eKhSACIR інституційному репозитарії Харківської державної академії культури
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Output price risk and fertilizer use decisions in Burkina Faso
No full textWe investigate whether the fluctuations of agricultural output prices may be a contributing factor to the low level of production intensification in developing countries. We analyze the specific effect of maize price risks on fertilizer use decisions in Burkina Faso, distinguishing between the predictable (trends and seasonality for example) and unpredictable (volatility) components of price fluctuations. By introducing these two components into Isik (2002)'s framework, we establish that both are theoretically expected to decrease fertilizer use. We conduct an empirical assessment of our model applied to the maize sector in Burkina Faso, by combining a database on local cereal markets and a panel database on farm households’ production choices over the 2009-2011 period. We control for individual assets and access to fertilizers, and we establish that: higher maize prices increase fertilizer use; unpredictable maize price fluctuations decrease the level of fertilizer use; while predictable maize price fluctuations have no significant effect on fertilizer use. Our results suggest that policy-makers should focus on output price volatility, as a factor which may impede the intensification of agricultural production in Sub-Saharan Africa
Managing tradeoffs between ecosystem services: exploring win-no-loss scenarios with an evolutionary technique
No full textNational audienceModels and optimization techniques are useful tools supporting the management of land for the provision of conflicting ecosystem services. Such methods meet the following difficulties. (i) Modelling the spatial heterogeneity of ecosystem services provision requires a high computational effort. (ii) Optimization techniques need to cope with many policy and physical constraints and with several management variables interacting in non-linear way. (iii) Different services are often not substitutable, thus optimization techniques must treat them separately without building aggregated indices. In this study we aim at proposing a methodological framework for supporting the design of win-no-loss scenarios, i.e., allocating land uses and land covers for maximizing the provision of a service, without causing losses in other services. We apply our methodological framework at the French scale. For addressing (i) we use Small Agricultural Regions (SARs) as spatial units. Those units are not too big, so the spatial heterogeneity is represented, and not too small, so to have a low computational demand. We build ecological production functions to estimate the provision of ecosystem services at the SAR level using management and geographical variables. The ecosystem services we consider are crop and animal production, biodiversity, carbon sequestration and storage, pollination, timber production, and recreation. Management variables are the fraction of land covers in each SAR, and crop cultivation intensity (e.g., pesticide inputs). We design scenarios for assigning management variables to the different SARs and, in turn, we optimize one service at the French scale, imposing a constraint of no-loss on the others. For the optimization we use an evolutionary algorithm, which is able to address (ii) and, (iii). The evolutionary technique promotes land covers that deliver multiple services and softens the tradeoffs by allocating land covers delivering competing services in different SARs. We discuss the strength and weak points of the modelling framework and of the evolutionary technique for optimization
Siropins, novel serine protease inhibitors from gut microbiota acting on human proteases involved in inflammatory bowel diseases
No full textBackground: In eukaryotes, the serpins constitute a wide family of protease inhibitors regulating many physiological pathways. Many reports stressed the key role of serpins in several human physiopathologies including mainly the inflammatory bowel diseases. In this context, eukaryotic serpins were largely studied and their use to limit inflammation was reported. In comparison to that, bacterial serpins and mainly those from human gut microbiota remain poorly studied. Results: The two genes encoding for putative serpins from the human gut bacterium Eubacterium sireaum, display low sequence identities. These genes were overexpressed and the encoded proteins, named Siropins, were purified. Activity studies demonstrated that both purified proteins inhibited serine proteases but surprisingly they preferentially inhibited two human serine proteases (Human Neutrophil Elastase and Proteinase3). The biochemical characterization of these Siropins revealed that Siropin 1 was the most active and stable at low pH values while Siropin 2 was more thermoactive and thermostable. Kinetic analysis allowed the determination of the stoichiometry of inhibition (SI) which was around 1 and of the association rate constants of 7.7 x 10(4) for the Human Neutrophil Elastase and 2.6 x 10(5) for the Proteinase3. Moreover, both Siropins displayed the ability to inhibit proteases usually present in fecal waters. Altogether our data indicate the high efficiency of Siropins and their probable involvement in the control of the overall intestine protease activity. Conclusions: Here we report the purification and the biochemical characterization of two novel serpins originated from Eubacterium sireaum, a human gastro-intestinal tract commensal bacteria. These proteins that we called Siropins, efficiently inhibited two human proteases reported to be associated with inflammatory bowel diseases. The determination of the biochemical properties of these enzymes revealed different temperature and pH behaviours that may reflect adaptation of this human commensal bacterium to different ecological environments. To the best of our knowledge, it is the first bacterial serpins showing an attractive inhibition of fecal proteases recovered from a mice group with chemically induced inflammation. Altogether our data highlight the interesting potential of Siropins, and serpins from the human gut microbiota in general, to be used as new alternative to face inflammatory diseases
