Climate and land-use changes effects on the distribution of a regional endemism: Melanophryniscus sanmartini (Amphibia, Bufonidae)

ABSTRACT Amphibians are the most threatened vertebrate group according to the IUCN. Land-use and land cover change (LULCC) and climate change (CC) are two of the main factors related to declining amphibian populations. Given the vulnerability of threatened and rare species, the study of their response to these impacts is a conservation priority. The aim of this work was to analyze the combined impact of LULCC and CC on the regionally endemic species Melanophryniscus sanmartini Klappenbach, 1968. This species is currently categorized as near threatened by the IUCN, and previous studies suggest negative effects of projected changes in climate. Using maximum entropy methods we modeled the effects of CC on the current and mid-century distribution of M. sanmartini under two IPCC scenarios - A2 (severe) and B2 (moderate). The effects of LULCC were studied by superimposing the potential distribution with current land use, while future distribution models were evaluated under the scenario of maximum expansion of soybean and afforestation in Uruguay. The results suggest that M. sanmartini is distributed in eastern Uruguay and the south of Brazil, mainly related to hilly and grasslands systems. Currently more than 10% of this species' distribution is superimposed by agricultural crops and exotic forest plantations. Contrasting with a recent modelling study our models suggest an expansion of the distribution of M. sanmartini by mid-century under both climate scenarios. However, despite the rise in climatically suitable areas for the species in the future, LULCC projections indicate that the proportion of modified habitats will occupy up to 25% of the distribution of M. sanmartini. Future change in climate conditions could represent an opportunity for M. sanmartini, but management measures are needed to mitigate the effects of habitat modification in order to ensure its survival and allow the eventual expansion of its distribution.

Creación de alternativas productivas al modelo de la soja RR a partir de los criterios definidos por la población de Basavilbaso, Argentina

El consumo desmesurado de energía por parte de los países del Norte lleva a la creación de una deuda ecológica en los países del Sur. Ésta se debe, entre otros factores, al modelo agrario introducido con la “Nueva Revolución Verde”. En Argentina los monocultivos de sojaRR están potenciando la pérdida de la soberanía alimentaria en todo el país. Al mismo tiempo, las políticas energéticas europeas van a provocar una subida en la demanda de materias primas para la producción de biocombustible, lo que llevará a un aumento de la superficie de sojaRR en Argentina. El objetivo de este estudio es la creación de alternativas productivas mediante la implicación de la población de un municipio argentino. A través de la metodología de análisis social “CLIP” se han identificado los diferentes actores implicados en el modelo agrario que a lo largo del trabajo plantean propuestas de cambio para el sector agropecuario de su municipio. El resultado ha sido el planteamiento de cuatro grandes alternativas: la agricultura orgánica, la rotación de actividades, las producciones avícolas y apícolas y la diversificación de cultivos energéticos. Viendo que la tipología de consumo del Norte afecta directamente en la vida de los países del Sur, en todas las alternativas propuestas en este caso de estudio, se acaba por apostar por la creación de redes productivas y comerciales locales que potencien los beneficios en los países productores sin abandonar las posibilidades del mercado internacional.

Economic threshold levels for the velvetbean caterpillar on soybeans in Brazil: the social and the private perspectives

Pest Control is treated as a economic problem. The social and the private perspectives differ due to the consideration of the environmental and social impacts as well as technical aspects such as resistance, resurgence and secondary pests. A mathematical model is developed to determine and compare the social and the private optimum control strategies (which define the Economic Thereshold Levels) for the velvetbean caterpillar on soybeans in Brazil. The crop/pest system incorporates effects of predators and parasites, the soybean natural capacity to compensate for injury and the pesticide effects on both pests and its natural enemies; in the social case, the environmental and social impacts and the effects of pest resistance to the pesticide are incorporated. Consideration of density dependence, weather effects, randomnes of pest attack and risk aversion are discussed. The results can be compared with current control practices and IPM programme recomendations.

