OVERLAND FLOW AND SURFACE RUNOFF / Hydrological Science and Engineering

Cape Verde, off the coast of Senegal in western Africa, is a volcanic archipelago where soil and water conservation techniques play an important role in the overall subsistence of half a million inhabitants. In fact, the step slopes in the more agricultural islands due to it's volcanic origin, together with semi-arid and arid environments (the country is located in the Sahelian region), characterized by a very irregular wet season, with high intensity rainfall events, make life tough. The hard conditions lead during the first half of the XX century to frequent cycles of drought with severe implications on the local populations, with impressive numbers of deaths by famine, and a decrease of the number of local inhabitants by more than halve in some islands. Maintain the soil in place and the water inside the soil was there after a mater of survival, and the CapeVerdians implemented over the last half century a number of soil and water conservation techniques that cover all the landscape. In this work, we monitored a number of slope soil and water conservation techniques, such as terraces, half moons, live barriers, etc, together with two cultural strategies, used to plant corn and beans on one side and peanuts on the other, with a semi-quantitative methodology, to evaluate their effectiveness. A discussion is given on the costs and effectiveness of the techniques to reduce overland flow production and therefore erosion, and to promote rainfall infiltration.

Regulation of phosphate starvation responses in plants: signaling players and cross-talks.

Phosphate (Pi) availability is a major factor limiting growth, development, and productivity of plants. In both ecological and agricultural contexts, plants often grow in soils with low soluble phosphate content. Plants respond to this situation by a series of developmental and metabolic adaptations that are aimed at increasing the acquisition of this vital nutrient from the soil, as well as to sustain plant growth and survival. The development of a comprehensive understanding of how plants sense phosphate deficiency and coordinate the responses via signaling pathways has become of major interest, and a number of signaling players and networks have begun to surface for the regulation of the phosphate-deficiency response. In practice, application of such knowledge to improve plant Pi nutrition is hindered by complex cross-talks, which are emerging in the face of new data, such as the coordination of the phosphate-deficiency signaling networks with those involved with hormones, photo-assimilates (sugar), as well as with the homeostasis of other ions, such as iron. In this review, we focus on these cross-talks and on recent progress in discovering new signaling players involved in the Pi-starvation responses, such as proteins having SPX domains.

Up-regulation of the levels of expression and function of a constitutively active mutant of the hamster alpha1B-adrenoceptor by ligands that act as inverse agonists.

The alpha1-adrenergic agonist phenylephrine stimulated phospholipase D (PLD) activity in Rat 1 fibroblasts transfected to express either the wild-type hamster alpha1B-adrenoceptor or a constitutively active mutant (CAM) form of this receptor. The EC50 for agonist stimulation of PLD activity was substantially lower at the CAM receptor than at the wild-type receptor as previously noted for phenylephrine stimulation of phosphoinositidase C activity. Sustained treatment of cells expressing the CAM alpha1B-adrenoceptor with phentolamine resulted in a marked up-regulation in levels of this receptor with half-maximal effects produced within 24 h and with an EC50 of approx. 40 nM. Such an up-regulation could be produced with a range of other ligands generally viewed as alpha1-adrenoceptor antagonists but equivalent treatment of cells expressing the wild-type alpha1B-adrenoceptor was unable to mimic these effects. After sustained treatment of the CAM alpha1B-adrenoceptor expressing cells with phentolamine, basal PLD activity was increased and phenylephrine was now able to stimulate PLD activity to greater levels than in vehicle-treated CAM alpha1B-adrenoceptor-expressing cells. The EC50 for phenylephrine stimulation of PLD activity was not altered, however, by phentolamine pretreatment and the associated up-regulation of the receptor. After phentolamine-induced up-regulation of basal PLD activity, a range of alpha1-antagonists were shown to possess the characteristics of inverse agonists of the CAM alpha1B-adrenoceptor as they were able to substantially decrease the elevated basal PLD activity.

Market and institutional determinants in the regulation of conveyancers

Demand for law professionals in the conveyancing of property is decreasing because of market and institutional changes. On the market side, many transactions feature large, well-known parties and standardized transactions, which make professionals less effective or necessary for protecting the parties to private contracts. On the institutional side, public titling makes it possible to dispense with a broadening set of their former functions. Recording of deeds made professionals redundant as depositories of deeds and reduced demand for them to design title guarantees. Effective registration of rights increasingly substitutes professionals for detecting title conflicts with third parties and gathering their consent. Market changes undermine the information asymmetry rationale for regulating conveyancing, while institutional changes facilitate liberalizing not only conduct but also license regulations. These arguments are supported here by disentangling the logic of titling systems and presenting empirical evidence from the European and USA markets.

