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Computational models for the neural control of movement must take into account the properties of sensorimotor systems, including the signal-dependent intensity of the noise and the transmission delay affecting the signal conduction. For this purpose, this paper presents an algorithm for model-based control and estimation of a class of linear stochastic systems subject to multiplicative noise affecting the control and feedback signals. The state estimator based on Kalman filtering is allowed to take into account the current feedback to compute the current state estimate. The optimal feedback control process is adapted accordingly. The resulting estimation error is smaller than the estimation error obtained when the current state must be predicted based on the last feedback signal, which reduces variability of the simulated trajectories. In particular, the performance of the present algorithm is good in a range of feedback delay that is compatible with the delay induced by the neural transmission of the sensory inflow.

On the international markets, the European Union (EU) is the first commercial partner of the Africa, Caribbean and Pacific countries (ACP’s). During more than four decades, the EU granted to ACP’s countries a not mutual commercial preferences regime which facilitated the entrance and the competitiveness of ACP’s products on the European market. The trade relations between the EU and the ACP, rarely taken into account in empirical works, offer an executive convenient to the analysis of prices transmission. By means of co-integration and error-correction models and the Granger causality test, this thesis analyzes in which measure the European or international prices are passed on on banana, cocoa, coffee, sugar and vanilla export market and producer markets of the ACP’s countries. It also verifies the hypothesis of transitivity on the vanilla international market and its leadership by Madagascar. It tests finally the law of one price between the cocoa producer market of Ivory Coast and the world market. The analysis brings to light a cointegration relation between the European or international market and most of the ACP’s markets concerned. The market of traditional export products, as the cocoa and the coffee, are better integrated into European market or the world market than banana, sugar or vanilla markets. The European or international prices cause most of the ACP prices and not the opposite. On the vanilla international market, the hypothesis of transitivity was rejected. The export market of Madagascar is perfectly integrated into the French market of import, but, it is not integrated into the American market. Although Madagascar represents approximately 70 % of the world exports of vanilla, the Malagasy export market does not exercise the leadership towards the French market. The integration of the ivorian cocoa producer market to the world market improved after the liberalization of the cacao tree sector of 1999, in Ivory Coast. There is a bilateral causality, Sur les marchés internationaux, l’Union Européenne (UE) est le premier partenaire commercial des pays d’Afrique, des Caraïbes et du Pacifique (ACP). Durant plus de quatre décennies, l’UE a accordé aux pays ACP un régime des préférences commerciales non réciproques qui favorisait l’entrée et la compétitivité des produits ACP sur le marché européen. Les relations commerciales entre l’UE et les pays ACP, rarement prises en compte dans des travaux empiriques disponibles, offrent un cadre propice à l’analyse de la transmission des prix. En recourant aux modèles de cointégration et à correction d’erreur et au test de causalité de Granger, cette thèse analyse dans quelle mesure les prix européens ou internationaux sont transmis sur les marchés à l’exportation et au producteur des pays ACP de la banane, de cacao, du café, de la vanille et du sucre. Elle vérifie aussi l’hypothèse de transitivité sur le marché international de la vanille et le leadership de Madagascar. Enfin, elle analyse l’intégration et teste la loi du prix unique entre le marché au producteur de Côte d’Ivoire et le marché mondial de cacao. L’analyse met en évidence une relation de cointégration entre le marché européen ou international et la plupart de marchés ACP concernés. Les marchés de produits traditionnels d’exportation, tels que le cacao et le café, sont mieux intégrés au marché européen ou marché mondial que les marchés de la banane, de la vanille ou du sucre. Les prix européens ou internationaux déterminent la plupart des prix ACP et non l’inverse. Sur le marché international de la vanille, l’hypothèse de transitivité a été rejetée. Le marché à l’exportation de Madagascar est parfaitement intégré au marché français d’importation, mais, il ne l’est pas au marché américain. Alors que Madagascar représente environ 70% des exportations mondiales de la vanille, le marché malgache à l’exportation n’exerce pas de leadership sur le marché français. Ces résultats indiquent que la détention d’une part impor, (AGRO 3) -- UCL, 2010

P>Effects of physiological processes such as gestation, lactation and nutritional stress on stable isotope ratios remain poorly understood. To determine their impact, we investigated these processes in simultaneously fasting and lactating northern elephant seals (Mirounga angustirostris). Stable carbon and nitrogen isotope values were measured in blood and milk of 10 mother-pup pairs on days 5 and 22 of lactation. As long- and short-term integrators of diet, blood cells and serum may reflect foraging data or energy reserves from late gestation and lactation, respectively. Limited changes in isotopic signatures of maternal blood over the lactating period were highlighted. Nitrogen isotope fractionation associated with mother-to-offspring transfer of nutrients was generated between mother and offspring during gestation and lactation. This fractionation was tissue and time-specific, it varied between early and late lactation from +0.6 parts per thousand to +1.3 parts per thousand in blood cells and from +1.1 parts per thousand to nonsignificant value in serum. Therefore, if pups appear to be good proxies to investigate the female trophic ecology especially for C sources, much more caution is required in using delta 15N values. Further studies are also needed to better define the relative impact of fasting and lactation on the enrichment or depletion of isotopes in different tissues.

