African
Journals On-line
African Journal of Biotechnology
Volume 1 Number, 2 2002
Abstracts
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
Department of Molecular and Cell Biology, University of Cape Town, Private Bag, Rondebosch, 7701 South Africa
*Corresponding author; e-mail: [email protected]; tel: (021) 650-3263; fax: (021) 689-7573
Accepted 8 November 2002
Abstract
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 "resurrection plants" 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.
The diagnosis of trypanosome infections: applications of novel technology for reducing disease risk
Picozzi, K.1, Tilley, A.1, Fèvre, E.M.1, Coleman, P.G.1, Magona, J.W.2, Odiit, M.2, Eisler, M.C3 and Welburn S.C.1*
1 Centre for Tropical Veterinary Medicine, Royal (Dick) School of Veterinary Studies, The University of Edinburgh, Easter Bush, Roslin, Midlothian, Scotland, EH25 9RG, UK
2 Livestock Health Research Institute, PO Box 96, Tororo, Uganda
3 University of Glasgow Veterinary School, Bearsden Road, Glasgow, Scotland
*Corresponding author; tel: +44 131 650 6228; fax: + 44 131 7348; e-mail: [email protected]
Accepted 12 November 2002
Abstract
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 Whatman® FTA® 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.
Monoterpenes reduced adducts formation in rats exposed to aflatoxin B1
J. Abiodun Elegbede1* and Michael N. Gould2
1 UNLV Cancer Institute/Chemistry Department, University of Nevada Las Vegas, 4505 Maryland Parkway, Las Vegas, NV 89154-4003
2 McArdle Laboratory for Cancer Research, University of Wisconsin-Madison, WI 53706-1599
* Corresponding author; tel: 1-(702) 895-3174; fax: 1-(702) 895-4072; e-mail: [email protected]
Accepted 13 November 2002
Abstract
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 (p<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.
Estimates of biological nitrogen fixation by Pterocarpus lucens in a semi arid natural forest park in Senegal using 15N natural abundance method
Sylla S N1*, Ndoye I1, Gueye M2, Ba A T1 and Dreyfus B3
1 UCAD, Faculté des Sciences et Techniques, Département de BV, BP 5005, Dakar, Sénégal.
2 MIRCEN/Centre ISRA-IRD, BP 1386, Dakar, Sénégal.
3 LSTM, IRD _ CIRAD, TA10/J, Campus de Baillarguet, 34398, Montpellier, France.
*Corresponding author; e-mail: [email protected], tel: +221-8 49 33 22, fax: +221-8 32 16 75
Accepted 15 November 2002
Abstract
Nitrogen (N2) fixation by Pterocarpus lucens in a natural semi arid ecosystem, in Ferlo, Senegal was estimated using 15N natural abundance (¶15N) procedure. Other non-fixing trees accompanying P. lucens in the same area were also investigated as control. Results showed an important variation of ¶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 ¶15N values (‰) 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.
Bio-deterioration of breadfruit (Artocarpus Communis) in storage and its effects on the nutrient composition
Amusa, N.A1*, Kehinde, I. A.2 and Ashaye, O. A1
1 Institute of Agricultural Research and Training, Obafemi Awolowo University, Moor Plantation, P.M.B 5029, Ibadan, Nigeria
2 Department of Biological Sciences University of Agriculture, Abeokuta, Nigeria
*Corresponding author; e-mail: [email protected]
Accepted 18 November 2002
Abstract
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.
Effect of cold temperature storage on the quality attributes of pawpaw and guava leathers
Babalola S. O.1, Ashaye O. A.2*, Babalola A. O.1 and Aina J.O.3
1 NIHORT, P.M.B 5342, idishin, Ibadan, Nigeria
2 I.A.R&T, Obafemi Awolowo University, P. M. B. 5029, Ibadan, Nigeria
3 Department of Food Technology, University of Ibadan, Ibadan, Nigeria
*Corresponding author; e-mail: [email protected]
Accepted 18 November 2002
Abstract
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 ± 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.
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
Department of Energy Plant Research Laboratory, Michigan State University, East Lansing, Michigan 48824.
Y Present address: International Livestock Research Institute, P.O. Box 30709, Nairobi, Kenya.
*Corresponding author; tel: 254-2-630743, fax: 254-2-631499, e-mail: [email protected]
Accepted 18 November 2002
Abstract
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.
Characterization of potential ethylene-producing rhizosphere bacteria of Striga-infested maize and sorghum
Olubukola O. Babalola1,2*, Elie O. Osir2 and Abiodun I. Sanni1
1 Department of Botany and Microbiology, University of Ibadan, Ibadan Nigeria
2 International Centre of Insect Physiology and Ecology, Nairobi, Kenya
*Corresponding author; tel: 234-803-703-5965; e-mail: [email protected]
Accepted 12 November 2002
Abstract
Three rhizosphere bacteria, Pseudomonas sp., Enterobacter sakazakii and Klebsiella 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.
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