2017-01-21T07:33:00Z http://www.academicjournals.org/oai-pmh/handler
oai:academicjournals.org:AJB:3D7E3A3635 2002-11-30T00:00:00Z AcademicJournals AJB AJB:2002
Episodic bioavailability of environmental mercury: implications for biotechnological control of mercury pollution O. A. Ogunseitan Perennial wildfires in Africa and other continents contribute an estimated 8 x 105 kg of mercury to the global atmosphere with a residence time of approximately one year. This phenomenon changes the flux of biologically available mercury in natural microbial communities where enzymatic actions, including mercuric reductase and organomercurial lyase activities, underpin the biogeochemical cycling of mercury with repercussions for human exposure to toxic forms of the element. To elucidate the impact of episodic mercury bioavailability on the response of microbial communities, the expression of microbial proteins and nucleic acids in environmental strains of Pseudomonas species were evaluated under various concentrations of mercury ranging from 0 to 500 M. Routine cultivation of Pseudomonas aeruginosa PU21 containing the 142.5 kb plasmid Rip64 in medium containing 100 g of Hg++/ml (500 M) exhibited a prolonged lag phase survived by hyper-resistant cells able to grow in medium containing 200 g of Hg++/ml. Nucleic acid analyses showed a distinct mutation in the merA gene encoding for mercuric reductase activity in cells able to grow at elevated mercury concentrations. A similar mutation was detected in the merR locus which serves as the regulator of themer operon. Mutations were not detected in merC which encodes for a hydrophobic membrane-associated protein implicated in active mercury transport. Protein profiles of cells grown with elevated mercury concentrations were associated with a stable increase in the production of specific polypeptides. In addition, the survival and genetic response of naturally-occurring mercury resistant bacteria inoculated into contaminated environmental samples were monitored in microcosm experiments over a 30 day period. The results suggest that sudden exposure to high concentrations of mercury either decimates the bacterial population or selects for hyper-resistant strains with high level of constitutive expression of active proteins, including mercuric reductase. Methyl mercury was observed to cause a higher level of induction for mercuric reductase than the specific substrate, inorganic mercury. The selection of hyper-resistant strains is potentially useful for biotechnological strategies to control the bioavailability of mercury, and thereby potentially reducing the re-uptake of mercury into vegetation in regions frequently subjected to wildfires. Key words: Mercury pollution, wildfires, mercuric reductase, organomercurial lyase, proteomics, microorganisms, detoxification. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/3D7E3A3635 http://dx.doi.org/10.5897/AJB2002.000-001 en Copyright © 2002 O. A. Ogunseitan
oai:academicjournals.org:AJB:3097501638 2002-11-30T00:00:00Z AcademicJournals AJB AJB:2002
Swarming modulatory effects of some amino acids on Proteus strains from Lagos, Nigeria Bamidele A. Iwalokun and Babatunde O. Akinwumi Swarming motility, a multicellular behaviour characterized by periodic concentric growth on solid media has severally been reported as a constraint in the clinical investigation of mixed-culture infections involving Proteus and as a requirement for virulence. While media are being formulated to restrain swarming in this organism, the roles played by amino acids in the biogenesis of swarming have not been fully clarified. The effects of 20 amino acids on swarming, extracellular protease activity, cellular RNA level and total protein concentration in 20 clinical Proteus strains from Lagos, Nigeria were investigated. At 0.5mM concentration, glutamine, serine, and methionine were the only amino acids found to enhance swarming motility on M9 minimal medium (7.1ndash;11.3 mm), cause significant increases in protease activity (33.7ndash;48.3 units/ml), total protein concentration (22.5ndash;28.6 mg/ml) and cellular RNA concentration (192.8ndash;264.7 mg/ml) when compared to values obtained for other 17 amino acids (P lt; 0.05). Furthermore, the amino acid induced swarming in these strains was found to vary directly and significantly (P lt; 0.05) with protease activity and cellular RNA concentration. The exclusion of methionine, serine and glutamine when supplementing antiswarming media for clinical investigation of Proteus - associated polymicrobial infections in Nigeria is suggested. Key words: Proteus strains, swarming motility, amino acids, Lagos. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/3097501638 http://dx.doi.org/10.5897/AJB2002.000-002 en Copyright © 2002 Bamidele A. Iwalokun and Babatunde O. Akinwumi
oai:academicjournals.org:AJB:0409D24655 2002-11-30T00:00:00Z AcademicJournals AJB AJB:2002
Biological nitrogen fixation in Crotalaria species estimated using the 15N isotope dilution method R.T. Samba, S.N. Sylla, M. Neyra, M. Gueye, B. Dreyfus and I. Ndoye A greenhouse experiment was conducted to measure nitrogen fixation in threeCrotalaria species : C. ochroleuca, C. perrottetii and C. retusa growing in Senegal by using 15N direct isotope dilution technique. Two non-fixing plants, Senna obtusifoliaand Senna occidentalis served as reference plants. The amount of nitrogen fixed two months after planting was obtained using the average of the two reference plants. The atom % 15N excess in the Crotalaria species was significantly lower than that of the reference plants, indicating that significant nitrogen fixation occurred in the three plants. Significant differences were observed between the Crotalaria species; C. ochroleucayielded more dry matter weight and total nitrogen than did C. perrottetti and C. retusa. The % nitrogen derived from atmosphere (%Ndfa) in leaves and stems was also higher in C. ochroleuca. There was no significant difference in %Ndfa in the whole plant between the three Crotalaria species (47% to 53%). In contrast, interspecific variability was observed based on the %Ndfa. C. ochroleuca significantly exhibited the higher amount of total nitrogen fixed, equivalent to 83 kg of nitrogen fixed per hectare. Based on these data, it was concluded that C. ochroleuca could be used in multiple cropping systems in Senegal for making more nitrogen available to other plants. Key words: Crotalaria spp, isotope dilution, 15N, nitrogen fixation, reference plant. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/0409D24655 http://dx.doi.org/10.5897/AJB2002.000-003 en Copyright © 2002 R.T. Samba, S.N. Sylla, M. Neyra, M. Gueye, B. Dreyfus and I. Ndoye