Plants have evolved antioxidant molecules to help them withstand environmental stresses. Humans may also benefit from these defense molecules through their consumption in fruits and vegetables. Dietary antioxidants are indeed believed to play a very important role in the human body defense system, protecting, as in plants, against oxidative damage induced by Reactive Oxygen Species (ROS), which are known to be involved in the pathogenesis of aging and many degenerative diseases such as cardiovascular diseases and cancers. In this review, we compare the systems involved in ROS production and scavenging in humans and in plants. We focus mainly on the description of the best-known dietary antioxidants: ascorbate (vitamin C), tocopherols (vitamin E), carotenoids, and phenolic compounds. Their redox properties, metabolism and functions are discussed from both a human and a plant perspective.

The effect of two digestible protein levels (310 and 469 g/kg DM) on the relative lysine (Lys; g Lys/kg DM or g Lys/100 g protein) and the absolute Lys (g Lys intake/kg0.75 per d) requirements was studied in rainbow trout fry using a dose-response trial. At each protein level, sixteen isoenergetic (22-23 MJ digestible energy/kg DM) diets were tested, involving a full range (2-70 g/kg DM) of sixteen Lys levels. Each diet was given to one group of sixty rainbow trout fry (mean initial body weight 0.78 g) reared at 15 degrees C for 31 feeding d. The Lys requirements were estimated based on the relationships between weight, protein, and Lys gains (g/kg0.75 per d) and Lys concentration (g/kg DM or g/100 g protein) or Lys intake (g/kg0.75 per d), using the broken-line model (BLM) and the non-linear four-parameter saturation kinetics model (SKM-4). Both the model and the response criterion chosen markedly impacted the relative Lys requirement. The relative Lys requirement for Lys gain of rainbow trout estimated with the BLM (and SKM-4 at 90 % of the maximum response) increased from 16.8 (19.6) g/kg DM at a low protein level to 23.4 (24.5) g/kg DM at a high protein level. However, the dietary protein content affected neither the absolute Lys requirement nor the relative Lys requirement expressed as g Lys/100 g protein nor the Lys requirement for maintenance (21 mg Lys/kg0.75 per d).

The mitogen-activated protein kinases (MAPK) and nuclear factor kappaB (NF-kappaB) are involved in transduction cascades that play a key role in inflammatory response. We tested the ability of preselected natural polyphenolic extracts (grape seed, cocoa, sugar cane, oak, mangosteen and pomegranate) to modulate intestinal inflammation using human intestinal Caco-2 cells treated for 4h with these extracts and then stimulated by cytokines for 24 or 48h. The effect of polyphenolic extracts, at 50mumol of gallic acid equivalent/l, was investigated on inflammation-related cellular events: (i) NF-kappaB activity (cells transfected with a NF-kappaB-luciferase construct), (ii) activation of Erk1/2 and JNK (western blotting), (iii) secretion of interleukin 8 (IL-8) (ELISA), (iv) secretion of prostaglandin (PG) E(2) (ELISA), (v) production of NO (Griess method). Results show that: (i) sugar cane, oak and pomegranate extracts inhibited NF-kappaB activity (from 1.6 to 1.9-fold) (P<0.001); (ii) pomegranate slightly inhibited Erk1/2 activation (1.3-fold) (P=0.008); (iii) oak and pomegranate decreased NO synthesis by 1.5-fold (P<0.001) and that of IL-8 by 10.3 and 6.7-fold respectively; (iv) pomegranate and cocoa decreased PGE(2) synthesis by 4.6 (P<0.0001) and 2.2-fold (P=0.001), respectively. We suggest that pomegranate extract could be particularly promising in dietary prevention of intestinal inflammation.

