Caractérisation des sols de la vallée rizicole de Tamra dans l’île de Mar, Centre-Ouest du Sénégal

Tamra est une vallée très sollicitée pour la culture du riz par les  populations des quatre villages implantés dans l’île de Mar. L’étude pédologique a été menée suivant trois toposéquences transversales le long de la vallée. Les différents types de sols rencontrés dans ce milieu fluvio-marin sont disposés d’une manière quasi-concentrique autour de la vallée. Les sols sont affectés par le processus de salinisation et d’acidification. Les causes principales de l’avancée de ce biseau salé le long de la vallée seraient liées à l’environnement climatique peu favorable qui sévit depuis plusieurs années et qui s’exprime par des sécheresses récurrentes. La texture sableuse de ces sols, à dominance de sables fins, et leur niveau topographique font que certains d’entre eux sont exceptionnellement inondés. Ainsi, la réalisation d’une carte d’aptitude culturale des sols s’impose pour une meilleure utilisation des terres de la vallée de Tamra.Mots clés : Tamra, sols, fertilité, salinisation, acidification

Grassland structural heterogeneity in a savanna is driven more by productivity differences than by consumption differences between lawn and bunch grasses

Savanna grasslands are characterized by high spatial heterogeneity in vegetation structure, aboveground biomass and nutritional quality, with high quality short- grass grazing lawns forming mosaics with patches of tall bunch grasses of lower quality. This heterogeneity can arise because of local differences in consumption, because of differences in productivity, or because both processes enforce each other (more production and consumption). However, the relative importance of both processes in maintaining mosaics of lawn and bunch grassland types has not been measured. Also their interplay been not been assessed across landscape gradients. In a South African savanna, we, therefore, measured the seasonal changes in primary production, nutritional quality and herbivore consumption (amount and percentage) of grazing lawns and adjacent bunch grass patches across a rainfall gradient. We found both higher amounts of primary production and, to a smaller extent, consumption for bunch grass patches. In addition, for bunch grasses primary production increased towards higher rainfall while foliar nitrogen concentrations decreased. Foliar nitrogen concentrations of lawn grasses decreased much less with increasing rainfall. Consequently, large herbivores targeted the biomass produced on grazing lawns with on average 75 % of the produced biomass consumed. We conclude that heterogeneity in vegetation structure in this savanna ecosystem is better explained by small- scale differences in productivity between lawn and bunch grass vegetation types than by local differences in consumption rates. Nevertheless, the high nutritional quality of grazing lawns is highly attractive and, therefore, important for the maintenance of the heterogeneity in species composition (i.e. grazing lawn maintenance)

Caractérisation des sols de la zone des Niayes de Pikine et de Saint Louis (Sénégal)

La zone des Niayes fournit l’essentiel de la production maraîchère du Sénégal. Cependant, son potentiel agricole a été sérieusement réduit par la dégradation des terres dont les aléas climatiques de ces dernières décennies ainsi que les mauvaises pratiques culturales sont les causes. Cette étude se propose de caractériser les sols de la zone afin d’identifier les différentes unités. Pour se faire, des profils pédologiques ont été décrits dans différentes localités, et leurs paramètres physico-chimiques déterminés. Les résultats de l’analyse factorielle de correspondance (AFC) de la matrice des profils et paramètres physico-chimiques ont révélé l’existence, selon la salinité, de trois groupes de sols répartis dans toutes les Niayes. L’analyse a aussi montré l’existence selon l’alcalinité ou l’acidité et la teneur en calcium échangeable, de deux groupes de sols retrouvés uniquement dans la partie nord. La salinisation des sols plus marquée au niveau des bas-fonds de la partie sud, s’expliquerait par l’abaissement de la nappe phréatique et l’intrusion des eaux de mer. A cela s’ajoute les apports non négligeables des embruns marins dans les zones proches de l’océan, et les effets du barrage de Diama et du canal de délestage ouvert sur la Langue de Barbarie à Saint-Louis.Mots clés: AFC, Niayes, Profil pédologiqu

Effects of experimental Neisseria meningitis W135 infection on serotoninergic parameters in mice

This study investigated the effects of Neisseria menigitidis W135 infection via intraperitoneal route on plasma free tryptophan concentration, brain serotonin and 5-hydroxyindole acetic acid (5-HIAA) levels in albino mice fed normal and tryptophan-enriched diets. The kinetics of appearance of viable bacteria in the blood, brain and liver following infection were also investigated. The serotoninergic parameters were determined by colorimetric and HPLC methods while colony counts were measured by plate count technique. Compared to normal diet, the tryptophan-enriched diet resulted in significantly (

Experimental study of slow sand filtration for the treatment of various wastewaters in tropical environment

