Department of Molecular Biology and Biotechnology

Permanent URI for this collection

https://repository.udsm.ac.tz/handle/123456789/42

Browse

Browsing Department of Molecular Biology and Biotechnology by Issue Date

Filter results by year or month
Now showing 1 - 20 of 186
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Screening of Peach Fruit Cultivars in the Southern Highlands of Tanzania
    (1988) Nyomora, Agnes M. S.
    The Southern Highlands of Tanzania lie between Latitudes 6° 31'S and 10° 75'S at a Longitude of 30° 30'E and 36° 30'E. More than 30% of the area is at an elevation of between 1 500 m to above 2 500 m.a.s.l. The weather is generally cool. Temperature range between a mean maximum of 23°C and mean minimum of 14°C. The coolest months May, June, July and August have mean minimum temperatures below 10°C decreasing with increasing altitude. Frost during these months is common. Rainfall totals over 800 mm, with the rainy season being between the months of November - April. The soils are generally of medium to high fertility. The potential for growing temperate fruits in the Southern Highlands of Tanzania is therefore very high. The important temperate fruits grown in the region include peaches, plums, apples and pears produced mainly at the subsistence level of 15–30 trees per household. A few farmers and public institutions have bigger orchards of between 2 and 5 acres yielding between 10 and 20 kg per tree compared to 30–40 kg obtained in average orchards elsewhere. The main problems of temperate fruit production in the region are low fruit yield per tree and poor quality fruits as a result of poor cultivars, management practices and inadequate chilling. Research activities have been in existence since 1973. The fields of investigation are collection of improved cultivars and screening them for adaptability as well as management trials. Research work on peaches has advanced much more than that on apples, pears and plums. The latter are still at the level of observation orchards. Of the local collection of peaches results to date are in favour of TCEC, DF no. 58, and Dabaga no. 14. Flordabelle peach and Sunred nectarine, of the cultivars imported in 1976, do well in our tropical climate.
  • Thumbnail Image
    Item
    Women in Horticulture: A Case Study of Mbeya Rural Area in Tanzania
    (1989) Nyomora, Agnes M. S.
    A case study was undertaken at Uyole, a small village in Mbeya region (Latitude 8 53's and Longitude 33 39'E) to find out the extent of women involvement and problems in horticultural crop production. Horticultural crops commonly grown at Uyole include tomatoes, cabbage, onion, garlic, carrots and amaranthus. Of the 50 women interviewed, less than 10% were involved in the actual production as well as both production and retailers) of the crops. A large percentage of the production was in the hands of men particularly when the crops attained a commercial status. Household activities among other reasons prevented women from involving themselves into this labour intensive and risky adventure.
  • Thumbnail Image
    Item
    Nitrogen Fixation by Methanobacterium Formicicum
    (1991-02) Magingo, Francis S.; Stumm, Claudius K.
    Methanobacterium formicicum utilized molecular nitrogen as the sole nitrogen source for growth as monitored by methane production and culture turbidity measurements. The rate of methane production by the bacteria was correlated to nitrogen gas concentrations. In the absence of nitrogen gas or any other nitrogen source, the bacteria completely stopped growing. The presence of selenium and molybdenum in the culture medium was vital for the growth of the bacteria under nitrogen fixing conditions.
  • Thumbnail Image
    Item
    Influence of Hydraulic Retention Time on Start-Up and Process Stability of Polyurethane Carrier Reactions
    (1992) Rubindamayugi, M. S. T.; Op Den Camp, H. J. M.; Lubberding, H. J.; Gijzen, H. J.; Vogels, G. D.
    Influence of hydraulic retention time (HRT) on start-up of Polyurethane Carrier Reactors treating Volatile Fatty Acids (VFA) based wastewater, at constant organic loading rate (OLR) was investigated. OLR was increased stepwise after start-up to evaluate the influence of HRT on process stability. Four parallel experiements were conducted at HRTs of 48, 24, 18 and 12 hours. Results indicate an influence of HRT on duration of start-up period, and process stability after start-up. The reactor operating at HRT of 24 hours required only a relatively stort start-up period and showed higher process stability under steady-state condition. Analysis of individual VFA degradation indicated that butyrate and propionate consuming acetogenic bacteria increased in sigmoid fashion during start-up. Changes in acetate degradation do not show the true increase of acetoclastic population. Instead they reflect concomitant activity of VFA catabolizing acetogens and aceloclastic methanogens . Immobilized biomass increased exponentially during the first three weeks of start-up. The differences in start-up periods between reactors was probably due to differences in quality and activity of biomass immobilized at different HRTs. The HRT of 24 hours was most optimal to obtain stable reactor performance within a short startup period.