A broad-spectrum reverse transcription-polymerase chain reaction (RT-PCR) protocol was developed for detecting Soil-borne cereal mosaic virus (SBCMV) isolates, responsible for mosaic diseases in Europe, using primers targeting the highly conserved 3'-untranslated region of RNA-1 and RNA-2 of SBCMV. The 3'-end region is a privileged target for the detection of a wide range of isolates, because of sequence conservation, of the tRNA-like structure, the major role in viral replication and the signal amplification due to the presence of numerous genomic and subgenomic RNAs. The primers were also designed for virus quantitation using real-time RT-PCR with SYBR-Green chemistry. No cross-reaction with Wheat spindle streak mosaic virus, frequently associated with SBCMV, was observed. The use of RT-PCR and real-time quantitative RT-PCR allowed a more sensitive detection and quantitation of SBCMV to be made than was the case with ELISA. The methods enabled European isolates of SBCMV from Belgium, France, Germany, Italy and the UK to be detected and quantified. Real-time RT-PCR represents a new tool for comparing soil inoculum potential as well as cultivar resistance to SBCMV.

Polyphenols represent a large family of plant secondary metabolites implicated in the prevention of various diseases such as cancers and cardiovascular diseases. The potato is a significant source of polyphenols in the human diet. In this study, we examined the expression of thirteen genes involved in the biosynthesis of polyphenols in potato tubers using real-time RT-PCR. A selection of five field grown native Andean cultivars, presenting contrasting polyphenol profiles, was used. Moreover, we investigated the expression of the genes after a drought exposure. We concluded that the diverse polyphenolic profiles are correlated to variations in gene expression profiles. The drought-induced variations of the gene expression was highly cultivar-specific. In the three anthocyanin-containing cultivars, gene expression was coordinated and reflected at the metabolite level supporting a hypothesis that regulation of gene expression plays an essential role in the potato polyphenol production. We proposed that the altered sucrose flux induced by the drought stress is partly responsible for the changes in gene expression. This study provides information on key polyphenol biosynthetic and regulatory genes, which could be useful in the development of potato varieties with enhanced health and nutritional benefits.

BACKGROUND: Pleiotropic Drug Resistant transporters (PDR) are members of the ATP-Binding Cassette (ABC) subfamily which export antifungals and other xenobiotics in fungi and plants. This subfamily of transmembrane transporters has nine known members in Saccharomyces cerevisiae. We have analyzed the complex evolution of the pleiotropic drug resistance proteins (Pdrp) subfamily where gene duplications and deletions occur independently in individual genomes. This study was carried out on 62 Pdrp from nine hemiascomycetous species, seven of which span 6 of the 14 clades of the Saccharomyces complex while the two others species, Debaryomyces hansenii and Yarrowia lipolytica, are further apart from an evolutive point of view. RESULTS: Combined phylogenetic and neighborhood analyses enabled us to identify five Pdrp clusters in the Saccharomyces complex. Three of them comprise orthologs of the Pdrp sensu stricto, Pdr5p, Pdr10p, Pdr12p, Pdr15p, Snq2p and YNR070wp. The evolutive pathway of the orthologs of Snq2 and YNR070w is particularly complex due to a tandem gene array in Eremothecium gossypii, Kluyveromyces lactis and Saccharomyces (Lachancea) kluyveri. This pathway and different cases of duplications and deletions were clarified by using a neighborhood analysis based on synteny. For the two distant species, Yarrowia lipolytica and Debaryomyces hansenii, no neighborhood evidence is available for these clusters and many homologs of Pdr5 and Pdr15 are phylogenetically assigned to species-based clusters. Two other clusters comprise the orthologs of the sensu lato Pdrp, Aus1p/Pdr11p and YOL075cp respectively. The evolutionary pathway of these clusters is simpler. Nevertheless, orthologs of these genes are missing in some species. CONCLUSION: Numerous duplications were traced among the Hemiascomycetous Pdrp studied. The role of the Whole Genome Duplication (WGD) is sorted out and our analyses confirm the common ancestrality of Pdr5p and Pdr15p. A tandem gene array is observed

Fungi cause serious infections in the immunocompromised and debilitated, and the incidence of invasive mycoses has increased significantly over the last 3 decades. Slow diagnosis and the relatively few classes of antifungal drugs result in high attributable mortality for systemic fungal infections. Azole antifungals are commonly used for fungal infections, but azole resistance can be a problem for some patient groups. High-level, clinically significant azole resistance usually involves overexpression of plasma membrane efflux pumps belonging to the ATP-binding cassette (ABC) or the major facilitator superfamily class of transporters. The heterologous expression of efflux pumps in model systems, such Saccharomyces cerevisiae, has enabled the functional analysis of efflux pumps from a variety of fungi. Phylogenetic analysis of the ABC pleiotropic drug resistance family has provided a new view of the evolution of this important class of efflux pumps. There are several ways in which the clinical significance of efflux-mediated antifungal drug resistance can be mitigated. Alternative antifungal drugs, such as the echinocandins, that are not efflux pump substrates provide one option. Potential therapeutic approaches that could overcome azole resistance include targeting efflux pump transcriptional regulators and fungal stress response pathways, blockade of energy supply, and direct inhibition of efflux pumps.

