Browsing Biological Sciences by Title
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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) -
Mpuchane, S.; Allotey, J.; Matsheka, I.; Simpanya, M.; Coetzee, S.; Jordaan, A.; Mrema, N.; Gashe, B.A. (ICIPE - African Insect Science for Food and Health, http://journals.cambridge.org/action/displayJournal?jid=JTI, NaN, 2006)[more][less]
Abstract: Domestic cockroaches Blattella germanica were trapped from various homes in Gaborone, Botswana using ‘Dyroach’ traps. Isolations of bacteria, yeasts and moulds were done on external body parts and on the faecal pellets using various selective media. Body parts of cockroaches were also fixed with OsO4 vapour for 24 h, sputter coated with gold under special conditions and examined in a Phillips (1) XL30 ESEM in low vacuum mode. Awide spectrum of bacteria including common food spoilage and pathogenic organisms, such as Bacillus spp., Staphylococcus spp., Escherichia coli, Pseudomonas spp., Enterobacter spp., Klebsiella spp., Erwinia spp. Salmonella sp., Shigella sp. and Serratia spp. were isolated. Yeasts commonly associated with food spoilage, such as Pichia sp., Candida sp. and Torulopsis spp. were found on many cockroaches. In addition, various groups of moulds, some associated with food spoilage and others known to produce mycotoxins, such as Aspergillus flavus, Aspergillus fumigatus and Aspergillus parasiticus were isolated. Antimicrobial sensitivities of bacterial isolates revealed resistance patterns to various agents. Since cockroaches are prevalent in homes, particularly in food preparation areas and since their body parts and faecal pellets have been found in food storage areas, concern about their impact on food quality and safety is raised and possible control measures including education of communities on proper sanitation are suggested. URI: http://hdl.handle.net/10311/1005 Files in this item: 1
Matsheka_IJTIS_2006.pdf (193.3Kb) -
Mpoloka, S.W.; Kgotlele, T.; Wally, A. (Academic Journals, www.academicjournals.org, April 17, 2008)[more][less]
Abstract: Allele frequencies for nine short tandem repeat (STR) loci from the AmpFlSTR® Profiler Plus PCR Amplification Kit were determined in five subpopulations across Botswana and tested for suitability for use in individual identification. DNA was extracted from whole blood samples collected from 150 unrelated individuals. Targeted regions of DNA (vWA, FGA, D3S1358, D5S818, D7S820, D8S1179, D13S317, D18S51, D21S11 and the sex determining locus Amelogenin) were amplified using multiplexed PCR. The alleles showed a high degree of polymorphism, with heterozygosity above 67%, indicating that there is no significant inbreeding within the subpopulations. Matching probability was below 0.2 hence power of discrimination was high, indicating that the alleles from the five subpopulations can be used in human identifications. The present study is the first reported attempt at determining allele frequencies of subpopulations in Botswana and could possibly be used in developing a national DNA database. URI: http://hdl.handle.net/10311/1010 Files in this item: 1
mpoloka ajb paper.pdf (292.5Kb) -
Chaturvedi, P.; George, S.; Milinganyo, M.; Tripathi, Y.B. (John Wiley & Sons, Ltd, http://onlinelibrary.wiley.com/journal/10.1002/(ISSN)1099-1573, NaN, 2004)[more][less]
Abstract: In this study, the methanol extract of Momordica charantia fruit extract was administered to diabetic rats to assess the long term effect of the extract on the lipid profile and the oral glucose tolerance test. Treatment for 30 days showed a significant decrease in triglyceride, low density lipoprotein and a significant increase in high density lipoprotein level. A significant effect on oral glucose tolerance was also noted. Chronic administration showed an improvement in the oral glucose tolerance curve. The effect was more pronounced when the test was done in rats fed the extract on the day of the test compared with tests done in rats which were not fed the extract on the same day. URI: http://hdl.handle.net/10311/1017 Files in this item: 1
Chaturvedi_PR_2004.pdf (258.2Kb) -
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.; Segale, M. (Academic Journals http://www.academicjournals.org/SRE/index.htm, NaN, 2007)[more][less]
