Development of 55 novel polymorphic microsatellite loci for the critically endangered L. (Actinopterygii: Perciformes: Percidae) and cross-species amplification in five other percids

International audienceBy combining biotin-enrichment protocol and next generation pyrosequencing, through 454 GS-FLX Titanium technology, 55 polymorphic microsatellites loci with perfect motif were isolated from the Rhone streber (), a critically endangered European fish species. Eight multiplex PCR kits were optimised in order to genotype a total of 58 polymorphic loci, including three previously published loci. The level of genetic diversity was assessed for 68 , 30 , 33 and four individuals. Amplification success was also assessed on and using single individuals. These markers will be useful to investigate the population structure of the highly fragmented Rhone streber. They represent a powerful tool for conservation issues and evolutionary approaches of this endemic species. Moreover, part of our markers demonstrated applicability to other percid species, allowing for potential applications to fisheries and aquaculture management

Characterization of the function of thymic stromal lymphopoietin in lymphopoiesis and lymph node organogenesis

Interleukin (IL)-7 is a cytokine, which is crucial for the development of the murine immune system. It is required for lymphopoiesis and for the development of peripheral lymph nodes (LN). IL-7-/-mice have impaired B and T cell lymphopoiesis, decreased numbers of peripheral B and T cells and are devoid of γδ T cells. IL-7 signals through a receptor composed of the common γ (γc) and the IL-7Rα chain. The latter chain can also pair with the γc-like chain called thymic stromal lymphopoietin receptor (TSLPR). Both form the receptor of the cytokine called thymic stromal lymphopoietin (TSLP). . Originally identified for its capacity to promote B cell development in vitro, TSLP was later shown to induce dendritic cell maturation, to trigger allergic diseases and to drive TH2 differentiation. Several evidences suggested that TSLP might play a role in fetal B lymphopoiesis and that fetal but not adult cells were TSLP-responsive. However, the function of TSLP in hematopoiesis and in LN organogenesis in vivo remained elusive. In the work presented in the first part of this thesis, I have characterized the function of TSLP in adult lymphopoiesis. This study shows that TSLP transgene (Tg) expression restored all developing B cell compartments in the bone marrow (BM), DN1 and DN2 thymocytes and thymic architecture, and all peripheral B and αβ and γδ T cell compartments in IL-7-/- mice. The expression of the TSLP Tg increased thymic and splenic cellularities. The analysis of the junctions of the immunoglobulin heavy chain locus showed that the DNA of B cells from IL-7-/- TSLP Tg mice contained N nucleotides, suggesting that adult hematopoietic progenitors are TSLP-responsive. Moreover, BM chimera experiments showed that WT BM precursors differentiated towards Band T-cell lineages in response to TSLP, further suggesting that adult hematopoietic cells are TSLP-responsive. In this line, we show that TSLP had the capacity to promote the proliferation and the differentiation of DN1 and DN2 thymocytes as well as the differentiation of uncommitted adult BM precursors towards the B and the T cell lineage in vitro. Hence, these results altogether showed that TSLP has the capacity to promote long-term adult lymphopoiesis in the absence of IL-7. Lymph node (LN) development starts during fetal life and crucially relies on the interaction between the hematopoietic lymphoid tissue inducer (LTi) cells and the mesenchymal organizer cells. Both together cluster in a cellular aggregate called LN anlage. This LN anlage is colonized by peripheral lymphocytes after birth, and gives rise to a mature LN organized into B cell follicles and a T-cell zone. Mice deficient for IL-7 or for molecules of the IL-7 signaling pathway lack several LN but the reasons underlying this defect are still not clear. As IL-7 regulates the size of the LTi cell pool, a possibility is that LN development in IL-7-/- mice is impaired because of insufficient LTi cell number. Alternatively, it was proposed that the lack of colonization of the LN anlage by peripheral lymphocytes might prevent the maintenance of the LN anlage. I show in the second part of this thesis, that TSLP overexpression increased LTi cell number and restored LN development in IL-7-/- and RAG2-/- γc -/- mice, suggesting that LTi cell number is a critical parameter for LN organogenesis. The LN anlage of RAG2-/- γc -/- TSLP Tg mice were devoid of peripheral lymphocytes, ruling out that lymphocytes are required for LN maintenance. Thus, the results shown here define organizer and LTi cells as the minimal cellular requirement for LN development and suggest that the lack of LN in mice lacking molecules of the IL-7 pathway is the result of suboptimal LTi cell number. This study further shows that lymphocyte colonization is required for establishing a correct LN architecture and for the differentiation of some mesenchymal populations within the LN microenvironment. Overall, this study shows that TSLP can substitute IL-7 for murine lymphopoiesis and for LN organogenesis and suggest that the impaired lymphopoiesis and LN organogenesis in IL-7-/- mice is the consequence of limited availability of endogenous TSLP

The IL-7 signaling pathway regulates lymph node development independent of peripheral lymphocytes

Lymph node (LN) organogenesis is initiated by the interaction between hematopoietic lymphoid tissue inducer (LTi) cells and the mesenchymal organizer cells. Mice in which the IL-7 signaling pathway has been disrupted have a severe defect in LN development; however, the reasons underlying this defect are as yet unknown. In this study, we show that the overexpression of thymic stromal lymphopoietin (TSLP) increased LTi cell numbers and restored LN development in IL-7(-/-) and RAG2(-/-) gamma(c)(-/-) mice. The TSLP-mediated LN restoration was strictly dependent on LTi cells and independent of lymphocyte colonization. Increased LTi cell numbers in the LN anlagen of RAG2(-/-) gamma(c)(-/-) TSLP transgenic mice were associated with the restoration of organizer cells, suggesting that LTi cell number is a critical parameter for LN organogenesis. Our results shed light on the minimal cellular requirement for LN development during ontogeny. We show that the presence of LTi and organizer cells, but not of peripheral lymphocytes, is critical for LN development and persistence and further suggest that the IL-7 signaling pathway regulates LN organogenesis by controlling the size of the LTi cell pool

