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An assessment of rhizobial infection, metabolite release and growth response in agriculturally important legume and cereal crops
No full textIncludes bibliographical references (leaves 149-180).Reports on the natural and laboratory infection of cereals by rhizobium provided the impetus to embark on research using African landraces of sorghum and millet to study their interaction with rhizobia. Seven strains of root-nodule bacteria (namely Rhizobium GHR2, Bradyrhizobium japonicum Tal 110, Sinorhizobium meliloti strain 1, Rhizobium leguminosarum bv. viceae Cn6, R. leguminosarum bv. viceae strain 30, Rhizobium NGR234 and Azorhizobium caulinodans ORSS71, hereafter referred to as ""rhizobia"") that fix N2, were used to study rhizobial effects on sorghum and millet seedlings grown aseptically in Leonard jars with Yz strength Hoagland nutrient solution containing 1 mM KN03
Potential use of rhizobial bacteria as promoters of plant growth for increased yield in landraces of African cereal crops.
No full textRhizobia form root nodules that fix nitrogen (N2) in symbiotic legumes. Extending the ability of these bacteria to fix N2 in non-legumes such as cereals would be a useful technology for increased crop yields among resource-poor farmers. Although some inoculation attempts have resulted in nodule formation in cereal plants, there was no evidence of N2 fixation. However, because rhizobia naturally produce molecules (auxins, cytokinins, abscicic acids, lumichrome, rhiboflavin, lipo-chito oligosaccharides and vitamins) that promote plant growth, their colonization and infection of cereal roots would be expected to increase plant development, and grain yield. We have used light, scanning, and transmission electron microscopy to show that roots of sorghum and millet landraces from Africa were easily infected by rhizobial isolates from five unrelated legume genera. With sorghum, in particular, plant growth and phosphorus (P) uptake were significantly increased by rhizobial inoculation, suggesting that field selection of suitable rhizobia/cereal combinations could increase yields and produce fodder for livestock production
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Potential use of rhizobial bacteria as promoters of plant growth for increased yield in landraces of African cereal crops
Full text linkRhizobia form root nodules that fix nitrogen (N2) in symbiotic legumes. Extending the ability of these bacteria to fix N2 in non-legumes such as cereals would be a useful technology for increased crop yields among resource-poor farmers. Although some inoculation attempts have resulted in nodule formation in cereal plants, there was no evidence of N2 fixation. However, because rhizobia naturally produce molecules (auxins, cytokinins, abscicic acids, lumichrome, rhiboflavin, lipo-chito-oligosaccharides and vitamins) that promote plant growth, their colonization and infection of cereal roots would be expected to increase plant development, and grain yield. We have used light, scanning, and transmission electron microscopy to show that roots of sorghum and millet landraces from Africa were easily infected by rhizobial isolates from five unrelated legume genera. With sorghum, in particular, plant growth and phosphorus (P) uptake were significantly increased by rhizobial inoculation, suggesting that field selection of suitable rhizobia/cereal combinations could increase yields and produce fodder for livestock production
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Potential use of rhizobial bacteria as promoters of plant growth for increased yield in landraces of African cereal crops
Full text linkRhizobia form root nodules that fix nitrogen (N2) in symbiotic legumes. Extending the ability of these bacteria to fix N2 in non-legumes such as cereals would be a useful technology for increased crop yields among resource-poor farmers. Although some inoculation attempts have resulted in nodule formation in cereal plants, there was no evidence of N2 fixation. However, because rhizobia naturally produce molecules (auxins, cytokinins, abscicic acids, lumichrome, rhiboflavin, lipo-chito-oligosaccharides and vitamins) that promote plant growth, their colonization and infection of cereal roots would be expected to increase plant development, and grain yield. We have used light, scanning, and transmission electron microscopy to show that roots of sorghum and millet landraces from Africa were easily infected by rhizobial isolates from five unrelated legume genera. With sorghum, in particular, plant growth and phosphorus (P) uptake were significantly increased by rhizobial inoculation, suggesting that field selection of suitable rhizobia/cereal combinations could increase yields and produce fodder for livestock production.
