305 research outputs found

    The potential roles of lime and molybdenum on the growth, nitrogen fixation and assimilation of metabolites in nodulated legume: A special reference to Phaseolus vulgaris L.

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    Most soils in sub-Saharan Africa are acidic and have low contents of calcium (Ca2+), magnesium (Mg2+) and molybdenum (Mo). Higher concentrations and contents of hydrogen ion (H+), aluminium (Al3+) and manganese (Mn2+) found in these acidic soils are known to be the major causes of poor plant growth due to their toxicity effects to plants and micro organisms such as N-fixing bacteria. Molybdenum is also a component of some bacterial nitrogenase and therefore, is especially important for plants that live in symbiosis with nitrogen-fixing bacteria such as Rhizobium. Calcium, magnesium and molybdenum deficient plants exhibit poor growth. The most common management practice to ameliorate these acidic soil problems is through the surface application of lime or molybdenum and/ orseed pelleting. The potential role(s) of lime and Mo in legumes with respect to growth, assimilation of metabolites, N-fixation and growth is given special attention in this review

    Dynamic removal of replication protein A by Dna2 facilitates primer cleavage during Okazaki fragment processing in Saccharomyces cerevisiae

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    Eukaryotic Okazaki fragments are initiated by an RNA/DNA primer, which is removed before the fragments are joined. Polymerase d displaces the primer into a flap for processing. Dna2 nuclease/helicase and flap endonuclease 1 (FEN1) are proposed to cleave the flap. The single-stranded DNA binding protein, replication protein A (RPA), governs cleavage activity. Flap-bound RPA inhibits FEN1. This necessitates cleavage by Dna2, which is stimulated by RPA. FEN1 then cuts the remaining RPA-free flap to create a nick for ligation. Cleavage by Dna2 requires that it enter the 5'-end and track down the flap. Since Dna2 cleaves the RPA-bound flap, we investigated the mechanism by which Dna2 accesses the protein-coated flap for cleavage. Using a nuclease-defective Dna2 mutant, we showed that just binding of Dna2 dissociates the flap-bound RPA. Facile dissociation is specific to substrates with a genuine flap, and will not occur with an RPA-coated single strand. We also compared the cleavage patterns of Dna2 with and without RPA to better define RPA stimulation of Dna2. Stimulation derived from removal of DNA folding in the flap. Apparently, coordinated with its dissociation, RPA relinquishes the flap to Dna2 for tracking in a way that does not allow flap structure to reform. We also found that RPA strand melting activity promotes excessive flap elongation, but it is suppressed by Dna2-promoted RPA dissociation. Overall, results indicate that Dna2 and RPA coordinate their functions for efficient flap cleavage and preparation for FEN1

    Étude de quelques Trachelomonas Ehr. (Euglenophyta) nouveaux ou peu connus pour la Côte d’Ivoire

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    La presente etude taxinomique, effectuee au microscope photonique, porte sur des prelevements effectues au filet a plancton de 20 µm de vide de maille dans les rivieres Agneby et Bia, dans le Sud de la Cote dfIvoire. Elle fait suite aux cinquante-huit taxons du meme genre Trachelomonas Ehr.  (Euglenophyta) deja decrits au microscope electronique a balayage et vise a faire connaitre 22 taxons dont 19 non encore signales et 3 peu connus (rares) en Cote dfIvoire : Trachelomonas armata (Ehrenberg) Stein fo. inevoluta Deflandre, Tr dubia Swirenko emend. Deflandre et Tr lefevrei Deflandre. Les echantillons ont ete preleves entre 1995 et 2000. Sur les vingt-deux (22) taxons decrits, on compte onze (11) especes, sept (7) varietes et quatre (4) formes. Mots cles : Taxinomie, Trachelomonas, Euglenophyta, eau douce, Sud Cote dfIvoire

    Sustained response to infliximab treatment in two cases of early rheumatoid arthritis that has been maintained after drug withdrawal

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    The authors report two cases of active seropositive rheumatoid arthritis who were treated in an early phase of the disease with infliximab plus methotrexate obtaining a clinical remission. The benefit was maintained after the discontinuation of the anti-TNF alpha inhibitor for adverse events, indicating that the early administration of the drug may be followed by a sustained remission

