Browsing Research articles (Dept of Biological Sciences) by Issue Date
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Moseki, B.; Buru, J.C. (Academic Journals, http://www.academicjournals.org/, NaN, 2010)[more][less]
Abstract: The aim of this study was to assess the growth response of Sesuvium portulacastrum (L.) (a halophyte) to various NaCl concentrations and hence determine how it is adapted to grow optimally under saline conditions. S. portulacastrum was grown hydroponically in various NaCl concentrations (that is, 0, 100, 200, 400 and 600 mol m-3 NaCl). It was found to exhibit a growth pattern typical of dicotyledonous halophytes. It attained maximal growth at 200 mol m-3 NaCl concentration in hydroponic cultures. It accumulated large concentrations of Na+ and Cl- with the leaves having the highest ion content. These ions are believed to be sequestered in the vacuole. S. portulacastrum also accumulated proline in high concentrations and this proline appeared to adjust the cytoplasmic ion concentration to balance that of the vacuole. URI: http://hdl.handle.net/10311/961 Files in this item: 1
Moseki_SRE_2010.pdf (102.5Kb) -
Mpoloka, S.W. (Academic Journals, www.academicjournals.org, August 18, 2010)[more][less]
Abstract: Residual long-term effects of increased UV-B radiation were investigated in an indigenous plant species, Dimorphotheca sinuata, by analysing photosynthetic gene expression. Reductions were observed in the amount of the rbcL and psbA mRNA expressed in progeny of plants that were previously subjected to enhanced UV-B levels. However, observed reductions did not attain statistical significance. This could explain the reduction in net biomass and physiological and biochemical parameters observed by other researchers as a result of UV-B exposure. Results from this study with plants grown in the absence of UV-B point to changes in the regulation of photosynthetic genes and such mutations due to raised UV-B levels could cause permanent changes in plant populations. URI: http://hdl.handle.net/10311/1011 Files in this item: 1
Mpoloka SRE 2010.pdf (122.9Kb) -
Moseki, B.; Dintwe, K. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: The effects of water stress on the photosynthetic characteristics of two locally-cultivated sorghum cultivars (‘Segaolane’ and ‘Town’) were investigated over a period of weeks. Water stress was imposed on 1-week-old plants by withholding water. Measurements of chlorophyll fluorescence were used to determine changes in the efficiency of light utilization for electron transport, the occurrence of photoinhibition of photosystem II photochemistry on the sorghum cultivars. Drought treatment significantly decreased leaf area in all species, an important factor in drought-induced decreases in photosynthetic productivity. Water-stressed ‘Town’ exhibited a decrease in maximum photochemical efficiency of PSII (estimated from dark-adapted Fν⁄Fм ratio) with increasing period of withholding water. Light-adapted Fν’⁄Fм’ estimated the efficiency of excitation energy transfer to open PSII centres. Water-stressed ‘Town’ displayed a decrease in the efficiency of excitation energy transfer to open PSII reaction centres throughout the entire study period. The quantum yield of PSII electron transport (фPSII), which represents electron flow beyond PSII, decreased markedly in water-stressed ‘Town’ compared with that of water-stressed ‘Segaolane’. These initial findings indicate that ‘Town’ is more prone to photoinhibition than ‘Segaolane’. URI: http://hdl.handle.net/10311/962 Files in this item: 1
Moseki_AJPSB_2011.pdf (96.03Kb) -
Chaturvedi, P.; Pipedi-Tshekiso, M.; Moseki, B.; Kwape, P.E. (Academic Journals, http://www.academicjournals.org/SRE, NaN, 2011)[more][less]
Abstract: Bark of Bauhinia purpurea tree was collected and both the water and methanol extracts were prepared. Both extracts were tested for free radical scavenging activities and phenol content. Water extract was then tested for its protective potentials against alcohol induced toxicity. For this experiment, twenty rats were randomly divided into four groups, alcohol control group, normal control and two experimental groups. The rats in alcohol control group received alcohol (5 g/kg), rats in normal control were given water. Rats in two experimental groups were administered two doses of methanol extract (50 and 100 mg/kg respectively) plus alcohol (5 g/kg) for 30 days. At the end of the experiment, rats were killed after ether anesthesia. Liver and blood samples were collected for biochemical measurements. Parameters measured were thiobarbituric acid reactive substances, serum glutamate oxaloacetate transaminase, serum glutamate pyruvate transaminase, reduced glutathione, glutathione peroxidase, superoxide dismutase, catalase and ascorbic acid. Results showed that both methanol and water extracts scavenged free radicals equivalent to gallic acid scavenging and were found rich in total phenol content. Results of in vivo experiments showed that the water extract inhibited lipid peroxidation, protected the experimental animals from hepatic toxicity and maintained the levels of antioxidants in dose dependent manner. URI: http://hdl.handle.net/10311/1018 Files in this item: 1