oai:academicjournals.org:AJB:B206BBB657 2002-11-30T00:00:00Z AcademicJournals AJB AJB:2002
Persistence of Rhizobium inoculants originating from Leucaena leucocephala fallowed plots in Southwest Nigeria O.A. Ojo and O.E. Fagade Ten core soil samples were collected from experimental plots at IITA, SW Nigeria that were previously inoculated with Rhizobium strains (IRC1045 and IRC 1050) specific for Leucaena leucocephala at two depths; 0ndash;15 cm and 15ndash;30 cm. The control soil samples were collected at similar depths from an adjacent field with no previous history of legume cultivation. Six weeks after planting of L. leucocephala in the soil samples in the greenhouse shoots, roots and nodules were harvested aseptically. Typing of the nodules as well as the identification of the persisting population of the introduced strains were based on the intrinsic resistance of IRC 1045 and IRC 1050 to streptomycin at 500 mg/ml and nodules were found to be made up of 100% of previously introduced strains. The potency and competitive ability of the recovered IRC 1045 and IRC 1050 were thus confirmed via the pot experiment and plant reinfection experiment in the greenhouse. At 0ndash;15 cm and 15ndash;30 cm depths 8.0 x 104 and 9.0 x 104 rhizobia/g of soil were recovered respectively in spite of the 10-year fallow period. Biomass production with the three woody legumes revealed Root and Shoot dry weights of the following order of magnitude Senna siamea gt; L. leucocephala gt; Senna spectabilis. This report showed the great potential of application of Rhizobium technology in low input sustainable agricultural practice and environmental pollution abatement for non-use of chemical nitrogen fertilizers. Key words: Agriculture, Leucaena leucocephala, nodulation, persistence, rhizobium. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/B206BBB657 http://dx.doi.org/10.5897/AJB2002.000-004 en Copyright © 2002 O.A. Ojo and O.E. Fagade
oai:academicjournals.org:AJB:3FCE5D66374 2002-12-30T00:00:00Z AcademicJournals AJB AJB:2002
Physiological and molecular insights into drought tolerance Sagadevan G Mundree, Bienyameen Baker, Shaheen Mowla, Shaun Peters, Saberi Marais, Clare Vander Willigen, Kershini Govender, Alice Maredza, Samson Muyanga, Jill M Farrant and Jennifer A Thomson Minireview Water is a major limiting factor in world agriculture. In general, most crop plants are highly sensitive to even a mild dehydration stress. There are however, a few genera of plants unique to Southern Africa, called ldquo;resurrection plantsrdquo; which can tolerate extreme water loss or desiccation. We have used Xerophyta viscosa, a representative of the monocotyledonous resurrection plants to isolate genes that are associated with osmotic stress tolerance. Several genes that are differentially expressed, and that confer functional sufficiency to osmotically-stressed Escherichia coli are being studied at the molecular and biochemical levels. In this review, we use this as a basis to discuss the physiological and molecular insights into drought tolerance. Key words: Drought stress, reactive oxygen species, osmoprotectants, abscisic acid, transcription factors. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/3FCE5D66374 http://dx.doi.org/10.5897/AJB2002.000-006 en Copyright © 2002 Sagadevan G Mundree, Bienyameen Baker, Shaheen Mowla, Shaun Peters, Saberi Marais, Clare Vander Willigen, Kershini Govender, Alice Maredza, Samson Muyanga, Jill M Farrant and Jennifer A Thomson
oai:academicjournals.org:AJB:BEBDE066403 2002-12-30T00:00:00Z AcademicJournals AJB AJB:2002
The diagnosis of trypanosome infections: applications of novel technology for reducing disease risk Picozzi, K., Tilley, A., Fegrave;vre, E.M., Coleman, P.G., Magona, J.W., Odiit, M., Eisler, M.C and Welburn S.C. Full Length Research Paper Reliable DNA based methodologies to determine prevalence of trypanosome species in domestic livestock have been available for over 10 years. Despite this, they are rarely used to generate baseline data for control operations for these diseases in the field. Rather, such operations tend to rely on data which can be generated using low technology methods such as direct observation of parasites by light microscopy. Here we show the pitfalls of relying on such low tech methodology which, although simple in its application, can provide inaccurate and inadequate data on which to base control methodologies. Our analysis of 61 cattle selected for trypanosome carrier status by either microscopy, low PCV or poor condition score, showed that 90% were infected with trypanosomes while 84% of the total were infected with T. brucei. Diagnosis by PCR on buffy coat preparations on Whatmanreg; FTAreg; matrices was the most sensitive methodology relative to the gold standard, whereas microscopy was the least sensitive. Keywords: sleeping sickness, human African trypanosomiasis, epidemiology, chemotherapy, PCR. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/BEBDE066403 http://dx.doi.org/10.5897/AJB2002.000-007 en Copyright © 2002 Picozzi, K., Tilley, A., Fegrave;vre, E.M., Coleman, P.G., Magona, J.W., Odiit, M., Eisler, M.C and Welburn S.C.
