Production and purification of fumonisins from a highly toxigenic Fusarium verticilloides strain

Fumonisins are the major mycotoxins produced by Fusarium verticilloides and F. proliferatum fungi which are widely found as contaminants in corn and corn screenings. These molecules are hepatotoxic and nephrotoxic for several species and carcinogenic in rodents. Moreover their consumption was linked to high prevalence of human oesophageal cancer in certain geographic areas. The aim of this work was to improve FB1 production and purification procedures in laboratory conditions in order to produce large quantities of semi-purified toxin that may be used in experimental intoxications of farm animals. We used a highly toxigenic strain of Fusarium verticilloides (NRRL-3428) isolated from feeds. Influence of substrate, temperature, water content, culture recipient size and screen analysis of the substrate on fumonisin production was tested. Optimal production was obtained when strain was grown on coarsely cracked corn with 50% water content at 21°C during 5 weeks. This allowed the production of 3 to 4 g of fumonisin B1 per kg of culture material. The composition of the extracts was found to be as follow : 54% FB1, 8% FB2, 9% FB3 and 29% of pigments coming from corn. The ratio observed between FB1 and FB2 is comparable to the one reported in naturally contaminated corn. Further purification of these extracts on SAX columns led to the removal of pigments and to obtain of fumonisins extracts pure enough to be used for intra-venous or intra-peritoneal injection

Plant response to environmental conditions: assessing potential production, water demand, and negative effects of water deficit

This paper reviews methods for analyzing plant performance and its genetic variability under a range of environmental conditions. Biomass accumulation is linked every day to available light in the photosynthetically active radiation (PAR) domain, multiplied by the proportion of light intercepted by plants and by the radiation use efficiency. Total biomass is cumulated over the duration of the considered phase (e.g., plant cycle or vegetative phase). These durations are essentially constant for a given genotype provided that time is corrected for temperature (thermal time). Several ways of expressing thermal time are reviewed. Two alternative equations are presented, based either on the effect of transpiration, or on yield components. Their comparative interests and drawbacks are discussed. The genetic variability of each term of considered equations affects yield under water deficit, via mechanisms at different scales of plant organization and time. The effect of any physiological mechanism on yield of stressed plants acts via one of these terms, although the link is not always straightforward. Finally, I propose practical ways to compare the productivity of genotypes in field environments, and a “minimum dataset” of environmental data and traits that should be recorded for that

Salamanca. Fortificaciones. 1812 (1836)

Escala también expresada en 200 toesasCopia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 201

Concepts, approches et outils pour la conception et le développement d'idéotypes variétaux adaptés à une agriculture durable

Développer de nouvelles variétés pour une agriculture durable Produire des idéotypes variétaux adaptés à une agriculture durable représente un défi pour les généticiens et les écophysiologistes. Il s'agit de développer des plantes plus résilientes aux contraintes environnementales, a priori plus économes en intrants. Cependant, les protections contre les stress biotiques et abiotiques ont généralement un coût en termes de métabolisme. Il ne s'agit donc pas à proprement parler de " tolérance ", mais de la recherche d'un optimum entre protections et rendement maximum. Cet optimum varie selon les couples " région x système de culture ", suivant la nature, l'intensité et la position dans le cycle végétatif des stress les plus fréquents. Par exemple, les plantes les plus " plastiques ", réduisant la surface foliaire, la transpiration ou la durée de leur cycle végétatif en condition de stress hydrique, sont généralement adaptées à des régions où se produisent des déficits hydriques fréquents et sévères. Ceci réduit leurs besoins en eau, et leur permet ainsi de terminer le cycle en bonnes conditions, mais aussi la photosynthèse cumulée si les conditions redeviennent favorables. Au contraire, les plantes dont la croissance et la transpiration sont résilientes au déficit hydrique sont souvent les plus adaptées aux climats tempérés secs. La caractérisation d'idéotypes adaptés repose donc sur une analyse fréquentielle du climat tel qu'il est ressenti par la plante, prenant en compte date de semis, durée du cycle ou composition du peuplement végétal (homogène ou en mélange). Une démarche de sélection en deux temps Il n'est guère possible de mener un programme de sélection de novo pour chaque couple " région du monde x système de culture ". Les recherches se dirigent donc vers une démarche en deux temps, d'une part l'analyse génétique de caractères impliqués dans la résilience aux conditions environnementales, aboutissant à une valeur agronomique d'allèles, d'autre part la construction d'idéotypes adaptés à une région donnée, fondée sur la combinaison de ces allèles. Les modèles et les méthodes expérimentales mis en jeu pour ces deux étapes sont différents. La première étape repose sur des plates-formes de phénotypage, permettant d'analyser génétiquement de grandes collections de plantes dans des conditions variées. Ces plates formes, en serre ou au champ, impliquent des conditions semi-contrôlées et des mesures intensives des conditions environnementales et des réponses des génotypes. La seconde étape comprend une phase in sillico de recherche d'allèles favorables à une situation donnée (prenant en compte les résultats de l'étape précédente), puis le test d'un nombre limité de combinaisons prometteuses dans des essais au champ, accompagné d'une étude fréquentielle issue de la simulation du rendement de génotypes portant différentes combinaisons d'allèles. Cette simulation permet de prévoir la fréquence à laquelle une combinaison d'allèles est favorable dans une région et un système de culture donnés. La sélection de variétés adaptées à une agriculture durable donne de nouvelles responsabilités à des disciplines comme l'agronomie, la modélisation des plantes, et (de plus en plus) les sciences sociales. L'analyse génétique, la recherche et le test d'idéotypes au champ se trouvent dans des étapes individualisées, impliquant chacune des groupes publics et privés. Les partenariats qui se mettent en place dans des projets Investissements d'avenir (nationaux), européens (UE FP7) ou internationaux préfigurent probablement une nouvelle organisation du travail en génétique-amélioration des plantes. (Texte intégral