Chaturvedi_SRE_2011.pdf (207.7Kb) -
Setshogo, M.P.; Mbereki, C.M. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: The sale of herbal medicine, either as concoctions or single plant specimens, has become common in the streets and main shopping centres of major towns and cities in Botswana. A study was undertaken to collect information on the uses of medicinal plants sold by street vendors in Gaborone, Botswana during June 2008 to December 2008. The indigenous knowledge of the street vendors and the plants used for medicinal purposes were collected through questionnaire and personal interviews during field trips. The survey showed that the street vendors used 47 species of plants distributed in 45 genera belonging to 29 families to treat various diseases and health conditions. The documented medicinal plants were mostly used to cure skin sores, sexually transmitted diseases (STD) and asthma. In this study, the most dominat families are the Asteraceae and Fabaceae, each with 5 species and roots were most frequently used for the treatment of diseases accounting for 62% of the medicines sold. This study showed that many people in Botswana still continue to depend on medicinal plants for primary healthcare. URI: http://hdl.handle.net/10311/922 Files in this item: 1
Setshogo_AJPSB_2011.pdf (876.4Kb) -
Baloi, B.; Matsheka, M.I.; Gashe, B.A. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: Halophilic bacteria from the Makgadikgadi salt pans in north central Botswana were isolated using culture-dependent methods. Polymerase chain reaction (PCR) amplification of the 16S rRNA gene and phylogenetic analysis were used to identify the strains. Culturing was done aerobically in six different complex salt media. Salt concentrations used were 1Halophilic bacteria from the Makgadikgadi salt pans in north central Botswana were isolated using culture-dependent methods. Polymerase chain reaction (PCR) amplification of the 16S rRNA gene and phylogenetic analysis were used to identify the strains. Culturing was done aerobically in six different complex salt media. Salt concentrations used were 15, 20, 25 and 30% (2.6, 3.4, 4.3 and 5.1 M, respectively) NaC1, at pH 7.2 to pH 8.0. Four colony morphology types were isolated in axenic cultures comprising Gram-positive cells. Universal bacterila primers were used to amplify 16S rDNA from chromosomal DNA isolated from three of the four distinct colony groups. Restriction enzyme digest analysis of the 16S rDNA revealed seven RFLP types. Five of the RFLP types were subjected to sequencing. Comparison of the 16S rDNA sequence alignment to reference sequence data bases showed samples S2012A3, S2012B2 and S2012B3 to have between 95 and 99% homology to Bacillus sp. BH 164 and Bacillus sp. HS 136T, a novel species recently described as Bacillus persepolensis. Isolate S4102D4 showed 95 to 99% homology to Thalassobacillus sp. JY0201 and Thalassobacillus sp. FIB228 and Halobacillus sp. MO56 species. All five isolates had at least 95% similarity to published sequences implying they could be species within the described genera. A sub-tree drawn to compare the isolates indicated two phyletic lines with S4102D4 being an outlying strain and S2012A3, S2012B and S2012B3 being a closely related clonal group all of which branch from Bacillus sp. BH 164. Pending conclusive culture, biochemical and polar lipid composition data these microorganisms are regarded as previously un-described and therefore novel species of halophilic bacteria. URI: http://hdl.handle.net/10311/920 Files in this item: 1
Matsheka_AJPSB_2011.pdf (525.8Kb) -
Mubyana-John, T.; Wright, M.G. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: A study assessing fungi isolated from three climatic regions of Botswana as a possible control for root knot nematodes (Meloidogyne spp.) affecting the tomato(Lycopersicon esculentum L. var. ‘Money maker’) crops was conducted. Out of 1,250 soil fungal isolates, only 232 soil fungi from the Okavango Delta, Bobirwa district and different saltpans in Botswana could be sub cultured, and screened for antagonism against Meloidogyne sp. Seven of the isolates i.e., Trichoderma sp., Penicillium sp., Dendriphiopsis sp., Fusarium chlamydosporium, Cochliobolus sativus, Aspergillus fumigatus and an unidentified sterile fungus showed potential to immobilize nematode juveniles on agar plates within 2-4 days. C. sativus and Dendriphiopsis sp. showed maximum paralysis on agar plates and eventually death of the Meloidgyne sp. juveniles. In greenhouse studies using tomato plants the fungi alleviated the effect of nematodes by increasing plant, shoot height and root weight as compared to the reference controls. Cochliobolus sativus and Trichoderma sp. showed maximum plant protection of tomato plants under greenhouse conditions. Fungi ability to produce cellulase and chitinase were some of the mechanisms studied. The results indicated that Trichoderma sp., Penicillium sp., Dendriphiopsis sp., Fusarium chlamydosporium, Cochliobolus sativus and Aspergillus fumigatus are nematode antagonistic fungi indigenous to Botswana that can be used to control nematodes as they are better adapted in comparison to introduced fungi. URI: http://hdl.handle.net/10311/917 Files in this item: 1
