Comportement du phosphore dans le sédiment des barragesde la partie aval du bassin versant d'Oum Rabiaa (Maroc)

L'étude du phosphore, facteur clef responsable de l'eutrophisation des eaux continentales, a été entreprise afin d'évaluer les potentialités de mobilité de cet élément dans les sédiments de la partie aval du bassin versant d'Oum Rabiaa : Imfout - Océan atlantique ; caractérisé par la présence de trois retenues de barrages en série (Imfout, Daourat et Sidi Maachou).La présence de ces trois retenues de barrages en série conditionne la répartition du phosphore des sédiments de ce tronçon en réduisant les apports fluviaux vers l'aval. La spéciation du phosphore des sédiments montre que le phosphore se trouve majoritairement sous forme inorganique (68 %) ; la fraction CaCO3 -P étant majoritaire par rapport à celle de Fe(OOH)-P. Les fractions organiques représentent 32 %. La mobilité mesurée du phosphate est de 20 % du phosphore total, les fractions du phosphore présentent une mobilité représentant prés de 15 % du PT. La différence mesurée entre la mobilité considérée par fraction et la mobilité totale, observée lors d'un cycle annuel, s'explique par la mobilité interne, au sein du sédiment, entre les différentes fractions. Les conditions environnementales (pH, oxygène dissous)en sont responsables puisqu'elles favorisent le relargage par une fraction en même temps que le stockage par une autre.The study of the phosphorus, factor responsible for the freshwater eutrophication, has been undertaken in order to evaluate potentialities of mobility of this element in sediments of the down part of the Oum Rabiaa basin (Imfout - Atlantic Ocean); characterized by the three dams in series (Imfout, Daourat and Sidi Maachou).The presence of these three dams in series is responsible of the distribution of the phosphorus in the sediments of this section by reducing fluvial contributions to the endorsement. The speciation of phosphorus of sediment show that the phosphorus was principally present in inorganic form (68%); the fraction CaCO3 -P was higher than that of the Fe(OOH)-P. The organic fractions represented 32% of total phosphorus. The phosphate mobility accounted for 20% of total phosphorus, the fractions mobility accounted for 15% of PT. The difference measured between the mobility considered by fraction and the total mobility, observed during of an annual cycle, was explained by the internal mobility, to the breast of the sediment, between the different fractions. Environnemental conditions (pH, dissolved oxygen) are responsible since they favor the release by a fraction at the same time that the stocking by an other

Qualité physico-chimique des eaux du réservoir Daourat ; impact e la vidange sur son fonctionnement

