Etude de la culture en couloirs de manioc (Manihot esculenta CRANTZ) à base de Gliricidia sepium en Côte d’Ivoire

L’objectif de l’étude est de recommander aux paysans un système de production de manioc à la fois rentable et préservatrice de l’environnement. Pour atteindre cet objectif, deux systèmes améliorés de culture en couloirs (manioc amélioré Yavo/soja vert (Mung bean)/Gliricidia sepium avec un apport de fumure de fond minérale_200 kg/ha de NPK_10-18-18 ou organique_10 t/ha de fiente de poule) ont été mis en compétition avec le système traditionnel (association manioc local/arachide). Les systèmes de culture en couloirs ont bien couvert le sol comparativement au système traditionnel. Les taux moyens de débourrage du manioc ont varié de 80,15 à 82,03% pour la variété locale et de 80,11 à 75,08% pour la variété Yavo. Ces taux ont montré des interactions site x variété significatives et des interactions année x site très hautement significatifs. La culture en couloirs a enregistré un rendement moyen général en racines tubéreuses fraîches de 40 t/ha contre 13 t/ha dans le système traditionnel. Elle a permis d’augmenter le rendement du manioc de 27 t/ha. La culture en couloirs pourrait constituer une solution intéressante de remplacement du système traditionnel. Il est donc possible d’obtenir des rendements élevés à l’unité de surface grâce à la culture en couloirs de manioc.Mots-clés : manioc, Yavo, gliricidia sepium, soja vert, culture en couloirs, Côte d’Ivoire

The pyrogeography of eastern boreal Canada from 1901 to 2012 simulated with the LPJ-LMfire model

Wildland fires are the main natural disturbance shaping forest structure and composition in eastern boreal Canada. On average, more than 700 000 ha of forest burns annually and causes as much as CAD 2.9 million worth of damage. Although we know that occurrence of fires depends upon the coincidence of favourable conditions for fire ignition, propagation, and fuel availability, the interplay between these three drivers in shaping spatiotemporal patterns of fires in eastern Canada remains to be evaluated. The goal of this study was to reconstruct the spatiotemporal patterns of fire activity during the last century in eastern Canada's boreal forest as a function of changes in lightning ignition, climate, and vegetation. We addressed this objective using the dynamic global vegetation model LPJ-LMfire, which we parametrized for four plant functional types (PFTs) that correspond to the prevalent tree genera in eastern boreal Canada (Picea, Abies, Pinus, Populus). LPJ-LMfire was run with a monthly time step from 1901 to 2012 on a 10 km2 resolution grid covering the boreal forest from Manitoba to Newfoundland. Outputs of LPJ-LMfire were analyzed in terms of fire frequency, net primary productivity (NPP), and aboveground biomass. The predictive skills of LPJ-LMfire were examined by comparing our simulations of annual burn rates and biomass with independent data sets. The simulation adequately reproduced the latitudinal gradient in fire frequency in Manitoba and the longitudinal gradient from Manitoba towards southern Ontario, as well as the temporal patterns present in independent fire histories. However, the simulation led to the underestimation and overestimation of fire frequency at both the northern and southern limits of the boreal forest in Québec. The general pattern of simulated total tree biomass also agreed well with observations, with the notable exception of overestimated biomass at the northern treeline, mainly for PFT Picea. In these northern areas, the predictive ability of LPJ-LMfire is likely being affected by the low density of weather stations, which leads to underestimation of the strength of fire- weather interactions and, therefore, vegetation consumption during extreme fire years. Agreement between the spatiotemporal patterns of fire frequency and the observed data across a vast portion of the study area confirmed that fire therein is strongly ignition limited. A drier climate coupled with an increase in lightning frequency during the second half of the 20th century notably led to an increase in fire activity. Finally, our simulations highlighted the importance of both climate and fire in vegetation: despite an overarching CO2- induced enhancement of NPP in LPJ-LMfire, forest biomass was relatively stable because of the compensatory effects of increasing fire activity

Effects of cattle and poultry manures on organic matter content and adsorption complex of a sandy soil under cassava cultivation (Manihot esculenta, Crantz)