    Fertilisation des sols avec la litiere foliaire en zone Subsahelienne du Burkina Faso: Diversite des especes, effets sur les rendements du sorgho

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    Organic matter sources management for soil fertility improvement has been the subject of many researches. Agroforestry is one of the topics addressed by these researches. In Burkina Faso\u2019s Northern Center, leaf litter of woody species is collected, piled, crumbled before spreading in fields. This practice is not well known in the rest of the country. The present study aims to provide information on the diversity of spontaneous plant species concerned, farmers\u2019 motivations of litter crumbling and to evaluate, empirically the effects of litter spreading on sorghum yields. A participatory study, using qualitative surveys and biometric field measurements, was conducted in five villages in the Northern Center of Burkina Faso. Because of their availability, accessibility, and agronomic performance, plants such as Vitellaria paradoxa , Anogeissus leiocarpa , Combretum micranthum , Lannea microcarpa and Diospyros mespiliformis were the species whose leaf litter was valued most. Measurements achieved in situ indicate that sorghum yields from fields that received Vitellaria leaf litter for the first time were lower than those in the control plots. On the other hand, fields that received this litter for three consecutive years were more productive. A scientific study on leaf litter chemical characteristics and their influence on soil fertility parameters should be considered in order to validate local knowledge and to improve knowledge about these practices.La gestion des sources de mati\ue8res organiques, pour am\ue9liorer la fertilit\ue9 des sols, a fait l\u2019objet de nombreuses recherches. L\u2019agroforesterie est une des th\ue9matiques abord\ue9es par ces recherches. Dans le Centre-Nord du Burkina Faso, la liti\ue8re foliaire des esp\ue8ces ligneuses est ramass\ue9e, mise en tas, \ue9miett\ue9e avant d\u2019\ueatre \ue9pandue dans les champs. Cette pratique est peu connue dans le reste du pays. La pr\ue9sente \ue9tude visait \ue0 fournir des informations sur la diversit\ue9 des esp\ue8ces v\ue9g\ue9tales spontan\ue9es concern\ue9es, les motivations paysannes de l\u2019\ue9miettement de la liti\ue8re et \ue0 \ue9valuer, empiriquement et par des mesures, les effets de l\u2019\ue9pandage de ces liti\ue8res sur les rendements du sorgho. Une \ue9tude participative, \ue0 l\u2019aide d\u2019enqu\ueates qualitatives et des mesures biom\ue9triques dans des champs, a \ue9t\ue9 men\ue9e dans cinq villages du Centre Nord du Burkina Faso. A cause de leur disponibilit\ue9, leur accessibilit\ue9, leur performance agronomique, les plantes telles que Vitellaria paradoxa , Anogeissus leiocarpa , Combretum micranthum , Lannea microcarpa , Diospyros mespiliformis ont \ue9t\ue9 cit\ue9es comme \ue9tant les esp\ue8ces dont la liti\ue8re des feuilles est valoris\ue9e. Les mesures r\ue9alis\ue9es in situ montrent que, les rendements du sorgho dans les champs ayant re\ue7u de la liti\ue8re foliaire de Vitellaria pour la premi\ue8re fois, ont \ue9t\ue9 inf\ue9rieurs \ue0 ceux des parcelles t\ue9moin. Par contre, les champs ayant re\ue7u cette liti\ue8re pendant trois ann\ue9es cons\ue9cutives ont \ue9t\ue9 plus productifs. Dans l\u2019optique de valider les savoirs locaux et d\u2019approfondir les connaissances sur l\u2019effet des liti\ue8res foliaires sur la fertilit\ue9 du sol, une \ue9tude scientifique sur leur caract\ue9ristique chimique et sur leur influence sur les param\ue8tres de fertilit\ue9 du sol, est \ue0 envisager

    Characterizing cassava farmer typologies and their seed sourcing practices to explore opportunities for economically sustainable seed business models in Rwanda

