Browsing Biological Sciences by Title
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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) -
Matsheka, M.I.; Lastovica, A.J.; Elisha, B.G. (American Society for Microbiology. http://jcm.asm.org/, NaN, 2001)[more][less]
Abstract: A 1.6-kb DNA fragment isolated from a Campylobacter concisus genomic library gave C. concisus-specific restriction fragment length patterns when it was used as a probe in hybridization studies. All of the strains tested, including type strains and clinical isolates, contained a 0.5-kb HindIII fragment that hybridized to the probe. DNA sequencing of the 1.6-kb fragment identified three open reading frames (ORFs). One of the ORFs encodes the carboxy terminus of GyrB, and the translational products of ORF2 and ORF3 showed similarity to hypothetical proteins, previously identified in Campylobacter jejuni. DNA-DNA hybridization studies with a fragment internal to ORF3 showed that this sequence was responsible for the signal observed with the 0.5-kb HindIII fragment. A rapid PCR assay was developed and evaluated. Primers that annealed to the extremities of the 1.6-kb fragment were used to obtain an amplicon of the correct size from both reference and clinical strains of C. concisus. URI: http://hdl.handle.net/10311/306 Files in this item: 1
Molecular identification of.pdf (4.701Mb) -
Mogobe, K.D.; Tshiamo, W.; Bowelo, M. (Elsevier, www.rhmjournal.org.uk, NaN, 2007)[more][less]
Abstract: This paper describes the maternity monitoring system in Botswana, developed in 1998, and the main methods used: maternal death and morbidity reviews at service delivery level, analysis by the National Maternal Mortality Audit Committee of data from the reviews as reported on two forms, perinatal reviews and surveys using process indicators. We carried out a study of these findings to examine whether the system was working well. Surveys using process indicators in 2001 and 2006 were analysed. Other data examined were from 2004–2006 and early 2007. The Maternal Death Notification Form was found to be comprehensive but not all health facilities were submitting them and some gave incomplete information. In 2001, 70% of pregnant women attended antenatal care but access to emergency obstetric care was uneven. In 2006, 28 facilities with maternity services surveyed were providing 24-hour delivery care, but laboratory, theatre and blood supplies were more limited, and only 50% of doctors and 67% of midwives had life-saving skills. Antibiotics were widely available, but there were shortages of magnesium sulphate, diazepam, oxytocics and manual vacuum aspiration kits. Recommendations for improvements have been made, training for skilled attendants is ongoing and a medical school has just opened at the University of Botswana. URI: http://hdl.handle.net/10311/498 Files in this item: 1
DintleMogobe2007Mortality.pdf (944.3Kb) -
Gnonlonfin, G.J.B.; Hell, K.; Fandohan, P.; Siame, A.B. (Elsevier B.V. www.elsevier.com/locate/ijfoodmicro, NaN, 2008)[more][less]
Abstract: The presence of fungi, aflatoxins and fumonisin B1 in cassava and yam chips (during 28 processing and storage) were evaluated during two consecutive seasons in two agroecological zones of Benin (Northern Guinea Savannah, NGS and Sudan Savannah, SS). The Benin samples were assessed for moisture content, fungal infestation and total aflatoxin and fumonisin B1 contamination. During the two seasons, samples collected from the NGS, had moisture contents ranging from 10.0 to 14.7% in cassava chips and from 11.4 to 15.3% in yam chips. In samples from the SS, moisture content ranged from 10.1 to 14.5% and 11.1 to 14.5% in cassava and yam chips, respectively. A. flavus was the predominant fungal species. The maximum cfu/g in cassava and yam chips was 8950 and 6030, respectively. Other fungal species isolated included P. chrysogenum, M. piriformis, Phoma sorghina, F. verticillioides, R. oryzae and Nigrospora oryzae. High performance liquid chromatography analysis of both cassava and yam chips showed no contamination by either aflatoxins or fumonisin B1. URI: http://hdl.handle.net/10311/317 Files in this item: 1
Mycoflora and natural occurrence.pdf (5.959Mb) -
Moyo, S.; Gashe, B.A.; Collison, E.K.; Mpuchane, S. (Elsevier / www.elsevier.com/locate/ijfoodmicro, NaN, 2003)[more][less]
Abstract: This present study was undertaken to find optimum conditions of pH, temperature and, period of incubation for the pectinolytic activity of Kluyveromyces wickerhamii isolated from rotting fruits and to assess the effect of these factors by use of response surface methodology (RSM). A central composite rotatable design was used as an experimental design for the analysis of the allocation of treatment combinations. A second order polynomial regression model was fitted and was found adequate, with an R2 of 0.94469 ( P < 0.001). The effects of temperature and pH were the most significant factors in influencing enzyme production. Estimated optimum conditions were as follows: pH 5.0, temperature, 32 jC and an incubation period of 91 h. Pectinesterase (PE), pectin lyase (PL), and cellulase activities were not detected. Pectinase production was partially constitutive. Pectin was degraded by the isolated strain of K. wickerhamii in the current study, and the pectinolytic activity is referred to as polygalacturonase (PG) activity. Crude enzyme extract was thermostable at various temperatures and, stimulated by the presence of Ca2 + ions but inhibited by other ions like Mg2 +, Zn2 +, Co2 +, Mn2 + and Na+. URI: http://hdl.handle.net/10311/228 Files in this item: 2
license.txt (1.998Kb)Moyo_IJFM_2003.pdf (2.012Mb) -
Morobe, I.C.; Obi, C.L.; Nyila, M.A.; Gashe, B.A.; Matsheka, M.I. (Academic Journals, http://www.academicjournals.org/AJB, NaN, 2009)[more][less]