Advances in pharmacological studies of silymarin

Silymarin is the flavonoids extracted from the seeds of Silybum marianum (L) Gearth as a mixture of three structural isomers: silybin, silydianin and silychristin, the former being the most active component. Silymarin protects liver cell membrane against hepatotoxic agents and improves liver function in experimental animals and humans. It is generally accepted that silymarin exerts a membrane-stabilizing action preventing or inhibiting membrane peroxidation. The experiments with soybean lipoxygenase showed that the three components of silymarin brought about a concentration-dependent non-competitive inhibition of the lipoxygenase. The experiments also showed an analogous interaction with animal lipoxygenase, thus showing that an inhibition of the peroxidation of the fatty acid in vivo was self-evident. Silybin almost completely suppressed the formation of PG at the highest concentration (0.3 mM) and proved to be an inhibitor of PG synthesis in vitro. In our experiments, silybin at lower dose (65 mg/Kg) decreased liver lipoperoxide content and microsomal lipoperoxidation to 84.5% and 68.55% of those of the scalded control rats respectively, and prevented the decrease of liver microsomal cytochrome p-450 content and p-nitroanisole-0-demethylase activity 24 h post-scalding. Effects of silymarin on cardiovascular systen have been studied in this university since 1980. O. O silymarin 800 mg/Kg/d or silybin 600 mg/Kg/d reduced plasma total cholesterol, LDL-C and VLDL-C. They however, enhanced HDL-C in hyperlipenic rats. Further studies showed that silymarin enhanced HDL-C in hyperlipemic rats. Further studies showed that silymarin enhanced HDL-C but didn't affect HDL-C, a property of this component which is beneficial to treatment of atherosclerosis. The results showed silymarin 80 mg or silybin 60 mg decreased in vitro platelet aggregation (porcentagem) in rats. The maximal platelet aggregation induced by ADP declined significantly, and time to reach maximal platelet aggregation and five-minute disaggregation didn't change. In our experiments, iv silybin 22,4 mg/kg lowered the amplitude and duration of diastolic blood pressure (DBP) more than those of systolic (SBP), but the descending aortic blood flow, cardiac contractility and ECG did not change significantly in anesthetized open-chest cats. The results indicated a reduction of peripheral resistance and dilatatory action on the resistant blood vessels. These effects are beneficial to coronary heart disease. We also observed the effects of silybin on morphological change, the release of glutamic oxaloacetate aminotrasferase (GOT) and lactate dehydrogenase (LDH) as well as the radioactivity of 3H-TdR incorporated into DNA in normal cardiac cells and cells infected by coxsackie B5, virus os newborn rats. The results showed that silynin did not affect the morphology of normal cell, and that the pathological change of cells infected by virus was delayed and reduced as compared to control. We have investigated the effect of silybin on synthesis and release of LTs in the cultured porcine cerebral basilar arteries (PCBA). Silybin 100 and 500 µmol/L declined the amounts of LTs released from the PCBA incubsated in the presence of A 23187, AA and indomenthacin. The result suggests that silybin can inhibit the activity of 5-lipoxygenase of cerebral blood vessel and may protect the brain from ischemia.

Life cycle of Misumenops pallida (Araneae, Thomisidae)

Postembryonic development of Misumenops pallida (Keyserling) (Araneae, Thomisidae), one of the most abundant predator species in soybean fields in Buenos Aires Province (Argentina) was studied. The life cycle was observed in the laboratory from egg sacs collected in the field, and from egg sacs spined in the laboratory by gravid females collected in the field. Results indicated that instar length and feeding rate increased throughout the life cycle being higher in females than in males. Greater mortality was observed to third and fourth instars decreasing thereafter. These results may contribute to deternmine the efficiency of this species as a natural enemy of insect pests of soybean.

Recombinant " Physcomitrella patens " as a sensitive tool to study heat sensing and heat-shock signal transduction in plants