Iron toxicity occurs under flooded conditions such as those prevailing in lowland rice fields and is due to an excess of ferrous ions. Ferritin is a multimeric protein responsible for Fe sequestration and storage, playing a key role in Fe homeostasis. Our aim was to study the modalities of overall ferritin synthesis in different organs of young seedlings from the African rice species (Oryza glaberrima) in relation to the putative involvement of abscisic acid (ABA) and oxidative stress in signalling processes. Seedlings from a moderately resistant to iron toxicity cultivar were grown in hydroponic culture for 2 weeks and treated with 500 mg l(-1) Fe2+ in the presence or in the absence of 200 A mu M ABA, 50 A mu M methylviologen or 50 A mu M fluridone. Iron treatment increased iron and malondialdehyde concentration in all organs as well as ABA in roots and laminae. Although ferritin protein was detected in controls plants, iron treatment strongly reinforced its accumulation in sheaths and laminae after 24 h and 72 h. Ferritin mRNA was induced as early as 24 h after the beginning of the Fe-treatment in sheaths and, to a higher extent, in laminae. In the absence of iron treatment, exogenous ABA increased ferritin mRNA in laminae only but did not lead to further ferritin accumulation. Unexpectedly, it decreased ferritin mRNA levels in the sheaths of iron-treated plants and may thus have a dual influence depending on the considered organ. The inhibitor of ABA synthesis fluridone reduced endogenous ABA but did not compromise ferritin gene expression or ferritin synthesis, whatever the iron dose. Methyviologen application induced obvious oxidative damages but reduced ferritin synthesis. It is suggested that the signalling pathway leading to ferritin synthesis in the semi-aquatic African rice species may involve other components than those reported for typical terrestrial plants.

Flavonoids have been proposed to exert beneficial effects in a multitude of disease states However, evidence of potential toxic actions has also emerged. Since large doses of flavonoids can be encountered in the intestine simultaneously with ingested drugs and pollutants, this study aimed at investigating nine individual flavonoid compounds and their interactions with the major intestinal isoforms of cytochrome P450, i.e. CYPs 1A1 and 3A4, using human intestinal Caco-2 cells cultivated in a serum-free medium. Genistein, quercetin and chrysin provoked a dose-dependent inducing effect on the CYP1A1 activity. measured with the EROD assay. However, they did not affect the CYP1A1 mRNA expression, suggesting they are not aryl hydrocarbon receptor-ligands in intestinal cells and act at a post-transcriptional level. Chrysin, at 50 mu M, was detected as a potent inhibitor of the TCDD-induced CYP1A1 activity, leading the activity to ca. 10% of the TCDD-control value (n = 3), this effect involving, at least partly, direct interactions at the enzyme level. Quercetin was also shown to significantly inhibit the constitutive CYP3A4 activity, measured by the 6 beta-(OH)-testosterone assay, and to impair its induction by 1,25-vitamin D-3. Chrysin, quercetin and genistein, were detected as significant inhibitors of the 1,25-vitamin D-3-induced CYP3A4 activity. In vivo, these effects could result in reduced activation of procarcinogens and/or in drug bioavailability limitation. They underline the importance of intestinal studies to assess food safety and health risks linked to the ingestion of flavonoid-enriched supplements or functional foods. (C) 2009 Elsevier Ireland Ltd All rights reserved.

The influence of environment and genetics on total phenolic content and hydrophilic antioxidant capacity (H-ORAC) of potato tubers was evaluated using 13 native Andean genotypes. Cultivars were grown at two highland locations in Peru: Huancayo and Huancani. Environmental conditions significantly affected the total phenolic contents and H-ORAC values in a cultivar-dependent mariner. However, the potato genotype was the most determining factor of the observed variations. The effects of environment on individual phenolic compounds were also significant in terms of quantity, whereas the chemical profile remained stable across environmental conditions. To gain an insight into the observed antioxidant capacity of potato extracts, the individual and combined antioxidant effects of the main potato phenolic compounds were investigated. The ORAC values of reconstituted polyphenol Mixtures reflecting the authentic phenolic composition of potato extracts were higher than expected from the summing of the ORAC values of individual phenolic compounds, indicating synergistic effects. The authentic potato extracts showed either a higher or a lower ORAC value than their reconstituted counterparts, suggesting positive or negative interactions with other compounds. Taken together, Our results lead us to the following conclusions: (i) the hydrophilic antioxidant capacity observed in potato extracts is the result of various and complex interactions that could be attributed to phenolic compounds, to other non-identified molecules, and to synergistic as well as antagonistic effects between all these components and (ii) the high stability of the ranking of cultivars across environment in terms of phenolic content and antioxidant capacity indicates that the native Andean cultivars could be confidently used within breeding programs aiming at improving the health-promoting Value of potato. (C) 2009 Elsevier Inc. All rights reserved.