An overall perspective on banking regulation

We survey the theory of banking regulation from the general perspectiveof regulatory theory. Starting by considering the different justificationsof financial intermediation, we proceed to identify the market failuresthat make banking regulation necessary. We then succinctly compare how theanalysis of regulation compares in the domains of banking and industrialorganization. Finally we analyse why a safety net for banks could be partof banking regulation and how it can be structured in an efficient way.

Reorganization of a deeply incised drainage: role of deformation, sedimentation and groundwater flow

Deeply incised drainage networks are thought to be robust and not easily modified, and are commonly used as passive markers of horizontal strain. Yet, reorganizations (rearrangements) appear in the geologic record. We provide field evidence of the reorganization of a Miocene drainage network in response to strike-slip and vertical displacements in Guatemala. The drainage was deeply incised into a 50-km-wide orogen located along the North America-Caribbean plate boundary. It rearranged twice, first during the Late Miocene in response to transpressional uplift along the Polochic fault, and again in the Quaternary in response to transtensional uplift along secondary faults. The pattern of reorganization resembles that produced by the tectonic defeat of rivers that cross growing tectonic structures. Compilation of remote sensing data, field mapping, sediment provenance study, grain-size analysis and Ar(40)/Ar(39) dating from paleovalleys and their fill reveals that the classic mechanisms of river diversion, such as river avulsion over bedrock, or capture driven by surface runoff, are not sufficient to produce the observed diversions. The sites of diversion coincide spatially with limestone belts and reactivated fault zones, suggesting that solution-triggered or deformation-triggered permeability have helped breaching of interfluves. The diversions are also related temporally and spatially to the accumulation of sediment fills in the valleys, upstream of the rising structures. We infer that the breaching of the interfluves was achieved by headward erosion along tributaries fed by groundwater flow tracking from the valleys soon to be captured. Fault zones and limestone belts provided the pathways, and the aquifers occupying the valley fills provided the head pressure that enhanced groundwater circulation. The defeat of rivers crossing the rising structures results essentially from the tectonically enhanced activation of groundwater flow between catchments.