Abstract: Four types of extracts were prepared from Melia azedarach fruits. These were methanol extract and three types of water decoctions; urine treated water decoction (UE), milk treated water decoction (ME) and plain water decoction (WE). Different doses of these four extracts were tried in normal rats to estimate the hypoglycemic activity of these extracts against glucose induced hyperglycemia. Most potent doses of all the extracts were assessed for their effects on lipid peroxidation, toxic effects on liver and reduced glutathione which is considered as first line of defense against free radicals in normal rats after 10 days of oral administration. All the extracts were found to posses hypoglycemic properties. Methanol extract showed toxic effects on the liver as indicated by high activities of Serum glutamate oxaloacetate (SGOT) and serum glutamate pyruvate tranasaminase (SGPT). It also indicated high rate of lipid peroxidation and depleted reduced glutathione levels of plasma. On the other hand three water decoctions showed very low activities of SGOT, SGPT, very low rates of lipid peroxidation and high levels of reduced glutathione. Extract prepared by the Ayurvedic method reduce blood glucose in glucose induced hyperglycemic rats and impart no toxicity. URI: http://hdl.handle.net/10311/181 Files in this item: 2
Effects of different types of water.pdf (836.9Kb)license.txt (1.998Kb) -
Mpoloka, S.W. (Academic Journals. http://www.academicjournals.org/AJB, NaN, 2008)[more][less]
Abstract: Over the past few decades, there has been a depletion of the stratospheric ozone layer due to emissions of halogen-containing compounds of anthropogenic origin. This has resulted in a concomitant increase in solar ultraviolet-B radiation. High levels of UV-B radiation are responsible for multiple biologically harmful effects in both plants and animals. In plants, these effects include DNA damage, which often causes heritable mutations affecting various physiological processes, including the photosynthetic apparatus, protein destruction and signal transduction via UV-B photoreceptors. High UV-B levels introduce a number of different lesions, predominantly cyclobutane pyrimidine dimmers (CPDs) and pyrimidine (6-4) pyrimidinone products [(6-4) PPs] in the genome. These could adversely affect plant growth, development and morphology, especially the productivity of sensitive crop species. This paper reviews the genetic effects of long-term UV-B exposure in plants. URI: http://hdl.handle.net/10311/491 Files in this item: 1
Effects of prolonged.pdf (2.345Mb) -
Siele, M.P.; Mubyana-John, T.; Bonyongo, M.C. (Global Science Books http://www.globalsciencebooks.com/index.php?page=shop.product_details&category_id=1&flypage=shop.flypage&product_id=5&option=com_virtuemart&Itemid=56&vmcchk=1&Itemid=56, NaN, 2008)[more][less]
Abstract: Soil cover influences soil biological and chemical processes in various ways. The effects of soil cover (bare soil without litter, litter cover, Mopane tree canopy and grass cover) on soil respiration and microbial population at four sites in the Mopane woodland of north western Botswana were investigated. Soil respiration rates were measured using an infrared gas analyzer. Nitrifying bacterial populations were quantified by MPN on ammonium and nitrite calcium carbonate media, oligotrophs on 1% nutrient agar, actinomycetes on starch casein agar, bacteriovorous protozoans by MPN on sodium chloride agar baited with Enterobacter, and fungal biomass carbon using buried slides were also determined. Soil respiration in different habitats was significantly influenced by type of cover, diurnal temperature variations and soil moisture. Soils under cover showed significantly higher soil respiration than the bare soils. Autochthonous bacterial populations in the Mopane woodland soils consisted mostly of oligotrophs which varied insignificantly between seasons. Fungi were the most dominant microorganisms in all the Mopane woodland soils, with biomass of 162.05 to 282.14 μg C/g soil in the wet season and 11.84 to 44.16 μg C/g soil in the dry season. Microscopic observation of buried slides revealed that fungi play a vital role in holding soil particles together in these soils. The results showed a strong positive relationship between changes in fungal biomass and fluctuation of soil respiration. However, no clear correlation was observed between the variation of soil respiration and other microbial populations (oligotrophic bacteria, actinomycetes, and nitrifying bacteria). Overall these results indicate that in soils under Mopane tree canopy, fungi contribute significantly to soil structure and soil respiration. Other microbial populations consist mostly of oligotrophs which show minimal seasonal variations. Soil moisture significantly influences seasonal fluctuation in soil respiration. URI: http://hdl.handle.net/10311/292 Files in this item: 1
The Effects of Soil Cover.pdf (6.625Mb) -
Evaluation of methods for the isolation, detection and quantification of cyanobacterial hepatotoxinsMsagati, T.A.M.; Siame, B.A.; Shushu, D.D. (Elsevier Ltd. http://www.elsevier.com/wps/find/journaldescription.cws_home/505509/description#description, NaN, 2006)[more][less]