Kit ligand and Il7 differentially regulate Peyer's patch and lymph node development

Hematopoietic lymphoid tissue inducer (LTi) cells initiate lymph node (LN) and Peyer's patch (PP) development during fetal life by inducing the differentiation of mesenchymal organizer cells. The growth factor signals underlying LTi cell development and LN and PP organogenesis remain poorly understood. LTi cells express the Il7r and the receptor tyrosine kinase Kit, whereas organizer cells express their cognate ligands. To determine the relative significance of Il7 and Kit signaling in LTi cell homeostasis and PP and LN development, we have analyzed mice deficient for Kit (Kit(W/Wv)), Il7 (Il7(-/-)), or both (Il7(-/-) Kit(W/Wv)). Unlike Kit(W/Wv) and Il7(-/-) single mutants, Il7(-/-) Kit(W/Wv) mice were almost devoid of LTi cells in their mesenteric LN anlage. This LTi deficiency was associated with a block in mesenchymal LN organizer cell generation and the absence of almost all LNs. In contrast, intestinal LTi cell numbers, PP organizer cell generation, and PP development were strongly affected by impaired Kit signaling, but were independent of Il7. Hence, Kit and Il7 act synergistically in LN organogenesis, whereas Kit signaling, but not Il7, critically regulates PP organogenesis and LTi cell numbers in the intestine. Consistent with these differential growth factor requirements for PP and LN development, PP organizer cells expressed higher Kitl and lower Il7 levels than did LN organizer cells. Collectively, these results demonstrate that Kit and Il7 differentially control PP and LN organogenesis through the local growth factor-driven regulation of LTi cell numbers

Polymer solar cells with electrodeposited CuSCN nanowires as new efficient hole transporting layer

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Teneur en acide linoléique conjugué (CLA) dans l'Emmental français : Effet de la saison, de la zone de production, de la fabrication et du mode de préparation culinaire

International audienceConjugated linoleic acid (CLA), and especially rumenic acid, are isomers of linoleic acid which have a great potential in human nutrition for their beneficial properties. The most important sources of natural CLA are milk and dairy products such as cheese. This study was delineated to assess the effects of sampling according to the cheese wheel, the seasonal and regional influence on CLA content in French Emmental cheese and, finally, the effects of culinary preparation of three different dishes (gratin, béchamel sauce and cheese fondue) and processed cheese. The rumenic acid content of Emmental cheese varied between 0.6% and 1.5% of total fatty acids according to the season and region of production, and appeared homogeneous through the cheese wheel. The culinary utilization and processing did not change the rumenic acid content of Emmental cheese.Les isomères conjugués de l'acide linoléique (CLA) et, en particulier, l'acide ruménique (C18:2 9 cis 11 trans) possèdent des effets bénéfiques d'un grand intérêt en nutrition humaine. Le lait et les produits laitiers, tels que les fromages, sont d'importantes sources naturelles d'acide ruménique. Ce travail avait pour but d'en établir la répartition au sein de la meule de fromage, d'étudier l'influence de la saison et de l'origine régionale sur la teneur en CLA de l'Emmental français et enfin, de mesurer les effets de son utilisation, soit en cuisine dans la préparation de sauce béchamel, de gratin et de fondue, soit dans la fabrication de fromage fondu. La teneur de l'Emmental français en acide ruménique varie de 0,6 % à 1,5 % de la teneur totale en acide gras selon la saison et la région de production, elle est homogène au sein de la meule de fromage. Aucune modification significative de la teneur en CLA n'est observée lors de l'utilisation de l'Emmental, aussi bien pour les trois préparations culinaires que pour la fabrication de fromage fondu

Germline heterozygous mutations in Nxf1 perturb RNA metabolism and trigger thrombocytopenia and lymphopenia in mice

In eukaryotic cells, messenger RNA (mRNA) molecules are exported from the nucleus to the cytoplasm, where they are translated. The highly conserved protein nuclear RNA export factor1 (Nxf1) is an important mediator of this process. Although studies in yeast and in human cell lines have shed light on the biochemical mechanisms of Nxf1 function, its contribution to mammalian physiology is less clear. Several groups have identified recurrent NXF1 mutations in chronic lymphocytic leukemia (CLL), placing it alongside several RNA-metabolism factors (including SF3B1, XPO, RPS15) whose dysregulation is thought to contribute to CLL pathogenesis. We report here an allelic series of germline point mutations in murine Nxf1. Mice heterozygous for these loss-of-function Nxf1 mutations exhibit thrombocytopenia and lymphopenia, together with milder hematological defects. This is primarily caused by cell-intrinsic defects in the survival of platelets and peripheral lymphocytes, which are sensitized to intrinsic apoptosis. In contrast, Nxf1 mutations have almost no effect on red blood cell homeostasis. Comparative transcriptome analysis of platelets, lymphocytes, and erythrocytes from Nxf1-mutant mice shows that, in response to impaired Nxf1 function, the cytoplasmic representation of transcripts encoding regulators of RNA metabolism is altered in a unique, lineage-specific way. Thus, blood cell lineages exhibit differential requirements for Nxf1-mediated global mRNA export