Wastewater treatment by slow sand filtration is a biological process which consists in filtering wastewater through a porous media. The objective of this study was to evaluate the performances of this biotechnology under tropical climate. Three sand filters were monitored at ONAS (Cambérène wastewater treatment plant in Dakar, Senegal). The filters were built with local materials, and were constituted with a feeding tank of approximately 180 litters, a column (two meters high and 30-25 cm diameter). The filters were filled with sand (75 cm), gravel (25 cm) and wastewater (90 cm). The results showed that with sand of d10 equal to 0.58 mm and flow rate of 0.05 m/h, the filtration cycle was relatively long for the first run with pretreated wastewater. At the level of the primary settling tank, with flow a rate of 0.08 m/h, the removal rates were about 12.75%, 16.31%, 12.92%, 5.45%, 7.09% and 10.50% for TSS, COD, BOD5, nitrogen phosphorus and faecal coliforms respectively. At the level of the clarifier, with a filtration of 0.15 m/h, the removals were 1.4% for TSS, 1.84% for COD, 1.09% for BOD5 11.38% for nitrogen, 5.18% for phosphorus and 1.74% of faecal coliforms.Keywords: Flow rate; filtration cycle, removal; sand filtration; tropical climate, wastewater

Взаимосвязь понятий «стиль» и «имидж» как эстетическая проблема

<div><p>The intestinal microbiota influences the development and function of myeloid lineages such as neutrophils, but the underlying molecular mechanisms are unresolved. Using gnotobiotic zebrafish, we identified the immune effector Serum amyloid A (Saa) as one of the most highly induced transcripts in digestive tissues following microbiota colonization. Saa is a conserved secreted protein produced in the intestine and liver with described effects on neutrophils <i>in vitro</i>, however its <i>in vivo</i> functions remain poorly defined. We engineered <i>saa</i> mutant zebrafish to test requirements for Saa on innate immunity <i>in vivo</i>. Zebrafish mutant for <i>saa</i> displayed impaired neutrophil responses to wounding but augmented clearance of pathogenic bacteria. At baseline, <i>saa</i> mutants exhibited moderate neutrophilia and altered neutrophil tissue distribution. Molecular and functional analyses of isolated neutrophils revealed that Saa suppresses expression of pro-inflammatory markers and bactericidal activity. Saa’s effects on neutrophils depended on microbiota colonization, suggesting this protein mediates the microbiota’s effects on host innate immunity. To test tissue-specific roles of Saa on neutrophil function, we over-expressed <i>saa</i> in the intestine or liver and found that sufficient to partially complement neutrophil phenotypes observed in <i>saa</i> mutants. These results indicate Saa produced by the intestine in response to microbiota serves as a systemic signal to neutrophils to restrict aberrant activation, decreasing inflammatory tone and bacterial killing potential while simultaneously enhancing their ability to migrate to wounds.</p></div

Associations between alcohol consumption and anxiety, depression, and health-related quality of life in colorectal cancer survivors

Purpose  Alcohol consumption is a major risk factor for colorectal cancer (CRC). It is currently poorly understood, however, how alcohol and different alcoholic beverage types are related to psychosocial outcomes in CRC survivors.  Methods  We used data of N = 910 CRC survivors from the pooled EnCoRe and PROCORE cohorts and harmonized them into five time points: at diagnosis and 3, 6, 12, and 24 months post-diagnosis. Generalized estimated equation models were used to examine longitudinal associations of alcohol consumption, including consumption of beer, wine, and liquor, with anxiety, depression, and health-related quality of life (HRQoL), while correcting for sociodemographic, lifestyle, and clinical factors.  Results  Survivors were on average 67 years and 37% was female. In the first 2 years post-diagnosis, survivors who consumed more alcoholic drinks/week reported lower anxiety and depressive symptoms and better HRQoL on all domains and symptom scales. This was the case for moderate and heavy amounts of alcohol and mostly for consuming beer and wine, but not for liquor. Associations were more often significant for men and for younger persons (< 67 years at baseline).  Conclusions  Generally, alcohol consumption was observed to be longitudinally related to less anxiety and depression and better HRQoL in CRC survivors. Implications for Cancer Survivors Although alcohol consumption is generally unfavorable due to increased risk of carcinogenesis and worse prognosis after CRC, it seems to be associated with better psychosocial outcomes in the first 2 years after diagnosis and treatment. More research is needed to gain knowledge about reasons for drinking and causality. Netherlands Trial Registry (www.trialregister.nl, NL6904

Body Size, Physical Activity and Risk of Colorectal Cancer with or without the CpG Island Methylator Phenotype (CIMP)

We investigated how body size and physical activity influence the risk of the CpG island methylator phenotype (CIMP) in colorectal cancer (CRC).In the Netherlands Cohort Study (n = 120,852), risk factors were self-reported at baseline in 1986. After 7.3 years of follow-up, 603 cases and 4,631 sub-cohort members were available. CIMP status according to the Weisenberger markers was determined using methylation specific PCR on DNA from paraffin embedded tumor tissue. Hazard rate ratios (HR) and 95% confidence intervals for CIMP (27.7%) and non-CIMP (72.3%) tumors were calculated according to BMI, BMI at age 20, BMI change, trouser/skirt size, height, and physical activity.-trend = 0.02).Body size, especially central adiposity, may increase the risk of both CIMP and non-CIMP tumors. Body fat at young age may differentially influence risk. Physical activity appears to decrease the risk of CRC regardless of these molecular subtypes

Species-area relationships are modulated by trophic rank, habitat affinity, and dispersal ability

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