Analyse protéomique d'alterations de propriétés sensorielles et technologiques de la viande de dinde.

Les objectifs de cette étude sont de caractériser des altérations des qualités sensorielles et technologiques de la viande de dinde et de mettre en relation ces altérations avec les caractéristiques des protéines musculaires. Nous avons, tout d'abord, sélectionné des muscles Pectoralis major (PM) de dindes en fonction de leur couleur. Les propriétés sensorielles et technologiques de la viande ne diffèrent jamais entre le groupe ayant une couleur « normale » et le groupe ayant une couleur « pâle » (expérience couleur). Dans un deuxième temps, nous avons essayé d'analyser l'effet de la vitesse de chute du pH post mortem sur la qualité de la viande issue du PM de dinde. Cet effet a été mesuré avec différents types génétiques de dindes : des souches BUT9 (expériences BUT9.1 et BUT9.2) et BIG6 (expérience BIG6) comparées dans des conditions d'abattage commercial ou des souches BUT9 et Label Rouge (expérience Label) comparées en générant artificiellement le défaut PSE. Nos différentes expériences montrent que le pouvoir de rétention en eau et la texture de la viande sont diminués lorsque la glycolyse musculaire post mortem est accélérée. Par contre, la couleur de la viande est peu affectée. Nous avons aussi mis en évidence des altérations de protéines de structure (α-actinine), de protéines contractiles (actine et chaîne lourde de la myosine) et de protéines sarcoplasmiques (GAPDH, aldolase A, myokinase, ATP synthase et phosphorylase). Le type génétique des dindes ne semble pas être déterminant dans l'augmentation de l'apparition des défauts de qualité de viande. ABSTRACT : The main purposes of this study are to characterize sensory and technological meat quality alterations and to make a link between these alterations and protein characteristics in turkey muscle. First, we have selected turkey Pectoralis major (PM) muscles with different meat color. Sensory and technological meat quality characteristics never differ between pale and normal meat. Then, we have tried to analyze the effect of the rate of pH decline on turkey breast muscle quality. This effect was evaluated with several genotypes of turkeys: BUT9 and BIG6 compared in commercial conditions and BUT9 and Label Rouge line compared by artificial induction of the PSE syndrome. Our experiments show that water holding capacity and tenderness of turkey meat were lowered when the rate of glycolysis was increased. However, meat color does not seem to be modified. By using SDS-PAGE and 2 dimensional electrophoresis gels, we also report some alterations of structural protein (α-actinine), contractile proteins (actin and myosin heavy chain) and sarcoplasmic enzymes (GAPDH, aldolase A, myokinase, ATP synthase and phosphorylase). Finally, the genotype of the animals does not seem to be a simple decisive factor concerning the increase of meat quality defects

Towards the total synthesis of gambieric acid A

Over the past three decades, numerous polycyclic ether natural products have been isolated from marine organisms. All of these unusual compounds possess a wide range of biological activities. In 1992, a new family of polyethers was discovered from the marine dinoflagellate Gambierdiscus toxicus: gambieric acids A–D, which show antifungal activity against a variety of filamentous fungi. The purpose of this thesis is to show the progress towards the synthesis of F–J ring system of gambieric acid A. First, the large scale synthesis of I–G ring fragment using the two directional ring closing metathesis developed in the laboratory is described including the improvements made to the previous synthesis. Subsequently, the efficient introduction of the methyl group of the F ring using a 1,4 addition with a cuprate reagent to an a,b-unsaturated lactone is discussed in detail. In addition, efficient introduction of the side chain to the J ring using a cyclic siloxane using a model system is also reported, after the exploration of ten different approaches. Finally, studies concerning the final stages of the synthesis are discussed

A proteomic approach to study local chicken breeds characterization

Aim of this study is to apply a proteomic approach for characterization of local chicken breeds. The experiment involved a total of 29 males of Pépoi, Padovana, and Ermellinata local chicken breeds. Sarcoplasmic protein fractions of breast muscle were analysed by bidimensional electrophoresis. Image analysis followed by statistical analysis enabled to differentiate groups of individuals on the similarities of protein expression. Individuals were distinguished into clusters and groups, corresponding to the breed of origin. Results evidenced a possible utilisation of proteomic approach in the field of breed characterization studies as an alternative to genomic analyses performed using molecular markers, both for breed and product traceability purposes

Approche métabolomique pour la recherche de marqueurs métaboliques de la qualité technologique des foies gras

La maîtrise de la fonte lipidique des foies gras à la cuisson représente aujourd’hui un enjeu majeur pour les acteurs de la filière. L’amélioration des différentes étapes : élevage-gavage, abattage et transformation des foies a permis de réduire les pertes lipidiques à la cuisson. Cependant une part de la variabilité de ce paramètre reste mal contrôlée. Pour mieux comprendre cette variabilité, les caractéristiques intrinsèques de deux groupes de foies gras avec des valeurs extrêmes de rendement technologique ont été comparées. Leurs métabolites hydrophiles ont été analysés en RMN du proton, puis comparés. Ces résultats ont renforcé l’idée que i) le catabolisme protéique est plus élevé dans les foies avec des rendements technologiques faibles que dans ceux avec des rendements élevés et ii) que le stress oxydatif semble moindre dans les foies avec des rendements technologiques élevés. Les membranes plasmiques pourraient avoir une meilleure intégrité ce qui expliquerait la plus grande rétention de lipides lors de la cuisson dans ce groupe de foie gras