SUMMARY When exposed to heat stress, plants display a particular set of cellular and molecular responses, such as chaperones expression, which are highly conserved in all organisms. In chapter 1, I studied the ability of heat shock genes to become transiently and abundantly induced under various temperature regimes. To this aim, I designed a highly sensitive heat-shock dependent conditional gene expression system in the moss Physcomitrella patens, using the soybean heatinducible promoter (hsp17.3B). Heat-induced expression of various reporter genes was over three orders of magnitude, in tight correlation with the intensity and duration of the heat treatments. By performing repeated heating/cooling cycles, a massive accumulation of recombinant proteins was obtained. Interestingly, the hsp17.3B promoter was also activated by specific organic chemicals. Thus, in chapter 2, I took advantage of the extreme sensitivity of this promoter to small temperature variations to further address the role of various natural and organic chemicals and develop a plant based-bioassay that can serve as an early warning indicator of toxicity by pollutants and heavy metals. A screen of several organic pollutants from textile and paper industry showed that chlorophenols as well as sulfonated anthraquinones elicited a heat shock like response at noninducing temperatures. Their effects were synergistically amplified by mild elevated temperatures. In contrast to standard methods of pollutant detection, this plant-based biosensor allowed to monitor early stress-responses, in correlation with long-term toxic effect, and to attribute effective toxicity thresholds for pollutants, in a context of varying environmental cues. In chapter 3, I deepened the study of the primary mechanism by which plants sense mild temperature variations and trigger a cellular signal leading to the heat shock response. In addition to the above described heat-inducible reporter line, I generated a P. patens transgenic line to measure, in vivo, variations of cytosolic calcium during heat treatment, and another line to monitor the role of protein unfolding in heat-shock sensing and signalling. The heat shock signalling pathway was found to be triggered by the plasma membrane, where temperature up shift specifically induced the transient opening of a putative high afimity calcium channel. The calcium influx triggered a signalling cascade leading to the activation of the heat shock genes, independently on the presence of misfolded proteins in the cytoplasm. These results strongly suggest that changes in the fluidity of the plasma membrane are the primary trigger of the heatshocksignalling pathway in plants. The present thesis contributes to the understanding of the basic mechanism by which plants perceive and respond to heat and chemical stresses. This may contribute to developing appropriate better strategies to enhance plant productivity under the increasingly stressful environment of global warming. RÉSUME Les plantes exposées à des températures élevées déclenchent rapidement des réponses cellulaires qui conduisent à l'induction de gènes codant pour les heat shock proteins (HSPs). En fonction de la durée d'exposition et de la vitesse à laquelle la température augmente, les HSPs sont fortement et transitoirement induites. Dans le premier chapitre, cette caractéristique aété utilisée pour développer un système inductible d'expression de gènes dans la mousse Physcomitrella patens. En utilisant plusieurs gènes rapporteurs, j'ai montré que le promoteur du gène hsp17.3B du Soja est activé d'une manière. homogène dans tous les tissus de la mousse proportionnellement à l'intensité du heat shock physiologique appliqué. Un très fort taux de protéines recombinantes peut ainsi être produit en réalisant plusieurs cycles induction/recovery. De plus, ce promoteur peut également être activé par des composés organiques, tels que les composés anti-inflammatoires, ce qui constitue une bonne alternative à l'induction par la chaleur. Les HSPs sont induites pour remédier aux dommages cellulaires qui surviennent. Étant donné que le promoteur hsp17.3B est très sensible à des petites augmentations de température ainsi qu'à des composés chimiques, j'ai utilisé les lignées développées dans le chapitre 1 pour identifier des polluants qui déclenchent une réaction de défense impliquant les HSPs. Après un criblage de plusieurs composés, les chlorophénols et les antraquinones sulfonés ont été identifiés comme étant activateurs du promoteur de stress. La détection de leurs effets a été réalisée seulement après quelques heures d'exposition et corrèle parfaitement avec les effets toxiques détectés après de longues périodes d'exposition. Les produits identifiés montrent aussi un effet synergique avec la température, ce qui fait du biosensor développé dans ce chapitre un bon outil pour révéler les effets réels des polluants dans un environnement où les stress chimiques sont combinés aux stress abiotiques. Le troisième chapitre est consacré à l'étude des mécanismes précoces qui permettent aux plantes de percevoir la chaleur et ainsi de déclencher une cascade de signalisation spécifique qui aboutit à l'induction des gènes HSPs. J'ai généré deux nouvelles lignées afin de mesurer en temps réel les changements de concentrations du calcium cytosolique ainsi que l'état de dénaturation des protéines au cours du heat shock. Quand la fluidité de la membrane augmente après élévation de la température, elle semble induire l'ouverture d'un canal qui permet de faire entrer le calcium dans les cellules. Ce dernier initie une cascade de signalisation qui finit par activer la transcription des gènes HSPs indépendamment de la dénaturation de protéines cytoplasmiques. Les résultats présentés dans ce chapitre montrent que la perception de la chaleur se fait essentiellement au niveau de la membrane plasmique qui joue un rôle majeur dans la régulation des gènes HSPs. L'élucidation des mécanismes par lesquels les plantes perçoivent les signaux environnementaux est d'une grande utilité pour le développement de nouvelles stratégies afin d'améliorer la productivité des plantes soumises à des conditions extrêmes. La présente thèse contribue à décortiquer la voie de signalisation impliquée dans la réponse à la chaleur.