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    Open Access Article; Published online: 30 Nov 2021The overdependency on local cassava varieties and informal seed sources by farmers in Rwanda has contributed to the spread of cassava viral diseases. The use of improved planting materials made available through formal seed sources, that assure seed quality, is one way to prevent future disease outbreaks. In order to increase the availability of, and farmers access to, such materials there is increasing interest to develop seed business models. This study aims to understand seed sourcing practices of different farm typologies to inform the development of tailored seed business models. A total of 390 farmers were interviewed and the collected data was analyzed into clusters, resulting in seven farm typologies. Seed sourcing strategies, seed replacement dynamics and purchasing behavior of these typologies were explored via a seed tracing study. We find that more commercial oriented farmers have better access to formal seed sources. Nevertheless, the majority of farmers in all typologies accessed new varieties and quality cassava seed via informal channels. At both formal and informal sources, cash investments in seed were mainly made by the categories of better-off farmers, and were one-time investments to acquire a new variety. Based on farmers current seed sourcing practices, clarifications on the differences between farmers and their willingness-to-pay, the roles of seed degeneration, cost-benefit analysis, value propositions and profit formulas seem important requirements for the further development of viable cassava seed business models. We conclude that tailoring seed business models can have a high potential as it acknowledges differences among farmers, but that careful coordination is needed to ensure that one approach or intervention does not contrast with and/or undermine the others

    Prioritising public health: a qualitative study of decision making to reduce health inequalities

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    <p>Abstract</p> <p>Background</p> <p>The public health system in England is currently facing dramatic change. Renewed attention has recently been paid to the best approaches for tackling the health inequalities which remain entrenched within British society and across the globe. In order to consider the opportunities and challenges facing the new public health system in England, we explored the current experiences of those involved in decision making to reduce health inequalities, taking cardiovascular disease (CVD) as a case study.</p> <p>Methods</p> <p>We conducted an in-depth qualitative study employing 40 semi-structured interviews and three focus group discussions. Participants were public health policy makers and planners in CVD in the UK, including: Primary Care Trust and Local Authority staff (in various roles); General Practice commissioners; public health academics; consultant cardiologists; national guideline managers; members of guideline development groups, civil servants; and CVD third sector staff.</p> <p>Results</p> <p>The short term target- and outcome-led culture of the NHS and the drive to achieve "more for less", combined with the need to address public demand for acute services often lead to investment in "downstream" public health intervention, rather than the "upstream" approaches that are most effective at reducing inequalities. Despite most public health decision makers wishing to redress this imbalance, they felt constrained due to difficulties in partnership working and the over-riding influence of other stakeholders in decision making processes. The proposed public health reforms in England present an opportunity for public health to move away from the medical paradigm of the NHS. However, they also reveal a reluctance of central government to contribute to shifting social norms.</p> <p>Conclusions</p> <p>It is vital that the effectiveness and cost effectiveness of all new and existing policies and services affecting public health are measured in terms of their impact on the social determinants of health and health inequalities. Researchers have a vital role to play in providing the complex evidence required to compare different models of prevention and service delivery. Those working in public health must develop leadership to raise the profile of health inequalities as an issue that merits attention, resources and workforce capacity; and advocate for central government to play a key role in shifting social norms.</p

    The relationship between levels of education of entrepreneurs and their business success: A study of the province of KwaZulu-Natal, South Africa

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    The small, medium and micro enterprise (SMME) sector has been widely recognized as an engine of economic growth in South Africa. The implementation of the National Small Business Strategy (NSBS) in 1995 established important objectives for the sector to address such problems as lack of access to markets and procurement, lack of access to finance and credit, low skills and education levels, lack of access to information and a shortage of effective support institutions. In response, the South African government established institutions and programmes designed to improve access to sources of finance, market opportunities, technology, training and development and education. This paper examines whether there is a relationship between the level of education of SMME owners and the growth of their businesses, using labour force and turnover as success indicators. The study adopted a mixed method approach, including questionnaire surveys, observations and face-to-face interviews. The results indicate that in the two years preceding the study there had been a relationship between the owner/manager's level of education and the business's ability to grow by increasing its labour force and annual turnover. This study, conducted in a developing economy, therefore supports the findings of similar studies in developed economies, that the level of education of an entrepreneur and the success of their business are related
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