Role and regulation of polyphosphate in leishmania parasites

Le protozoaire unicellulaire Leishmania est l'agent responsable de la leishmaniose, une maladie parasitaire humaine qui se manifeste par des lésions de la peau, se résolvant le plus souvent spontanément, jusqu'à des lésions viscérales fatales. Le parasite est transmis de l'insecte à l'hôte mammifère lors d'un repas sanguin de la mouche des sables et y réside respectivement sous formes extra- et intracellulaires. On estime que cette maladie touche environ 12 millions de personnes dans 98 pays. Etant donné que les médicaments disponibles à ce jour sont faiblement efficaces et/ou hautement toxiques, il est indispensable de consolider les connaissances sur le fonctionnement et la survie du parasite pour pouvoir développer de nouvelles stratégies de traitements et de préventions. Tous les organismes vivants, dont Leishmania, contiennent du polyphopshate (polyP). Cette molécule chargée négativement est constituée de trois jusqu'à plusieurs centaines de résidus de phosphates reliées par des liaisons à haute énergie. Le polyP sert donc de source d'énergie et de réservoir de phosphate; dans certaines espèces, il joue aussi un rôle dans l'adaptation au stress et la virulence de pathogènes. Ceci nous a amené à étudier le rôle du polyP dans le parasite Leishmania. L'enzyme responsable de la synthèse de polyP a été identifié récemment dans la levure : il s'agit de la chaperone de transport vacuolaire 4 (Vtc4). Nous avons identifié un homologue de Vtc4 chez les Trypanosomatidae, et avons donc décidé d'examiner sa fonction dans le métabolisme du polyP chez Leishmania. En éliminant l'expression de Vtc4 chez L. major et L. guyanensis, nous avons pu démontrer qu'il est indispensable pour la production de polyP chez Leishmania. De plus, nous avons constaté que ces parasites possèdent des chaînes de polyP allant de trois jusqu'à environ 300 résidus de phosphate. Le taux de polyP dans la cellule est précisément régulé et varie entre un très haut niveau durant la phase proliférative des promastigotes à un niveau bas en phase stationnaire tardive, alors que l'expression de Vtc4p reste stable. Dans les amastigotes intracellulaires, seulement des petites quantités de polyP et de Vtc4p sont détectées. En outre, l'absence de Vc4p et de polyP n'a pas d'effet significatif sur les infections in vivo de souris, ce qui indique que le polyP n'est pas nécessaire au développement de la leishmaniose. Ceci suggère que Vtc4p n 'est pas une bonne cible pour le développement de nouveaux traitements contre Leishmania. "Néanmoins, la présence du polyP favorise fortement la survie du parasite suite à un choc de température (37°C) et aide ainsi à sa persistance intracellulaire pendant les premiers jours d'infection de macrophages. En résumé, nos résultats indiquent que si le polyP a peu d'importance pendant l'infection et le développement de la leishmaniose chez la souris, il est par contre crucial pour l'adaptation à des situations de stress comme l'augmentation de la température. Le fait que le polyP a été conservé dans tous les organismes durant l'évolution suggère toutefois que cette molécule joue un rôle fondamental. Etant donné que l'absence de polyP n'a pas d'effet sur la survie des amastigotes, il pourrait être plus important dans la forme promastigote infectant la mouche des sables. - The unicellular protozoan parasite Leishmania is the causative agent of the human disease leishmaniasis, which can range from self-healing skin lesions to fatal visceral lesions. The parasite is transmitted from the insect vector to the mammalian host when the sand fly takes its blood meal and exists in an extra- and an intracellular form, respectively. The disease is estimated to affect 12 million people in 98 countries and currently available drug treatments are of relatively low potency and/or high toxicity. Thus, investigating parasite survival mechanisms and parasite adaptation to the two host environments contributes to the general understanding of Leishmania propagation and might therefore help to develop future treatments or preventions. All living cells, including Leishmania, contain a negatively charged polymer of a few up to several hundred phosphate residues. These so-called polyphosphates (polyPs) serve as an energy source and phosphate reservoir. In some organisms, polyP is also involved in adaptation to stresses and virulence of pathogens. Therefore we were interested in investigating the importance of polyP in Leishmania parasites. Recently, an eukaryotic enzyme responsible for polyP synthesis has been identified as the vacuolar transporter chaperone 4 (Vtc4) in yeast. We, and others, found a Vtc4 homologue in trypanosomatids and decided to examine its potential function in polyP metabolism. By generating VTC4 knock-out cell lines in L. major and Vtc4 knock-down cell lines in L. guyanensis, we were able to demonstrate that Vtc4p is responsible for the total amount of cellular polyP. We also observed that Leishmania polyP chain length ranges from a few up to around 300 residues and that its level is tightly regulated. PolyP abundance is highest during the logarithmic proliferating phase of promastigotes and decreases in the stationary phase, while Vtc4 protein expression remains stable during both phases. In the intracellular amastigote form, only low amounts of polyP and Vtc4p were detectable. Furthermore, absence of Vtc4p and polyP did not have a significant effect on in vivo mouse infections, indicating that polyP is not necessary for Leishmania disease progression. This suggests that Vtc4p would be a poor drug target against Leishmania infection. However, presence of the polymer strongly supported parasite survival during heat shock (37°C) and thereby promoted intracellular persistence during the first days of macrophage infections. Taken together, we found that polyP has little importance in Leishmania {in vivo) infection but that it plays a crucial role during adaptation to stress, such as heat shock. Given that polyP has been preciously conserved in all organisms during evolution it seems to play a fundamental role. Since absence of polyP does not affect amastigote survival, it might be significant for promastigote existence in the sand fly vector.

Entry regulation and intersectoral reallocation

We study how restrictions on firm entry affect intersectoral factor reallocation when openeconomies experience global economic shocks. In our theoretical framework, countries trade freelyin a range of differentiated sectors that are subject to country-specific and global shocks. Entryrestrictions are modeled as an upper bound on the introduction of new differentiated goods followingshocks. Prices and quantities adjust to clear international goods markets, and wages adjustto clear national labor markets. We show that in general equilibrium, countries with tighter entryrestrictions see less factor reallocation compared to the frictionless benchmark. In our empiricalwork, we compare sectoral employment reallocation across countries in the 1980s and 1990s withproxies for frictionless benchmark reallocation. Our results indicate that the gap between actualand frictionless reallocation is greater in countries where it takes longer to start a firm.