Regulation theory and transformation of agriculture: a literature review
No full textThe article is based on a literature review of research related to the French Regulation Theory (RT) and applied to agriculture and food. It analyzes the changes in this sector and proposes a new research agenda. In the first part we examine research findings embedded in RT in the 1980’s and 1990’s, focusing on the emergence and crisis of the economic regime of agriculture of industrialised countries during the fordist period. In the second part we show how this body of research continues the analysis of different dimensions of agricultural transformation, and progressively combines with other research programs. However, we argue that the new international context of agriculture and food is an opportunity to renew RT research on this sector and to understand its different economic regimes and their transitions in various national contexts.El artículo se apoya en una revisión de los trabajos de investigación inscriptos en la teoría regulacionista (TR) y aplicada a la agricultura y al sector agroalimentario, para analizar las transformaciones de este sector y contribuir a la elaboración de una nueva agenda de investigación. En una primera parte, nosotros recordamos los trabajosa de un periodo fundacional, en el curso de los años 1980 y 1990, centrado en el análisis de la emergencia y luego la crisis de un modelo fordista en la agricultura. En una segunda parte, nosotros mostramos como esos trabajos, prosiguiendo el análisis de las diferentes dimensiones de las transformaciones agrícolas y agroalimentarias, se han combinado luego con otros programas de investigación. Por ello, nosotros defendemos la idea de que el nuevo contexto internacional de la agricultura y de la alimentación ofrece una oportunidad para volver a emprender trabajos de la TR sobre ese sector y comprender los diferentes regímenes de funcionamiento que están asociados en diversos contextos nacionales y sus transiciones.L’article s’appuie sur une revue des travaux de recherche français inscrits dans la théorie régulationniste (TR) et appliqués à l’agriculture et l’agroalimentaire, pour analyser les transformations de ce secteur et contribuer à l’élaboration d’un nouvel agenda de recherche. Dans une première partie, nous rappelons les travaux d’une période fondatrice, au cours des années 1980 et 1990, centrée sur l’analyse de l’émergence puis de la crise du modèle agricole de la période fordiste. Dans une deuxième partie, nous montrons comment ces travaux, en poursuivant l’analyse des différentes dimensions des transformations agricoles et agroalimentaires, se sont ensuite combinés avec d'autres programmes de recherche. Pour autant, nous défendons l’idée que le nouveau contexte international de l'agriculture et de l'alimentation offre une opportunité pour relancer les travaux de la TR sur ce secteur et pour comprendre les régimes et les transitions agricoles dans différents contextes nationaux
Sensitive, highly resolved, and quantitative H-1-C-13 NMR data in one go for tracking metabolites in vegetal extracts
No full textInternational audienceThe quantification of metabolites is essential for understanding and improving biological systems. With the aim to quantify in one map a complex mixture composed of low concentrated metabolites, a new experiment called the H-1-C-13 QUIPU HSQC allows improving of both resolution and sensitivity for investigation of vegetal extracts
The Evolution of Orphan Regions in Genomes of a Fungal Pathogen of Wheat
No full textFungal plant pathogens rapidly evolve virulence on resistant hosts through mutations in genes encoding proteins that modulate the host immune responses. The mutational spectrum likely includes chromosomal rearrangements responsible for gains or losses of entire genes. However, the mechanisms creating adaptive structural variation in fungal pathogen populations are poorly understood. We used complete genome assemblies to quantify structural variants segregating in the highly polymorphic fungal wheat pathogen Zymoseptoria tritici. The genetic basis of virulence in Z. tritici is complex, and populations harbor significant genetic variation for virulence; hence, we aimed to identify whether structural variation led to functional differences. We combined single-molecule real-time sequencing, genetic maps, and transcriptomics data to generate a fully assembled and annotated genome of the highly virulent field isolate 3D7. Comparative genomics analyses against the complete reference genome IPO323 identified large chromosomal inversions and the complete gain or loss of transposable-element clusters, explaining the extensive chromosomal-length polymorphisms found in this species. Both the 3D7 and IPO323 genomes harbored long tracts of sequences exclusive to one of the two genomes. These