eKhSACIR інституційному репозитарії Харківської державної академії культури
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Development of genomic selection in dairy cattle in two emerging countries: South Africa and India
No full textIn large developed countries, genomic selection has radically transformed dairy cattle breeding, with collateralimpact on the international semen market. Emerging countries are often strong semen importers. Few of them are Interbull members. However, if they are a member, MACE evaluations of progeny tested bulls give them access to EBV on their own scale. At least in theory, this allows for a rational choice of semen to import. This is no longer the case with genomic evaluations, for which the constitution of a proper reference population is complex. As a consequence, the gap between countries with expertise in genomic selection and the others is widening fast. However, genomic selection also offers new opportunities in emerging countries, because it does not require sophisticated national performance recording systems and it more easily leads to selection adapted to local environments. The prototype for national genomic evaluation in Holstein cattle, exploiting the participation of the country to Interbull MACE evaluations, in order to enlarge the reference population while accommodating two very contrasted feeding systems. In India, BAIF, the largest Indian NGO in agriculture, is developing a female reference population of crossbred Bos taurus × Bos Indicus animals, facing a number of challenges such as very small average herd sizes, progress of dairy cattle in harsh environments
Modelling the choice between and the costs of multiple-use vs. specialized forest management
No full textInternational audienceForests provide ecosystem services jointly with timber production. In some cases, private forest owners implement management actions in order to enhance the provision of such services. They may get direct benefits from this decision such as private amenity values or effects on (e.g., hunting), they may have altruist traits in their utility function for providing public goods (e.g., biodiversity conservation, carbon sequestration), or they may be incited for by a public authority and compensated for the costs. Specifically, this paper focuses on the decision of setting aside forest land. It raises the more general question of the efficiency of multiple-use vs. specialized management of forest lands. Wepropose an econometric analysis to identify factors of the set-aside choice and to measure the impact of this decision on forest management costs. A flexible cost function is modelled and estimated for both types of management. The percentages of old/mature deciduous and old/mature coniferous forests are used as biodiversity and carbon indicators. Results show that the set-aside choice depends on the landowners’ income and on their socio-economic characteristics. Set-aside decision has a significant and positive impact on the managementcosts. This implies that the additional private and public benefits achieved from specialized relative to multiple-use management should exceed this cost premium
Méthylation de l’ADN de la glande mammaire bovine, marque épigénétique en lien avec la production laitière ?
No full textNational audienceLa glande mammaire est un organe qui subit des cycles de croissance, différenciation et régression au cours des périodes de puberté, gestation, lactation et involution. Les facteurs environnementaux liés à la conduite d’élevage (fréquence de traite, alimentation) ou à la santé des animaux sont connus pour faire varier l’expression d’un grand nombre de gènes et modifier les niveaux de production de lait (Dessauge et al. 2011, Boutinaud et al. 2013, Younis et al. 2016). Des régulations épigénétiques pourraient contribuer en partie à la régulation de la production de lait. Des études réalisées chez les rongeurs ou lagomorphes ont montré qu’une combinaison d’évènements épigénétiques à l’échelle globale ou locale au niveau de certains gènes se met en place ou s’efface au cours du développement de la glande mammaire et sous-tend l’expression des gènes (Rijnkels et al. 2010). Chez le bovin, il a été décrit depuis longtemps une hypométhylation de l’ADN dans la région 5’du gène de la caséine as1 (CSN1S1) quand ce gène est exprimé (Platenburg et al. 1996). Il a été montré plus récemment que le stade de développement (gestation et involution) ou des facteurs environnementaux comme la fréquence de traite ou la santé de la mamelle pouvaient moduler la méthylation de l’ADN dans la région régulatrice distale en amont de ce gène. Dans la glande mammaire bovine, cette zone de l’ADN est moins méthylée pendant la lactation qu’à la puberté, la gestation ou l’involution (Vanselow et al. 2006, Nguyen et al. 2014, Singh et al. 2012). Par contre cette zone est plus méthylée lors d’une infection avec Escherichia Coli ou lors d’une réduction de la fréquence de traite à une fois par jour (Vanselow et al. 2006, Nguyen et al. 2014). La méthylation globale de l’ADN peut également indiquer des modifications épigénétiques en