oai:academicjournals.org:AJB:9E440F46435 2002-12-30T00:00:00Z AcademicJournals AJB AJB:2002
Monoterpenes reduced adducts formation in rats exposed to aflatoxin B1 J. Abiodun Elegbede and Michael N. Gould Full Length Research Paper Perillyl alcohol and d-limonene are naturally occurring plant compounds that exhibited anti-carcinogenic activities in mammary tumor models. The effects of these monoterpenes at the initiation stage of aflatoxin B1-induced hepatocarcinogenesis were investigated. Male F344 rats were fed Control or treatment diets throughout the study and exposed to aflatoxin for 5 days. Three days after the last aflatoxin dose, blood and liver samples were obtained. Analysis of liver samples showed that both limonene and perillyl alcohol significantly inhibited (plt;0.05) aflatoxin-DNA adducts formation in hepatocytes. The monoterpenes may have potential for use as chemopreventive agent against aflatoxin-induced liver cancer. Keywords: Aflatoxin B1, hepatocarcinogenesis, monoterpenes, chemoprevention. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/9E440F46435 http://dx.doi.org/10.5897/AJB2002.000-008 en Copyright © 2002 J. Abiodun Elegbede and Michael N. Gould
oai:academicjournals.org:AJB:70C85EC6463 2002-12-30T00:00:00Z AcademicJournals AJB AJB:2002
Estimates of biological nitrogen fixation by Pterocarpus lucens in a semi arid natural forest park in Senegal using 15N natural abundance method Sylla S N, Ndoye I, Gueye M, Ba A T and Dreyfus B Full Length Research Paper Nitrogen (N2) fixation by Pterocarpus lucens in a natural semi arid ecosystem, in Ferlo, Senegal was estimated using 15N natural abundance (part;15N) procedure. Other non-fixing trees accompanying P. lucens in the same area were also investigated as control. Results showed an important variation of part;15N in leaves between the nitrogen-fixing tree (P. lucens) and reference plants, whereas no significant differences were recorded in amount of nitrogen (%). The relative part;15N values (permil;) were higher in non-fixing plants than in fixing plants considered. Calculations of %Ndfa gave rates ranging between 26% and 49%. The values of %Ndfa depend largely on soil and the reference plants. The contribution of nitrogen derived from fixation in leaves reached 28.9 kg.N/ha and 10.8 kg.N/ha in ferruginous and in sandy soil respectively. Key words: Pterocarpus lucens, 15N natural abundance, semi arid lowland, biological nitrogen fixation, natural ecosystem Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/70C85EC6463 http://dx.doi.org/10.5897/AJB2002.000-009 en Copyright © 2002 Sylla S N, Ndoye I, Gueye M, Ba A T and Dreyfus B
oai:academicjournals.org:AJB:BADF1146488 2002-12-30T00:00:00Z AcademicJournals AJB AJB:2002
Bio-deterioration of breadfruit (Artocarpus Communis) in storage and its effects on the nutrient composition Amusa, N.A, Kehinde, I. A. and Ashaye, O. A Full Length Research Paper The bio-deterioration of breadfruit in storage and its effects on the nutrient composition of the fruit was investigated at Ibadan, Southwestern Nigeria. Freshly dropped fruits were stored under laboratory conditions for a period of 9 days. Aspergillus niger, Rhizopus stolonifer, Botryodiplodia theobromae, Mycovellosiella fulva, Penicillium sp. and Aspergillus flavus, were found associated with deteriorating breadfruit in storage The freshly harvested breadfruit has 70.2% carbohydrate which reduced to 59.4% within 9 days of storage under room temperature. The amount of fat content, protein and the energy of the breadfruit also reduced in fruit samples stored for 9 days, while there was an increase in the moisture content, crude fibre, and ash content of the breadfruits in storage. The mineral contents also increased during the period of storage. Key words: Artocarpous communis, bio-deterioration, breadfruit, storage nutrient composition, pathogens. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/BADF1146488 http://dx.doi.org/10.5897/AJB2002.000-010 en Copyright © 2002 Amusa, N.A, Kehinde, I. A. and Ashaye, O. A
oai:academicjournals.org:AJB:196E8806508 2002-12-30T00:00:00Z AcademicJournals AJB AJB:2002
Effect of cold temperature storage on the quality attributes of pawpaw and guava leathers Babalola S. O., Ashaye O. A., Babalola A. O. and Aina J.O. Short Communication The effect of cold temperature storage on the quality attributes of pawpaw and guava leathers was evaluated. Pawpaw leather was significantly higher than guava leather in calorific content, water activity, pH and total mould count throughout the duration of storage. However Guava leather was higher in texture. Sensory scores in relation to period of storage showed that Guava leather gave better result in overall acceptability at zero, one and two months of storage at 8 plusmn; 10C. Guava leather also gave better sensory qualities in fruitiness, smell, chewiness, toughness, colour, and overall acceptability when varietal influence is considered. Guava leather is better accepted. Key words: Pawpaw, guava sensory, leather, storage. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/196E8806508 http://dx.doi.org/10.5897/AJB2002.000-011 en Copyright © 2002 Babalola S. O., Ashaye O. A., Babalola A. O. and Aina J.O.
oai:academicjournals.org:AJB:4EE56EA6542 2002-12-30T00:00:00Z AcademicJournals AJB AJB:2002
Influence of carbon source on the expression of Cochliobolus carbonum xylan-degrading enzyme genes Nyerhovwo J. TonukariY, , John S. Scott-Craig and Jonathan D. Walton Short Communication The expression of four Cochliobolus carbonum endo-1,4-b-xylanase genes (XYL1,XYL2, XYL3, XYL4), and an exo-1,4-b-xylosidase gene (XYP1) was studied following the growth of the fungus in minimal medium containing glucose, sucrose, xylose, xylan, pectin, or cellulose. The XYL1 and XYL2 genes were expressed only when the culture medium contained xylan or cellulose. Both XYL3 and XYL4 are induced by xylose and xylan, and XYP1 expression is induced by xylose, xylan, pectin and cellulose. None of these genes is expressed in glucose or sucrose media. The differential expression of these enzymes may provide means for the fungus to adapt to different conditions. Key words: Cell wall degrading enzymes, Cochliobolus carbonum, xylan, xylanase. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/4EE56EA6542 http://dx.doi.org/10.5897/AJB2002.000-012 en Copyright © 2002 Nyerhovwo J. TonukariY, , John S. Scott-Craig and Jonathan D. Walton
oai:academicjournals.org:AJB:193B7056569 2002-12-30T00:00:00Z AcademicJournals AJB AJB:2002