  • Thumbnail Image
    Item
    Foliar Boron Application Enhances Almond Yields
    (1996) Brown, Patrick H.; Hu, Hening; Nyomora, Agnes M. S.; Freeman, Mark
    A three-year study in California shows that foliar boron (B) applications can increase yield in almonds even where there are no visible leaf symptoms of B deficiency. Data suggest that foliar applications act specifically to enhance the number of flowers that set fruit.
  • Thumbnail Image
    Item
    Saccharification and Alcohol Fermentation in Starch Solution of Steam-exploded Potato
    (1996-12) Kobayashi, Fumihisa; Sawada, Tatsuro; Nakamura, Yoshitoshi; Ohnaga, Makoto; Mtui, Godliving Y. S.; Ushiyama, Tomoo
    Steam explosion pretreatment of potato for the efficient production of alcohol was experimentally studied. The amount of water-soluble starch increased with the increase of steam pressure, but the amounts of methanol-soluble material and Klason lignin remained insignificant, regardless of steam pressure. The potatoes exploded at high pressure were hydrolyzed into a low molecular liquid starch, and then easily converted into ethanol by simultaneous saccharification and fermentation using mixed microorganisms: an amylolytic microorganism,Aspergillus awamori, and a fermentation microorganism,Saccharomyces cerevisiae. The maximal ethanol concentration was 4.2 g/L in a batch culture at 15 g/L starch concentration, and 3.6 g/L in a continuous culture fed the same starch concentration. In the fed-batch culture, the maximal ethanol concentration increased more than twofold, compared to the batch culture.
  • Thumbnail Image
    Item
    Boron Determination in Biological Materials by Inductively Coupled Plasma Atomic Emission and Mass Spectrometry: Effects of Sample Dissolution Methods
    (Springer Link, 1997) Nyomora, Agnes M. S.; Sah, R. N.; Brown, Patrick H.; Miller, R. O.
    This study compares four sample dissolution methods for Boron determination in two National Institute of Standard and Technology (NIST) botanical Standard Reference Materials (SRMs) and three Agriculture Canada/NIST RMs, each having a reference (certified or best estimate) B concentration. The dissolution treatments consisted of: 1) dry ashing at 500° C, 2) wet digestion with HNO3 + H2O2, 3) extraction with hot HNO3 and 4) closed vessel microwave dissolution. The samples were spiked before and after imposing dissolution treatments to study B recovery by inductively coupled plasma mass spectrometric (ICP-MS) analysis. Microwave digests of NIST SRM 1515 and some in-house RMs were also used to compare the B values of ICP-MS and ICP-AES (atomic emission spectrometry). While all three digestion methods (dry ashing, wet ashing and microwave) dissolved botanical samples, only the microwave method worked well for animal tissues. In terms of B values in these materials, there was no significant difference among the three digestion treatments. Near 100% recovery of B spiked before and after the sample dissolution indicates that there may not be a significant loss of B during the dissolution process used in this study. Extraction with hot HNO3 was as effective as the three digestion treatments, and B values for this method agreed well with reference values. For the botanical materials studied, the B values determined by ICP-AES were not significantly different from ICP-MS values. This study shows that a simple, time and labor efficient hot HNO3 extraction is as effective as other digestion/dissolution methods for quantitative B recovery from biological materials.
  • Thumbnail Image
    Item
    Fall Foliar-applied Boron Increases Tissue Boron Concentration and Nut Set of Almond
    (1997) Nyomora, Agnes M. S.; Brown, Patrick H.; Freeman, Mark
    Fruit set is the major determinant of productivity in almond [Prunus dulcis (Mill D.A. Webb)] where seed is the commercial product. Boron influences flowering and fruit set in a number of crops, but little has been reported on this subject in almond. Here, we investigated the effect of a fall foliar application of B on fruit set and tissue B concentration in open pollinated `Butte' and `Mono' almond over a 2-year period. Early fall B application significantly increased the vegetative, floral, and fruit tissue B concentration in the subsequent year. The greatest increase in organ B concentration was observed in flower buds, flowers, and hulls. Recent work has demonstrated that B forms a B-sorbitol complex in Prunus species. This B-sorbitol complex is phloem mobile and is transported to sink organs. Here we demonstrate that fall-applied B is absorbed by the leaf and is subsequently transported (presumably as the B-sorbitol complex) to floral buds where it is available to flowers and, hence, influences fruit set and yield. It is concluded that fall foliar-applied B is a useful fertilization strategy that can be used to optimize tissue B concentration in species in which B is phloem mobile. Boron applied at 245 and/or 490 ppm significantly increased fruit set in `Butte' and `Mono' and increased yield of `Butte' in 1994 on open-pollinated trees (yield was not determined in 1993). The highest initial and second fruit set was associated with either the 245 or 490 ppm B treatments in both cultivars and both years. This increased fruit set resulted in yield increases of 53% and 4%, respectively, for `Butte' and `Mono'. Of the two cultivars, `Butte', which had lower tissue B concentration before B application, responded more significantly in yield to B application. Application of 735 ppm B was less effective than either 245 and 490 ppm B; however, no visual symptoms of excess B were observed.
