Papers by Prof. Onasanya Amos
Plant Disease, 2008
Rice yellow mottle virus (RYMV) of the genus Sobemovirus is a major biotic constraint to rice (Or... more Rice yellow mottle virus (RYMV) of the genus Sobemovirus is a major biotic constraint to rice (Oryza sativa) production in Africa. First reported in Kenya during 1966, RYMV was later found in most countries in Africa where rice is grown (1). In countries in westernmost Africa (The Gambia, Guinea-Bissau, Mauritania, and Senegal), plants with leaf yellowing and mottling symptoms were observed, but RYMV was never isolated. Rice is the staple food in The Gambia. In 2006, four samples were collected from local rice varieties in the Kuntaur Region in the center of The Gambia. Mechanical inoculation with leaf extracts from all samples caused typical yellow mottle symptoms on the susceptible rice varieties BG90-2, Bouaké 189, and IR64. RYMV was detected in the four samples collected by ELISA with polyclonal antisera (2). The 720-nt coat protein gene was amplified for each isolate by reverse-transcriptase-PCR with primers 5′-CAAAGATGGCCAGGAA-3′ (sense) and 5′-CTCCCCCACCCATCCCGAGAATT-3′ (anti...
Scientific research and essays
High titer polyclonal antibodies for serological diagnostic purposes were locally produced to for... more High titer polyclonal antibodies for serological diagnostic purposes were locally produced to for- ty isolates of rice yellow mottle virus (RYMV) collected from different sites across four West African countries (18- from Cote d'Ivoire, 2- from Burkina Faso, 5- from Mali and 15- from Niger Repu- blic). This was achieved by immunizing rabbits with purified viral preparations. The primary goal
American Journal of Plant Sciences, 2014
ABSTRACT An experiment was conducted at Malakabad (Gadera) Dargai Malak and KPK to study the effe... more ABSTRACT An experiment was conducted at Malakabad (Gadera) Dargai Malak and KPK to study the effect of different levels of nitrogen and phosphorus on the yield of maize varieties in randomize complete block design with split plot arrangement. Different fertilization treatments (0:0, 100:0, 100:50, 100:100, 150:0, 150:50, 150:100, 150:150 N:P kg • ha −1) were assigned to main plot while, maize varieties (Azam, Jalal and local) were kept in sub-plots. Data regarding emergence m −2 , days to emergence, days to tasseling, days to silking, number of cobs plant −1 , plant height, grains cob −1 , 1000-grain weight and grain yield were recorded. Emergence m −2 , days to emergence, days to tasseling, days to silking, plant ha −1 at harvest were not significantly affected by different levels of nitrogen and phosphorus while number of cob plant −1 , thousand grains weight, plant height, grains cob −1 and grain yield were significantly affected. Maximum grain yield (5356 kg • ha −1) was recorded in Jalal variety, when it was fertilized with 150:100 N:P kg • ha −1 . Of the factors included in this study, maize cultivars and NP fertilization treatments were dominant in determining grain yield as well as its related components, suggesting that cultivar selection and optimum fertiliza-tion are effective strategies to improve grain yield. However, multiplication and multi-year studies are required to test these results using different cultivars under varying edaphic and climatic con-ditions.
The Moringa tree, Moringa oleifera is planted around the world and it is naturalized in many loca... more The Moringa tree, Moringa oleifera is planted around the world and it is naturalized in many locales. A lot of medicinal and therapeutic properties have been attributed to several part of this multipurpose tree, mostly as a result of its protein content. Heat treatment was carried out on the protein extracts of the leaf, seed, root and stem of Moringa oleifera. Protein extract was divided into three batches, out of which two were subjected to heating at 75 °C and 100 °C, and the remaining one served as control. Comparative UV absorption spectra analysis was carried out on the control protein extracts and heat-treated protein extracts of the leaf, seed, root and stem of Moringa oleifera. A plot of absorbance values at 280 nm against concentrations of the standard produced highly significant (p≤0.01) standard linear curve. The standard linear equation y = 0.0197x + 0.0005 was generated from the plot, where y and x represents absorbance values at 280 nm and protein concentration respectively. The standard linear equation was used to deduce the concentration of the control protein extracts and heat-treated protein extracts of the leaf, seed, root and stem of Moringa oleifera. The protein concentration was highest in the leaf control protein extracts (43.7 %) and was the lowest in the 100 °C heat treated stem protein extract (17.1%). Due to the effect of heat, the comparison of absorbance spectra of the control protein extracts and heat-treated protein extracts were different, having several peaks at different wavelengths. Cluster analysis of absorbance spectra optical density values revealed four clusters (cluster 1, cluster 2, cluster 3, cluster 4) among the control protein extracts and heat-treated protein extracts. Cluster 1 and cluster 2 were made up of closely related protein extracts, cluster 3 consisted of protein extract from seed, root and stem that served as control, heated at 75 °C and 100 °C, while cluster 4 consisted of root protein extract heated at 75 °C and stem protein extract that served as control. The variations in the cluster grouping among the control protein extracts and heat-treated protein extracts obtained in this study could possibly as a result of different levels of heat tolerance among different Moringa oleifera proteomic compositions.