Characterization of potential ethylene-producing rhizosphere bacteria of Striga-infested maize and sorghum Olubukola O. Babalola, Elie O. Osir and Abiodun I. Sanni Short Communication Three rhizosphere bacteria, Pseudomonas sp., Enterobacter sakazakii andKlebsiella oxytoca, were analyzed for genetic variation. DNA fingerprint patterns of the three bacteria were markedly different when amplified with different primers. In total, 68 bands were produced by the three primers, 62 of which where variable. The number of polymorphic RAPD loci per isolate ranged from one to 13. Cluster analysis indicated that E. sakazakii and K. oxytoca are the most closely related of the three. Key words: Bacteria, RAPD-PCR, Striga hermonthica. Academic Journals 2002 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/193B7056569 http://dx.doi.org/10.5897/AJB2002.000-013 en Copyright © 2002 Olubukola O. Babalola, Elie O. Osir and Abiodun I. Sanni
oai:academicjournals.org:AJB:79CA2B88674 2003-01-31T00:00:00Z AcademicJournals AJB AJB:2003
Actinorhizal, mycorhizal and rhizobial symbioses: how much do we know? Diaga Diouf,, Tahir A. Diop, and Ibrahima Ndoye, Minireview In this review, we discuss the recent progress in research on symbiotic association of rhizobia, Frankia and fungi with plant roots. We compare infection processes of symbiotic establishment; structure, functioning and molecular biology of the symbiotic organ including the regulation of genes implicated in rhizobial, actinorhizial and arbuscularmycorhizal symbioses. Key words: Symbiosis, nodule, mycorrhiza, symbiotic genes. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/79CA2B88674 http://dx.doi.org/10.5897/AJB2003.000-1001 en Copyright © 2003 Diaga Diouf,, Tahir A. Diop, and Ibrahima Ndoye,
oai:academicjournals.org:AJB:18B6E5D8681 2003-01-31T00:00:00Z AcademicJournals AJB AJB:2003
Effects of mixed nitrogen sources on biodegradation of phenol by immobilized Acinetobacter sp. strain W-17 Desouky Abd-El-Haleem, Usama Beshay, Abdou O. Abdelhamid , Hassan Moawad and Sahar Zaki Full Length Research Paper Using Ca-alginate immobilized cells of Acinetobacter sp. strain W-17, the effects of ammonium-N and nitrate-N on the biodegradation of phenol were investigated.Degradation experiments in three different culture media; minimal salts medium (MSM), simulated (SW) and modified simulated wastewater (MSW) were performed. With the freely suspended cells (cell dry weight 0.2 g/l), complete phenol (500 mg/l) degradation was achieved after incubation for 120 h. Using the immobilized cells, the time was reduced to 24 h in MSM medium, and 15 h in the MSW. The results also indicate thatstrain W-17 can tolerate to high concentrations of NH4+-N (63 mg/l) and NO3--N (1000 mg/l) without a significant loss in the phenol biodegradation rate. Moreover, the presence of 500 mg/l phenol in the MSW had no considerable effect on the removal of both ammonium-N and nitrate-N. Repeated use of immobilized cells revealed that they could be used as much as five times without loss of activity. Our findings could be extended to enhance biotreatment of phenol contamination in a variety of biological treatment processes. Key words: Phenol, biodegradation, immobilization, Acinetobacter, Ca-alginate, ammonium, nitrate. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/18B6E5D8681 http://dx.doi.org/10.5897/AJB2003.000-1002 en Copyright © 2003 Desouky Abd-El-Haleem, Usama Beshay, Abdou O. Abdelhamid , Hassan Moawad and Sahar Zaki
oai:academicjournals.org:AJB:A18F80E8687 2003-01-31T00:00:00Z AcademicJournals AJB AJB:2003
Diversity of indigeneous bradyrhizobia associated with three cowpea cultivars (Vigna unguiculata (L.) Walp.) grown under limited and favorable water conditions in Senegal (West Africa) Tatiana Krasova-Wade, , , Ibrahima Ndoye, , Serge Braconnier, Benoit Sarr, Philippe de Lajudie and Marc Neyra Full Length Research Paper The diversity of Bradyrhizobium strains nodulating three cowpea (Vigna unguiculataL. Walp.) cultivars in favorable and water-limited conditions occuring at flowering was analysed. PCR- Restriction Fragment Length Polymorphism (PCR-RFLP) analysis of 16S-23S rDNA intergenic spacer region (IGS) directly applied on 85 crushed nodules distinguished four genetic profiles, IGS types I, II, III and IV. The distribution of these IGS types according to water conditions and cowpea cultivars (B-21, TN 88-63 and Mouride) showed that nodulating strains appeared more diverse in water-limited condition. More than three quarters of prospected nodules presented the IGS type I. They were formed on all three cultivars and in both water conditions. Only a small part of nodules was distributed between the IGS type II, III and IV. Nodules showing the IGS types II and III were found mainly in limited conditions on TN 88-63 and Mouride cultivars, whereas nodules presenting the IGS type IV were collected only from cultivars B-21 and Mouride, in both water conditions. Strains corresponding to the different profiles were isolated. The phylogenetic analysis of 16S rRNA gene sequences showed that they belong to the genus, Bradyrhizobium. The sequence analysis of 16S-23S rDNA IGS revealed that the strains exhibiting IGS types II, III and IV were closely related to some Faidherbia albida isolates from Senegal. IGS type II can be assigned with at least 98% similarity to Bradyrhizobium genospecies IV. IGS types III and IV showed more than 96% similarity with genospecies VII and could belong to the same genospecies. IGS type I, the most frequent, exhibits low IGS similarity with reported sequences in the databases, and could represent a new genospecies. Key words: Bradyrhizobium, Vigna unguiculata, water-limited condition, PCR-RFLP, 16S rDNA, 16S-23S rDNA IGS. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/A18F80E8687 http://dx.doi.org/10.5897/AJB2003.000-1003 en Copyright © 2003 Tatiana Krasova-Wade, , , Ibrahima Ndoye, , Serge Braconnier, Benoit Sarr, Philippe de Lajudie and Marc Neyra
oai:academicjournals.org:AJB:3F7BA308693 2003-01-31T00:00:00Z AcademicJournals AJB AJB:2003
Pre-harvest deterioration of Sour sop (Annona muricata) at Ibadan Southwestern Nigeria and its effect on nutrient composition N. A. Amusa, O. A. Ashaye, M. O. Oladapo and O.O. Kafaru Short Communication The etiology of pre-harvest deterioration of Soursop (Annona muricata) fruit in Ibadan, southwestern Nigeria and the effects on its nutrient composition was investigated. Four fungal pathogens including Botryodiplodia theobromae, Fusariumsp., Rhizopus stolonifer and Aspergillus niger were found associated with the pre-harvest deteriorating soursop . B. theobromae was the most prevalent and the most pathogenic inducing rot of 75 mm in diameter within four days of inoculation. There was a remarkable reduction in carbohydrate and protein contents of the fungal infected fruits while all other nutrients and mineral assayed were higher in the infected fruits than the non-infected ones. Key words: Annona muricata, fungal pathogens, pre-harvest deterioration. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/3F7BA308693 http://dx.doi.org/10.5897/AJB2003.000-1004 en Copyright © 2003 N. A. Amusa, O. A. Ashaye, M. O. Oladapo and O.O. Kafaru
oai:academicjournals.org:AJB:AA983B68699 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