Application of ZnO-Functionalised-Sepiolite in weaning piglet diets

The objective was to evaluate the effect of ZnO-Functionalised-Sepiolite (ZnO-Sepiolite) to fulfil Zn requirements and health status of weaning piglets. Pre-starter Basal Diet (BD, corn– soybean based, from weaning till 14 days on trial) was calculated to provide 27 mg Zn/kg feed from raw materials and had no added ZnO and no antibiotics or organic acids. Treatments during pre-starter period were: 1) BD+90% of NRC Zn requirements completed with ZnO (ZnO90); 2) BD+90% of NRC Zn requirements completed with ZnO-Sepiolite (ZnOS90); 3) BD+3000 mg ZnO/kg of diet (ZnO3000); 4) BD+150 mg added Zn/kg diet from ZnO-Sepiolite (ZnOS150). The starter feed (corn–soybean based, from 14 till 31 days on trial) was common for all piglets, and met 90% NRC Zn requirements by adding ZnO. Diarrhea affected more than 50% of the animals of ZnO90, ZnOS90 and ZnOS150, and 33% of the ZnO3000 animals. Animals from ZnOS90 tended (Pb0.10) to improve Gain to Feed ratio (G:F) compared to animals from ZnO90 (0.830 kg/kg vs. 0.811 kg/kg for G:F). Performance of animals from ZnO3000 was not significantly different from the other treatments, and was numerically similar to animals from ZnOS90. The inclusion of ZnO at 3000 mg/kg of feed in the pre-starter period numerically decreased P in serum at the end of this period, with no effect on Ca level; normal levels were restored after 2 weeks of feeding the same levels of Zn than other animals. Animals fed ZnOSepiolite diets had numerically higher serum Ca than ZnO90 and ZnO3000 at 12 days and higher than ZnO90 at 28 days. Serum Zn levels were significantly higher for ZnO3000 than the other treatments.

Interaction of Diocleinae Lectins with Glycoproteins Based in Surface Plasmon Resonance

Interaction of glucose/mannose-binding lectins in solution with immobilized glycoproteins was followed in real time using surface plasmon resonance technology. The lectins which share many biochemical and structural features could be clearly differentiated in terms of their specificity for complex glycoconjugates. The most prominent interaction of the lectins with PHA-E comparing with soybean agglutinin, both glycoproteins exhibiting high mannose oligosaccharides, suggests that the whole structure of the glycoproteins themselves, may interfere in affinity. These findings also support the hypothesis that minor amino acid replacements in the primary sequence of the lectins might be responsible for their divergence in fine specificity and biological activities. This is the first report using surface plasmon resonance technology that evidences differences of Diocleinae lectins in respect their fine glycan-specificity.

Benznidazole vs benznidazole in multilamellar liposomes: how different they interact with blood components?

In spite of its widespread use, benznidazole's (BNZ) toxicity and low efficacy remains as major drawbacks that impair successful treatments against Chagas disease. Previously, attempting to increase the selectivity and reduce its toxicity on infected tissues, multilamellar liposomes (MLV) composed of hydrogenated soybean phosphatidylcholine (HSPC): distearoyl-phosphatidylglycerol (DSPG): cholesterol (CHOL) 2:1:2 mol:mol loaded with BNZ (MLV-BNZ) were designed. In this work we compared different properties of MLV-BNZ with those of BNZ. Opposite to other hydrophobic drugs, the results indicated that slight changes of BNZ×s association degree to proteins and lipoproteins should not modify the percentage of unbound drug available to exert pharmacological action. On the other hand, when loaded in MLV, BNZ reduced its association to plasma proteins in 45% and became refractory to the sinking effect of blood, dropping 4.5 folds. Additionally, when loaded in MLV, BNZ had higher volume distribution (160 ± 20 vs 102 ± 15 ml/kg) and total clearance (35.23 ± 2.3 vs 21.9 ± 1.4 ml/h.kg), and lower concentration-time curve (7.23 ± 0.2 vs 9.16 ± 0.5 µg.h/ml) than BNZ. Hence, these studies showed that for MLV-BNZ, the amount of BNZ can be substantially increased, from 25 to 70%, being this formulation more rapidly cleared from circulation than free drug; also due to the lower interaction with blood components, lower side effects can be expected.

