Thermodynamics of Twisted DNA with Solvent Interaction

The imaginary time path integral formalism is applied to a nonlinear Hamiltonian for a short fragment of heterogeneous DNA with a stabilizing solvent interaction term. Torsional effects are modeled by a twist angle between neighboring base pairs stacked along the molecule backbone. The base pair displacements are described by an ensemble of temperature dependent paths thus incorporating those fluctuational effects which shape the multisteps thermal denaturation. By summing over $\sim 10^7 - 10^8$ base pair paths, a large number of double helix configurations is taken into account consistently with the physical requirements of the model potential. The partition function is computed as a function of the twist. It is found that the equilibrium twist angle, peculiar of B-DNA at room temperature, yields the stablest helicoidal geometry against thermal disruption of the base pair hydrogen bonds. This result is corroborated by the computation of thermodynamical properties such as fractions of open base pairs and specific heat.Comment: The Journal of Chemical Physics (2011) in pres

Effect of chemical fertilizers on production of yams (nyù) of passore in farmers’ environment

Nyù is the main morphotype of yams of Passoré. It is generally cultivated without chemical fertilizer. The study aims to determine the effect of one rate of chemical fertilizers on the yield of yams « nyù » of Passoré in farmers’ environment of Burkina Faso and to collect the appreciations of the various actors about tubers in the production chain. The results reveal that chemical fertilizer involved a better expression of the agro-morphological parameters and an increase of the tubers yield which reaches 42.5 t / ha compared to the field not fertilized where tuber yield is slow (9 t / ha). However, tubers obtained of treated field have not a good organoleptic quality whereas the tubers of untreated fields have good taste. Moreover, the chemical fertilizer changed also the morphology, taste and consistency of the tubers. These results could help all actors to choose the best method of nyù production according to their objectives.Keywords: nyù, yam, mineral fertlizer, Passoré, Burkina Fas

Current status of Colletotrichum capsici strains, causal agents of Brown blotch disease of cowpea in Burkina Faso

Brown blotch disease, caused by Colletotrichum capsici, is an important disease of cowpea with a significant yield losses ranging from 42 to 100% in West Africa. In this study, a specific polymerase chain reaction (PCR) primer set CC1F1/CcapR was used to characterize and to study the phylogenetic relationship of thirty eight strains of Colletotrichum species. This primer set is capable of amplifying only C. capsici from different fungal structures and provide a powerful tool for C. capsici detection in brown blotch disease in cowpea. Phylogenetic analysis from neighbor-joining (NJ) showed a high genetic variability in the rDNA-ITS region of the isolates. The isolates formed four groups or clusters on the basis of specific fragment analysis. Groups I, II, and III consist of strains containing specific region length of twenty one nucleotides and were considered as variant 1 of C. capsici. Group IV was a heterogeneous and consists of variants 1, 2, 3, and 4 of C. capsici.Keywords: Cultivars, internal transcribed spacer (ITS) sequence, Colletotrichum specie

Évaluation de la diversité génétique des sorghos à grains sucrés (Sorghum bicolor (L.) Moench) du Nord du Burkina Faso

Objectif : L’étude a pour objectif de déterminer le niveau de diversité agromorphologique des sorghos à grains sucrés du Nord du Burkina et d’estimer les paramètres génétiques de la collection en vue d’identifier les meilleures stratégies d’amélioration variétale.Méthodologie et résultats : Les résultats de l’étude réalisée sur 37 accessions selon un dispositif blocs Fisher à trois répétitions révèlent une importante diversité morphologique structurée autour des caractères végétatifs et du rendement et une répartition des accessions en quatre groupes sur la base principalement de la hauteur de la plante et du rendement grains par plante. L’évaluation des paramètres génétiques a montré une faible différence entre les coefficients de variation phénotypique et génotypique et une héritabilité au sens large élevée pour tous les caractères. Les caractères liés au rendement ont exprimé une héritabilité au sens large et un gain génétique attendu élevé alors que les caractères végétatifs ont enregistré une héritabilité au sens large élevée et un faible gain génétique attendu. Le cycle a présenté une héritabilité au sens large élevé et un gain génétique attendu modéré.Conclusion et application : Les 4 groupes obtenus qui sont des entités constituées de pools de gènes différents pourraient servir de géniteurs pour la création de variétés répondant aux attentes des paysans. La diversité génétique observée au sein des sorghos à grains sucrés du Nord du Burkina pourrait être exploitée dans les programmes de sélection du sorgho. Les résultats de l’évaluation des paramètres génétiques permettent d’envisager l’amélioration des sorghos à grains sucrés par une méthode de sélection directe.Mots clés : Sorghos à grains sucrés, diversité agromorphologique, Nord du Burkina Fas