The molecular initiation and subsequent acquisition of disease resistance in plants Emma Wanjiru Gachomo, Olusola Olusoji Shonukan and Simeon Oloni Kotchoni Minireview Interactions between disease resistance (R) genes in plants and their corresponding pathogen avirulence (Avr) genes are the key determinants of whether a plant is susceptible or resistance to a pathogen attack. Evidence has emerged that these gene-for-gene interactions in the perception of pathogenic invasions and development of acquired resistance in plants involve different molecular and hormonal transduction pathways, which are still poorly understood. It has become apparent that plants actively produce several phytohormones such as ethylene, jasmonate, salicylic acid, and reactive oxygen intermediates prior to upregulation of R genes. The physiological role of these molecules in plant resistance to pathogens is beginning to attract attention. The use of transgenic plants in recent attempts, including development of mutants with altered R genes, has provided new insights into the mechanisms involved in pathogen perception, signal transduction and subsequent resistance to disease in plants. This review tries to summarize current knowledge of pathogen-related genes in plants, and how they can be use to improve disease resistance in agronomically valuable plants. It also describes the molecular basis of defense mechanisms in plants under pathogen attack. Key words: Avr, resistance gene, hypersensitivity, pathogenesis-related proteins, transgenic, plant-defense. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/AA983B68699 http://dx.doi.org/10.5897/AJB2003.000-1005 en Copyright © 2003 Emma Wanjiru Gachomo, Olusola Olusoji Shonukan and Simeon Oloni Kotchoni
oai:academicjournals.org:AJB:39B819B8703 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
Variations in fatty acid proportions during desiccation of Telfairia occidentalis seeds harvested at physiological and agronomic maturity Nkang A, Omokaro D, Egbe A and Amanke, G Full Length Research Paper The effect of desiccation on lipid content, fatty acid composition and the antioxidative enzymic capacity was investigated in seeds of Telfairia occidentalis, harvested at physiological and agronomic maturity. Seeds were dried at 5 and 28 oC, environments that induced different drying and metabolic rates. Desiccation of seeds was associated with decreased antioxidative enzymic capacity (of peroxidase and polyphenoloxidase), and thus increased likelihood of free radical attack and decreased viability (germinability). Agronomically mature seeds contained predominantly saturated fatty acids (tridecanoic), with very low levels of the major fatty acids of edible oilseeds (palmitic, stearic or the unsaturated C18 fatty acids). There was increased accumulation of the mono-unsaturated (oleic) and polyunsaturated (linoleic) fatty acids when seeds were dried at 28 oC and moisture contents have reduced to about 42 % or lower. In contrast, seeds dried at 5 oC maintained high levels of saturated fatty acids and lower levels of monounsaturated or polyunsaturated fatty acids. Results suggest the need to develop different post-harvest protocols for seed storage, and for processing T.occidentalis to lsquo;improversquo; the seed fatty acid profile as an oilseed for human and animal food. Key words: Agronomic maturity, desiccation, fatty acid, lipid peroxidation, oilseed. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/39B819B8703 http://dx.doi.org/10.5897/AJB2003.000-1006 en Copyright © 2003 Nkang A, Omokaro D, Egbe A and Amanke, G
oai:academicjournals.org:AJB:759E6BA8708 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
The use of a novel phage-based technology as a practical tool for the diagnosis of tuberculosis in Africa Tracy Seaman, Andre Trollip, Richard Mole and Heidi Albert Full Length Research Paper Sub-Saharan Africa has experienced a significant increase in tuberculosis cases in recent years, fuelled by high rates of TB-HIV co-infection in the region. The diagnosis of tuberculosis is based largely on clinical assessment, sputum smear microscopy and chest radiography. Although smear microscopy is useful for detecting the most infectious cases, a significant portion of cases are negative on sputum smears, making diagnosis more difficult. New tests are urgently needed. The FASTPlaqueTB test, a bacteriophage-based method, has been evaluated in several studies in Africa and elsewhere. Studies in South Africa and Pakistan reported that between half and two-thirds of smear-negative culture-positive TB cases were detected by theFASTPlaqueTB test within 2 days. This suggests a beneficial role for this test in the early diagnosis of clinically suspected smear-negative cases. The same technology has been applied to develop a rapid test to indicate multi-drug resistant TB,FASTPlaqueTB-MDRi. This test gave equivalent results to conventional drug susceptibility methods, but with more rapid results. The tests are simple to perform and require no specialised equipment, making the technology suitable for widespread implementation. Key words: Tuberculosis, bacteriophage, diagnostic test, phage amplification technology, multi-drug resistance, drug susceptibility test. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/759E6BA8708 http://dx.doi.org/10.5897/AJB2003.000-1007 en Copyright © 2003 Tracy Seaman, Andre Trollip, Richard Mole and Heidi Albert
oai:academicjournals.org:AJB:CC3DD488712 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
Relationship between genetic similarity and some productive traits in local chicken strains Bahy Ahmed Ali, Mohamed Morsy Mohamed Ahmed, Osama Mahmoud Aly Short Communication Random amplified polymorphic DNA (RAPD) technique was applied to detect genetic similarity between five local chicken strains that have been selected for eggs and meat production in Egypt. Based on six oligonucleotide primers, the genetic similarity between the egg-producing strains (Anshas, Silver Montazah and Mandarah) ranged from 72.4 to 85.4%. While the genetic similarity between the two chicken strains selected for meat production (Baheij and El-Salam) is 86.9%. Key words: Chicken, local strains, RAPD-PCR, genetic similarity. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/CC3DD488712 http://dx.doi.org/10.5897/AJB2003.000-1008 en Copyright © 2003 Bahy Ahmed Ali, Mohamed Morsy Mohamed Ahmed, Osama Mahmoud Aly
oai:academicjournals.org:AJB:C55E9F48715 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
