WORLD CEREALS MARKETS UNDER ALTERNATIVE COMMON AGRICULTURAL POLICY REFORMS

Previous quantitative assessments of likely impacts of recent reforms of the Common Agricultural Policy (in particular the Agenda 2000) differ across empirical studies. Differences are mainly due to the ways the policy instruments are taken into account (explicit modeling or implicit modeling i.e. using ad-valorem equivalents). The aim of this paper is to assess empirically the impacts of recent reforms of the Common Agricultural Policy and the consequences of the Mid-Term proposals on world cereals markets. We develop an econometric, dynamic, multi-product, partial equilibrium commodity model that focuses on arable crops. Major exporters and major importers are modeled separately, other countries being included in a "rest of the world" category. For the countries or regions explicitly integrated the model estimates supply, demand and trade. The model we develop has two important features: i) the parameters estimated in the behavioral equations (supply and demand) satisfy regularity conditions and ii) the agricultural policy instruments (in particular CAP instruments) are modeled in an explicit way. In the empirical section, attention focuses on the world cereals market. We provide a market outlook through the year 2009 for three different scenarios: baseline projections and two scenarios based on different assumptions regarding the evolution of the Common Agricultural Policy (the Mid-Term Review scenario and the decoupling scenario). Estimated effects of the mid-term scenario on EU crop prices depend on the relationship between EU and world market prices.Agricultural and Food Policy,

Spatio-temporal requirements for transposable element piRNA-mediated silencing during Drosophila oogenesis

International audienceDuring Drosophila oogenesis, transposable element (TE) repression involves the Piwi-interacting RNA (piRNA) pathway which ensures genome integrity for the next generation. We developed a transgenic model to study repression of the Idefix retrotrans-poson in the germline. Using a candidate gene KD-approach, we identified differences in the spatio-temporal requirements of the piRNA pathway components for piRNA-mediated silencing. Some of them (Aub, Vasa, Spn-E) are necessary in very early stages of oogenesis within the germarium and appear to be less important for efficient TE silencing thereafter. Others (Piwi, Ago3, Mael) are required at all stages of oogenesis. Moreover, during early oogenesis, in the dividing cysts within the germarium, Idefix anti-sense transgenes escape host control, and this is associated with very low piwi expression. Silencing of P-element-based transgenes is also strongly weakened in these cysts. This region, termed the 'Piwiless pocket' or Pilp, may ensure that new TE insertions occur and are transmitted to the next generation, thereby contributing to genome dynamics. In contrast, piRNA-mediated silencing is strong in germline stem cells in which TE mobilization is tightly repressed ensuring the continued production of viable germline cysts

Overexpression of the Mitochondrial T3 Receptor p43 Induces a Shift in Skeletal Muscle Fiber Types

In previous studies, we have characterized a new hormonal pathway involving a mitochondrial T3 receptor (p43) acting as a mitochondrial transcription factor and consequently stimulating mitochondrial activity and mitochondrial biogenesis. We have established the involvement of this T3 pathway in the regulation of in vitro myoblast differentiation.We have generated mice overexpressing p43 under control of the human α-skeletal actin promoter. In agreement with the previous characterization of this promoter, northern-blot and western-blot experiments confirmed that after birth p43 was specifically overexpressed in skeletal muscle. As expected from in vitro studies, in 2-month old mice, p43 overexpression increased mitochondrial genes expression and mitochondrial biogenesis as attested by the increase of mitochondrial mass and mt-DNA copy number. In addition, transgenic mice had a body temperature 0.8°C higher than control ones and displayed lower plasma triiodothyronine levels. Skeletal muscles of transgenic mice were redder than wild-type animals suggesting an increased oxidative metabolism. In line with this observation, in gastrocnemius, we recorded a strong increase in cytochrome oxidase activity and in mitochondrial respiration. Moreover, we observed that p43 drives the formation of oxidative fibers: in soleus muscle, where MyHC IIa fibers were partly replaced by type I fibers; in gastrocnemius muscle, we found an increase in MyHC IIa and IIx expression associated with a reduction in the number of glycolytic fibers type IIb. In addition, we found that PGC-1α and PPARδ, two major regulators of muscle phenotype were up regulated in p43 transgenic mice suggesting that these proteins could be downstream targets of mitochondrial activity. These data indicate that the direct mitochondrial T3 pathway is deeply involved in the acquisition of contractile and metabolic features of muscle fibers in particular by regulating PGC-1α and PPARδ