Statut de la matière organique des Cambisols et des Lixisols sous formations naturelles de longue durée en zone Nord-Soudanienne au Burkina Faso

L’étude vise à évaluer la matière organique des Cambisols et des Lixisols sous formations naturelles de longue durée en zone climatique nord-soudanienne et à établir, les relations entre cette composante édaphique et les propriétés physiques, chimiques et biologiques de ces deux types de sol. L’étude a été menée dans deux formations naturelles protégées depuis 1936 (forêt classée de Yabo) et 1938 (forêt classée de Sâ) au Burkina Faso. Les analyses ont porté sur la quantification du carbone total et de l’azote total et sur la détermination des taux respectifs de carbone et d’azote dans les fractions (0 - 50 μm), (50 - 200 μm) et (200 - 2000 μm). La respiration du sol (CO2 dégagé) et le taux de carbone de la biomasse microbienne ont aussi été mesurés. Les résultats montrent que les deux unités de sol renferment, en moyenne, 8 à10 g kg-1 sol de carbone total et environ 1 g kg-1 sol d’azote total. Ces valeurs sont supérieures à celles des sols des zones sahélienne et  sud-soudanienne. Pour les lixisols, ce sont les facteurs climatiques qui ont permis d’expliquer ces teneurs en carbone total et en azote total. Pour les cambisols, ce sont les caractéristiques texturales qui ont été incriminées. Par ailleurs, plus de 70 % de carbone total et plus de 80 % de l’azote total sont liés aux particules argilo-limoneuses (0 - 50 μm). Les quantités de carbone associées aux fractions inférieures à 200 μm ont eu des corrélations positives, avec la capacité d’échange cationique et la somme des bases échangeables ;  andis que l’activité biologique globale a eu une corrélation positive avec le pH. L’étude suggère, également, qu’une mise en valeur agricole de telles unités de sol, doit être accompagnée d’amendements organiques et d’aménagements antiérosifs, pour accroître leurs productivités. Mots-clés : Burkina Faso, Cambisols, Lixisols, fractionnement de la matière organique, activité biologiqu

Productivity characteristics and development strategies of Sclerocarya birrea in Burkina Faso

Sclerocarya birrea is a major component of agroforestry parks of Sudano-Sahelian zones, which is exploited by rural populations in Burkina Faso. Recently, Sclerocarya birrea kernel marketing has increasingly developed in Ouagadougou (capital of Burkina Faso). This study aimed at evaluating the productivity, understanding the socio-cultural uses and socio-economic importance of S. birrea among local populations of Burkina Faso. The study has shown that S. birrea is a very fructiferous plant. The number of fruits yielded per tree ranges from 136 to 4256, with mean fruit weight and diameter that are respectively 12.66 and 26.71 mm. The number of kernels per fruit ranged from 1 to 3, with a mean diameter of 4.75 mm. All is not clearly separated to multi-purpose uses. All organs are used in 36 different ways. The pulp and kernels of the fruit are the only by-products marketed by women and mainly girls who dropped out of school.Sclerocarya birrea , composante majeure des parcs agro-forestiers des zones soudano-sah\ue9liennes, est bien connue et exploit\ue9e par les populations rurales au Burkina Faso. Ces derni\ue8res ann\ue9es, la commercialisation des amandes de S. birrea est de plus en plus d\ue9velopp\ue9e \ue0 Ouagadogou (capitale du Burkina Faso). L\u2019objectif de cette \ue9tude est d\u2019\ue9valuer les param\ue8tres de la productivit\ue9 et \ue0 conna\ueetre les usages socio-culturels et l\u2019importance socio-\ue9conomique de S. birrea, afin d\u2019utiliser l\u2019exploitation des fruits comme strat\ue9gie de sa domestication et de sa valorisation. L\u2019\ue9tude a montr\ue9 que S. birrea est une plante tr\ue8s fructif\ue8re, le nombre de fruits par arbre varie de 136 \ue0 4256 avec un poids et diam\ue8tre moyens de fruit respectivement de 12,66 et 26,71 mm. Le nombre d\u2019amandes varie de 1 \ue0 3 par fruit. L\u2019esp\ue8ce a des usages multiples. Tous les organes sont utilis\ue9s avec 36 utilisations diff\ue9rentes. La pulpe du fruit et l\u2019amande sont les seuls commercialis\ue9s par les femmes et surtout les jeunes filles d\ue9scolaris\ue9es. Les revenus engrang\ue9s servent \ue0 l\u2019achat de vivre, aux soins m\ue9dicaux, \ue0 payer la scolarit\ue9, les fournitures scolaires etc. La production fruiti\ue8re \ue9tant importante, il existe donc un recours \ue9conomique pour les populations locales comme incitation \ue0 prot\ue9ger l\u2019esp\ue8ce