The outcome of a total dietary approach using a wide range of n-3 polyunsaturated fatty acids (PUFA) enriched food items on cardiovascular diseases called for further investigation. The study objective was to assess the effect of an ALA-enriched food supply on cardiovascular risk factors in healthy males. A dietary intervention (single-blind field trial with pre- and post-measurements) was performed with 59 healthy males in a Belgian prison. Over a period of 12 weeks they were supplied with an n-3 enriched diet (containing 6.5 g n-3 PUFA/day compared to 4 g n-3 PUFA/day in the standard diet) that was substituted for their regular diet, increasing mainly the alpha-linolenic acid intake (from 2.8 to around 5 g/day). The results indicated no impact on subjects waist circumference, weight and BMI or systolic blood pressure. In contrast, the diastolic blood pressure significantly decreased during the intervention period (from 74.6 +/- A 8.2 to 71.7 +/- A 10.1 mmHg; P < 0.02). Moreover, the HDL-cholesterol level increased in non-smoking participants (from 0.97 +/- A 0.25 to 1.06 +/- A 0.23 mmol/l; P < 0.03). In summary, the study demonstrated that enrichment of commonly eaten food items with n-3 fatty acids provides the opportunity to increase the n-3 fatty acid intake and to decrease the n-6/n-3 ratio which results in a decreasing diastolic blood pressure and an increase of HDL-cholesterol (in non-smokers).

Inflammatory bowel diseases (IBD) arise from multiple causes, including environmental factors, gut microflora, immunity, and genetic predispositions. In the course of IBD, immune homeostasis and intestinal mucosa barrier integrity are impaired. Among natural preventive treatments that have been identified to date, polyphenols appear as promising candidates. They have been shown to protect against several diseases, including cardiovascular diseases and cancers, and they have anti-inflammatory properties in non-intestinal models. This paper will review the literature that has described to date some effects of polyphenols on intestinal inflammation. Studies, conducted using in vivo and in vitro models, provide evidence that pure polyphenolic compounds and natural polyphenolic plant extracts can modulate intestinal inflammation.

The present experiment investigated whether lysine (Lys) utilization efficiency is affected by dietary protein level in rainbow trout when Lys is first limiting in the diet. Eighteen isoenergetic (22.9 MJ digestible energy/kg dry matter (DM)) Lys-deficient diets containing 250,450 or 650 g crude protein/kg DM and between 6 and 20 g Lys/kg DM were prepared. Wheat gluten, and a crystalline amino acid (AA) mixture corresponding to 47% of the total dietary nitrogen, were used as the principal dietary AA sources. L-Lys.HCl was supplemented at the expense of a dispensable AA mixture. Each diet was fed twice a day to apparent satiety to one group of 70 fry for 30 days. Whole-body protein accretion and Lys gain were determined by the comparative slaughter technique and used to evaluate Lys utilization efficiency above maintenance. Increasing the dietary Lys concentration resulted in linear increases of Lys gain, protein gain and voluntary feed intake. Lys gain or protein accretion increased linearly with increasing dietary Lys intake at all three protein levels and there was no significant difference amongst the regressions, indicating that Lys utilization efficiency was not affected by protein level. Therefore, all data were pooled to calculate a single linear regression for all treatments. Lys was utilized with an efficiency of 71 (SE 3) % above maintenance and 117 (SE 13.6) g Lys intake were required for 1 kg protein accretion in trout fry. Finally, increasing the protein level in isoenergetic diets led to a dramatic decrease of voluntary feed intake in trout, suggesting that fish regulate their feed consumption to achieve a certain target protein deposition and not on the basis of energy intake, at least at marginal Lys intake in wheat gluten-based diets. (C) 2008 Elsevier B.V. All rights reserved.

