The plasmids pDN211 and pDNll, isolated from the gene bank of the Rhizobium japonicum strain I-110, have been reported to complement two different Nif+ Hup· (nitrogen fixation positive and hydrogen uptake negative) mutants. A 5.9-kb Hindiii DNA fragment of the cosmid pHU52, isolated from the gene bank of R. japonicum strain 122DES, has been reported to code for the two polypeptide subunits of uptake hydrogenase. To determine homology between the structural genes of uptake hydrogenase of the two strains, a Southern blot of the Hindiii restriction fragments of the plasmids pDN211 and pDN11 was hybridized to the 5.9-kb Hindiii fragment. A 6.0-kb HindIII DNA fragment of pDN11 was observed to be homologous to the hup DNA probe. Thus, the hup genes of the two Rhizobium strains are conserved. Colony hybridization with the 5.9-kb DNA as the probe was used to detect the homologous hup genes in alfalfa-, chickpea- and pigeonpea- Rhizobium species. These Rhizobium species were also successfully derepressed for uptake hydrogenase in free living conditions. It was found that 30% of the alfalfa-, 30% of the chickpea- and 21% of the pigeonpea- Rhizobium strains tested were Hup+ as determined by the methylene blue (MB) reduction assay. All but one strain of alfalfa- (Celpril Ind. 3623) and one strain of pigeonpea- Rhizobium (IC3282) that showed strong homology to the hup DNA probe also exhibited MB reduction activity. The Hup+ strains of alfalfa- and pigeonpea- Rhizobium produced significantly higher yields as compared to the Hup- strains, whereas those of the chickpea-Rhizobium strains produced significantly lower yields as compared to the Hup- strains. Two of the alfalfa-Rhizobium strains, USDA1024 and CmRm~, exhibited Hup activities greater than any reported previously for this bacterial species. The cosmid-borne hup genes of R. japonicum were successfully expressed in all strains tested but the enzyme activities were very low in alfalfa-Rhizobium compared to those in chickpea- and pigeonpea-Rhizobium species. The relative efficiency of N2-fixation was significantly increased by the transfer of hup genes into the chickpea- and pigeonpea- Rhizobium strains.

There are numerous situations where trees are grown together with herbaceous plants. In these situations there will be some degree of competition between their root zones, depending on the water content of the soils and crop and tree root distribution . Two studies were conducted : the first with maple (Acer platanoides) grown in turf grass, and the second with willow (Salix matsudana) grown in more deeply rooted barley . The objectives of this study were to quantify the effect of herbaceous competition of potential tree water stress under irrigation and when the soil is allowed to dry-down . Soil water uptake was measured in both studies to 1.2 m depth and outwards to 1.2-2.10 m away from the tree . In the maple-turf grass study, water content was measured in a single line away from the tree , while four lines covering a quadrant of the surface area were measured in willow . Water relations stomatal conductance and water potential, and tree growth were also monitored in both studies. Water uptake in turf plots was statistically different from mulch plots by depth and distance during three seasons. Water uptake was greatest at 0-60 cm depth in the turf treatments compared with mulch treatments. Soil water in mulched plots decreased slowly during the growing season. There were no statistical differences between bare soil and barley competition water uptake after soil surface water was depleted. There were marked differences in tree root characteristics as a result of competition from turf or barley roots. The root systems of maples in the mulch and willow in bare soil extended laterally and fine roots were evident. Tree roots extended deeper and fine root were reduced under competition from turf and barley. Trees growing with turf and barley had fewer roots in the top 0.3 m soil surface while trees in mulch and bare soil had more and greater diameter roots at the same depth. Early in the season, when water content is high, root competition for water was not evident, and late in the season after turf roots and barley had depleted the soil water, trees exhibited more negative predawn leaf water potential and less stomatal conductance in response to water stress during a soil dry-down period. Tree growth was measured periodically during 1994, 1995, and 1996. Leaf area and stem growth comparisons showed a significant increase in size as a result of the absence of competition in both species, with mulch and bare soil treatments. Leaf area in mulched trees was twice that in turf treatments. In summary, we found that competition resulted in deeper tree root growth and less top growth in the presence of herbaceous competitors.

