abstract / Biological Sciences / Doctoral / Doctor of Philosophy

Fluorescence spectroscopy was examined as a potential technique for identifying aerosol particles like bacterial spores. This technique was used for laboratory measurements on some common biological agent simulants. We have measured the intrinsic steady-state fluorescence emission spectra as a function of the excitation wavelength for several bacterial spores (washed and unwashed) in dry and aqueous suspensions at room temperature using excitation wavelengths from 200 to 600 nm. These measurements were compared to those of common, naturally occurring biological components like fungal spores and pollen and non spore samples like ovalbumin. The spectra of samples were combined into fluorescence profiles or fluorescence fingerprints. Different substrates were used for collection and detection of spores. Each bacterium produces a unique in vitro fluorescence profile when measured in dried and aqueous suspension and exhibits a strong maximum in its fluorescence emission spectrum near 330-340 nm. The fluorescence profiles were reproducible. The complexity of microorganisms made the interpretation of their spectral signature a difficult task. Principal components analysis (PCA) and cluster analysis were done as a data reduction technique for detection and identification from different backgrounds. PCA illustrates that linear combination of detected fluorescence intensities, which are present in different ratios in each of samples studied, can be used to discriminate biological agent simulants from other biological samples. The hydration effects, washing effects and the role of tryptophan on spore fluorescence were also investigated. The emission spectra of the dried spores showed a maximum near 330 nm, suggesting a hydrophobic environment for its tryptophan residues. The aqueous solution of tryptophan showed fluorescence shifted to 360 nm and in ethanol solution the maximum was shifted to 340 nm, suggesting a rather more polar average location of the tryptophan. To find the limit of detection we measured the quantum efficiency (QE) of a few samples. We concluded that spectroscopy techniques coupled with effective interpretation models are applicable to biological simulants agents. Index Heading: Bacteria; Spores; Identification; Fluorescence; Fluorescence Quantum Efficiency; Principal Components Analysis; Cluster Analysis.

Cowpea (Vigna unguiculata L.) is an important legume, especially in the hot, dry tropics and subtropics of sub-Saharan Africa. It has been widely reported to be drought tolerant. Cowpea is a highly nutritious, multi-purpose crop, used as a leafy vegetable and grain legume with potential to contribute to food security in marginal areas. However, the crop is still classified as a neglected underutilised species; legume research focus has been mainly devoted to established legumes such as common bean and soybeans. There is a need to collect empirical information on cowpea which could be used to advise farmers on management strategies. This study evaluated cowpea responses to water stress under controlled and field conditions. Initially, two cowpea varieties (Brown and White birch) were evaluated for seed quality using the standard germination that was laid out in a completely randomised design and each variety was replicated for times. Electrolyte conductivity test was also performed under laboratory conditions. Thereafter, a pot trial was conducted to evaluate cowpea response to water stress imposed at different growth stages under varying growth temperatures. The pot trial comprised three factors: temperature [High (33/27ºC), Optimum (27/21ºC) and Low (21/15ºC)], water regimes (no stress, terminal stress, intermittent stress – vegetative and intermittent stress - flowering) and cowpea varieties. Lastly, a field trial was conducted to evaluate cowpea production as well as the effect of sequential leaf harvesting on yield under irrigated and rainfed conditions. The field trial was laid out as a split-plot design, with water regime (irrigation vs. rainfed) as main factors, cowpea varieties as sub-factor and sequential harvesting (no harvest, harvested once and harvested twice), replicated three times. All treatments were arranged in a randomised complete block design. Results of the initial study showed that germination capacity and vigour of cowpea varieties were significantly different (P < 0.001). White birch had higher electrolyte leakage than Brown birch. Pot trial results showed that cowpea growth (leaf area, leaf number and plant height) was vigorous in the high temperature regime compared with optimum and low temperature regimes. Chlorophyll content index was higher under high temperature relative to optimum and low temperature regimes, respectively. Under low and optimum temperature regimes, cowpea growth was stunted; cowpea failed to flower and form yield. Whereas, under high temperature regime, cowpea growth was vigorous hence flowered and formed yield. Vegetative growth was more sensitive to water stress than flowering stage. Terminal stress and stress imposed during flowering resulted in increased proline accumulation relative to no stress and stress imposed during vegetative growth. Harvest index was lower when water stress was imposed during vegetative relative to flowering stage. Field trial results showed that cowpea growth was sensitive to water stress. Plant height, leaf number, chlorophyll content index and stomatal conductance were lower under rainfed relative to irrigated conditions. Sequential harvesting of leaves had no significant effect on cowpea yield. It is concluded that tropical temperature conditions are most suitable for cowpea production; the controlled environment study showed best crop performance under 33/27ºC. In the context of varieties used for the present study, vegetative growth was the most sensitive stage to water stress. Cowpea performed better under rainfed relative to irrigated conditions with respect to yield formation. Low temperature was found to be more limiting to cowpea growth, development and productivity compared with water stress. Whereas, under high temperature conditions, water stress was more limiting to plant growth and productivity. White birch may be used as a dual purpose crop due to its ability to produce reasonable grain yield regardless of defoliation. / Thesis (M.Sc.Agric)-University of KwaZulu-Natal, Pietermaritzburg, 2012.