This study describes the intraspecific variation of 30 edible-seed Lagenaria siceraria germplasm accessions from the University of Abobo-Adjame. These accessions were collected from three (Centre, East and South) geographical zones of Cote d'Ivoire. Selection based on seed size by the farmers has resulted in subdividing the species into two cultivars: large-seeded and small-seeded. The morphological diversity study of the collection included 18 accessions and 24 traits. The multivariate analysis of variance (MANOVA) showed a significant difference between the two groups of cultivars. Principal component analysis on 13 traits pointed out variations among individuals, mainly on the basis of flower, fruit, and seed size. Dendrogram with UPGMA method allowed clustering of the cultivars. The genetic structure analysis among accessions using allozyme markers showed the following values: 18.95% for the proportion of polymorphic loci (P), 1.21 for the number of alleles (A) and 0.053 for observed heterozygosity (Ho). The level of the within accessions genetic diversity (H-S = 0.188) was higher than the genetic variation among accessions (D-ST = 0.082). The estimates of F-statistics indicated a low level of genetic differentiation between accessions (F-ST = 0.298). Such a value suggested that L. siceraria maintains about 30% of its genetic variation among accessions. Nei genetic distances between the two cultivars were also low (0.002), indicating that cultivars were genetically similar enough to belong to the same genetic group.

High performance liquid chromatography coupled to an ultraviolet, diode array or fluorescence detector (HPLC/UV-FLD) has been used to set up a method to detect the 15(+1) EU priority polycyclic aromatic hydrocarbons (PAHs) in food supplements covering the categories of dried plants and plant extracts excluding oily products. A mini validation was performed and the following parameters have been determined: limit of detection, limit of quantification, precision, recovery and linearity. They were in close agreement with quality criteria described in the Commission Regulation (EC) No 333/2007 concerning the PAH benzo[a]pyrene in foodstuffs, except the not fluorescent cyclopenta[c,d]pyrene for which the UV detection leads to a higher limit of detection. Analysis of twenty commercial food supplements covering mainly the class of dried plants was performed to evaluate their PAHs contamination levels and to test the applicability of the method to various plant matrices. Fifty percent of analyzed samples showed concentration exceeding 2 mu g kg(-1) for one or more PAHs. (C) 2008 Elsevier B.V. All rights reserved.

Lowland rice is often subject to iron toxicity which may lead to yield reduction. In order to cope with this nutrient disorder, plants have developed resistance strategies. The aim of this research was to assess morphological and physiological parameters linked to iron toxicity resistance mechanisms and to identify quantitative trait loci (QTLs) involved in their genetic determinism. A segregating population consisting of 164 recombinant inbred lines (RILs) derived from a cross between Azucena and IR64 was tested twice in hydroponics at the vegetative stage at 0 and 250 mg Fe2+ l(-1). Morphological traits were measured on all 164 RILs. Physiological traits, which were too time-consuming to allow their measurement on all the population, were measured on the two parents and extreme individuals only, selected on the basis of their leaf bronzing index and shoot dry weight. A total of 24 putative QTLs was identified on chromosomes 1, 2, 3, 4, 7 and 11 for leaf bronzing index, shoot water content, shoot and root dry weight, relative variation of shoot and root dry weight, shoot iron concentration, stomatal resistance and chlorophyll content index. Several QTLs were detected in overlapping regions for different parameters. The pertinence of phenotyping extreme RILs only for a QTL analysis is discussed in this study. The QTL analysis allowed to better understand the physiological response of rice in the presence of an excess of ferrous iron, inclusive the relations existing between the stomata closure, the shoot water content reduction and the oxidative stress linked to these growth conditions.

The sugar porter family in yeasts encompasses a wide variety of transporters including the hexose transporters and glucose sensors. We analysed a total of 75 members from both groups in nine hemiascomycetous species, with complete and well-annotated genomes: Saccharomyces cerevisiae, Candida glabrata, Zygosaccharomyces rouxii, Kluyveromyces thermotolerans, Saccharomyces kluyverii, Kluyveromyces lactis, Eremothecium gossypii, Debaryomyces hansenii and Yarrowia lipolytica. We present a model for the evolution of the hexose transporters and glucose sensors, supported by two types of complementary evidences: phylogeny and neighbourhood analysis. Five lineages of evolution were identified and discussed according to different mechanisms of gene evolution: lineage A for HXT1, HXT3, HXT4, HXT5, HXT6 and HXT7; lineage B for HXT2 and HXT10; lineage C for HXT8; lineage D for HXT14; and lineage E for SNF3 and RGT2.