orphan regions contained 296 genes unique to the 3D7 genome and not previously known for this species. These orphan genes tended to be organized in clusters and showed evidence of mutational decay. Moreover, the orphan genes were enriched in genes encoding putative effectors and included a gene that is one of the most upregulated putative effector genes during wheat infection. Our study showed that this pathogen species harbored extensive chromosomal structure polymorphism that may drive the evolution of virulence. IMPORTANCE Pathogen outbreak populations often harbor previously unknown genes conferring virulence. Hence, a key puzzle of rapid pathogen evolution is the origin of such evolutionary novelty in genomes. Chromosomal rearrangements and structural variation in pathogen populations likely play a key role. However, identifying such polymorphism is challenging, as most genome-sequencing approaches only yield information about point mutations. We combined long-read technology and genetic maps to assemble the complete genome of a strain of a highly polymorphic fungal pathogen of wheat. Comparisons against the reference genome of the species showed substantial variation in the chromosome structure and revealed large regions unique to each assembled genome. These regions were enriched in genes encoding likely effector proteins, which are important components of pathogenicity. Our study showed that pathogen populations harbor extensive polymorphism at the chromosome level and that this polymorphism can be a source of adaptive genetic variation in pathogen evolution
Monolignol ferulate conjugates are naturally incorporated into plant lignins
No full textAngiosperms represent most of the terrestrial plants and are the primary research focus for the conversion of biomass to liquid fuels and coproducts. Lignin limits our access to fibers and represents a large fraction of the chemical energy stored in plant cell walls. Recently, the incorporation of monolignol ferulates into lignin polymers was accomplished via the engineering of an exotic transferase into commercially relevant poplar. We report that various angiosperm species might have convergently evolved to natively produce lignins that incorporate monolignol ferulate conjugates. We show that this activity may be accomplished by a BAHD feruloyl-coenzyme A monolignol transferase, OsFMT1 (AT5), in rice and its orthologs in other monocots
Microbiote intestinal chez le porc : paramètres génétiques de sa composition et liens avec des caractères immunitaires
No full textMicrobiote intestinal chez le porc : paramètres génétiques de sa composition et liens avec des caractères immunitaires. 48. Journées de la Recherche Porcin
Une méthode supervisée pour initialiser les centres des K-moyennes
No full textAu cours des dernières années, la classification à base de clustering s’est imposée comme un sujet de recherche important. Cette approche vise à décrire et à prédire un concept cible d’une manière simultanée. Partant du fait que le choix des centres pour l’algorithme des K-moyennes standard a un impact direct sur la qualité des résultats obtenus, cet article vise alors à tester à quel point une méthode d’initialisation supervisée pourrait aider l’algorithme des Kmoyennes standard à remplir la tâche de la classification à base des K-moyennes
Assessing ecological equivalence for wetland restoration by aggregating ecosystem services: consequences of the aggregation schemes
No full textNational audiencePopulation growth and increasing food demand are causing urban and agricultural expansion. This poses serious challenges on habitat and ecosystem conservation. According to environmental policies worldwide, when ecosystem removal is unavoidable, the loss of ecosystem services can be offset by restoring the same ecosystem elsewhere. Restoration policies need to establish a “currency” for assessing the ecological equivalence between ecosystem loss and ecosystem to be restored. Here we consider currencies based on the aggregation of several services provided by the ecosystems. We focus on wetlands and on the Alberta Wetland policy. Wetlands are considered among the most ecosystems in the world and provide various benefits. The Alberta Wetland policy scores each wetland by aggregating scores related to three ecosystem services they provide: hydrological health, water purification, and ecological health. The aggregation schemes can be e.g., weighted average (with different sets of weights), minimum or maximum. Gi en that different wetlands provide ecosystem services in different proportion, the choice of the aggregation scheme may lead to unintended consequences on the removal and restoration priorities, leading to different outcomes of the restoration process at the landscape scale. We simulate wetland removal and restoration following the rules provided by the Alberta Wetland policy using different aggregation schemes. The study area is the Beaver Hills sub-watershed (Alberta, Canada), an area characterized by many wetlands and subject to the expansion of the city of Edmonton in the next decades. Scores of wetlands ecosystem services are calculated starting from GIS-derived indicators. Results show that the aggregation scheme should be chosen in light of the preferred ecosystem service to restore on the landscape. By playing with different weights, weighted average can be used to prioritize a certain ecosystem service accounting for tradeoffs and synergies. Minimum or maximum aggregation can lead to the restoration of mono-functional vs multi-functional wetlands