The laboratory-scale University of Cape Town (UCT) process was designed to investigate the effects of changing COD/TP ratios on the performance of biological nutrient removal (BNR) processes. Specific objectives of the research were to investigate the effects of COD/TP ratio on the rates of phosphorus removal, COD removal, nitrogen removal, PHB utilization and oxygen uptake. The system was fed with municipal wastewater and operated at 20° C. The influent COD concentration was held approximately constant while the phosphorus concentration was varied to obtained the desired COD/TP ratio. Once robust enhanced biological phosphorus removal (EBPR) has been established, the COD/TP ratios of 20, 30, 40 and 60 were investigated. The COD/TP ratio of the influent wastewater was observed to have a substantial effect upon the performance of the UCT BNR system. The amount of phosphorus removed by the system and the percent phosphorus in the aerobic zone MLVSS decreased as the COD/TP ratio increased. In addition, the amount of phosphorus released in the anaerobic zone per unit of COD removed in the anaerobic zone increased as the COD/TP ratio decreased. From this research, the amount of anaerobic COD removal required to remove 1 mg/L of phosphorus in the aerobic zone approached a minimum value as the COD/TP ratio decreased. It was also shown that PHB production increased as the COD/TP ratio increased. The highest specific oxygen uptake rate was always observed in the second aerobic reactor and tended to increase as the COD/TP ratio increased. However, the changes in the COD/TP ratio did not significant affect COD removal, nitrogen removal and the observed yield coefficient, but did strongly affect the MLSS concentration. The MLSS concentration at the COD/TP ratio of 60 was only 55% of that at the COD/TP ratio of 20. A high level of anaerobic COD removal, an elevated percent phosphorus in the waste activated sludge (WAS) and a high soluble effluent phosphorus concentration can be used as indicators that the system is operating under COD limiting conditions. Several phenomena were also observed during this research. Firstly, the performance of the UCT BNR system for EBPR was greatly enhanced by reducing the aerobic volume. Secondly, the correlation between non-oxic phosphorus release and the aerobic phosphorus uptake improved when anoxic phosphorus release was taking into consideration. This indicated that the anoxic phosphorus release was not secondary release once the aerobic zone volume was reduced. Finally, no denitrification was observed in the aerobic zone from this study, based on the assumption that 12% of nitrogen was required for bacterial growth. / Master of Science