World Journal of Pharmaceutical Research
Natural products, most especially from plant origin, possess antioxidant properties which are kno... more Natural products, most especially from plant origin, possess antioxidant properties which are known to play crucial roles in preventing and treating various pathological conditions occasioned by free radicals. Crassocephalum rubens is a one of those plants, and this study investigated the protective properties of ethanolic extract of C. rubens (EECR) leaves against hepatic damage induced by carbon tetrachloride (CCl 4 ). Thirty rats divided into 6 groups (n=5) were used for the investigation. Group 1 served as normal control while groups 2, 3 and 4 were pretreated for 21 days with EECR leaves at 150 mg/kg, 300 mg/kg and 450 mg/kg b.w. respectively, prior to a single intraperitoneal administration of CCl 4 . Animals in groups 5 received only the extract at a dose of 450 mg/kg body weight while animals in group 6 were given only CCl 4 . All animals were sacrificed 24 h after the administration of CCl 4 . CCl 4 significantly (p < 0.05) induced marked hepatic damage as revealed by increased activities of plasma ALT, AST, GGT and ALP. Also, plasma total protein and albumin were significantly decreased in CCl 4 -treated animals relative to normal control. Analyses of antioxidant status showed that CCl 4 elicited a significant decrease in the activities of antioxidant enzymes, with an increase in malondialdehyde levels in liver. Pre-treatment with the EECR leaves at all doses tested however, significantly (p<0.05) reduced the observed biochemical lesions. The hepatoprotective effect of the EECR may be traceable to the presence of phytochemicals inherent in the plant.
AFRICAN JOURNAL OF BIOTECHNOLOGY
Genetic fingerprinting of 18 different isolates of Staphylococcus aureus from Nigeria using rando... more Genetic fingerprinting of 18 different isolates of Staphylococcus aureus from Nigeria using random amplified polymorphic DNA (RAPD) was carried out. Ten out of 100 Operon primers showed polymorphism among the isolates tested generating 88 bands, 51 of which were polymorphic with sizes ranging between 200 and 3,000 bp. All the isolates were classified completely into two major groups (Sa-1 and Sa-2) with twelve different subgroups. Sa-1 group originated from human while isolates from plant and animal origins formed the Sa-2 group. The twelve different subgroups suggest adaptation of S. aureus in the different host cells. This indicates possible relationship between host origin and genetic variation among S. aureus isolates. The DNA fingerprint defined for each race of S. aureus could be useful in epidemiological studies, medical diagnosis and the identification of new strains and their origins.
Biotechnology(Faisalabad)
environment interactions was applied to study the relationships between isolates and isogenic lin... more environment interactions was applied to study the relationships between isolates and isogenic lines. It showed two pathotypes: pathotype XNgP1 which is divided into two subgroups and pathotype XNgP2 which is divided into three subgroups. The lines and varieties were divided into four groups, i.e. resistant, moderately resistant, moderately sensitive, and sensitive. The population structure resulted in two major pathotypes: four isolates attacking most of the genetic structures and six others having a narrow spectrum. Conclusion and application: The genes Xa-1, Xa-4, Xa-7 and the combination of genes xa-5/xa-13 are effective and can be deployed as part of a strategy for sustainable management of the disease.
