Schémas de sélection: de la représentation généalogique au modèle statistique. Élaboration du modèle

International audienc

Genetic control of protein, oil and fatty acids content under partial drought stress and late sowing conditions in sunflower (Helianthus annuus)

The purpose of the present study was to map quantitative trait locus (QTLs) associated with percentage of seed protein, oil and fatty acids content under different conditions in a population of recombinant inbred lines (RILs) of sunflower. Three independent field experiments were conducted with well-, partial-irrigated and late-sowing conditions in randomized complete block design with three replications. High significant variation among genotypes is observed for the studied traits in all conditions. Several specific and non-specific QTLs for the aforementioned traits were detected. Under late-sowing condition, a specific QTL of palmitic acid content on linkage group 6 (PAC-LS.6) is located between ORS1233 and SSL66_1 markers. Common chromosomic regions are observed for percentage of seed oil and stearic acid content on linkage group 10 (PSO-PI.10 and SAC-WI.10) and 15 (PSO-PI.15 and SAC-LS.15). Overlapping occurs for QTLs of oleic and linoleic acids content on linkage groups 10, 11 and 16. Seven QTLs associated with palmitic, stearic, oleic and linoleic acids content are identified on linkage group 14. These common QTLs are linked to HPPD homologue, HuCL04260C001. Coincidence of the position for some detected QTLs and candidate genes involved in enzymatic and non-enzymatic antioxidants would be useful for the function of the respective genes in fatty acid stability.Key words: Sunflower, quantitative trait locus, simple sequence repeats, oil content, protein content, fatty acids

Relations génétiques entre caractéristiques de la phase juvénile et productivité chez le maïs ensilage I. - Vigueur au stade jeune et productivité

La vigueur au stade jeune, facteur de productivité et de stabilité du maïs ensilage, est mesurée au stade plantule (2 à 3 feuilles visibles) et au moment de la différenciation florale à partir de critères pondéraux. Trente familles de demi-frères denté x corné sont comparées pour ces critères, qui sont par ailleurs mis en relation avec des caractéristiques du stade adulte : productivité et teneur en matière sèche à la récolte, caractères morphologiques. Les productivités en matière sèche des organes en croissance au stade plantule sont fortement liées au prélèvement de matière sèche dans la semence. Il subsiste toutefois, au niveau des parties aériennes, des différences de vigueur qui, dans les conditions de l'essai, sont positivement liées aux différences de rendement en matière sèche à la récolte. Le poids de la partie ( 1er entrenoeud + coléoptile) semble intéressant comme covariable pour estimer correctement au champ un critère de rapidité de levée. On n'observe pas de liaison entre caractéristiques du stade adulte et vigueur au moment de la différenciation florale. La corrélation (rendement en matière sèche, teneur en matière sèche) observée dans cet essai est proche de zéro. On interprète ce fait par l'intervention d'un stress hydrique au cours de la période floraison-maturité, qui aura

Etude de la competition interparcellaire chez le tournesol.

10 illus.National audienc

Evaluation of nanostructured vectors for the treatment of osteoarticular pathologies

World Congress of the Osteoarthritis-Research-Society-International (OARSI), Paris, FRANCE, APR 24-27, 2014International audiencePurpose: One of the major problems in treatment of osteoarticular diseases is to reach cells inside the matrix to provide drug. Indeed, cartilage is an avascular tissue with a few cells feed by diffusion through a dense protein network (collagens, glycosaminoglycans). In this work we have designed polymeric nanoparticles (NPs) of poly (D, L-lactic/glycolic acid)(PLGA) synthesized by a double emulsion method, which are biocompatible, biodegradable and can encapsulate water-soluble agents. Our NPs are labelled with BSA coupled to a fluorescent dye (Cyanine-3) to follow them by epifluorescent microscopy. As articular cells expressed CD44, one receptor of hyaluronic acid (HA)(a main component of synovial fluid), the nanoparticles are recovered with HA in order to enhance targeting of cells. Here, we have studied the internalization kinetics of “empty” nanoparticles, and we have evaluated their neutrality on chondrocytes matrix synthesis, mesenchymal stem cell (MSC) differentiation and inflammatory response. Innocuity has been also evaluated in healthy animals, after direct intraarticular injection of labelled nanoparticles (inflammatory response, Extracellular matrix integrity).Methods: Articular cells (chondrocytes, synoviocytes) and MSC are isolated from human donors, and cultured as primary culture. First, cells are exposed with 100 μg/mL of NPs from 2 to 12 hours. At the end of the kinetic immunofluorescence pictures with DAPI (nuclear staining) are realized to assess of the internalization of NPs, expression of inflammatory markers (IL1ß, TNFα and Cox2) are monitored by RT-qPCR analysis, and confirmed by PGE2 and nitrites measurement in supernatant.In other hand we evaluate, with pellets culture system, the effect of NPs exposition on extracellular matrix synthesis by chondrocytes, with RT-qPCR analysis of specific markers (Col2, Aggrecan and COMP), and by histological study of pellets (Alcian blue staining of proteoglycans, Sirius Red staining of collagen). Finally by growing MSC into 3 different differentiation media, we investigate if NPs pre-treatment can interfere with differentiation ability of MSC onto chondrogenic, adipogenic or osteogenic pathway. RT-qPCR assays for differentiation markers according to culture conditions and specific staining of lipid vesicles or calcium deposits, allow us to confirm the differentiation of cells.Intraarticular injections were realized in healthy rat’s Knees. Structure of joint (synovium, cartilage, subchondral bone) was assessed by histological studies, performed at 7 and 10 days after injection (single and repeated).Results: For the different cell types, NPs are found into cytoplasm after 6 hours of exposition