Genetic diversity in cowpea [Vigna unguiculata (L.) Walp.] varieties determined by ARA and RAPD techniques Laiuml;ty Fall, Diaga Diouf, Mame Arama Fall-Ndiaye , Franccedil;ois Abaye Badiane and Mamadou Gueye Short Communication Cowpea, Vigna unguiculata (L.) Walp. presents phenotypical variabilities and in order to study the genetic diversity of cultivated Senegalese varieties, two experimental approaches were used. First, a physiological characterization based on nitrogen fixation was used to assess cowpea breeding lines. Inoculation with two Bradyrhizobiumstrains (NGR234 and ISRA312), showed a difference in nitrogen fixation potential between the cowpea varieties. Diongoma is the highest nitrogen fixing variety, whereas Mouride is the lowest. The second approach employed genetic characterization based on DNA polymorphism to screen. Results suggest that random amplified polymorphic DNA (RAPD) technology can be used to reorganize the national germplasm in order to eliminate the putative duplicates, and to identify elite varieties. Key words: Vigna unguiculata, nitrogen fixation, cowpea, molecular markers, RAPD. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/C55E9F48715 http://dx.doi.org/10.5897/AJB2003.000-1009 en Copyright © 2003 Laiuml;ty Fall, Diaga Diouf, Mame Arama Fall-Ndiaye , Franccedil;ois Abaye Badiane and Mamadou Gueye
oai:academicjournals.org:AJB:12C840C32267 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
The Biochemical Society of Kenya Daniel Masiga Editorial Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/12C840C32267 http://dx.doi.org/10.5897/AJB2004.000-2021 en Copyright © 2003 Daniel Masiga
oai:academicjournals.org:AJB:3D2922332287 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
Opportunities in Africa for training in genome science Daniel K. Masiga and Raphael D. Isokpehi Perspective Genome science is a new type of biology that unites genetics, molecular biology, computational biology and bioinformatics. The availability of the human genome sequence, as well as the genome sequences of several other organisms relevant to health, agriculture and the environment in Africa necessitates the development and delivery of several types and levels of training that will enhance the use of genome data and the associated computational resources. A survey of initiatives that provide opportunities for training in genome science is presented. Current efforts to increase the ability of African scientists to computationally process and analyse genomic and post-genomic data have the potential to produce excellent scientists who perform cutting-edge, hypothesis-based research, and who will accelerate the continentrsquo;s scientific and technological development. Key words: Bioinformatics, collaboration, computational biology, genome science. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/3D2922332287 http://dx.doi.org/10.5897/AJB2004.000-2022 en Copyright © 2003 Daniel K. Masiga and Raphael D. Isokpehi
oai:academicjournals.org:AJB:5E14DF632314 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
Research communications in the 21st century Nyerhovwo J. Tonukari Perspective Scientific inquiry thrives only in a society that fosters the free flow of ideas and information. The power of online (internet) publication in democratizing science and incorporating scientists from developing countries into the scientific community is profound. The desired and obvious properties of scientific publishing such as accessibility, economy, quality, innovation, and retrieval can be more readily achieved with electronic methods. Online publication is much cheaper and faster, and that is major reason Africa should embrace the open access model for research communication. An open access African journal (the African Journal of Biotechnology) is evaluated. Key words: Open access, African Journal of Biotechnology, research communications. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/5E14DF632314 http://dx.doi.org/10.5897/AJB2004.000-2023 en Copyright © 2003 Nyerhovwo J. Tonukari
oai:academicjournals.org:AJB:EACB56132327 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
Agricultural genomics and sustainable development: perspectives and prospects for Africa Jesse Machuka Review The genomes of various organisms have now been fully sequenced, including human and representative microbial, insect, animal and plant genomes. The research challenge in the post-genome era is to establish how genes and proteins function to bring about changes in phenotype. Some of these phenotypes, and products obtainable through modern biotechnology, are of crucial importance within the context of sustainable development of African economies. The greatest ultimate impact will be in agricultural genomics, especially for marker assisted selection and breeding programs in crop and animal agriculture, development of animal disease diagnostics and vaccines, crop genetic engineering to overcome abiotic and biotic stresses and for improvement of the nutritional quality of major food staples. It is imperative that African countries become key players in the ldquo;gene revolutionrdquo; since the cost of leaving them behind may be higher than the cost of empowering them to become players in mastering and benefiting from biotechnology. This paper highlights the potential impact of the latest advances in modern biotechnology, including genomics and bioinformatics, on sustainable development, in line with the goals of the New Partnership for Africa#39;s Development (NEPAD). These include acceleration of economic growth, eradication of widespread and severe poverty and efforts to halt the marginalization of Africa in the globalization process. Key words: Genomics, modern biotechnology, agriculture, sustainable development, Africa. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/EACB56132327 http://dx.doi.org/10.5897/AJB2004.000-2024 en Copyright © 2003 Jesse Machuka
oai:academicjournals.org:AJB:2687D2032340 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
Plant genetic resources: Advancing conservation and use through biotechnology N. Kameswara Rao Full Length Research Paper Conservation and sustainable use of genetic resources is essential to meet the demand for future food security. Advances in biotechnology have generated new opportunities for genetic resources conservation and utilization. Techniques like in vitro culture and cryopreservation have made it easy to collect and conserve genetic resources, especially of species that are difficult to conserve as seeds. While technologies like enzyme-linked immunosorbent assay (ELISA) and polymerase chain reaction (PCR) have provided tools that are more sensitive and pathogen specific for seed health testing, tissue culture methods are now widely applied for elimination of systemic diseases such as viruses for safe exchange of germplasm. Molecular markers are increasingly used for screening of germplasm to study genetic diversity, identify redundancies in the collections, test accession stability and integrity, and resolve taxonomic relationships. The technology is also expanding the scope of genetic resources utilization. Key words: Biotechnology, conservation, plant genetic resources. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/2687D2032340 http://dx.doi.org/10.5897/AJB2004.000-2025 en Copyright © 2003 N. Kameswara Rao
