Claire Gaillard

The porcine Major Histocompatibility Complex and related paralogous regions: a review

The physical alignment of the entire region of the pig major histocompatibility complex (MHC) has been almost completed. In swine, the MHC is called the SLA (swine leukocyte antigen) and most of its class I region has been sequenced. Over one hundred genes have been characterised, including the classical class I and class I-related genes, as well as the class II gene families. These results in swine provide new evidence for the striking conservation during the evolution of a general MHC framework, and are consistent with the location of the class I genes on segments referred to as permissive places within the MHC class I region. Recent results confirm the involvement of the SLA region in numerous quantitative traits.

Properties of cellulose/pectins composites: implication for structural and mechanical properties of cell wall.

The primary cell wall of dicotyledonous plants can be considered as a concentrated polymer assembly, containing in particular polysaccharides among which cellulose and pectins are known to be the major components. In order to understand and control the textural quality of plant-derived foods, it is highly important to elucidate the rheological and microstructural properties of these components, individually and in mixture, in order to define their implication for structural and mechanical properties of primary plant cell wall. In this study, the rheological and microstructural properties of model systems composed of sugar-beet microfibrillated cellulose and HM pectins from various sources, with varied degrees of methylation and containing different amounts of neutral sugar side chains, were investigated. The influence of the presence of calcium and/or sodium ions and the biopolymer concentrations on the properties of the mixed systems were also studied. The characterizations of the mixed system, considered as a simplified model of primary plant cell wall, showed that whatever the structural characteristics of the pectins, the ionic conditions of the medium and the biopolymer concentrations, the gelation of the composite was mainly controlled by cellulose. Thus, the cellulose network would be the principal component governing the mechanical properties of the cell walls. However, the neutral sugar side chains of the pectins seem to play a part in the interactions with cellulose, as shown by the interesting viscoelastic properties of cellulose/apple HM pectins systems. The rigidity of cellulose/pectins composite was strongly influenced by the structural characteristics of pectins. The particular properties of primary plant cell walls would thus result from the solid viscoelastic properties of cellulose, its interactions with pectins according to their structural characteristics (implication of the neutral sugar side chains and the specific potential calcic interactions) and of the distribution of the components in separate phases.

Construction of a cytogenetically anchored microsatellite map in rabbit.

Rabbit (Oryctolagus cuniculus) represents a valuable source of biomedical models and corresponds to a small but active economic sector in Europe for meat and fur. The rabbit genome has not been thoroughly studied until recently, and high-resolution maps necessary for identification of genes and quantitative trait loci (QTL) are not yet available. Our aim was to isolate over 300 new and regularly distributed (TG)n or (TC)n rabbit microsatellites. To achieve this purpose, 164 microsatellite sequences were isolated from gene-containing bacterial artificial chromosome (BAC) clones previously localized by fluorescence in situ hybridization (FISH) on all the rabbit chromosomes. In addition, 141 microsatellite sequences were subcloned from a plasmid genomic library, and for 41 of these sequences, BAC clones were identified and FISH-mapped. TC repeats were present in 62% of the microsatellites derived from gene-containing BAC clones and in 22% of those from the plasmid genomic library, with an average of 42.9% irrespective of the microsatellite origin. These results suggest a higher proportion of (TC)n repeats and a nonhomogeneous distribution of (TG)n and (TC)n repeats in the rabbit genome compared to those in man. Among the 305 isolated microsatellites, 177 were assigned to 139 different cytogenetic positions on all the chromosomes except rabbit Chromosome 21. Sequence similarity searches provided hit locations on the Human Build 35a and hypothetical assignments on rabbit chromosomes for ten additional microsatellites. Taken together, these results report a reservoir of 305 new rabbit microsatellites of which 60% have a cytogenetic position. This is the first step toward the construction of an integrated cytogenetic and genetic map based on microsatellites homogeneously anchored to the rabbit genome.

Monitoring the architecture of anionic κ-carrageenan/cationic glycine betaine amide surfactant assemblies by dilution: A multiscale approach

The interaction between glycine betaine-based cationic surfactant and algal polysaccharide κ-carrageenan was studied by investigating the dilution effect of the surfactant/polymer assemblies driven by electrostatic interactions. Two aqueous solutions of cationic surfactant and κ-carrageenan at two molar ratios (3.5 and 0.8) diluted with factors of 5 and 10 times, were tested by various analytical methods including a multiscale observation by Transmission Electron Microscopy (TEM) and Laser Scanning Confocal Microscopy (LSCM) to understand the solution behavior of surfactant and oppositely charged polymer at both nano- and micrometer scale. Raman spectroscopy as well as confocal Raman imaging were applied to give Supplementary information about the surfactant/polysaccharide interactions and the distribution of assemblies. These analyses confirmed the formation of singular hybrid surfactant/polymer nano-, microobjects and they revealed the influence of dilution on the nanostructures. These results give an insight of the mechanism of the dilution effect on surfactant/polymer assemblies that could be valuable in pharmaceutical formulations, food and cosmetics fields.

Exploitations familiales et renouvellement des générations. L’exemple du canton de Seurre en Côte d’Or (France)

En France, l’installation de jeunes agriculteurs selon le modele de l’exploitation familiale a toujours ete prioritaire au niveau des lois d’orientation agricoles. L’evaluation d’un programme visant l’installation de jeunes issus de familles non agricoles a revele, en 1997 dans le canton de Seurre (Bourgogne, France), un contexte qui leur est defavorable et une specialisation des exploitations en productions vegetales qui s’accompagne d’une pression fonciere forte. Cette situation a conduit a privilegier l’installation des enfants d’agriculteurs au sein de societes de type parents-enfants. Le depart a la retraite des parents confronte ces societes familiales a deux generations au renouvellement de la main-d’œuvre et implique des strategies d’evolution reperees en 2004. Une majorite des exploitants partant en retraite ne sera pas remplacee lorsque l’orientation vers la specialisation vegetale ainsi que l’augmentation de la productivite du travail peuvent etre confortees. Dans ces situations, l’exploitation conduite et geree en famille devient une exploitation d’origine familiale prevue pour une seule personne, le chef d’exploitation, ce qui amene a une nouvelle coherence du fonctionnement du systeme exploitation-famille.