The mining industry is a significant contributor to the Canadian economy. However, the mining activities can be detrimental to the environment due to the release of pollutants. Ammonia is one of the noxious and toxic contaminants associated with mining, ammonia contamination is created by the oxidizing agent in explosives. The explosives impacted mining wastewater (EIMWW) usually contains ammonia and other metal ions. The ammonia in EIMWW could harm the aquatic environment by the depletion of oxygen and its lethal toxicity to aquatic organisms. Before release to environment, EIMWW needs to be treated with an easy-to-operate method for ammonia removal at the remote mining sites. Ion-exchange (IE) with zeolite is an effective method for ammonia removal that is easy-to-operate, is not significantly impacted by cold temperature or toxicity effects. However, the traditional IE regeneration approach of using high concentration NaCl solutions creates a secondary polluting stream. Chlorine regeneration of ammonia-loaded zeolite appears to be a promising option, an evaluation of this option is the main topic of this thesis. This thesis includes three initiatives. The first is a set of multi-cycle batch loading-regeneration tests to assess the viability of ammonia removal with a commercial zeolite (SIR-600) for the treatment of a synthetic EIMWW (containing total ammonia nitrogen (TAN), K, and Ca) and to examine the performance of different ion-exchange regeneration solutions. The long-term TAN uptake of SIR-600 regenerated using a NaOCl (100 mg free Cl2/L) solution was 0.24 meq/g, which was approximately 20% lower than that after a NaCl regeneration. However, chlorine regeneration is promising because the selectivity of SIR-600 for TAN over Ca and K increased after the chlorine regeneration. To simulate recycling of the NaOCl regenerants, K and Ca were added to the NaOCl solution, it did not substantially affect the subsequent SIR-600’s ion uptake. This initiative represents a significant contribution since the earlier studies into chlorine regeneration did not investigate the impact of competing ions. The second initiative addressed concerns regarding the long-term integrity of SIR-600 arising from its exposure to high chlorine concentrations during the regeneration. The five-week long chlorine batch exposure tests with solutions of up to 1000 mg free Cl2/L showed that chlorine exposure did not significantly affect the SIR-600’s characteristics in terms of particle size distribution, surface area, FTIR spectra and ion uptake. Thus, SIR-600 has the potential for long-term use in field applications. The final initiative evaluated the feasibility of chlorine regeneration for continuous flow IE column systems used for ammonia removal from a synthetic EIMWW. Continuous flow column systems are important because these are the standard IE units used in full-scale applications. Multi-cycle column loading-regeneration tests were performed to compare the zeolite performance using a NaOCl (1000 ppm as free Cl2) solution with that using a 5% NaCl regeneration. The influence of loading duration was also assessed. The use of 6-hr loading cycles were shown to be preferable to 23-hr loading cycles because it had lower effluent concentrations and they could achieve higher overall TAN mass removals per unit time. After three operational cycles, the SIR-600 had similar TAN uptake performances (0.21 meq/g Vs. 0.21 meq/g) after NaOCl regeneration and after salt (NaCl) regeneration. This is in contrast to the lower TAN uptakes for the NaOCl regeneration in the batch tests, this indicates that batch tests are not always representative of full-scale applications. Compared to NaCl regenerated SIR-600, SIR-600 after NaOCl regeneration had a higher preference for TAN over Ca and K, which makes this type of regeneration very promising. Its only apparent limitation is that the NaOCl regeneration required a longer duration. During the NaOCl regeneration, the main mechanism appears to be the oxidation of ammonia to nitrogen gas and hydrogen ions, however the Na in the NaOCl solution also seems to have a role in the regeneration.

No description available.

Obesity, a disease characterized by excess adipose tissue (AT), is a growing worldwide epidemic. The Centers for Disease Control and Prevention (CDC), in 2017-2018, reported the prevalence of obesity in adults in the United States was 42.4% . Obesity increases the risk for many other serious health conditions such as type 2 diabetes, cardiovascular diseases, stroke, and some cancers. In individuals with obesity, the hypertrophic expansion of adipocytes, the main cell type within AT, is not matched by new vessel formation, leading to AT hypoxia. As a result, hypoxia inducible factor-1⍺ (HIF-1⍺) accumulates in adipocytes inducing a transcriptional program that upregulates profibrotic genes and biosynthetic enzymes such as lysyl oxidase (LOX) synthesis. This excess synthesis and crosslinking of extracellular matrix (ECM) components cause AT fibrosis. Although fibrosis is a hallmark of obese AT, the role of fibroblasts, cells known to regulate fibrosis in other fibrosis-prone tissues, is not well studied. Adipocytes are mechanoresponsive and affected by different microenvironmental cues, including hypoxia and mechanical (un)loading. Yet, no study has focused on the role of the aforementioned factors on the adipocyte mechanical response, including actin cytoskeletal remodeling. This dissertation aims to develop an in vitro model of healthy/diseased AT to explore the effect of microenvironmental cues on adipocyte function and actin cytoskeletal remodeling. The first aim is to study (1) the crosstalk between fibroblasts and adipocytes in a co-culture model and (2) the effect of hypoxia on the ras homolog gene family member A (RhoA)/Rho-associated coiled-coil kinases (ROCK) mechanical pathway and actin cytoskeletal remodeling in adipocytes. We confirmed that hypoxia creates a diseased phenotype by inhibiting adipocyte maturation and inducing actin stress fiber formation facilitated by myocardin-related transcription factor A (MRTF-A/MKL1) nuclear translocation. The second aim explores the effects of mechanical unloading (simulated microgravity) on key adipocyte functions and actin cytoskeletal remodeling. This study demonstrated that mechanical unloading enhances adipocyte maturation via increased lipogenesis and lipolysis and cortical actin remodeling, which together further enhanced glucose uptake. However, disrupting cortical actin remodeling by using inhibitors or exposure to a high concentration of free fatty acids (FFAs) diminished enhanced adipocyte functions observed in simulated microgravity. Overall, the results of these studies support the importance of microenvironmental cues on adipocyte actin cytoskeletal remodeling. Therefore, targeting mechanical pathways that regulate actin cytoskeletal remodeling can be used to improve adipocyte function and AT metabolism and possibly treat related diseases such as type 2 diabetes and obesity. / Bioengineering