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

Mitochondrial physiology

As the knowledge base and importance of mitochondrial physiology to evolution, health and disease expands, the necessity for harmonizing the terminology concerning mitochondrial respiratory states and rates has become increasingly apparent. The chemiosmotic theory establishes the mechanism of energy transformation and coupling in oxidative phosphorylation. The unifying concept of the protonmotive force provides the framework for developing a consistent theoretical foundation of mitochondrial physiology and bioenergetics. We follow the latest SI guidelines and those of the International Union of Pure and Applied Chemistry (IUPAC) on terminology in physical chemistry, extended by considerations of open systems and thermodynamics of irreversible processes. The concept-driven constructive terminology incorporates the meaning of each quantity and aligns concepts and symbols with the nomenclature of classical bioenergetics. We endeavour to provide a balanced view of mitochondrial respiratory control and a critical discussion on reporting data of mitochondrial respiration in terms of metabolic flows and fluxes. Uniform standards for evaluation of respiratory states and rates will ultimately contribute to reproducibility between laboratories and thus support the development of data repositories of mitochondrial respiratory function in species, tissues, and cells. Clarity of concept and consistency of nomenclature facilitate effective transdisciplinary communication, education, and ultimately further discovery

WORLD CEREALS MARKETS UNDER ALTERNATIVE COMMON AGRICULTURAL POLICY REFORMS

Previous quantitative assessments of likely impacts of recent reforms of the Common Agricultural Policy (in particular the Agenda 2000) differ across empirical studies. Differences are mainly due to the ways the policy instruments are taken into account (explicit modeling or implicit modeling i.e. using ad-valorem equivalents). The aim of this paper is to assess empirically the impacts of recent reforms of the Common Agricultural Policy and the consequences of the Mid-Term proposals on world cereals markets. We develop an econometric, dynamic, multi-product, partial equilibrium commodity model that focuses on arable crops. Major exporters and major importers are modeled separately, other countries being included in a "rest of the world" category. For the countries or regions explicitly integrated the model estimates supply, demand and trade. The model we develop has two important features: i) the parameters estimated in the behavioral equations (supply and demand) satisfy regularity conditions and ii) the agricultural policy instruments (in particular CAP instruments) are modeled in an explicit way. In the empirical section, attention focuses on the world cereals market. We provide a market outlook through the year 2009 for three different scenarios: baseline projections and two scenarios based on different assumptions regarding the evolution of the Common Agricultural Policy (the Mid-Term Review scenario and the decoupling scenario). Estimated effects of the mid-term scenario on EU crop prices depend on the relationship between EU and world market prices

Impacts of the Luxembourg compromise on world markets for arable crops

The CAP reform (June 2003) in the arable crop sector is marked by implementation of decoupled payments and reductions to direct aid. These changes could affect not only the arable crop markets of the various countries of the European Union, but also world markets, and that in wheat in particular, since the EU is one of the main wheat exporters. To assess impacts on world markets for arable crops (and in particular on world prices), we used a partial equilibrium model developed at INRA, funded by the Ministry for Agriculture, Food, Fisheries and Rural Affairs and by Pluriagri (Trades Union). The consequences of reform on world markets are rather limited

Impacts du compromis de Luxembourg sur les marchés mondiaux des grandes cultures

La réforme de la PAC de juin 2003 dans le secteur des grandes cultures est marquée par l'introduction d'un paiement découplé et par la diminution des aides directes. Ces modifications peuvent avoir des répercussions sur les marchés des grandes cultures des différents pays de l'Union européenne mais aussi sur les marchés mondiaux et particulièrement sur celui du blé puisque l'UE est l'un des principaux exportateurs de cette céréale. Pour mesurer les répercussions sur les marchés mondiaux des grandes cultures (et notamment sur les prix mondiaux) on utilise un modèle d'équilibre partiel développé à l'INRA, financé par le ministère de l'Agriculture, de l'Alimentation, de la Pêche et des Affaires rurales et par Pluriagri (association rassemblant des professionnels). Les conséquences de la réforme sur les marchés mondiaux sont assez faibles