oai:academicjournals.org:AJB:76F44A332351 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
Estimates of outcrossing rates in Moringa oleifera using Amplified fragment length polymorphism (AFLP) Muluvi GM, Sprent JI, Odee D and Powell W Full Length Research Paper The mating system in plant populations is influenced by genetic and environmental factors. Proper estimates of the outcrosing rates are often required for planning breeding programmes, conservation and management of tropical trees. However, althoughMoringa oleifera is adapted to a mixed mating system, the proportion of selfing has not been previously estimated. The current work therefore, shows the use of AFLP markers in a mating system study of M. oleifera seed orchard. Data revealed a mixed mating system with a multilocus outcrossing rate (tm) of 0.74. It further demonstrated that AFLP markers, though dominant with a lower information content than co-dominant markers are adequate for the study of the mating system in plant populations. The 26% selfing observed in M. oleifera can lead to overestimation of the proportion of additive genetic variance and appropriate adjustments are therefore required. However, the presence of selfing as well as early sexual maturity (6 months to 1 year) in M. oleiferaprovides an opportunity for developing inbred lines and hybridisation. Additionally, in designing M. oleifera seed orchards, randomisation and minimum distance between related individuals need to be worked out to maximise cross-fertilisation among unrelated clones and minimise selfing or mating among related ramets. Key words: Moringa oleifera, mating system, outcrossing rates, amplified fragment length polymorphism. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/76F44A332351 http://dx.doi.org/10.5897/AJB2004.000-2026 en Copyright © 2003 Muluvi GM, Sprent JI, Odee D and Powell W
oai:academicjournals.org:AJB:5E2BE3F32358 2003-02-28T00:00:00Z AcademicJournals AJB AJB:2003
Comparative genetics of alcoholism in the Kenyan populations Korir Elena Doudoladova, Ochieng David and Ndiritu Douglas Full Length Research Paper Hepatic alcohol dehydrogenase and aldehyde dehydrogenase are major enzymes in the metabolism of exogenous ethanol. These enzymes are polymorphic and are involved in alcohol drinking and risk of alcoholism in some world populations. Three hundred and seventy one samples of hair root lyzates from five Kenyan communities were screened for ADH 2, ADH 3 and ALDH 2 polymorphisms via isoelectric focusing. Additional information on alcohol drinking behaviour, alcohol intake, frequency of alcohol drinking, preference of alcoholic drinks, and alcohol dependence was collected via interview and questionnaire. SAS JPIN statistical program was used to analyze obtained data using chi-square, Anova and t-tests. The results showed that ADH 2*2, ADH 3*1 and ALDH 2*2 alleles do not have protective properties against risk of alcoholism in the selected Kenyan populations. Other factors than ADH and ALDH polymorphisms interfered in the protective mechanism of the latter alleles against excessive alcohol drinking. Key words: Alcohol, ADH, ALDH, polymorphism, alcohol drinking, alcoholism. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/5E2BE3F32358 http://dx.doi.org/10.5897/AJB2004.000-2027 en Copyright © 2003 Korir Elena Doudoladova, Ochieng David and Ndiritu Douglas
oai:academicjournals.org:AJB:42166218746 2003-03-31T00:00:00Z AcademicJournals AJB AJB:2003
Molecular phylogeny of Fusarium species by AFLP fingerprint Mohmed A. Abdel-Satar, Mohmed. S. Khalil, I. N. Mohmed, Kamel A. Abd-Elsalam, and Joseph A. Verreet Full Length Research Paper The high-resolution genotyping method of amplified fragment length polymorphism (AFLP) analysis was used to study the genetic relationships within and between natural populations of five Fusarium spp. AFLP templates were prepared by the digestion ofFusarium DNA with EcoRI and MseI restriction endonucleases and subsequent ligation of corresponding site-specific adapters. An average of 44 loci was assayed simultaneously with each primer pair and DNA markers in the range 100 to 500 bp were considered for analysis. A total of 80 AFLP polymorphic markers were obtained using four primer combinations, with an average of 20 polymorphic markers observed per primer pair. UPGMA analyses indicated 5 distinct clusters at the phenon line of 30% on the genetic similarity scale corresponding to the 5 taxa. The similarity percent of each group oscillated between 87 and 97%. The phenetic dendrogram generated by UPGMA as well as principal coordinate analysis (PCA) grouped all of the Fusariumspp. isolates into five major clusters. No clear trend was detected between clustering in the AFLP dendrogram and geographic origin, host genotype of the tested isolates with a few exceptions. The results of the present study provide evidence of the high discriminatory power of AFLP analysis, suggesting the possible applicability of this method to the molecular characterization of Fusarium. Key words: AFLP, Fusarium, molecular phylogeny, selective amplification. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/42166218746 http://dx.doi.org/10.5897/AJB2003.000-1010 en Copyright © 2003 Mohmed A. Abdel-Satar, Mohmed. S. Khalil, I. N. Mohmed, Kamel A. Abd-Elsalam, and Joseph A. Verreet
oai:academicjournals.org:AJB:625D95E8750 2003-03-31T00:00:00Z AcademicJournals AJB AJB:2003
Biodeterioration of the African star apple (Chrysophylum albidum) in storage and the effect on its food value N. A. Amusa, O.A. Ashaye and M. O. Oladapo Full Length Research Paper The biodeterioration of the African star apple fruits in storage was investigated at Ibadan, southwestern Nigeria. Eight fungal isolates were found associated with the deteriorating fruits. The fungi are Botryodiplodia theobromae, Rhizopus stolonifer,Aspergillus niger, A. tamarii, A. flavus, Fusarium spp, Penicilium spp andTrichoderma spp. All the fungal isolates were pathogenic on the star apple fruits with the exception of Trichoderma spp. The African star apple fruits stored for up to 5 days were associated with severe fungal infections and had significantly reduced crude protein, crude fat and moisture content while dry matter, potassium, calcium and sodium increased compared to the freshly harvested fruits. Key words: Chrysophilum albidum, biodeterioration, fungal pathogens, storage. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/625D95E8750 http://dx.doi.org/10.5897/AJB2003.000-1011 en Copyright © 2003 N. A. Amusa, O.A. Ashaye and M. O. Oladapo
oai:academicjournals.org:AJB:A9470428757 2003-03-31T00:00:00Z AcademicJournals AJB AJB:2003