This study examined the A and B horizons of deep, developed and moderately unsaturated sandy ferrallitic soils amended with cattle and poultry manures under cassava (Manihot esculenta Crantz) cultivation. Therefore, a plot experiment was carried out by using a randomized complete blocks design in 4 replications and fields treatments which included unfertilized (control) and one dose (10 t/ha) of both manures. The study of the different fractions of animal manures showed that the poultry had the greatest content of C (organic carbon), N (nitrogen), P (phosphorus), K (potassium), Ca (calcium) and C:N ratio (p < 0.01). However, the value of Mg (magnesium) in the studied manures was not significantly different (p < 0.01). The manure treatment significantly increased the soil organic matter contents from 0.46 to 2.8 and 1.1% respectively with poultry and cattle manures (p < 0.01). Organic fertilizer significantly increased the cation exchange capacity from 1.7 to 12.75 and 3.8 me:100 g and the bases saturation content from 47 to 80 and to 76% respectively with the poultry and cattle manures (p < 0.01). The organic fertilizer showed significant effect on earthworms populations Hyperiodrilus africanus (Oligochaeta, Eudrilidae) in the soil, with 128 and 85% respectively about the poultry and cattle manures compared to the control (p < 0.01).Key words: Cattle manure, poultry manure, cassava, organic matter, cation exchange capacity, basessaturation content

Nod2 Downregulates TLR2/1 Mediated IL1β Gene Expression in Mouse Peritoneal Macrophages

Nod2 is a cytosolic pattern recognition receptor. It has been implicated in many inflammatory conditions. Its signaling has been suggested to modulate TLR responses in a variety of ways, yet little is known about the mechanistic details of the process. We show in this study that Nod2 knockdown mouse peritoneal macrophages secrete more IL1β than normal macrophages when stimulated with peptidoglycan (PGN). Muramyl dipeptide (MDP, a Nod2 ligand) + PGN co-stimulated macrophages have lower expression of IL1β than PGN (TLR2/1 ligand) stimulated macrophages. MDP co-stimulation have similar effects on Pam3CSK4 (synthetic TLR2/1 ligand) mediated IL1β expression suggesting that MDP mediated down regulating effects are receptor dependent and ligand independent. MDP mediated down regulation was specific for TLR2/1 signaling as MDP does not affect LPS (TLR4 ligand) or zymosan A (TLR2/6 ligand) mediated IL1β expression. Mechanistically, MDP exerts its down regulating effects by lowering PGN/Pam3CSK4 mediated nuclear cRel levels. Lower nuclear cRel level were observed to be because of enhanced transporting back rather than reduced nuclear translocation of cRel in MDP + PGN stimulated macrophages. These results demonstrate that Nod2 and TLR2/1 signaling pathways are independent and do not interact at the level of MAPK or NF-κB activation

Gain control network conditions in early sensory coding

Gain control is essential for the proper function of any sensory system. However, the precise mechanisms for achieving effective gain control in the brain are unknown. Based on our understanding of the existence and strength of connections in the insect olfactory system, we analyze the conditions that lead to controlled gain in a randomly connected network of excitatory and inhibitory neurons. We consider two scenarios for the variation of input into the system. In the first case, the intensity of the sensory input controls the input currents to a fixed proportion of neurons of the excitatory and inhibitory populations. In the second case, increasing intensity of the sensory stimulus will both, recruit an increasing number of neurons that receive input and change the input current that they receive. Using a mean field approximation for the network activity we derive relationships between the parameters of the network that ensure that the overall level of activity of the excitatory population remains unchanged for increasing intensity of the external stimulation. We find that, first, the main parameters that regulate network gain are the probabilities of connections from the inhibitory population to the excitatory population and of the connections within the inhibitory population. Second, we show that strict gain control is not achievable in a random network in the second case, when the input recruits an increasing number of neurons. Finally, we confirm that the gain control conditions derived from the mean field approximation are valid in simulations of firing rate models and Hodgkin-Huxley conductance based models

Linking emotional distress to unhealthy sleep duration: analysis of the 2009 National Health Interview Survey