In Africa, rice is the staple food in Gambia, Guinea Bissau, Guinea, Côte d'Ivoire, Liberia, Sene... more In Africa, rice is the staple food in Gambia, Guinea Bissau, Guinea, Côte d'Ivoire, Liberia, Senegal and Sierra Leone. In other countries, rice is replacing traditional grain crops (sorghum, millet, maize). So there is a growing demand for rice. Growth in demand for rice is double the rate of population growth. At the same time, production is insufficient to cover the needs and governments have to import rice, enlarging the trade deficit. In 2008, sub-Saharan Africa (SSA) imported for more than $US 3.6 billion of rice, mainly from Asia, to fill the gap between production and consumption. However, Africa cannot continue to rely on imports, as Asia may soon not be able to export rice and may even become a net importer . The recent dramatic decrease in world rice availability and increase in prices indicate that importing rice is no longer a sustainable strategy. Therefore, African countries are developing their largely unexploited rice potential to boost domestic production. However, both the development of new areas and the intensification of rice cultivation will bring new problems, among which rice diseases are important. Rice blast disease is a major constraint to rice cultivation.
Resistance of Enterococcus faecalis to a wide variety of antibiotics has been severally reported.... more Resistance of Enterococcus faecalis to a wide variety of antibiotics has been severally reported. Antibiotic resistance only cannot explain the virulence of E. faecalis as an emerging pathogen of public health concern, causing a variety of human infections. In the present study, incidence of putative virulence determinants among E. faecalis strains isolated from different categories of food canteens namely; primary-school, fast-food and commoners' canteens (bukataria) in Osun States, Nigeria was investigated. Six hundred and fifty-eight isolates were examined for the expressions of three putative virulence determinant factors; gelatinase, aggregation substance and cytolysin activator by phenotypic tests. Meanwhile, twenty selected representative strains were examined for virulence determinant genes; gelatinase (gelA), aggregation substance (asa 1), cytolysin activator (cylA), enterococcal surface protein (esp) and collagen-binding protein (ace) as well as confirmation of their i...
International Journal of Agricultural Research, 2008
International Journal of Genetics and Molecular Biology, 2013
ISRN Spectroscopy, 2013
This work reports on the isolation and determination of biotransformation products obtained from ... more This work reports on the isolation and determination of biotransformation products obtained from the organoarsenic compounds that are present in Fucus distichus when it was subjected to an open anaerobic decomposition by using the Hydride Generation Gas Chromatography Atomic Absorption Spectrometry (HG-GC-AAS) and High Performance Liquid Chromatography Inductively Coupled Plasma Mass Spectrometry (HPLC-ICP-MS). The seaweed and filtrate residues obtained from the open anaerobic degradation procedure were extracted in methanol and partitioned in phenol-ether-water mixtures to obtain water soluble extracts. The water soluble extracts were cleaned up and separated on a gel permeation Sephadex G15 column. Arsenic species concentrations were determined by using HG-GC-AAS. Final characterization of the biotransformation isolates was carried out on HPLC-ICP-MS. Only two arsenic species, 2-dimethylarsinoyl ethanol (DMAE) and dimethylarsinic acid (DMAA), were positively identified in the water soluble extract of the marine brown algae. The two arsenic species are strong intermediate candidates in the biosynthesis of arsenobetaine from oceanic arsenate in marine food webs.
ISRN Molecular Biology, 2013
ABSTRACT Bacterial leaf blight (BLB) of rice is a very destructive disease worldwide and is cause... more ABSTRACT Bacterial leaf blight (BLB) of rice is a very destructive disease worldwide and is caused by Xanthomonas oryzae pv. oryzae (Xoo).The aim of the present study was to examine if the Xoo virulence pathotypes obtained using phenotypic pathotyping could be confirmed using molecular approach. After screening of 60 Operon primers with genomic DNA of two Xoo isolates (virulent pathotype, Vr, and mildly virulent pathotype, MVr), 12 Operon primers that gave reproducible and useful genetic information were selected and used to analyze 50 Xoo isolates from 7 West African countries. Genetic analysis revealed two major Xoo virulence genotypes (Mta and Mtb) with Mta having two subgroups (Mta1 and Mta2). Mta1 (Vr1) subgroup genotype has occurrence in six countries and Mta2 (Vr2) in three countries while Mtb genotype characterized mildly virulence (MVr) Xoo isolates present in five countries. The study revealed possible linkage and correlation between phenotypic pathotyping and molecular typing of Xoo virulence. Xoo virulence genotypes were known to exist within country and there was evidence of Xoo pathogen migration between countries. Durable resistance rice cultivars would need to overcome both Mta and Mtb Xoo virulence genotypes in order to survive after their deployment into different rice ecologies in West Africa.
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Papers by Prof. Onasanya Amos