Dextran sulfate enhances the level of an oxidative DNA damage biomarker, 8-oxo-7,8-dihydro-2 0-deoxyguanosine, in rat colonic mucosa

Dextran sodium sulfate (DSS) given in drinking water can induce colonic Inflammation and produce colorectal tumors in rodents, although it is not directly genotoxic. The hypothesis that DSS can produce free radicals and induce oxidative DNA damage in colonic mucosa has been tested. In rats fed for 2 days with water containing 3% and 6% DSS, colonic Inflammation manifestations were recorded and 8-oxo-7,8-dihydro-2 0-deoxyguanosine (8-oxodGuo), a major biomarker of oxidative DNA damage, was assayed in colonic mucosa. As compared with control rats given pure water, inflammatory manifestations were seen in rats given DSS. At the same time, 8-oxodGuo levels in colonic mucosa were doubled (P , 0:001). These results suggest that formation of oxidative DNA damage in colonic mucosa depends on inflammation and maybe on the production of reactive oxygen species. This study shows that DSS can induce oxidative DNA damage within only 2 days, which could explain in part its carcinogenic properties

R-SHIM: Deterministic Concurrency with Recursion and Shared Variables

Concurrent programming languages are good for embedded systems because they match the parallelism of their environments, but most concurrent languages are nondeterministic, making coding in them unwieldy. We present R-SHIM, the core of a language with concurrent recursive procedure calls and disciplined shared variables that remains deterministic -- the behavior of a program is scheduling-independen

HPLC assay of zearalenone and reduced metabolites in S9 fractions of duck liver

HPLC analysis of zearalenone (ZEA), zearalenols (-ZOL and ß-ZOL) and zearalanols (-ZAL and ß-ZAL) was developed, in order to obtain a sensitive and reproducible method to quantify ZEA and its reduced metabolites in subcellular fractions of animal livers (S9 samples). Optimal in vitro metabolism was observed by incubating 5 mg S9 proteins with 0.016 μmol. ZEA. Acetonitrile and diethylether/chloroform mixture were compared for extraction, as well as different mobile phases and two detection modes in HPLC analysis. Extracted samples were eluted with water/acetonitrile (55:45, v/v) at a flow-rate of 1.0 ml/min-1, resulting in well separated peaks between ZEA and the metabolites. The limits of detection ranged from 0.5 to 2 ng/mg S9 proteins using UV, and from 0.04 to 4 ng/mg S9 proteins, using fluorescence detection. Fluorescence showed a ten-fold higher sensitivity than UV detection for ZEA and -ZOL. Repeatability (10 assays) was 2.7% to 6.99% for zearalenols. Day-by-day coefficients of variation for zearalenone and zeranols with UV detection were 3.3 to 8.5 %, and 2.5 to 4.3 %, respectively. This analysis applied to S9 samples from ducks after 30 min of ZEA incubation allowed to demonstrate that -ZOL is the main reduced metabolite in the duck. The present method is particularly adapted for studying in vitro metabolism of ZEA and inter-species variations

Variations in zearalenone activation in avian food species

Zearalenone (ZEA), a widely distributed oestrogenic fusariotoxin, constitutes a potential risk for human and animal health. ZEA is metabolised to the main metabolites identified in vitro and in vivo: alpha-zearalenol (α-ZOL) and beta-zearalenol (β-ZOL). The efficiency to produce alpha-reduced metabolites appears of particular interest in risk assessment as alpha-reduced metabolites constitute activated forms whereas beta-reduced metabolites are less oestrogenic than ZEA. In this study ZEA activation was compared in avian food species. ZEA and its reduced metabolites were quantified in subcellular fractions of six avian species and rat livers. The α-ZOL/β-ZOL ratio in rats was 19. The various avian food species cannot be considered to be equivalent in terms of ZEA reduction (P<0.001). Quails represented high “beta reducers”, with α-ZOL/β-ZOL ratio less than two. Weak “beta reducers” included on one part ducks and chickens showing α-ZOL/β-ZOL ratio greater than 3 and up to 5.6 and on a second part geese, showing a lower production of α-ZOL than other poultry. Comparisons of enzyme kinetics in ducks and in quails show that these variations can be explained by the action of various isoforms of dehydrogenases. These results are relevant to food safety, in the context of frequently inevitable contamination of animal feed