Extracellular protease of Pseudomonas fluorescens CHA0, a biocontrol factor with activity against the root-knot nematode Meloidogyne incognita.

In Pseudomonas fluorescens CHA0, mutation of the GacA-controlled aprA gene (encoding the major extracellular protease) or the gacA regulatory gene resulted in reduced biocontrol activity against the root-knot nematode Meloidogyne incognita during tomato and soybean infection. Culture supernatants of strain CHA0 inhibited egg hatching and induced mortality of M. incognita juveniles more strongly than did supernatants of aprA and gacA mutants, suggesting that AprA protease contributes to biocontrol.

Effects of dietary protein type on oxidized cholesterol-induced alteration in age-related modulation of lipid metabolism and indices of immune function in rats.

Exogenous oxidized cholesterol disturbs both lipid metabolism and immune functions. Therefore, it may perturb these modulations with ageing. Effects of the dietary protein type on oxidized cholesterol-induced modulations of age-related changes in lipid metabolism and immune function was examined using differently aged (4 weeks versus 8 months) male Sprague-Dawley rats when casein, soybean protein or milk whey protein isolate (WPI) was the dietary protein source, respectively. The rats were given one of the three proteins in diet containing 0.2% oxidized cholesterols mixture. Soybean protein, as compared with the other two proteins, significantly lowered both the serum thiobarbituric acid reactive substances value and cholesterol, whereas it elevated the ratio of high density lipoprotein-cholesterol/cholesterol in young rats, but not in adult. Moreover, soybean protein, but not casein and WPI, suppressed the elevation of Delta6 desaturation indices of phospholipids in both liver and spleen, particularly in young. On the other hand, WPI, compared to the other two proteins, inhibited the leukotriene B4 production of spleen, irrespective of age. Soybean protein reduced the ratio of CD4(+)/CD8(+) T-cells in splenic lymphocytes. Therefore, the levels of immunoglobulin (Ig)A, IgE and IgG in serum were lowered in rats given soybean protein in both age groups except for IgA in adult, although these observations were not shown in rats given other proteins. Thus, various perturbations of lipid metabolism and immune function caused by oxidized cholesterol were modified depending on the type of dietary protein. The moderation by soybean protein on the change of lipid metabolism seems to be susceptible in young rats whose homeostatic ability is immature. These observations may be exerted through both the promotion of oxidized cholesterol excretion to feces and the change of hormonal release, while WPI may suppress the disturbance of immune function by oxidized cholesterol in both ages. This alleviation may be associated with a large amount of lactoglobulin in WPI. These results thus showed a possibility that oxidized cholesterol-induced perturbations of age-related changes of lipid metabolism and immune function can be moderated by both the selection and combination of dietary protein.

Reconstitution into liposomes of the tonoplast ATP-and pyrophosphate-dependent proton pumps from Rubus hispidus cell cultures.

The ATP- and pyrophosphate-dependent proton pumps from tonoplast-enriched vesicles prepared from Rubus hispidus cell cultures were solubilized in the presence of polyoxyethylene(9,10)p-t-octylphenol (Triton X-100) and reconstituted into liposomes of soybean phospholipids, using Bio-Beads SM-2 to remove the detergent. The specific activity of the two pumps was greatly increased by the solubilization-reconstitution procedure. Identical characteristics were found for pyrophosphate-dependent proton transport in native and reconstituted vesicles. On the other hand, the ATP-dependent proton transport of the reconstituted vesicles was no longer inhibited by KNO3.