Production of alkaline protease by Teredinobacter turnirae cells immobilized in Ca-alginate beads Usama Beshay Full Length Research Paper The conditions for immobilizing the new alkaline protease-producing bacteria strainTeredinobacter turnirae by entrapment in calcium alginate gel were investigated. The influence of alginate concentration (20, 25 and 30 g/l) and initial cell loading (ICL) on enzyme production were studied. The production of alkaline protease improved significantly with increasing alginate concentration and reached a maximum enzyme yield of 8000 U/ml at 25 g/l alginate concentration. This was about 176.8% higher than that obtained by free cells (2890 U/ml). The immobilized cells produced alkaline protease consistently over 5 repeated cycles and reached a maximal value of 9000 U/ml on the third cycle. This was 311.4% (3.11-fold) as compared with the control (free cells). Simple mass balance analysis was applied to describe the growth and the protease production behaviour of both fractions the cells in free form and the entrapped in Ca-alginate beads. Scanning electron microscope studies indicated the internal distribution pattern of the cells encapsulated in Ca-alginate beads. The results presented in this paper show the potential for using immobilized T. turnirae cells in Ca-alginate for the production of a novel alkaline protease. Key words: Alkaline protease, Ca-alginate, immobilization, Teredinobacter turnirae, repeated batch. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/A9470428757 http://dx.doi.org/10.5897/AJB2003.000-1012 en Copyright © 2003 Usama Beshay
oai:academicjournals.org:AJB:52484338765 2003-03-31T00:00:00Z AcademicJournals AJB AJB:2003
A capillary electrophoretic method for isolation and characterization of grape xylem proteins Ashok K. Jain and Sheikh M. Basha Full Length Research Paper European (Vitis vinifera) and American (Vitis labrusca) grape species succumb to a bacterial disease known as Piercersquo;s Disease (PD). In contrast, muscadine grape genotypes (Vitis rotundifolia) are tolerant/resistant to PD. This is due to the unique biochemical composition of muscadine xylem. However, because of low protein concentration, conventional methods such as low-pressure chromatography and PAGE are unsuitable for grape xylem protein characterization. In addition, these procedures are tedious, time-consuming and require large amount of sample. This study reports a procedure for isolating and separating proteins from muscadine and bunch grape xylem tissue. The procedure consists of separation of xylem from cortex and phloem, removal of pigments and other gummy substances from xylem with ethanol: ethylacetate (2:1) and subsequent Capillary Electrophoretic (CE) analysis of xylem protein extracts to achieve desired resolution. Number of peaks, peak height and areas, retention time and baseline position were used to compare resolution and study the effect of sample and separation buffer. Xylem tissue proteins extracted with 0.05% sodium borate buffer (pH 8.3) and subjected to CE using 1.2% sodium borate (pH 8.3) as a separation buffer were found to yield most satisfactory resolution of grape xylem proteins. The data obtained by CE were consistent and reproducible, and hence, is well suited to obtain excellent resolution of xylem tissue protein for identifying differences in protein composition among the grape genotypes. Key words: Capillary electrophoresis, grape, Vitis, xylem, Piercersquo;s disease, protein. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/52484338765 http://dx.doi.org/10.5897/AJB2003.000-1013 en Copyright © 2003 Ashok K. Jain and Sheikh M. Basha
oai:academicjournals.org:AJB:0F91E5332390 2003-03-31T00:00:00Z AcademicJournals AJB AJB:2003
Plant gene technology: social considerations Berhanu Abraha Tsegay Perspective The genetic modification of plants by gene technology is of immense potential benefits, but there may be possible risks. The advantages and social concerns of plant gene technology are discussed. Key words: Gene technology, genetically modified plant, agriculture. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/0F91E5332390 http://dx.doi.org/10.5897/AJB2004.000-2028 en Copyright © 2003 Berhanu Abraha Tsegay
oai:academicjournals.org:AJB:9AFCC6032406 2003-03-31T00:00:00Z AcademicJournals AJB AJB:2003
Microcystis aeruginosa: source of toxic microcystins in drinking water Oberholster PJ, Botha A-M and Grobbelaar JU Review Cyanobacteria are one of the earthrsquo;s most ancient life forms. Evidence of their existence on earth, derived from fossil records, encompasses a period of some 3.5 billion years in the late Precambrian era. Cyanobacteria are the dominant phytoplanton group in eutrophic freshwater bodies worldwide. They have caused animal poisoning in many parts of the world and may present risks to human health through drinking and recreational activity. Cyanobacteria produce two main groups of toxin namely neurotoxins and peptide hepatotoxins. They were first characterized from the unicellular species, Microcystis aeruginosa, which is the most common toxic cyanobacterium in eutrophic freshwater. The association of environmental parameters with cyanobacterial blooms and the toxicity of microcystin are discussed. Also, the synthesis of the microcystins, as well as the mode of action, control and analysis methods for quantitation of the toxin is reviewed. Key words: Cyanobacteria, microcystins, mcyB gene, PCR-RFLP. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/9AFCC6032406 http://dx.doi.org/10.5897/AJB2004.000-2029 en Copyright © 2003 Oberholster PJ, Botha A-M and Grobbelaar JU
oai:academicjournals.org:AJB:C6BFA0232421 2003-03-31T00:00:00Z AcademicJournals AJB AJB:2003
Screening cowpea [Vigna unguiculata (L.) Walp.] varieties by inducing water deficit and RAPD analyses Franccedil;ois Abaye Badiane, Diaga Diouf, Djibril Saneacute;, Omar Diouf,Venceslas Goudiaby and Nicolas Diallo, Full Length Research Paper The effects of water deficit induced by polyethylene glycol-6000 on some cowpea varieties, which belong to the national germplasm in Senegal are reported. Our results showed that, the length of the epicotyl was not affected by water deficit but the length of primary root was influenced only in Mouride variety. Water deficit influenced mostly the number of lateral roots. The 985 variety showed a great increase of its lateral root numbers and could be considered a drought tolerant variety. In contrast, the IT81D-1137 variety is very sensitive to water deficit because its lateral root number were reduced 3.8 fold compared to the control. These physiological studies were complemented by analyzing the genetic diversity of these varieties with random amplified polymorphic DNA (RAPD). The RAPD analysis suggested that the samples were also genetically diverse. Key words: Vigna unguiculata, drought tolerance, PEG, RAPD. Academic Journals 2003 TEXT text/html http://www.academicjournals.org/journal/AJB/article-abstract/C6BFA0232421 http://dx.doi.org/10.5897/AJB2004.000-2030 en Copyright © 2003 Franccedil;ois Abaye Badiane, Diaga Diouf, Djibril Saneacute;, Omar Diouf,Venceslas Goudiaby and Nicolas Diallo,