  • Thumbnail Image
    Item
    Microbial Treatment of Kraft Pulp Wastewater Pretreated with Ozone
    (1997-02) Nakamura, Y.; Sawada, T.; Kobayashi, F.; Mtui, Godliving Y. S.
    Kraft pulp wastewater was treated with a combination of ozone and activated sludge. The effects of pH on the degradation of lignin and the production of organic acids were examined experimentally in the ozonolysis of wastewater. The strong alkaline condition enhanced not only the degradation of lignin but also the production of organic acids. The dynamic behaviours of microbial growth and substrate consumption were investigated in the biodegradation of organic acids using activated sludge. Maleic acid and oxalic acid in the ozonized wastewater were degraded completely by the activated sludge. The immobilized activated sludge culture using polyurethane foam was effective in degrading organic acids.
  • Thumbnail Image
    Item
    Cytosolic Enzymes with a Mitochondrial Ancestry from the Anaerobic Chytrid Piromyces Sp. E2. Mol Microbiol 30:1017-1027
    (1998) Akhmanova, Anna; Voncken, Frank; Harhangi, Harry R.; Hosea, Ken M.; Vogels, Godfried D.; Hackstein, Johannes H. P.
    The anaerobic chytrid Piromyces sp. E2 lacks mitochondria, but contains hydrogen-producing organelles, the hydrogenosomes. We are interested in how the adaptation to anaerobiosis influenced enzyme compartmentalization in this organism. Random sequencing of a cDNA library from Piromyces sp. E2 resulted in the isolation of cDNAs encoding malate dehydrogenase, aconitase and acetohydroxyacid reductoisomerase. Phylogenetic analysis of the deduced amino acid sequences revealed that they are closely related to their mitochondrial homologues from aerobic eukaryotes. However, the deduced sequences lack N-terminal extensions, which function as mitochondrial leader sequences in the corresponding mitochondrial enzymes from aerobic eukaryotes. Subcellular fractionation and enzyme assays confirmed that the corresponding enzymes are located in the cytosol. As anaerobic chytrids evolved from aerobic, mitochondria-bearing ancestors, we suggest that, in the course of the adaptation from an aerobic to an anaerobic lifestyle, mitochondrial enzymes were retargeted to the cytosol with the concomitant loss of their N-terminal leader sequences.
  • Thumbnail Image
    Item
    Rooting Ability of Leucaena Leucocephala Stem Cuttings
    (1998-08) Dick, J.; Magingo, Francis S.; Smith, R. I.; McBeath, C.
    Single-node leafy and leafless cuttings harvested from one-year-old, 1.3 to 1.5 m tall Leucaena leucocephala seedlings were successfully rooted in a non-mist propagator which is suitable for use in the rural tropics. Cuttings with a leaf attached rooted more successfully than those without a leaf (71% and 39% respectively) and clones differed significantly (43% to 71%). There was also a clear pattern in rooting ability of cuttings collected sequentially down the main stem. Cuttings rooted most successfully when taken from node five to 13, counting from the apex; this was the region where internodes were longest (64 to 109 mm) of moderate diameter (2.9 to 5.5 mm) and all cuttings had a leaf attached.