Village Baseline Study: Site Analysis Report for Yatenga – Tougou, Burkina Faso

The village baseline study of Kononga village in the CCAFS site Yatenga-Tougou in Burkina Faso took place from 19th to 21st July 2011. Focus group discussions were conducted separately for men and women. Male and female participants believe that the natural resources in the village are deteriorating due to population increase and labour shortages related to the exodus of young people to gold mining sites. The village’s vision of the future includes more productive and fertile farmland, a denser forest, deeper and wider water reservoirs, and more boreholes. The men identified 21 organisations in the village, including 9 operating at the community level, while women identified 17 organisations, 10 of which operate at the community level. Men are considered the most important personal source of information in the village. The regional directorate for agriculture, hydrology and fishery resources (DRAHRA) is the single most relevant institutional source of climate and weather information for both male and female participants. Men and women gather information from outside the village via radio broadcasting and particularly Radio “Voix du paysan” (Voice of the Farmer). The market is the most important channel of information access for women. Women have a substantial role in agriculture and livestock production, as well as natural resource management but they have limited access to land or to improved technology or equipment, and few training opportunities

Cumulative effects of 20 years of fire, grazing and selective tree cutting on soil water infiltration in sudanian savanna-woodland ecosystem of West Africa

Structural and functional dynamics of savanna-woodland ecosystems are mainly shaped by fire, grazing and wood removal which effects depends both on their intensities. The long-term effects of those disturbances on key soil parameters are still largely unknown. We studied the cumulative effect of 20 years of early fire, grazing and selective tree cutting on soil water infiltration at two experimental sites with contrasting soil conditions (deep silty-clay versus shallow silty-sand) in the sudanian savanna-woodland ecosystems of Burkina Faso. Measurements were carried with a single ring infiltrometer at intervals of 5, 10, 20 and 30 minutes. Results showed that Grazing had negative effect at both sites (P<0.0001). Fire has no effect on infiltration rate at deep soil whereas it has a negative effect on shallow one. Selective wood cutting had beneficial effects for infitration rate at the site with shallow soil. Further, all combined effect of the diffreent treatment resulted in decrease infiltration rate as compared with the control (interaction exclosure, no cutting and no fire). The result suggested that projects which aim to manage or improve soil water properties must take in consideration occurrence of disturbances, soils type and avoid disturbance interaction mainly in shallow sandy soils.Keywords: Disturbances, soil water properties, Burkina Faso, soil compaction, early fire, savanna ecosystem

Exploring the potential of the cost-efficient tahmo observation data for hydro-meteorological applications in sub-saharan africa

The Trans-African Hydro-Meteorological Observatory (TAHMO) is a promising initiative aiming to install 20,000 stations in sub-Saharan Africa counteracting the decreasing trend of available measuring stations. To achieve this goal, it is particularly important that the installed weather stations are cost-efficient, appropriate for African conditions, and reliably measure the most important variables for hydro-meteorological applications. Since there exist no performance studies of TAHMO stations while operating in Africa, it is necessary to investigate their performance under different climate conditions. This study provides a first analysis of the performance of 10 selected TAHMO stations across Burkina Faso (BF). More specifically, the analysis consists of missing value statistics, plausibility tests of temperature (minimum, maximum) and precipitation, spatial dependencies (correlograms) by comparison with daily observations from synoptical stations of the BF meteorological service as well as cross-comparison between the TAHMO stations. Based on the results of this study for BF for the period from May 2017 to December 2020, it is concluded that TAHMO potentially offers a reliable and cost-efficient solution for applications in hydro-meteorology. The usage of wind speed measurements cannot be recommended without reservation, at least not without bias correcting of the data. The limited measurement period of TAHMO still prevents its usability in climate (impact) research. It is also stressed that TAHMO cannot replace existing observation networks operated by the local meteorological services, but it can be a complement and has great potential for detailed spatial analyses. Since restricted to BF in this analysis, more evaluation studies of TAHMO are needed considering different environmental and climate conditions across SSA