Phylogeographical structure, postglacial recolonization and barriers to gene flow in the distinctive Valais chromosome race of the common shrew (Sorex araneus).

Using one male-inherited and eight biparentally inherited microsatellite markers, we investigate the population genetic structure of the Valais chromosome race of the common shrew (Sorex araneus) in the Central Alps of Europe. Unexpectedly, the Y-chromosome microsatellite suggests nearly complete absence of male gene flow among populations from the St-Bernard and Simplon regions (Switzerland). Autosomal markers also show significant genetic structuring among these two geographical areas. Isolation by distance is significant and possible barriers to gene flow exist in the study area. Two different approaches are used to better understand the geographical patterns and the causes of this structuring. Using a principal component analysis for which testing procedure exists, and partial Mantel tests, we show that the St-Bernard pass does not represent a significant barrier to gene flow although it culminates at 2469 m, close to the highest altitudinal record for this species. Similar results are found for the Simplon pass, indicating that both passes represented potential postglacial recolonization routes into Switzerland from Italian refugia after the last Pleistocene glaciations. In contrast with the weak effect of these mountain passes, the Rhône valley lowlands significantly reduce gene flow in this species. Natural obstacles (the large Rhône river) and unsuitable habitats (dry slopes) are both present in the valley. Moreover, anthropogenic changes to landscape structures are likely to have strongly reduced available habitats for this shrew in the lowlands, thereby promoting genetic differentiation of populations found on opposite sides of the Rhône valley.

Eotaxin-1 (CCL11) up-regulation in tears during seasonal allergic conjunctivitis.

PURPOSE: To compare in-season eotaxin-1 levels in tears of patients suffering from seasonal allergic conjunctivitis (SAC) with (1) tears of normal subjects and (2) tears of SAC patients out of season. METHODS: Tears of 11 SAC patients and six control volunteers were collected during the pollen season. Tears of five SAC patients showing a strong sensitivity to grass pollen (skin-prick tests and specific serum IgE) were collected both in season and out of season. ELISA measured eotaxin-1 level. RESULTS: Eotaxin-1 concentration in tears of SAC patients [2,100+/-503 (SEM) pg/ml] and normal subjects (1,193+/-176 pg/ml) were significantly different (P=0.0049). Regarding allergic patients, the clinical score (sum of five allergic criteria) was significantly different in season and out of season (P=0.0043) as was also the case with eotaxin-1 concentration (P=0.024). CONCLUSIONS: The eotaxin-1 concentration in tears of patients showing hay fever could confirm a diagnosis of seasonal ocular allergy.

Modulation of cdk2, cyclin D1, p16INK4a, p21WAF and p27Kip1 expression in endothelial cells by TNF/IFN gamma.

BACKGROUND: Regional administration of high doses of tumor necrosis factor (TNF) and interferon gamma (IFN gamma) to metastatic melanoma patients causes selective disruption of the tumor vasculature. This effect is paralleled by decreased endothelial cell proliferation and suppressed integrin alpha V beta 3-mediated adhesion in vitro. Overexpression of the cyclin-dependent kinase (cdk) inhibitory protein p16INK4a was reported to interfere with integrin alpha V beta 3-dependent melanoma cell adhesion. MATERIALS AND METHODS: TNF- and IFN gamma-treated HUVEC were analyzed for cell cycle progression and for protein expression by flow cytometry and Western blotting, respectively. p16INK4a was overexpressed by transient transfection, and HUVEC adhesion was tested in short-term adhesion assays. RESULTS: TNF and IFN gamma synergistically induced a G1 arrest associated with reduced levels of cyclin D1 and cdk2, and increased expression of the cdk inhibitors p16INK4a, p21WAF and p27Kip1. p16INK4a overexpression, however, had no effect on alpha V beta 3-mediated adhesion. CONCLUSION: These results implicate the down-regulation of cyclin D1 and cdk-2, and up-regulation of p16INK4a, p21WAF and p27Kip1 in the suppression of endothelial cell proliferation induced by TNF/IFN gamma and demonstrate that increased p16INK4a levels are not sufficient to suppress alpha V beta 3-mediated endothelial cell adhesion.