  • Thumbnail Image
    Item
    Rate and Time of Boron Application Increase Almond Productivity and Tissue Boron Concentration
    (1999) Nyomora, Agnes M. S.; Brown, Patrick H.; Krueger, Bill
    Previous studies with tree species have demonstrated that foliar boron (B) promotes flowering, fruit set, and yield. However, for most species the optimum time for foliar B application has not been determined. This investigation was undertaken to study the effects of time and rate of B application on almond [Prunus dulcis (Mill D.A.Webb)] tissue B concentration, fruit set, and yield. Solubor (Na2B8O13.4H2O), a commercial product containing 20.5% B, was applied with a handgun sprayer either in September (3 weeks postharvest), December (dormancy), or February (budbreak) at rates of 0, 0.8, and 1.7 kg·ha–1 B to almond cv. Butte at one site (Parlier, Fresno County, Calif.), and of 0, 0.8, 1.25, 1.7, and 2.1 kg·ha–1 B on the same cultivar in August, September, or February at a second site (Orland, Glenn County, Calif.) using Borosol, a polyboronated commercial product containing 10% B. At site 1, September application was more effective in increasing tissue B concentration, fruit set, and yield than were December or February applications. The optimal rate was 0.8 to 1.7 kg·ha–1 B when applied in September. At site 2, application in 1996 and 1997 increased tissue B concentration almost linearly, especially when applied in August and February. Application at the highest rate (2.1 kg·ha–1 B) in September produced the greatest final fruit set and yield in 1996. February applications increased initial fruit set at both sites but were less effective than September applications in increasing yield. Application of B did not affect any yield variable in 1997. These results suggest that B should be applied immediately postharvest (September) for optimal effect on tissue B concentration, fruit set, and yield in almond
  • Thumbnail Image
    Item
    A Hydrogenosome with Pyruvate Formate-Lyase: Anaerobic Chytrid Fungi Use an Alternative Route for Pyruvate Catabolism. Mol Microbiol 32:1103-1114
    (Wiley, 1999) Akhmanova, Anna; Voncken, Frank; Hosea, Ken M.; Harhangi, H.; Keltjens, J. T.; Op Den Camp, H. J.; Vogels, G. D.; Hackstein, Johannes H. P.
    The chytrid fungi Piromyces sp. E2 and Neocallimastix sp. L2 are obligatory amitochondriate anaerobes that possesshydrogenosomes.Hydrogenosomes arehighly specialized organelles engaged in anaerobic carbon metabolism; they generate molecular hydrogen and ATP. Here, we show for the ®rst time that chytrid hydrogenosomes use pyruvate formate-lyase (PFL) and not pyruvate:ferredoxin oxidoreductase (PFO) for pyruvate catabolism, unlike all other hydrogenosomes studied to date. Chytrid PFLs are encoded by a multigene family and are abundantly expressed in Piromyces sp. E2 and Neocallimastix sp. L2. Western blotting after cellular fractionation, proteinase K protection assays and determinations of enzyme activities reveal that PFL is present in the hydrogenosomes of Piromyces sp. E2. The main route of the hydrogenosomal carbon metabolism involves PFL; the formation of equimolar amounts of formate and acetate by isolated hydrogenosomes excludes a signi®cant contribution by PFO. Our data support the assumption that chytrid hydrogenosomes are unique and argue for a polyphyletic origin of these organelles.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    The Potential of Agro-industrial Residues for Production of Biogas and Electricity in Tanzania
    (1999-02) Kivaisi, Amelia K.; Rubindamayugi, M.S.T.
    This paper gives an overview of the energy demands in Tanzania, and highlights the current serious shortage of electricity. Government strategy to alleviate the problem include exploitation of the country's big natural gas reserves for power generation, and utilization of the renewable energies such as solar, wind and biogas. Important agro-industrial residues with a large potential for anaerobic conversion into biogas and electricity are identified, and their production and locations are described. Tanzania generates a total of 468,100 tonnes organic matter from coffee, sisal, sugar and cereal residues annually. Laboratory scale determinations of methane yields from the residues gave 400 m3 CH4/ton VS of sisal pulp; 400 m3 CH4/ton VS of sisal production wastewater; 650 m3 CH4/ton VS of Robusta coffee solid waste; 730 m3 CH4/ton of Arabica coffee solid waste; 230 m3 CH4/ton VS of sugar filter mat and 450 m3 CH4/ton VS maize bran. Based on these results the estimated total annual potential electricity production from these residues is 1,135 million kWh. The total oil substitution from these residues has been estimated at 0.32 million tonnes crude diesel oil per annum equivalent to 2 % of the total energy consumption in Tanzania. Case studies on the coffee and sisal processing factories indicate that exploitation of the residues for the production of electricity on site these factories is feasible. Utilization of agro-industrial residues for biogas production has a big potential for reduction of environmental pollution. The potential substitution of fossil fuel with biogas represents an annual reduction in the net CO2 emission to the atmosphere of approximately 1.05 million tonnes. By treating the residues in controlled anaerobic systems it is possible to reduce the methane emission by about 189 million m3, and at the same time reduce contamination of surface and ground waters.