Key Words: Rhizobia, N2 fixation, plant growth, sorghum, millet
African Journal of Biotechnology Vol.3(1) 2004: 1-
Diagnosis of Bacterial Vaginosis and evaluation of associated factors: Comparable findings using Hay/ Ison’s and Nugent’s Scoring System
Full text linkAlthough Nugent’s criterion is considered as the gold standard for the diagnosis of bacterial vaginosis (BV), the method requires an experienced slide reader and considerable time and skill. We compared Hay/ Ison and Amsel with Nugent’s scoring criteria to determine the prevalence and corelates for BV among women of reproductive age attending reproductive health related clinics (family planning, post-natal and sexually transmitted Infection - STI) at Mbagathi County Referral Hospital in Nairobi. Vaginal specimens were collected from 201 consenting women, presenting with or without the vaginal symptoms of vaginitis. BV was diagnosed using Hay/ Ison, Amsel and Nugent’s method while factors corelates were gathered using structured interviews. Sensitivity, specificity, and predictive values for positive and negative test were calculated for both Hay/ Ison and Amsel methods using Nugent criteria as the gold standard. Corelates for BV in this population were evaluated against the three methods. There were 66 cases (32.8%) of BV by Amsel’s method, 79 cases (39.3%) of BV by Hay/ Ison’s Criteria and 72 (35.8%) cases by the Nugent’s method. Using Nugent criteria as the gold standard, the concordant, sensitivity, specificity, positive and negative predictive values of tests were. Amsel: 77.1%, 63.9%, 84.5%, 80.7% and 69.7% respectively, and Hay/ Ison: 96.5%, 100%, 94.6%, 100% and 91.1% respectively. Evaluating the performance of Hay/ Ison test against Amsel criteria, the standard method for clinical diagnosis; offered no improvement in sensitivity 72.7%, specificity 77.1%, NPV 85.3% and PPV 60.8% when compared to Nugent’s score. Factors independently associated with BV infection included. For all the three tests: Presence of clue cells; Nugent and Hay/ Ison methods: education level, marital status and positive for whiff tests: For Nugent and Amsel criteria: Presence of vaginal discharge and for Hay/ Ison test: condom use. Attributes of socio-demographic and sexual hygiene and behavior contributes to high prevalence of BV among women in the capital city of Kenya. The Hay/ Ison’s method shows good agreement with the Nugent criteria and can be recommended as a stand-alone alternative assay to Nugent’s criteria or as a confirmatory test for BV in this population. Key words: Nugent, Amsel and Hay/ Ison method Bacterial Vaginosis, Test performance, Correlates, Women of Reproductive Age, Western Kenya
Factors associated with bacterial contamination of shallow well water sources. Case Study of Juja hostels Kiambu County
Full text linkThe use of water from polluted water sources poses numerous public health challenges in developing countries. The ultimate purpose of any solid and liquid waste management plan is to mitigate environmental pollution; these goals become unachievable in the absence of a participatory approach to integrated waste management. This study sought to determine the extent of underground pollution of groundwater sources in Juja Town. Sanitary inspection and water quality analysis are complementary and valuable tools for characterizing and protecting water safety. The quality of the shallow wells is of great importance because it is used for consumption in Juja hostels. A two-stage cluster sampling strategy was adopted to obtain a representative sample size. Data collection involved the administration of questionnaires and field observation checklists, and E. coli levels present in the water were determined by the number of positive tubes in the table of computation of most probable number (MPN). Results showed that the predominant types of waste disposal practices observed in Juja were septic tank systems (77%) for liquid waste and private collection (87.3%) for solid waste methods. Sixty-eight per cent of the water samples were found to be positive (they exceeded the WHO (2004) maximum permissible load of 0.01/100 ml for drinking water. Three sanitary risk factors had a statistically significant effect on the dependent variable: the distance of the septic tank from the well on the level of water contamination (0.016), the liquid waste management plan (0.039), and the fitness of the water well cover on the level of water contamination (0.024). Shallow well water sources are unsuitable for use in food processing and drinking due to the presence of E. coli bacteria. The consequences of consuming contaminated water can be expensive to treat. Water from wells in Juja is contaminated with E. coli levels ranging from <3 - >1000 MPN/g, indicating fecal contamination in the area's underground water sources
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