Agricultural science and technology (S&T) is under great scrutiny. Reorientation towards more holistic approaches, including agroecology, has recently been backed by a global international assessment of agriculture S&T for development (IAASTD). Understanding the past and current trends of agricultural S&T is crucial if such recommendations are to be implemented. This paper shows how the concepts of technological paradigms and trajectories can help analyse the agricultural S&T landscape and dynamics. Genetic engineering and agroecology can be usefully analysed as two different technological paradigms. even though they have not been equally successful in influencing agricultural research. We used a Systems of Innovation (SI) approach to identify the determinants of innovation (the factors that influence research choices) within agricultural research systems. The influence of each determinant is systematically described (e.g. funding priorities, scientists' cognitive and cultural routines etc.). As a result of their interactions, these determinants construct a technological regime and a lock-in situation that hinders the development of agroecological engineering. Issues linked to breaking Out of this lock-in situation are finally discussed. (C) 2009 Elsevier B.V. All rights reserved.

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor mediating the adverse effects of dioxins and polycyclic aromatic hydrocarbons (PAHs). In this study, we investigated the genetic-, time-, dose-, species- and tissue-dependent AhR-mediated agonistic/antagonistic activities of three food flavonoids: quercetin, chrysin and genistein. To that end, four stably transfected cell lines were used in cell-based luciferase reporter gene assays: three lines were transformed with the ptKLuc vector harbouring four dioxin-responsive elements (DREs) upstream of the thymidine kinase promoter and the luciferase gene (HepG2-Luc, T-47D-Luc and H4IIE-ULg). The fourth is a patented cell line transformed with a different construct: H4IIE DR-CALUX (R). Both H4IIE cells were compared for their genetic construction. Human hepatoma (HepG2-Luc) and human breast tumour (T-47D-Luc) cells were compared for tissue-dependent effects. Rat hepatoma (H4IIE-ULg) and human hepatoma (HepG2-Luc) cells were compared for species-dependent activities. We concluded that quercetin, chrysin and genistein act in a time-, dose-, species- and tissue-specific way. For example, genistein displayed agonistic activities when exposed to rat hepatoma cells during 6 h but not after 24 h. Flavonoids displayed agonistic/antagonistic activities in human breast tumour cells, depending on the exposure time, while in human hepatoma cells, only antagonistic activities of flavonoids were measured. In addition, we report, in all the cells, a synergy between an isoflavone and two food contaminants; the 2,3,7,8-tetrachlorodibenzo-p-dioxin and 3-methylcholanthrene, a PAH. In rat cells, this synergy occurred when cells were exposed to flavonoids and contaminant for 6h, while it was observed in human cells only after 24 h. (C) 2008 Elsevier B.V All rights reserved.

In the context of the structural transformation of the Mexican economy, we conduct a comparative analysis of incomes of farm households relative to non-farm households over the last two decades. We use household-based budget surveys from 1984 to 2004 that are collected and harmonized by the Luxembourg Income Study. We first examine the evolution of average farm household income relative to average non-farm household income across Mexican regions over that period. Second, we show the evolution of low-income and inequality indicators of farm households relative to non-farm households across regions and years. We then investigate whether explanations for low farm income given in the literature also apply to Mexico by econometrically testing both household socio-demographic variables and macroeconomic variables such as commodity and labour market conditions, income- earning capacity and agricultural programmes.

Transmission des prix sur le marché mondial de la vanille: Une étude de cas du modèle de co-intégration sur le paradoxe du leadership de Madagascar

This study provides a stylized model on “Exit, voice and loyalty” as alternative strategic responses taken by Kenyan green beans farmers in the context of new and more stringent international food safety standards. On the analytical side, we use the Nash bargaining theory where the exporter and a representative grower bargain over the product quality level and the premium producer price. The comparative statics analysis shows that the producer bargaining power unlike the compliance costs has, ceteris paribus, a positive effect on the equilibrium quality level while these exogenous variables have ambiguous effects on producer price at equilibrium. Empirical results from logit model estimation with survey data at farm-level in Kenya show that households with highly educated members, access to credit and relatively large-size farms are more likely to participate in the certified supply chain. Off-farm income, live assets and distance of public services from the farm do not influence the compliance. In terms of policy implications, education and credit access could play an important role in the capacity-building of small-scale growers associations through public private partnership.

We estimate a farm-level cost function for Belgian crop farms using FADN data over the study period 1996-2006. We rely on an estimation of farmers' expected yields at the time cropping decisions are made rather than actual yields observed in the FADN data. The use of an ex ante cost function improves the cost function estimation. We subsequently suggest how our cost function can be used in simulations to analyze farmer response to changes in output price risk.