Abstract: Cyanobacterial hepatotoxins such as microcystins and nodularins have been responsible for the poisoning of both animals and humans who ingest or come into contact with toxic blooms. They are extremely stable in water due to their stable chemical structure and can tolerate radical changes in water chemistry, including pH and salinity. Different methods for the extraction and detection of these compounds have been reported. Extraction methods utilizing both aqueous and organic solvent systems have been reported. The detection methods ranging from immunological or biochemical assays such as enzyme linked immunosorbent assays (ELISA) and enzyme activity assays, to chemicals methods such as high performance liquid chromatography (HPLC) and more sophisticated liquid chromatographyà ¢ mass spectrometry (LC-MS) have been documented as well. We review some important aspects of cyanobacterial hepatotoxins and methods of analysis for these toxins. URI: http://hdl.handle.net/10311/218 Files in this item: 2
license.txt (1.998Kb) -
Mubyana-John, T.; Wutor, V.C.; Yeboah, S.O.; Ringrose, S. (Academic Journals. http://www.academicjournals.org/SRE, NaN, 2007)[more][less]
Abstract: The influence of wild fires on microbial community structure, soil organic matter, sulphur oxidising and nitrifying microbial populations in the floodplains of the Okavango Delta of Botswana was assessed. Microbial community structure was assessed by phospholipids ester-linked fatty acids (PLFA) quantification while microbial sulphur oxidisers were assessed by Most Probable Number (MPN). Community structure assessment showed that burning shifted the microbial community structure from single cellular bacteria being the dominant groups to filamentous fungi and actinomycetes being the most dominant groups. Generally burning increased the fungal component (18:2 w6) matrix from 3.40 to 8.35 while the actinomycetes and sulphur reducing bacterial (10 Me 16:0) component also increased from 1.02 to 1.70 mostly in the floodplains. Generally, the organic matter content declined with burning. However, the influence of burning on soil pH was non conclusive. Soil microbial biomass carbon increased slightly after the fire. The number of heterotrophic and nitrite-oxidizing and sulphur reducing bacteria increased. Overall, these results indicate that burning significantly alters the microbial community structure as large above ground losses of nutrients during and after burning often results in low quantities of nutrients released into the soil. URI: http://hdl.handle.net/10311/349 Files in this item: 1
Fire and.pdf (2.461Mb) -
Omari, K.; Mubyana, T.; Matsheka, M.I.; Bonyongo, M.C.; Veenendaal, E. (South African Journal of Botany http://www.elsevier.com/wps/find/journaldescription.cws_home/707238/description#description, NaN, 2004)[more][less]
Abstract: Effects of flooding on soil nitrogen (N), and asymbiotic nitrogen fixing bacterial (diazotroph) populations of the Okavango Delta were investigated. Diazotrophs from the rhizosphere of dominant annual and perennial grasses of the Okavango Delta were isolated on N-free composite media and identified applying morphological and biochemical criteria and Restriction Fragment Length Polymorphism (RFLP). Azotobacter species were found associated mostly with the grasses Andropogon guyanus and Vetevaria nigritiana (103CFU g–1 rhizosphere soil). Annual grasses such as Eragrostis inamoena, Setaria sphacelata as well as perennials showed insignificant populations (<101CFU g–1 soil). On the contrary, Azospirillum spp. was found associated with most of the grasses. Highest population densities (above 104MPN g–1 soil) were observed in rhizospheres of E. inamoena, Cympogon excavatus, Sporobolus acinifolis, Eragrostis lapila and Eragrostis rigidor and lowest population densities (below 102MPN g–1 soil) in rhizospheres of Andropogon guyanus and Panicum repens. Flooding increased the Azotobacter populations, while Azospirillum spp. populations were significantly reduced. Nitrogen-fixing sulphur reducers were observed in the rhizosphere of annuals (A. guyanus and P. repens) and only in perennials growing in flooded soils. No Beijerinckia species were found associated with any of the grasses. The highest soil nitrogen levels were detected in flooded soils (<0.20% N) while no N was detected in the rhizosphere soil of grasses growing in very dry soils (<5% moisture content). The results indicate that in the Okavango Delta, total soil nitrogen varies with flooding regime. With flooding, the diazotroph population shifts towards Azotobacter and Nfixing sulphur reducers while Azospirillum spp. are widespread in non-flooded soils. RFLP analysis of the 1 450bp amplicon using the restriction endonuclease Alu1, showed three different banding profiles, suggesting the occurrence of three different species of Azospirillum. URI: http://hdl.handle.net/10311/294 Files in this item: 1