Ng Ho Yuen Andus. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 105-131). / Abstracts in English and Chinese. / Chapter I --- Title page --- p.i / Chapter II --- Thesis committee --- p.ii / Chapter III --- Acknowledgement --- p.iii / Chapter IV --- Abstract --- p.v / Chapter V --- Abstract (Chinese version) --- p.vii / Chapter V --- Table of contents --- p.ix / Chapter VI --- List of abbreviations --- p.xv / Chapter VII --- List of figures --- p.xviii / General introduction --- p.1 / Chapter Chapter 1: --- Literature review --- p.5 / Chapter 1.1. --- Heat shock proteins (HSPs) --- p.6 / Chapter 1.1.1. --- Introduction --- p.6 / Chapter 1.1.2. --- The various heat shock proteins --- p.8 / Chapter 1.1.2.1. --- HSP100s --- p.8 / Chapter 1.1.2.2. --- HSP90s --- p.9 / Chapter 1.1.2.3. --- HSP70s --- p.12 / Chapter 1.1.2.3.1. --- ATPase reaction cycle of HSP70 and protein folding --- p.13 / Chapter 1.1.2.3.2. --- Protein translocation --- p.14 / Chapter 1.1.2.3.3. --- Selective lysosomal proteolysis --- p.16 / Chapter 1.1.2.4. --- HSP60s --- p.16 / Chapter 1.1.2.5. --- Small HSPs --- p.17 / Chapter 1.1.2.6. --- Ubiquitin --- p.19 / Chapter 1.1.3. --- HSP studies in fish --- p.21 / Chapter 1.1.3.1. --- In vivo works --- p.21 / Chapter 1.1.3.2. --- In vitro works --- p.23 / Chapter 1.2. --- Growth hormone / prolactin family in teleostean fishes --- p.26 / Chapter 1.2.1. --- Introduction --- p.26 / Chapter 1.2.2. --- Growth hormone (GH; somatotropin) --- p.29 / Chapter 1.2.2.1. --- Structure --- p.29 / Chapter 1.2.2.2. --- Actions --- p.29 / Chapter 1.2.2.3. --- Insulin-like Growth Factors (IGFs; somatomedins) --- p.31 / Chapter 1.2.3. --- Prolactin (PRL) --- p.34 / Chapter 1.2.3.1. --- Structure --- p.34 / Chapter 1.2.3.2. --- Actions --- p.35 / Chapter 1.2.4. --- Somatolactin (SL) --- p.37 / Chapter 1.2.4.1. --- Structure --- p.37 / Chapter 1.2.4.2. --- Actions --- p.38 / Chapter 1.2.5. --- Growth hormone receptor (GH-R) and prolactin receptor (PRL-R) --- p.39 / Chapter 1.3. --- Cortisol in teleostean fishes --- p.41 / Chapter 1.4. --- Salinity adaptation in teleosts --- p.44 / Chapter Chapter 2: --- Effect of in vitro thermal shock on HSP70 expression in whole blood of Sparus sarba --- p.46 / Chapter 2.1. --- Introduction --- p.47 / Chapter 2.2. --- Materials and methods --- p.49 / Chapter 2.2.1. --- Overall experimental design --- p.49 / Chapter 2.2.2. --- Experimental fish --- p.49 / Chapter 2.2.3. --- Blood sampling and preparation --- p.49 / Chapter 2.2.4. --- Thermal stress regimes --- p.50 / Chapter 2.2.5. --- Protein extraction --- p.51 / Chapter 2.2.6. --- Protein quantification --- p.51 / Chapter 2.2.7. --- Indirect enzyme-linked immunosorbent assay (ELISA) --- p.52 / Chapter 2.2.8. --- Protein gel electrophoresis and immunoblotting (Western blotting) --- p.54 / Chapter 2.2.9. --- Statistical analysis --- p.55 / Chapter 2.3. --- Results --- p.56 / Chapter 2.3.1. --- Validation of indirect ELISA --- p.56 / Chapter 2.3.2. --- Effect of in vitro thermal shock on HSP70 expression in whole blood of Sparus sarba --- p.56 / Chapter 2.4. --- Discussion --- p.60 / Chapter 2.5. --- Conclusion --- p.64 / Chapter Chapter 3: --- Effects of hormones on HSP70 expression in whole blood of Sparus sarba in vitro --- p.65 / Chapter 3.1. --- Introduction --- p.66 / Chapter 3.2. --- Materials and methods --- p.68 / Chapter 3.2.1. --- Overall experimental design and experimental fish --- p.68 / Chapter 3.2.2. --- Hormone treatments --- p.59 / Chapter 3.2.3. --- "Protein extraction and quantification, indirect ELISA，gel electrophoresis, and immunoblotting (Western blotting)" --- p.70 / Chapter 3.2.4. --- Statistical analysis --- p.70 / Chapter 3.3. --- Results --- p.71 / Chapter 3.3.1. --- Effect of Cortisol on HSP70 levels in whole Blood --- p.71 / Chapter 3.3.2. --- Effect of recombinant bream growth hormone on HSP70 levels in whole blood --- p.71 / Chapter 3.3.3. --- Effect of recombinant bream insulin-like growth factor-I on HSP70 levels in whole blood --- p.71 / Chapter 3.3.4. --- Effect of ovine prolactin on HSP70 levels in whole blood --- p.72 / Chapter 3.4. --- Discussion --- p.81 / Chapter 3.4.1. --- Effect of Cortisol on HSP70 levels in whole Blood --- p.81 / Chapter 3.4.2. --- Effect of recombinant bream growth hormone on HSP70 levels in whole blood --- p.83 / Chapter 3.4.3. --- Effect of recombinant bream insulin-like growth factor-I on HSP70 levels in whole blood --- p.85 / Chapter 3.4.4. --- Effect of ovine prolactin on HSP70 levels in whole blood --- p.86 / Chapter 3.5. --- Conclusion --- p.88 / Chapter Chapter 4: --- Effect on HSP70 expression in whole blood of Sparus sarba acclimated to various salinities --- p.89 / Chapter 4.1. --- Introduction --- p.90 / Chapter 4.2. --- Materials and methods --- p.92 / Chapter 4.2.1. --- Overall experimental design and experimental fish --- p.92 / Chapter 4.2.2. --- "Protein extraction and quantification, indirect ELISA, gel electrophoresis, and immunoblotting (Western blotting)" --- p.92 / Chapter 4.2.3. --- Statistical analysis --- p.93 / Chapter 4.3. --- Results --- p.94 / Chapter 4.4. --- Discussion --- p.97 / Chapter 4.5. --- Conclusion --- p.100 / Chapter Chapter 5: --- General discussion and conclusion --- p.101 / References --- p.105