La fonte lipidique du foie gras à la cuisson

La connaissance des facteurs biologiques, zootechniques et technologiques ainsi que des mécanismes qui contrôlent le taux de fonte des foies gras à la cuisson est primordiale pour la maîtrise du rendement technologique des foies gras. En effet, le taux de fonte à la cuisson a des répercussions sur les qualités organoleptiques des foies gras et sur les performances des unités de production

Effect of simplified feeding based only on wheat bran and brewer’s grain on rabbit performance and economic efficiency

[EN] Simplified diets are based on maximum incorporation of fodder and/or by-products into animal feed, thus minimizing the formulation and the costs. This study aimed to evaluate the possibility of feeding fattening rabbits with a simplified diet composed of only two agro-industrial by-products inexpensive and locally available: brewer’s grain and wheat bran. At weaning (35 days), 68 rabbits were divided into two identical groups (mean weight = 833 g) and housed in individual cages until slaughter (77 days). Each of the two groups (B0 and SF) was fed ad libitum either a commercial pelleted feed (control), or a simplified pelleted experimental diet "SF" containing 72% wheat bran and 27% brewer’s grain. The feed conversion was within the standards and similar in the two groups (3.55 on average). The growth rate and feed intake of B0 group were 12% higher (P <0.001) than that of the SF group (35.2g vs 31.2 and 128.3 vs 113 g/d). The cold carcass yield and the carcass weight were respectively higher (P <0.001) by 4 units and by 9% in the control group. The carcass of SF group was less fatty (perirenal fat: -23%, inguinal fat: -41% and scapular fat:-14%). The economic efficiency was 40% better for SF diet with almost 50 Algerian Dinar more benefit (/kg of meat) in current local market conditions.The authors thank the heads of the CFPA of Mechtras (Belaid Zaoueche, Ali Brahimi and Yazid Louchami) who placed the pedagogic rabbitry at our disposal, and Lounis Lounes for his assistance in the experimental trial. This study was partially carried out within the framework of the CMEP-TASSILI 13MDU883 project.Harouz-Cherifi, Z.; Kadi, SA.; Mouhous, A.; Bannellier, C.; Berchiche, M.; Gidenne, T. (2018). Effect of simplified feeding based only on wheat bran and brewer’s grain on rabbit performance and economic efficiency. World Rabbit Science. 26(1):27-34. https://doi.org/10.4995/wrs.2018.7765SWORD273426

Chloroquine enhances human CD8+ T cell responses against soluble antigens in vivo

The presentation of exogenous protein antigens in a major histocompatibility complex class I–restricted fashion to CD8+ T cells is called cross-presentation. We demonstrate that cross-presentation of soluble viral antigens (derived from hepatitis C virus [HCV], hepatitis B virus [HBV], or human immunodeficiency virus) to specific CD8+ T cell clones is dramatically improved when antigen-presenting dendritic cells (DCs) are pulsed with the antigen in the presence of chloroquine or ammonium chloride, which reduce acidification of the endocytic system. The export of soluble antigen into the cytosol is considerably higher in chloroquine-treated than in untreated DCs, as detected by confocal microscopy of cultured cells and Western blot analysis comparing endocytic and cytosolic fractions. To pursue our findings in an in vivo setting, we boosted groups of HBV vaccine responder individuals with a further dose of hepatitis B envelope protein vaccine with or without a single dose of chloroquine. Although all individuals showed a boost in antibody titers to HBV, six of nine individuals who were administered chloroquine showed a substantial CD8+ T cell response to HBV antigen, whereas zero of eight without chloroquine lacked a CD8 response. Our results suggest that chloroquine treatment improves CD8 immunity during vaccination

Proteomics and the search for welfare and stress biomarkers in animal production in the one-health context

Stress and welfare are important factors in animal production in the context of growing production optimization and scrutiny by the general public. In a context in which animal and human health are intertwined aspects of the one-health concept it is of utmost importance to define the markers of stress and welfare. These are important tools for producers, retailers, regulatory agents and ultimately consumers to effectively monitor and assess the welfare state of production animals. Proteomics is the science that studies the proteins existing in a given tissue or fluid. In this review we address this topic by showing clear examples where proteomics has been used to study stress-induced changes at various levels. We adopt a multi-species (cattle, swine, small ruminants, poultry, fish and shellfish) approach under the effect of various stress inducers (handling, transport, management, nutritional, thermal and exposure to pollutants) clearly demonstrating how proteomics and systems biology are key elements to the study of stress and welfare in farm animals and powerful tools for animal welfare, health and productivity