Flooding and its influence.pdf (2.253Mb) -
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) -
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) -
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) -
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) -
Mubyana, T.; Krah, M.; Totolo, O.; Bonyongo, M. (Journal of Arid Environments. http://www.elsevier.com/wps/find/journaldescription.cws_home/622855/description#description, NaN, 2003)[more][less]
Abstract: The effect of flooding on soil total nitrogen, phosphorus and microbial population in different vegetation zones (floodplain, island and woodland) and profile depth (0?1, 0?5, 2?0, 3?0, 4?0 and 5?0m) of the Okavango Delta was studied from February to July 1999. Total nitrogen significantly differed with soil profile depth, moisture regime and months. In the woodlands, insignificant total nitrogen was detected at all depths except at 0?1m, where 0?03% and 1?17% were detected in February and March, respectively. In the island samples, only 0?05% was detected at 4m in February. Nitrogen in the floodplain samples was concentrated in the A1 horizon where 0?12%, 0?61% and 0?03% were detected in February, March, and May, respectively. Organic phosphorus significantly differed with vegetation zone but not with months and depth. Although organic phosphorus was low (0?02–0?52%) at all sites, it was liberally distributed throughout the profiles. On the island, actinomycetes were only detected up to 2m in February and up to 3m in July. Fungi concentrated in the top 0?5m (103–105). In both the floodplain and island samples, bacteria concentrated in the upper 3m. However, after May, populations decreased significantly. In the floodplain, significant actinomycetes populations were only detected in the upper 0?5m. Generally, organic phosphorus showed positive correlations with fungal populations. This study indicates that these soils are low in total nitrogen and phosphorus. URI: http://hdl.handle.net/10311/293 Files in this item: 1
Influence of seasonal flooding.pdf (3.953Mb) -
Chaturvedi, P. (Oxford University Press, Oxford Journals; http://ecam.oxfordjournals.org/, March NaN, 2008)[more][less]
Abstract: In the present study, inhibitory effect of the methanol extract of Raphanus sativus root on lipid peroxidation has been carried out in normal rats. Graded doses of methanol extract of root of the plant (40, 80 and 120 mg kg 1 body weight) were administered orally for 15 days to experimental treated rats. Distilled water was administered to experimental control rats. At the end of experiment, rats were killed by decapitation after ether anesthesia. Blood and liver were collected to measure thiobarbituric acid reactive substance, reduced glutathione and activity of catalase. Results indicated that the extract of R. sativus root reduced the levels of thiobarbituric acid reactive substance significantly in all experimental treated groups (P50.05) as compared to the experimental control group. It also increased the levels of reduced glutathione and increased the activity of catalase. In vitro experiments with the liver of experimental control and experimental treated rats were also carried out against cumene hydroperoxide induced lipid peroxidation. The extract inhibited in vitro cumene hydroperoxide induced lipid peroxidation. R. sativus inhibits lipid peroxidation in vivo and in vitro. It provides protection by strengthening the antioxidants like glutathione and catalase. Inclusion of this plant in every day diet would be beneficial. Description: eCAM Advance Access originally published online on February 20, 2007 eCAM 2008 5(1):55-59; doi:10.1093/ecam/nel077 Version available here is the 2007 version. URI: http://hdl.handle.net/10311/182 Files in this item: 2
Inhibitory response of raphanus.pdf (861.5Kb)license.txt (1.998Kb) -
Mpoloka, S.W. (American-Eurasian Network for Scientific Information. http://www.aensi.org/aeb_online.html, NaN, 2008)[more][less]
Abstract: The nuclear 18S rDNA and chloroplast encoded rbcL gene sequences were used to investigate the evidence of residual UV-B induced mutagenesis in Dimorphotheca sinuata plants. The probes were generated by the polymerase chain reaction and labelled with a non-radioactive Digoxigenin label and used in Southern hybridization studies. High levels of variability in the 18S rDNA gene were found, pointing to genome rearrangements and possibly genome instability due to UV-B effects. URI: http://hdl.handle.net/10311/484 Files in this item: 1
Investigating evidence.pdf (1.233Mb) -
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) -
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)