  • Thumbnail Image
    Item
    A New Strategy for Treating Nets. Part 1: Formulation and Dosage
    (Wiley, 1999-03) Miller, J. E.; Buriyo, Amelia S.; Karugila, A.; Lines, J. D.
    The conventional dosages of pyrethroid insecticides on mosquito nets assume that nets will be retreated at6–12 month intervals. However, dosage should be related to washing of nets; if nets are only washed once ortwice a year, their dosage requirements will be different to those which are washed fortnightly. A ‘low-dose, fre-quent-wash’ retreatment system might be technically more appropriate and more affordable where nets arewashed frequently, as they are in Dar es Salaam. Moreover, for use as a domestic insecticide, water-based for-mulations of pyrethroid are preferable to the more commonly used emulsifiable concentrates (ECs). This paperreports laboratory evaluations of three formulations (ECs, Flowable, CS) of three pyrethroids (deltamethrin,lambdacyhalothrin, permethrin). Insecticidal activity was tested using serial bioassays at a range of dosagesusing Anopheles gambiae. The water-based formulations were no less effective than the ECs, even at the lowestdosages. Nets treated with 3 mg/m2and then repeatedly washed and retreated after each wash with either3 mg/m2or 1 mg/m2were subjected to gas chromatography analysis. This showed that the amounts ofpyrethroid in the nets accumulated rapidly over the first few wash-retreatment cycles and then remained fairlystable over subsequent cycles. These nets gave consistently high bioassay mortalities throughout the experi-ment, while the mortality declined rapidly after several washes with the nets that were treated at 3 mg/m2butnot retreated. Experimental huts were used to compare the effectiveness of these 2 net retreatment regimes andnets which were not retreated. All nets caused high mortality rates amongst Anopheles females, but had negligi-ble effects on culicines; either in killing them or in preventing feeding. Therefore use of a high ‘loading’ dose forinitial treatment with lower ‘maintenance’ doses for retreatment may be preferable to ensure that net userspromptly perceive the benefits of the insecticide against culicines.
  • Thumbnail Image
    Item
    Lignin-degrading Enzyme Production by Bjerkandera Adusta Immobilized on Polyurethane Foam
    (1999-10) Nakamura, Yoshitoshi; Mtui, Godliving Y. S.; Sawada, Tatsuro; Kuwahara, Masaaki
    Production of the lignin-degrading enzymes lignin peroxidase (Lip), manganese peroxidase (MnP), and laccase (Lac) by the white-rot fungus Bjerkandera adusta was investigated experimentally using polyurethane foam (PUF) as a carrier of immobilized fungal mycelia. An immobilized cell culture with a low-nitrogen medium yielded significantly greater LiP, MnP, and Lac activities in comparison with those obtained in a liquid culture. The maximum activities of the three enzymes were 450, 370, and 100 U/ml, respectively, under the following incubation condition: glucose concentration, 20 g/l; temperature, 30°C; pH 4.5. The activities of MnP and Lac were significantly higher than those reported using other incubation methods. Lignin was degraded to the extent of 40% and its decolorization ratio was about 70% at an incubation time of 40 h using lignin-degrading enzymes from B. adusta. Six different isozymes of MnP were synthesized by B. adusta, two of which exhibited high MnP activity. Our preliminary finding that extracellular enzymes from B. adusta are capable of degrading and decoloring lignin makes these enzymes attractive for further research aimed at their large-scale application in lignin depolymerization, pulp biobleaching, and the degradation of toxic pollutants.
  • Thumbnail Image
    Item
  • Thumbnail Image
    Item
    Foliar Application of Boron to Almond Trees Affects Pollen Quality
    (2000) Nyomora, Agnes M. S.; Brown, Patrick H.; Pinney, K.; Polito, V. S.
    The effect of boron (B) on in vivo and in vitro development of almond [Prunus dulcis (Mill.) D.A. Webb (syn. P. amygdalus Batsch)] pollen and pollen tubes and the resultant effect on fruit set was studied in mature trees. The cultivars Mono (pistil donor) and Butte (pollinizer) in an orchard with low soil B in Fresno, California were sprayed with B at 0, 0.8, 1.7, or 2.5 kg·ha–1 during Fall 1993. Pollen viability as indicated by the fluorescein diacetate method (FDA) was >85% and was not affected by field-applied B, however, in vivo pollen germination and tube growth were enhanced by foliar-applied B. More effect of applied B on in vivo growth appeared as pollen tubes progressed toward the ovary. For in vitro germination, foliar-applied B reduced bursting of tubes, and addition of B to the culture media significantly increased pollen germination and pollen tube growth