Ce travail concerne l'étude de la qualité physico-chimique de la masse d'eau du réservoir Daourat au Maroc ; situé sur le cours inférieur du bassin Oum Rbia. Une vidange du réservoir a lieu le 23 décembre 2001, l'impact de cette vidange sur la qualité physico-chimique de l'eau a été déduit à travers l'augmentation du débit à l'entrée et à la sortie du réservoir en décembre ; l'élévation du taux de la matière en suspension ; des concentrations en éléments nutritifs et de la chlorophylle " a ". Cette étude inclue également une analyse de régression qui a permis de déterminer une relation entre le phosphore et la chlorophylle " a " ; ainsi qu'une évaluation du niveau d'eutrophisation du réservoir Daourat.Les résultats fournis par les paramètres physico-chimiques ont révélé que la masse d'eau ne présente aucune stratification thermique ni anoxie et que le pH est alcalin. L'évolution des concentrations en éléments nutritifs dans la masse d'eau du réservoir dépend des apports exogènes et endogènes. Les apports exogènes sont dominés par les apports latéraux venant du bassin versant local peu boisé et caractérisé par un sol à vocation agricole responsable de l'enrichissement du milieu récepteur en éléments azotés. Les apports endogènes sont gouvernés par les interactions eau - sédiment suite à la minéralisation de la matière organique en période estivale et par le relargage d'éléments à partir du sédiment suite à la vidange et à la crue en période hivernale. L'impact de la vidange sur l'écosystème étudié a été déduit à partir des modifications des paramètres abiotiques et biotique enregistrés en décembre (période de vidange) dans le milieu du réservoir (S2) et son aval (S3). L'étude de la relation entre les orthophosphates et la chlorophylle " a " dégage une forte corrélation significative. Les données du phosphore et de la chlorophylle " a " classe le réservoir Daourat dans l'état hypereutropheThe Oum Rbia River is the longest river in Morocco with a total length of about 550 km. Studies conducted on this river have shown that agricultural activity is the main factor affecting the water quality. The current study focused on Daourat Reservoir, a part of the Oum Rbia River.The aim of this study was to investigate the water quality of the Daourat reservoir (physico-chemical parameters, nutrients and chlorophyll a) in order to estimate its eutrophication status. The influence of draining reservoir on water quality was also analysed. This survey also included a regression analysis that permitted the determination of the relationship between phosphorus and chlorophyll a, as well as an assessment of the level of eutrophication of the Daourat reservoir.A monthly survey was conducted to monitor changes in the hydrological cycle as well as possible seasonal variations during the period from 2001-2002. Water parameters (T°, pH, dissolved oxygen, suspended solids), nutrients (NH4+, NO3-, P-PO4, Tot-P) and chlorophyll a were determined according to standard French protocols (AFNOR, 1994). Annual nutrient inputs and outputs were calculated from the monthly discharge from the river and the monthly mean nutrient concentrations. The annual nutrient output was calculated similarly.The physico-chemical parameters and nutrient concentrations varied temporally in the Daourat Reservoir. The highest concentrations of nutrients were observed during summer and winter, with the lowest concentrations occurring in the spring. This evolution seemed to be influenced by the nature of the loads. Nutrient loading from the upstream regions of the reservoir was minimal compared to the contributions from the local catchment area and from internal loading from the sediments. Significant nutrient loading to the reservoir came from sediment resuspension on December 23, 2001 and by internal loading from sediments during the summer. The upstream reservoirs (Al Massira and Imfout) had minimal influence and were in fact responsible for the reduced fluvial contributions to the Daourat Reservoir. The increase in nutrient loads in the reservoir was responsible for high phytoplankton biomass, indicated by the high chlorophyll a values (mean 35 µg/L). The trophic state of the Daourat Reservoir was classified as hypereutrophic. Due to the large intra-annual variability of water quality, a properly designed monitoring program of reservoir water is recommended

Effect of different levels of nitrogen fertilizer on morphological and physiological parameters and nitrates accumulation of lettuce cultivars (Lactuca sativa L.)

The effect of nitrogen fertilizer level on growth and nitrate accumulation was studied in six lettuce cultivars (Lactuca sativa L.): ‘Batavia rouge’, ‘Vitalia’, ‘Great Laks’, ‘Type Beurre’, ‘Romaine’ and ‘Romaine LO3’. Three nitrogen levels: 0, 120 and 240 Kg.ha-1 was applied. During plant growth, agronomical parameters (root weight, fresh and dry matter, head diameter) and physiological parameters (nitrate concentration, chlorophyll fluorescence and sugar content) were evaluated. Results showed significant differences between cultivars and nitrogen treatment for the most agronomical and physiological parameters. The nitrogen treatment affects head weight and nitrate concentration in all cultivars; the cvs ‘Great Laks’ and ‘Type beurre’ accumulated respectively the less and high nitrate concentration. The highest nitrate concentration was recorded in external leaves whereas the lowest concentration was recorded in the central leaves for all cultivars. Furthermore, nitrate distribution and chlorophyll fluorescence on the leaves are closely related. This study revealed also correlation between root nitrate concentration, chlorophyll fluorescence and sugar content for all cultivars. This correlation depended on nitrogen fertilization level and the cultivar used

Methodology for classification and definition of epilepsy syndromes with list of syndromes: Report of the ILAE Task Force on Nosology and Definitions

Epilepsy syndromes have been recognized for \u3e50 years, as distinct electroclini-cal phenotypes with therapeutic and prognostic implications. Nonetheless, noformally accepted International League Against Epilepsy (ILAE) classification ofepilepsy syndromes has existed. The ILAE Task Force on Nosology and Definitionswas established to reach consensus regarding which entities fulfilled criteria for anepilepsy syndrome and to provide definitions for each syndrome. We defined an ep-ilepsy syndrome as “a characteristic cluster of clinical and electroencephalographicfeatures, often supported by specific etiological findings (structural, genetic, met-abolic, immune, and infectious).” The diagnosis of a syndrome in an individualwith epilepsy frequently carries prognostic and treatment implications. Syndromesoften have age- dependent presentations and a range of specific comorbidities. Thispaper describes the guiding principles and process for syndrome identification inboth children and adults, and the template of clinical data included for each syn-drome. We divided syndromes into typical age at onset, and further characterizedthem based on seizure and epilepsy types and association with developmental and/or epileptic encephalopathy or progressive neurological deterioration. Definitionsfor each specific syndrome are contained within the corresponding position papers