The African cash crop sector has witnessed widespread liberalisation reforms aimed at strengthening price incentives to farmers. However, some areas are confronted with a decline in input use. We have recourse to a two-stage Cournot game to account for the issue. In a context of credit rationing and imperfect contract enforceability, competition has the effect of tightening the input availability constraint while increasing the shadow value of credit. First, contrary to expectations, the impact of an extension of access to farm credit on aggregate input use, efficiency and peasants' income is shown to be ambiguous. Intuitively, relaxing the liquidity constraint entails a higher price elasticity of supply that results in a reduction of traders' profit margin. As a consequence, traders' incentives to contribute to input availability are weakened. The effects of subsidising inputs are also analysed. Second, normative insights are drawn regarding second best combinations of imperfect credit and output markets. Finally, the issue and consequences of contract unenforceability are discussed.

Cette étude analyse les facteurs déterminant les échanges de produits vivriers entre les marchés ruraux du Bénin et le marché de consommation de Cotonou. L’utilisation du modèle de Dixit-Stiglitz-Krugman sur des données en panel couvrant la période de 1999 à 2006 montre que les variables composant les coûts de transfert expliquent le commerce de la tomate et partiellement celui de la patate douce. Les trois variables étudiées telles que la distance, l’état des routes et le partage d’au moins une langue vernaculaire ont un impact respectivement de -0.82, 12.10 et 10.53 sur le commerce de la tomate entre les marchés. Seule la distance a une influence significativement négative de -2.08 sur le commerce de la patate douce.

Despite the preferential market access granted to ACP countries by the European Union in the context of the EU-ACP partnership agreement, African exports of agricultural and food products to EU face some trade barriers. Evidence from the available literature shows that food safety standards and other non-tariff measures can act as trade barriers. Using an extension of the price-wedge method that takes into account imperfect substitution and factor endowment in monopolistic competition, this study provides ad valorem tariff equivalent of several international food safety standards. We apply this method to panel data of European imports of fruit, vegetables and fish from Kenya, Tanzania, Uganda, and Zambia. Empirical results show that the tariff equivalent is about 36 per cent for avocados, ranges from 40 to 92 per cent for fresh peas and green beans and goes from 12 to 190 per cent for frozen fish fillet. In addition, we observe a strong home-good preference of more than 99 per cent for frozen fish fillet and an important variation of the tariff equivalent for all the products among the EU importing countries and over time.

Purpose: We investigated the process of bio-accumulation of 3,3′,4,4′,5-pentachlorobiphenyl (PCB-126) in cultured rat adipocytes, both in quantitative and kinetic terms. Methods: [3H]-labelled PCB-126 was added in the medium of primary cultures of rat adipocytes at the concentration of 2.5 nM. After 0.5, 1, 2, 4 and 8 h of incubation, media were collected for residual PCB-126 analysis and cells were harvested for stored PCB-126, triacylglycerols and protein quantification. The experiment was performed on cells, both at day 7 and 13 of the differentiation. Results: The process of adipocyte differentiation was followed through the changes in the cellular content in proteins and triacylglycerols. It appeared to be progressive and was fully accomplished on day 13. Days 7 and 13 were thus chosen for further experiments. In both conditions, the adipocytes were shown to accumulate PCB-126 very effectively. After 30 min, the 7-day cells had already accumulated 7% of the initial PCB quantity, whereas a value of 14% was registered for the 13-day cells. After 8 h, the accumulated amounts reached 29% and 69%, respectively. In average, the cells accumulated two times more pollutants on day 13 than on day 7. When the accumulated PCB-126 amounts were expressed per protein unit, the results were comparable for both days whereas when expressed per unit of triacylglycerols, they appeared significantly lower for the 13-day cells. The PCB-126 intracellular concentration was estimated to be between 80 and 440 times higher than in the medium after a contact time of 8 h.

This paper examines price dispersion in the European Union (EU15) and in three New Member States (Poland, Hungary and the Czech Republic) between 1995 and 2006. The research is motivated by the fact that the price convergence problem is at the top of the public agenda in many New Member States (NMS). The analysis utilizes both disaggregate and aggregate price data, including the prices of 157 products and two indices constructed using two different weighting procedures. For each category of goods the price dispersion is lower in EU15 than EU15 plus 3 NMS. Sigma convergence measured as a decline in the standard deviation over time is rejected. Unit root tests reject the validity of the Law of One Price (LOOP) for most of the estimations of indices but confirm the LOOP for individual goods. The half-lives are shorter for NMS than for the EU15.