Mbuyana-John_AJPSB_2011.pdf (813.1Kb) -
Murray-Hudson, M.; Mmopelwa, G. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: Most work globally on Phragmites spp. has been done in temperate northern hemisphere localities, where winter low temperatures and short day lengths cause a seasonal decrease in growth. In this study, we report above-ground stem length-mass relationships, stem densities and daily growth rates in 3 Phragmites australis reedbeds in the flood-pulsed, subtropical Okavango Delta, with the aim of assessing the economic value of this plant, which is widely used throughout north-western Botswana for cladding house walls and fencing yards. Stem density averaged 77m¯² in 32 plots. Length-mass relationships were best represented by a power function y = 8.05x¹•⁸⁵, where y is the dry mass in grams and x is the length in meters (r²=0.895). The mean daily growth rate was 0.015 m and did not appear to vary systematically with season. The maximum standing crop calculated from stem length was 2.89 kg m¯², and occurred in May 2005. Annual above-ground production was conservatively estimated at 20-30 t ha¯¹. Assuming that harvesting takes place not more than once annually, reed beds in the Okavango Delta are worth ~US$ 45,000 ha¯¹ at market. This land use value is over 90 times that of flood recession agriculture in the same area. URI: http://hdl.handle.net/10311/918 Files in this item: 1
Murray-Hudson_AJPSB_2011.pdf (1.180Mb) -
Banda, A.; Mubyana-John, T.; Taylor, J.E. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: The influence of burning on soil microbial dehydrogenase activity, nitrogen content and fungal population along the Boro route in the Okavango Delta was assessed in the flood and dry seasons. Soil samples from the burnt plots and the adjacent control un-burnt plots were cultured on agar plates using dilution methods. Fusarium spp. were dominant while Aspergillus species were low in burnt plots. The other fungi such as Drechslera sp., Exophiala jeanselmmei, Penicillium compactum and Chrysosporium merdarium were only in the burnt plots as compared to unburnt control plots. However, fungal diversity and soil dehydrogenase activity reduced after 6 months of burning showing significant increase in Chrysosporium merdarium in almost all the burnt plots. The influence of burning on soil nitrogen was insignificant instead flooding had a stronger influence on nitrogen content than burning. The results indicate that burning increased fungal diversity and biomass, however, reduces overall microbial enzyme activity after burning without influencing soil nitrogen and pH. URI: http://hdl.handle.net/10311/919 Files in this item: 1
Mbuyana_AJPSB_2011.pdf (220.0Kb) -
Muzila, M.; Setshogo, M.P.; Moseki, B.; Morapedi, R. (Global Science Books, http://www.globalsciencebooks.info/, NaN, 2011)[more][less]
Abstract: The genus Prosopis comprises 44 species. Extensive introgression and hybridization is suspected in the genus, which makes identification of the species very difficult. Accurate identification of the species is crucial in controlling invasive species, within this genus. That is so because the method of control is species specific. The objective of the study was to determine the taxonomic structure of Prosopis species in Southern Botswana. A systematic qualitative approach was used to sample the species such that specimen selection was based on observable morphological discontinuities. The morphological characters were subjected to multivariate analysis since the analysis has been reported to be good at identifying hybrids. The multivariate analysis included anova, cluster analysis, factor analysis and canonical correlation. The study revealed four pure lines of Prosopis and nine hybrid species. The pure lines are Prosopis chilensis, P. juliflora, P. velutina and P glandulosa and they all belong to one section, ALGAROBIA. The observed hybrids were P. chilensis x P. glandulosa, P. glandulosa x P. chilensis, P. juliflora x P. glandulosa, P. chilensis x P. juliflora, Acacia karroo x P. juliflora, P. glandulosa x P. pallid, P. juliflora x P. pallid, P. chilensis x P. juliflora x P. glandulosa and P. chilensis x P. pallida. It was therefore concluded that the Prosopis species in Southern Botswana have formed a hybrid swam. And for the hybrids P. chilensis x P. glandulosa and P. glandulosa x P. chilensis it was concluded that gene flow between P. chilensis and P. glandulosa is bidirectional. For the hybrid P. juliflora x P. glandulosa it was concluded that gene flow was from P. juliflora to P. glandulosa. URI: http://hdl.handle.net/10311/921 Files in this item: 1
Muzila_AJPSB_2011.pdf (252.4Kb)
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