Clusterin overexpression in mice exacerbates diabetic phenotypes but suppresses tumor progression in a mouse melanoma model

Clusterin (CLU) is an ATP-independent small heat shock protein-like chaperone, which functions both intra- and extra-cellularly. Consequently, it has been functionally involved in several physiological (including aging), as well as in pathological conditions and most age-related diseases, e.g., cancer, neurodegeneration, and metabolic syndrome. To address CLU function at an in vivo model we established CLU transgenic (Tg) mice bearing ubiquitous or pancreas-targeted CLU overexpression (OE). Our downstream analyses in established Tg lines showed that ubiquitous or pancreas-targeted CLU OE in mice affected antioxidant, proteostatic and metabolic pathways. Targeted OE of CLU in the pancreas, which also resulted in CLU upregulation in the liver likely via systemic effects, increased basal glucose levels in the circulation and exacerbated diabetic phenotypes. Furthermore, by establishing a syngeneic melanoma mouse tumor model we found that ubiquitous CLU OE suppressed melanoma cells growth, indicating a likely tumor suppressor function in early phases of tumorigenesis. Our observations provide in vivo evidence corroborating the notion that CLU is a potential modulator of metabolic and/or proteostatic pathways playing an important role in diabetes and tumorigenesis

An Investigation of Chlorine Ligands in Transition-Metal Complexes via 35Cl Solid-State NMR and Density Functional Theory Calculations

35Cl solid state NMR (SSNMR), in tandem with 35Cl NQR and density functional theory calculations, was used to characterize chlorine ligands in a series of transition-metal complexes exhibiting structural motifs common to organometallic catalysts. The differentiation of the various chlorine environments was possible, and insight into the origins of the 35Cl electric field gradient tensor parameters was provided. The applicability of 35Cl SSNMR to the study of surface supported transition-metal complexes was demonstrated, validating the use of this technique in the characterization of heterogeneous catalysts

Nrf2 is overexpressed in pancreatic cancer: implications for cell proliferation and therapy

<p>Abstract</p> <p>Background</p> <p>Nrf2 is a key transcriptional regulator of a battery of genes that facilitate phase II/III drug metabolism and defence against oxidative stress. Nrf2 is largely regulated by Keap1, which directs Nrf2 for proteasomal degradation. The Nrf2/Keap1 system is dysregulated in lung, head and neck, and breast cancers and this affects cellular proliferation and response to therapy. Here, we have investigated the integrity of the Nrf2/Keap1 system in pancreatic cancer.</p> <p>Results</p> <p>Keap1, Nrf2 and the Nrf2 target genes AKR1c1 and GCLC were detected in a panel of five pancreatic cancer cell lines. Mutation analysis of <it>NRF2 </it>exon 2 and <it>KEAP1 </it>exons 2-6 in these cell lines identified no mutations in <it>NRF2 </it>and only synonomous mutations in <it>KEAP1</it>. RNAi depletion of Nrf2 caused a decrease in the proliferation of Suit-2, MiaPaca-2 and FAMPAC cells and enhanced sensitivity to gemcitabine (Suit-2), 5-flurouracil (FAMPAC), cisplatin (Suit-2 and FAMPAC) and gamma radiation (Suit-2). The expression of Nrf2 and Keap1 was also analysed in pancreatic ductal adenocarcinomas (n = 66 and 57, respectively) and matching normal benign epithelium (n = 21 cases). Whilst no significant correlation was seen between the expression levels of Keap1 and Nrf2 in the tumors, interestingly, Nrf2 staining was significantly greater in the cytoplasm of tumors compared to benign ducts (P < 0.001).</p> <p>Conclusions</p> <p>Expression of Nrf2 is up-regulated in pancreatic cancer cell lines and ductal adenocarcinomas. This may reflect a greater intrinsic capacity of these cells to respond to stress signals and resist chemotherapeutic interventions. Nrf2 also appears to support proliferation in certain pancreatic adenocarinomas. Therefore, strategies to pharmacologically manipulate the levels and/or activity of Nrf2 may have the potential to reduce pancreatic tumor growth, and increase sensitivity to therapeutics.</p