Control of intracellular ion homeostasis is pivotal to plant salt tolerance. Plants have developed a number of mechanisms to keep ions at appropriate concentrations. Both transporters and channels on the plasma membrane play important roles in this function. Plant cyclic nucleotide-gated channels (CNGCs) in the plasma membrane are non-selective monovalent and divalent cation channels. So far, most studies on plant CNGCs have been conducted on heterologous systems. In planta, reverse genetic studies revealed the role of different CNGCs in cation uptake, transport and homeostasis. However, there is little information available about the functional characteristics of plant CNGCs. Among the 20 members of this protein family in Arabidopsis, only AtCNGC2 has been functionally identified as an ion channel; therefore, more functional characterization needs to be done on other members of this protein family. Several CNGCs were suggested to be involved in K+, Ca2+ and Na+ uptake and transport, but available information is scarce. This study investigated the relationship between CNGC10 and ion transport in Arabidopsis, with a particular emphasis on the involvement of CNGC10 in salt tolerance. Arabidopsis thaliana wild type (WT) and two AtCNGC10 antisense lines (A2 and A3) were used to characterise the impact of different level of salt stress on (i) root growth, ion concentration in tissues, ion fluxes across the root surface and intracellular ion concentration and pH at the seedling stage, and (ii) photosynthesis and ion concentration in tissues at the flowering stage. Plants of both antisense lines had higher K+ and lower Ca2+ and Mg2+ concentrations in shoots than WT plants when grown in non-salt control 1/4 Hoagland solution. Altered K+, Ca2+ and Mg2+ internal concentrations in AtCNGC10 antisense lines compared with WT plants under non-salt conditions indicated disturbed long distance ion transport, especially xylem loading/retrieval and/or phloem loading. The results of ion fluxes across the root surface also suggested that AtCNGC10 might be involved in transport of K+, Ca2+ and Mg2+ in tissue. Under sudden salt exposure, higher Na+ efflux and smaller K+ efflux in both antisense lines suggested that AtCNGC10 channels are involved in Na+ and K+ transport. The shoots of AtCNGC10 antisense lines A2 and A3 contained higher Na+ concentrations and significantly higher Na+/K+ ratios compared to WT, resulting in impaired photosynthesis and increased salt sensitivity in A2 and A3 than in WT plants. In contrast, seedlings of both antisense lines exposed to salt stress had lower shoot Na+/K+ ratios and longer roots than WT seedlings, indicating that A2 and A3 were more salt-tolerant than WT in the seedling stage, likely because growth is less dependent on photosynthesis in the seedling than in the flowering stage. These results suggested CNGC gene might play a different role during different developmental stages and in various plant organs.

