiquitynation-based cell-cycle indicator (Fucci) system, which allowed the visualization of the G1, G1/S transition and S/G2/M phases of the cell cycle in red, yellow or green fluorescent colors, respectively. We also used the retroviral RCAS system to express a Fucci cassette in chick embryos. We performed a comprehensive analysis of the cell cycle state of myogenic cells in fetal limb muscles, adult myoblast primary cultures and isolated muscle fiber cultures using the Fucci transgenic mice. We found that myonuclei of terminally differentiated muscle fibers displayed Fucci red fluorescence during mouse and chick fetal development, in adult isolated muscle fiber (ex vivo) and adult myoblast (in vitro) mouse cultures. This indicated that myonuclei exited from the cell cycle in the G1 phase and are maintained in a blocked G1-like state. We also found that cycling muscle progenitors and myoblasts in G1 phase were not completely covered by the Fucci system. During mouse fetal myogenesis, Pax7+ cells labeled with the Fucci system were observed mostly in S/G2/M phases. Proliferating cells in S/G2/M phases displayed a specific pattern in mouse fetal limbs, delineating individualized muscles. In addition, we observed more Pax7+ cells in S/G2/M phases at muscle tips, compared to the middle of muscles. These results highlight a specific spatial regionalization of cycling cells at the muscle borders and muscle–tendon interface during fetal development