Biofloc technology applied to rear shrimp Litopenaeus Stylirostris broodstock: An integrated and development research project in New Caledonia and French Polynesia

Shrimp farming in New-Caledonia faces up to difficulties. A fluctuating quality of broodstock prevents sustainable production of larvae in quantity and quality. The traditional extensive rearing method of broodstock in outdoor earthen ponds used in New Caledonia raises several issues: poor water quality control and biosecurity. Therefore it is fundamental to modify the broodstock culture strategy in order to achieve an easier water quality management and maximal biosecurity. Biofloc technology (BFT) offers easier water quality management, higher natural productivity, higher level of biosecurity, and could be a good alternative. Since 2011 a R&D program started under the supervision of IFREMER in New Caledonia and French Polynesia in order to study and develop biofloc technology for rearing shrimp L. stylirostris broodstock. In a first step we showed that biofloc (BFT) improved significantly the reproductive performances of shrimps and the quality of their larvae compared to Clear Water (CW) or Earthen Pond (EP), with: • A better final survival rate of broodstock from BFT compare to CW. • Females from BFT produced more eggs per spawn and spawned more frequently compared to females from CW or EP. • The larvae from BFT females had a significantly higher survival rate compared to larvae from CW females, respectively 70% (n=4) and 45% (n=4). In a second step we studied the underlying biological mechanisms explaining the better reproductive performance and health status of the broodstock from BFT rearing system, and the better quality of their larvae. We showed that the juvenile shrimp fed actively on biofloc, which represented 60% of their whole food (40% coming from pelleted diet). Biofloc represents a significant source of essential nutrients (vitamins, antioxidants, highly unsaturated fatty acids, …) or dietary bacteria which could act as probiotic. These dietary complements could explain the improved health status (immunity and oxidative status status), the better resistance to oxidative stress and a systematically better survival rate of the shrimp reared in BFT compared to those reared in CW

Involvement of the direct T3 mitochondrial pathway in mouse muscle development

P117International audienceIn previous studies, we have characterized a new hormonal pathway involving a mitochondrial T3 receptor (p43) acting as a mitochondrial transcription factor and consequently stimulating mitochondrial activity and mitochondriogenesis. Numerous studies bring evidence that besides their major role in the regulation of energetic metabolism, mitochondria also regulate important processes involved in development such as apoptosis or cell proliferation and differentiation. We have established the involvement of this T3 pathway in the regulation of myoblast differentiation, through the control of the expression of a set of nuclear genes, regulated by mitochondrial activity (myogenin, calcineurin and the c-myc proto-oncogene). In order to assess the physiological importance of this direct mitochondrial T3 pathway onmuscle development, with a particular attention to the acquisition of metabolic and contractile features of muscle fibres, we have generated mice overexpressing p43 under control of the human a-skeletal actin promoter. In agreement with the previous characterization of this promoter, northern-blot and western-blot experiments confirmed that p43 was specifically overexpressed in skeletal muscle. Studies performedon gastrocnemius permeabilized fibres using a highly sensitive oxygraph (Oroboros) indicated that p43 overexpression stimulates mitochondrial respiration and cytochrome c oxydase activity. Moreover, electron microscopy observations demonstrated the occurrence of a strong increase in muscle mitochondria number. Histoimmunochemistry experiments using antibodies raised against specific Myosin Heavy Chain (I, IIA, IIA+IIB) indicated that p43 overexpression induces significant changes in contractile features of muscle fibres. In gastrocnemius muscle, we observed an increase in the number of type I and type IIa fibres, associated to a decrease in the number of type IIB fibres. These data indicate that, as expected from our previous in vitro studies, p43 regulates mitochondrial activity in vivo, and is an important determinant of muscle fibres metabolic and contractile phenotype