Abstract not available

"April 2002" Includes bibliographical references (leaves 200-249)

A large number of weed seeds in the soil persist because of seed dormancy, and depletion of the seed bank through manipulation of seed dormancy has been suggested as one of the goals in weed control. This study was designed to investigate some of the factors which control dormancy and germination in Amaranthus retroflexus seeds. Germination studies were conducted at different temperatures, and either in continuous white light or in the dark. Higher temperatures increased germination and, although light interacted with temperature, its effect on germination varied with the temperature. In an attempt to determine changes in dormancy during dry storage, two lots of seeds were stored dry at different temperatures. Loss in dormancy increased with an increase in storage temperature and duration, but the time required for maximum germination varied according to the seedlot. Seeds germinated to higher percentages at high temperatures, but storage at higher temperatures and for prolonged duration resulted in seeds gaining the ability to germinate at lower temperatures. Changes in dormancy under field conditions were also examined. Seeds were buried at different depths and for different durations and they all lost viability with time, but this loss was greater in surface-sown and shallowly buried seeds. Dormancy was broken during cold periods and induced as warmer periods progressed. The effects of chemical stimulants on dormancy and germination were investigated. The response of seeds to ethephon and nitrate were assessed at different temperatures either at continuous white light or in the dark. Germination increased with the concentration of the chemicals, and a greater response was observed at lower temperatures. The response to light varied depending on temperature / Master of Science (Hons)

Bibliography: leaves 315-366. / 368 leaves : / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Assesses the action of dimethylxanthines on the contractility of respriatory and quadriceps femoris muscle in normal subjects and in patients at risk of respiratory muscle fatigue, using accepted techniques. / Thesis (M.D.)--University of Adelaide, Faculty of Medicine, 1992

"April 2002" / Includes bibliographical references (leaves 200-249) / xv, 249 leaves : ill., plates (some col.) ; 30 cm. / Title page, contents and abstract only. The complete thesis in print form is available from the University Library. / Thesis (Ph.D.)--University of Adelaide, Dept. of Animal Science, 2003