Objective The objective of the study was to examine the independent association of emotional distress with unhealthy sleep duration (defined as \u3c7 or \u3e8 hours). Methods Data from the 2009 National Health Interview Survey (NHIS), a cross-sectional household survey, were analyzed to investigate the associations of emotional distress with unhealthy sleep durations, adjusting for sociodemographic factors, health risks, and chronic diseases through hierarchical multiple logistic regression analysis. Participants A total of 27,731 participants (age range 18–85 years) from the NHIS 2009 dataset were interviewed. Measures Unhealthy sleep duration is defined as sleep duration \u3c7 or \u3e8 hours, whereas healthy sleep is defined as sleep duration lasting for 7–8 hours. Emotional distress is based on the Kessler 6 Non-Specific Distress Battery, which assesses the frequency of feeling sad, nervous, restless, hopeless, worthless, and burdened, over a 30-day period. Results Of the sample, 51.7% were female; 83.1% were white and 16.9% were black. Eleven percent experienced emotional distress and 37.6% reported unhealthy sleep. Adjusted logistic regression analysis revealed that individuals with emotional distress had 55% greater odds of reporting unhealthy sleep (odds ratio [OR] =1.55, 95% confidence interval [CI] =1.42, 1.68, P\u3c0.001). Conclusion Emotional distress, an important proxy for poor psychological health, was a significant predictor of unhealthy sleep, independent of the influences of several factors including demographic (age, education, sex, race/ethnicity, and family income), health risks (alcohol consumption and smoking status), and chronic diseases/conditions (diabetes, obesity, hypertension, heart disease, cancer, and arthritis)

Bacillus anthracis Peptidoglycan Stimulates an Inflammatory Response in Monocytes through the p38 Mitogen-Activated Protein Kinase Pathway

We hypothesized that the peptidoglycan component of B. anthracis may play a critical role in morbidity and mortality associated with inhalation anthrax. To explore this issue, we purified the peptidoglycan component of the bacterial cell wall and studied the response of human peripheral blood cells. The purified B. anthracis peptidoglycan was free of non-covalently bound protein but contained a complex set of amino acids probably arising from the stem peptide. The peptidoglycan contained a polysaccharide that was removed by mild acid treatment, and the biological activity remained with the peptidoglycan and not the polysaccharide. The biological activity of the peptidoglycan was sensitive to lysozyme but not other hydrolytic enzymes, showing that the activity resides in the peptidoglycan component and not bacterial DNA, RNA or protein. B. anthracis peptidoglycan stimulated monocytes to produce primarily TNFα; neutrophils and lymphocytes did not respond. Peptidoglycan stimulated monocyte p38 mitogen-activated protein kinase and p38 activity was required for TNFα production by the cells. We conclude that peptidoglycan in B. anthracis is biologically active, that it stimulates a proinflammatory response in monocytes, and uses the p38 kinase signal transduction pathway to do so. Given the high bacterial burden in pulmonary anthrax, these findings suggest that the inflammatory events associated with peptidoglycan may play an important role in anthrax pathogenesis

Nucleotide-Oligomerization-Domain-2 Affects Commensal Gut Microbiota Composition and Intracerebral Immunopathology in Acute Toxoplasma gondii Induced Murine Ileitis

Background Within one week following peroral high dose infection with Toxoplasma (T.) gondii, susceptible mice develop non-selflimiting acute ileitis due to an underlying Th1-type immunopathology. The role of the innate immune receptor nucleotide-oligomerization-domain-2 (NOD2) in mediating potential extra-intestinal inflammatory sequelae including the brain, however, has not been investigated so far. Methodology/Principal Findings Following peroral infection with 100 cysts of T. gondii strain ME49, NOD2-/- mice displayed more severe ileitis and higher small intestinal parasitic loads as compared to wildtype (WT) mice. However, systemic (i.e. splenic) levels of pro-inflammatory cytokines such as TNF-α and IFN-γ were lower in NOD2-/- mice versus WT controls at day 7 p.i. Given that the immunopathological outcome might be influenced by the intestinal microbiota composition, which is shaped by NOD2, we performed a quantitative survey of main intestinal bacterial groups by 16S rRNA analysis. Interestingly, Bifidobacteria were virtually absent in NOD2-/- but not WT mice, whereas differences in remaining bacterial species were rather subtle. Interestingly, more distinct intestinal inflammation was accompanied by higher bacterial translocation rates to extra- intestinal tissue sites such as liver, spleen, and kidneys in T. gondii infected NOD2-/- mice. Strikingly, intracerebral inflammatory foci could be observed as early as seven days following T. gondii infection irrespective of the genotype of animals, whereas NOD2-/- mice exhibited higher intracerebral parasitic loads, higher F4/80 positive macrophage and microglia numbers as well as higher IFN-γ mRNA expression levels as compared to WT control animals. Conclusion/Significance NOD2 signaling is involved in protection of mice from T. gondii induced acute ileitis. The parasite-induced Th1-type immunopathology at intestinal as well as extra-intestinal sites including the brain is modulated in a NOD2-dependent manner