Abstract: Listeria monocytogenes is known to cause epidemic and sporadic cases of listeriosis. The present study investigated the occurrence, antibiograms and molecular serotypes of the organism in various retail outlets in Gaborone, Botswana. Food samples were obtained randomly from selected supermarkets and street vendors in 5 geographical areas of Gaborone from May, 2007 to September 2007. L. monocytogenes was isolated and positively identified by using morphological and biochemical tests. From a total of 1324 food samples tested 57(4.3 %) were positive for L. monocytogenes. Out of the 57 isolates of L. monocytogenes 7 (12.3%), 3 (5.3%), 0 (0%), 27 (47.4%) and 20 (35.1%) were isolated from cheese, raw milk, meat (biltong), frozen cabbage and salad (coleslaw), respectively. From the 5 geographical areas selected for sampling in this study, Gaborone South recorded the highest number 19 (33.3%) of L. monocytogenes isolates while Gaborone West recorded the least, 7 (12.3%). The findings in this study reveal the presence of L. monocytogenes serotypes 1/2a and 1/2b in ready to eat food and highlight the need for education and training programmes in food safety in Gaborone, Botswana. URI: http://hdl.handle.net/10311/996 Files in this item: 1
Morobe_AJB_2009.pdf (86.64Kb) -
Chaturvedi, P.; George, S.; John, A. (British Journal of Biomedical Science. http://www.ibms.org/index.cfm?method=publications.british_journal, NaN, 2007)[more][less]
Abstract: In the present study, preventive and protective effects of Ocimum gratissimum in ethanol-induced hepatotoxicity are assessed in albino rats. A methanol extract of O. gratissimum leaves is prepared, with a yield of 3.5% (w/w) of the dry weight of leaves. Graded doses of the extract (10, 20, 40 and 80 mg/kg body weight), together with ethanol (5 gm/kg body weight) are administered orally to experimental groups for 30 days. Normal control rats receive distilled water only, while rats in an alcohol control group (AC) receive ethanol only for 30 days. O. gratissimum reduced the level of thiobarbituric acid reactive substance in all experimental groups (E1â E4). Alanine transaminase and aspartate transaminase levels fell in all experimental groups (E1â E4), but this reduction was significant only in groups E3 and E4 (P<0.05), indicating inhibition of lipid peroxidation by free radicals generated after ethanol metabolism. Levels of antioxidants also increased. Ascorbic acid and glutathione levels increased in all experimental groups (E1â E4; P<0.05 and P<0.01, respectively). A significant increase in catalase (P<0.05) was noted only in group E4, although an upward trend was noted in all experimental groups. This study shows that O. gratissimum prevents free radical damage to the liver and thus protects the organ from oxidative stress. URI: http://hdl.handle.net/10311/309 Files in this item: 1
Preventive and pro.pdf (2.493Mb) -
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) -
Bonyongo, M.C.; Mubyana, T. (South African Journal of Science, http://www.sajs.co.za/, NaN, 2004)[more][less]
Abstract: WETLANDS SUCH AS THE OKAVANGO Delta, located in semi-arid regions, are of great ecological, environmental and socio-economic importance. In most cases, however, few data exist on nutrient cycling in these areas. This paper presents preliminary results of an ongoing study, which investigates the influence of seasonal flooding on soil nutrient status in the different vegetation communities of the delta. Soil K, Na, and pH significantly increased with a decrease in soil moisture, with the values increasing from the primary floodplains to the islands communities. Available P, Ca and Mg decreased as the elevation gradient increased from the riverbed. Although nutrient status generally was highest in the floodplain vegetation areas adjacent to the riverbed, there was no significant difference in available P, Ca and Mg within the vegetation communities. Calcium levels in the different vegetation zones were more influenced by rainfall than floodplain vegetation community. Higher soil Ca was observed in the rainy season, while elevated Mg was recorded after the rains. Overall, these results indicate that flooding is an essential aspect of the Okavango Delta as it may be a primary source of some of the soil nutrients that support the high diversity of plants sustaining the delta’s ecosystem. URI: http://hdl.handle.net/10311/401 Files in this item: 1
Soil nutrient status.pdf (1.635Mb) -
Thior, I.; Gabaitiri, L.; Grimes, J.; Shapiro, R.; Lockman, S.; Kim, S.; Kebaabetswe, P.; Garmey, E.; Montano, M.; Peter, T.; Chang, S.; Marlink, R.; Essex, M. (Elsevier www.elsevier.com/locate/pateducou, NaN, 2007)[more][less]
Abstract: Objective: To determine uptake and socio-demographics predictors of acceptance of voluntary counseling and testing (VCT) among postpartum women in Botswana. Methods: Women attending maternal and child health clinics for their first post-partum or well baby visit in three sites in Botswana were offered VCTafter a written informed consent. A standardized questionnaire was used to collect socio-demographic characteristics and reasons for declining VCT. Results: From March 1999 to November 2000, we approached 1735 post-partum women. Only 937 (54%) of those approached accepted VCT. In multiple logistic regression analysis, younger maternal age, not being married, and less formal education were significant predictors of acceptance of VCT. Thirty percent of women who accepted VCT were HIV-positive. Conclusion: Our results indicated that in Botswana prior to the initiation of a government Mother to Child Transmission (MTCT) prevention program, younger, unmarried, and less educated post-partum women were more likely to undergo VCT. Practice implications: Our results have shown that interventions to improve VCT among post-partum women and more generally among women of reproductive age are warranted in Botswana. These interventions should account for differences such age, marital status, education, and partner involvement to maximize VCT uptake. URI: http://hdl.handle.net/10311/588 Files in this item: 1
GABAITIRI2007VOLUNTARY COUNSELING.pdf (642.1Kb)
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