Networks in Argentine agriculture: a multiple-case study approach

Argentina is among the four largest producers of soybeans, sunflower, corn, and wheat, among other agricultural products. Institutional and policy changes during the 1990s fostered the development of Argentine agriculture and the introduction of innovative process and product technologies (no-till, agrochemicals, GMO, GPS) and new investments in modern, large-scale sunflower and soybean processing plants. In addition to technological changes, a "quiet revolution" occurred in the way agricultural production was carried out and organized: from self-production or ownership agriculture to a contract-based agriculture. The objective of this paper is to explore and describe the emergence of networks in the Argentine crop production sector. The paper presents and describes four cases that currently represent about 50% of total grain and oilseed production in Argentina: "informal hybrid form", "agricultural trust fund", "investor-oriented corporate structure", and "network of networks". In all cases, hybrid forms involve a group of actors linked by common objectives, mainly to gain scale, share resources, and improve the profitability of the business. Informal contracts seem to be the most common way of organizing the agriculture process, but using short-term contracts and sequential interfirm collaboration. Networks of networks involve long-term relationships and social development, and reciprocal interfirm collaboration. Agricultural trust fund and investor-oriented corporate structures have combined interfirm collaboration and medium-term relationships. These organizational forms are highly flexible and show a great capacity to adapt to challenges; they are competitive because they enjoy aligned incentives, flexibility, and adaptability.

Desarrollo y validación de ensayos rápidos para la detección de aeroalérgenos ocupacionales/ambientales: soja i proteinas séricas de paloma

Tanto el asma ocupacional como la neumonitis por hipersensibilidad, como es el pulmón del cuidador de aves, son patologías respiratorias que se pueden prevenir o disminuir su aparición mediante la evitación de la fuente antigénica. Para poder actuar de forma preventiva es de utilidad el disponer de ensayos rápidos que sean capaces de estimar la presencia de alérgeno de forma inmediata. En el marco de este proyecto de dos años de duración tenemos por objeto el desarrollar y estandarizar dos métodos rápidos, inmunocromatográficos, para la determinación de alérgenos de soja y de proteínas séricas de paloma. Alérgenos que han sido seleccionados por su importancia en el medio como agentes causales de asma y neumonitis por hipersensibilidad, respectivamente. También tenemos por objeto determinar la carga de alérgeno de soja en la fracción de partículas menores de 10 micrómetros (PM10) en los alrededores del puerto de Barcelona y comprarla con los niveles en los filtros de partículas suspendidas totales (TSP). Como pasos previos al desarrollo de los ensayos rápidos se han producido anticuerpos específicos frente al extracto de cáscara de soja de bajo peso molecular y frente al suero de paloma, se ha desarrollado un ELISA tipo sándwich para cada alérgeno y parte de los anticuerpos se ha conjugado con oro coloidal. El ensayo inmunocromatográfico para la soja presenta un límite de detección de 6.25ng/ml y ha sido validado mediante el análisis de 119 muestras ambientales, presentando una elevada especificidad y sensibilidad. El ensayo inmunocromatográfico para la determinación de antígenos séricos de paloma requiere ser validado. Mediante un métodos de ELISA de inhibición se han determinado los niveles de alérgeno de soja en filtros PM10 y TSP. A pesar de la buena correlación entre los niveles de alérgeno en ambos filtros, se observó una amplia variación en la proporción PM10/TSP entre días.

In vivo visualization of F-actin structures during the development of the moss Physcomitrella patens.

* The 'in planta' visualization of F-actin in all cells and in all developmental stages of a plant is a challenging problem. By using the soybean heat inducible Gmhsp17.3B promoter instead of a constitutive promoter, we have been able to label all cells in various developmental stages of the moss Physcomitrella patens, through a precise temperature tuning of the expression of green fluorescent protein (GFP)-talin. * A short moderate heat treatment was sufficient to induce proper labeling of the actin cytoskeleton and to allow the visualization of time-dependent organization of F-actin structures without impairment of cell viability. * In growing moss cells, dense converging arrays of F-actin structures were present at the growing tips of protonema cell, and at the localization of branching. Protonema and leaf cells contained a network of thick actin cables; during de-differentiation of leaf cells into new protonema filaments, the thick bundled actin network disappeared, and a new highly polarized F-actin network formed. * The controlled expression of GFP-talin through an inducible promoter improves significantly the 'in planta' imaging of actin.