lien avec une variation de la production du lait. Elle est plus élevée ou a tendance à l’être dans les glandes mammaires qui produisent moins de lait après 1 traite par jour (Nguyen et al. 2013) ou lors d’une restriction alimentaire (Boutinaud et al. 2016). Par contre, les résultats divergent selon le type de changement de l’alimentation réalisé chez la génisse montrant (Choi et al. 1998) ou non (Freetly et al. 2014) une moindre méthylation globale d’ADN associée à une meilleure croissance de la glande mammaire et une plus grande expression des protéines majeures du lait pendant la gestation. Le taux de méthylation des cellules épithéliales du lait est similaire à celui de la glande mammaire mais différent de celui des leucocytes du lait (Gasselin et al. 2015). De nouvelles recherches sont nécessaires afin de confirmer s’il existe un lien entre le degré de méthylation globale de l’ADN d’un tissu ou d’un type de cellules et sa capacité de synthèse
Architecture génétique de la qualité de la graine chez Arabidopsis et le colza
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Integrating transcriptional activity in genome-scale models of metabolism
No full textPMID: 29322933International audienceBackground: Genome-scale metabolic models provide an opportunity for rational approaches to studies of the different reactions taking place inside the cell. The integration of these models with gene regulatory networks is a hot topic in systems biology. The methods developed to date focus mostly on resolving the metabolic elements and use fairly straightforward approaches to assess the impact of genome expression on the metabolic phenotype. Results: We present here a method for integrating the reverse engineering of gene regulatory networks into these metabolic models. We applied our method to a high-dimensional gene expression data set to infer a background gene regulatory network. We then compared the resulting phenotype simulations with those obtained by other relevant methods. Conclusions: Our method outperformed the other approaches tested and was more robust to noise. We also illustrate the utility of this method for studies of a complex biological phenomenon, the diauxic shift in yeast
Farm value evaluation: methods and challenges
No full textStatistics clearly show a continuous decline in the number of farms in Europe. One fourth of farms disappeared in Metropolitan France between 2000 and 2010. With 13,200 entering farmers in 2013, compared to 17,200 exiting farmers, the renewal rate was 77%. In this context, some concerns have been expressed regarding a lack of generational renewal in agriculture despite existing policies targeting this issue. This communication based on a literature review contributes to scientific knowledge and provides new perspectives to farm stakeholders and policy-makers on farm transfers, focusing specifically on the role of the value of the farm in this process. Agricultural sector is particularly affected by succession problems: high farm value due to animals as well as land, buildings and machinery; hence, high transfer cost; low attractiveness due to hard working conditions; and by contrast low profitability. Farm transfer depends on the value of the farm. There are numerous methods to assess the value but they are less used. The ‘patrimonial’ method based on the accounting/market value of the different assets the farm comprises is rather used. Therefore, the farm value depends also on sociological points of view, needs to take into account intangible assets and not only financial considerations
Biofilm-associated persistence of food-borne pathogens and related bacteria
No full textInternational audienc
Improvement of oxidative stability of dry emulsion containing antioxidants by modifying process conditions
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Modelling the drying of a droplet of sucrose solution on a solid surface
No full textInternational audienceIn food plants, often water is present in form of droplets deposited on the equipment surfaces, on the walls and the floor. Microbial growth can occur in these droplets especially if they contain nutritive substances like sucrose. A mathematical model was developed in order to predict the evolution of mass, temperature, sucrose concentration and water activity of a droplet of sucrose solution deposited on a solid surface. The model takes into account heat and mass transfer by convection at the air/liquid interface, radiation with surrounding walls, conduction inside droplet and solid surface as well as latent heat of vaporization. It predicts also the increasing concentration of sucrose and the associate decrease of water activity. Two drying periods are considered, first the radius of droplet surface contact remains constant and the contact angle decreases, then this angle remains constant (equal to the receding angle) and the radius tends to zero. The evolutions during drying of sucrose solutions of different initial concentrations were compared. This model could be coupled with a microbial model in which the growth rate depends both on temperature and water activity