A New Bifidobacteria Expression SysTem (BEST) to Produce and Deliver Interleukin-10 in Bifidobacterium bifidum

In the last years there has been a growing interest in the use of genetically modified bacteria to deliver molecules of therapeutic interest at mucosal surfaces. Due to the well-recognized probiotic properties of some strains, bifidobacteria represent excellent candidates for the development of live vehicles to produce and deliver heterologous proteins at mucosal surfaces. However, very few studies have considered this genus because of its complexity to be genetically manipulated. In this work, we report the development of a new Bifidobacteria Expression SysTem (BEST) allowing the production of heterologous proteins in Bifidobacterium bifidum. This system is based on: i) the broad host range plasmid pWV01, ii) a stress-inducible promoter, and iii) two different signal peptides (SPs) one issued from Lactococcus lactis (SPExp4) and issued from Bifidobacterium longum (SPBL1181). The functionality of BEST system was validated by cloning murine interleukin-10 (IL-10) and establishing the resulting plasmids (i.e., pBESTExp4:IL-10 and pBESTBL1181:IL-10) in the strain of B. bifidum BS42. We then demonstrated in vitro that recombinant B. bifidum BS42 harboring pBESTBL1181:IL-10 plasmid efficiently secreted IL-10 and that this secretion was significantly higher (sevenfold) than its counterpart B. bifidum BS42 harboring pBESTExp4:IL-10 plasmid. Finally, we validated in vivo that recombinant B. bifidum strains producing IL-10 using BEST system efficiently delivered this cytokine at mucosal surfaces and exhibit beneficial effects in a murine model of low-grade intestinal inflammation

Orientation de la Terre par mesure VLBI

Earth orientation by VLBI data analysisCe travail de thèse se situe dans le cadre du développement d'une chaîne originale d'analyse de VLBI (Very Large Baseline Interferometry) astrométrique et géodésique GLORIA (GLObal Radio Interferometric Analysis) par des équipes de l'Observatoire de Paris et de l'Institut Géographique National. Nous avons dans un premier temps développé et testé une modélisation astronomique et géophysique originale dans le cadre de la relativité générale avec une précision de 10 picosecondes. Dans un deuxième temps nous avons utilisé cette modélisation originale pour analyser trois ans d'observations du programme VLBI dédié à l'étude de la rotation terrestre. Nous avons développé un protocole statistique, basé sur des résolutions en norme l1 et en norme l2, permettant de détecter les observations atypiques. Les solutions obtenues, 747 évaluations journalière de temps universel, UT1-TAI, pour 1988-1990, ont une précision de 0,001 qui est celle attendue théoriquement étant donné la stratégie d'observation de ce programme

Stable radio sources and reference frame

International audienceThe analysis of geodetic VLBI sessions since the early days of VLBI allows one to get time series of radio source coordinates. The analysis of these time series in terms of time stability can help us in our quest for a subset of radio sources suitable for defining the axes of the next ICRF. What we do here is (i) to compute the time series, (ii) to select the most stable sources, and (iii) to assess that the reference frame as defined with these sources is more stable than the previously defined ICRF

Stable radio sources and reference frame

International audienceThe analysis of geodetic VLBI sessions since the early days of VLBI allows one to get time series of radio source coordinates. The analysis of these time series in terms of time stability can help us in our quest for a subset of radio sources suitable for defining the axes of the next ICRF. What we do here is (i) to compute the time series, (ii) to select the most stable sources, and (iii) to assess that the reference frame as defined with these sources is more stable than the previously defined ICRF

On radio source selection and frame stability

International audienc

Physical characteristics of the ICRF2 quasars

International audienceThis paper summarizes the way we obtained the physical information on the ICRF2 radio sources.This information includes the object type, redshift, 8.4 GHz and 2.3 GHz fluxes, spectral index, visual magnitude, a classification of spectrum, and comments. The physical characteristics are made available in ASCII format at the International Celestial Reference System Product Center (ICRS-PC) of the International Earth rotation and Reference systems Service (IERS) at:http://hpiers.obspm.fr/icrs-pcunder the section Information on radio source

On radio source selection to define a stable celestial frame

International audienceContext: The most accurate realization of a quasi inertial reference frame, the International Celestial Reference Frame (ICRF), is made of 212 defining extragalactic radio sources whose coordinates are determined using VLBI observations. Recent studies demonstrated however that using other sets of sources could improve the frame stability. Aims: This study examines a simple radio source selection scheme to define celestial reference frame axes more stable than the ones as currently defined by the ICRF. Methods: After having derived source coordinate time series from 26 years of VLBI observations, we select the most suitable sources on the basis of their positional variability (rms and slope), and observational history. We determine the axis stability of the frame defined by the selection, as well as its suitability for global geodetic VLBI analyses, i.e., determination of Earth orientation parameters and source and station coordinates. Results: We select four frames made of 196, 200, 262, and 269 sources, respectively, showing a satisfactory sky coverage in both hemispheres. Our selections provide a frame stability improved by up to 40% with respect to the ICRF, and by 20% with respect to the frame as defined by the 247 stable sources of Feissel-Vernier et al. (2006, A&A, 452, 1107). Reanalysis of data with respect to this frame gives astrometric catalogues aligned to the ICRF-Ext.2 within 17 muas. Effects on the Earth orientation parameter estimates and terrestrial reference frame determination remain marginal. Conclusions: In view of the generation of the next ICRF, we recommend that such an algorithm be taken into consideration along with other criteria based on individual characteristics of the radio sources

On radio source selection and frame stability

International audienc

Physical characteristics of the ICRF2 quasars

International audienceThis paper summarizes the way we obtained the physical information on the ICRF2 radio sources.This information includes the object type, redshift, 8.4 GHz and 2.3 GHz fluxes, spectral index, visual magnitude, a classification of spectrum, and comments. The physical characteristics are made available in ASCII format at the International Celestial Reference System Product Center (ICRS-PC) of the International Earth rotation and Reference systems Service (IERS) at:http://hpiers.obspm.fr/icrs-pcunder the section Information on radio source

OPERATIONAL AND RESEARCH ACTIVITY AT OPAR

International audienceThe IVS analysis center of the Paris Observatory (OPAR) was born in 1999 when the IVS was created. In the early years, the operational activity was mainly focused on the production ofUT1 from intensive sessions. The activity was renewed in 2007 with the submission of a new long term solution to the IVS. OPAR now proposes a larger number of VLBI products