This thesis evaluates the performance of a deammonification system designed as a two-step tech-nology consisting of an initial partial nitritation followed by an Anammox process. Operation of a technical-scale pilot plant at the Himmerfjärden Wastewater Treatment Plant (Grödinge, Swe-den) has been assessed. Oxygen Uptake Rate (OUR) to evaluate the respiration activity of nitrifi-ers in the system and batch tests to assess reaction rates have also been applied in the study. It was found that the total inorganic nitrogen elimination strongly depended on the nitrite-to-ammonium ratio in the influent to the Anammox reactor, which was correlated with the per-formance of the partial nitritation phase. Therefore, a control strategy for oxidation of ammo-nium to nitrite has been proposed. Controlled oxygen supply to the partial nitritation reactor is obligatory to obtain a proper pH drop indicating oxidation of ammonia to nitrite at the adequate ratio. A very high nitrogen removal efficiency (an average of 84%) and stable operation of the system have been reached. Conductivity measurements were also used to monitor the system influent nitrogen load and the nitrogen removal in the Anammox reactor. The data gathered from the operation of the pilot plant enabled the use of multivariate data analysis to model the process behaviour and the assessment of the covariances between the process parameters. The options for full-scale implementation of the Anammox systems have been proposed as a result of the study. / QC 20101115

INTRODUCTION: Exercise increases insulin stimulated glucose uptake (insulin action) if expended energy (kcal) is withheld following exercise, but the effect is blunted when expended energy is replaced as carbohydrate. Restricting carbohydrate and replacing expended energy as fat maintains increased insulin action in rodents; however, this effect has not been evaluated in humans. In humans, restricting carbohydrate intake following exercise may be a useful strategy to maximize the effect of individual exercise bouts on insulin action and promote gains in metabolic health over time. Therefore, the purpose of this study was to determine if carbohydrate restriction following exercise (carbohydrate deficit) increased insulin action in sedentary, overweight adults as hypothesized. METHODS: Ten healthy, sedentary, men and women, aged 21±2 years, body fat 37.3±3.1%, and VO2peak 34.6±1.2ml×kg-1×min-1 completed three, two-day experimental conditions in random order: 1) a no-exercise baseline condition (BASE), 2) exercise followed by a high-carbohydrate meal (HIGH-CHO= 76.3±2.5% CHO), and 3) exercise followed by a low-carbohydrate meal (LOW-CHO=17.8±0.1% CHO). On DAY 1, subjects came to the laboratory (early evening) and expended 30% of total daily energy expenditure on a cycle ergometer at 70% of VO2peak. Following exercise, an isocaloric meal (HIGH-CHO or LOW-CHO) was consumed to refeed the expended energy during exercise and venous blood samples were taken to record the insulin and glucose responses to the meals. Twelve hours later (Day 2), whole-body insulin action (steady-state glucose uptake per unit insulin) was measured using a continuous infusion of glucose with stable isotope tracers. A paired t-test was used to detect differences between exercise bouts and the glucose and insulin responses to the post-exercise meals. A one-way repeated measures ANOVA was performed to evaluate the effect of experimental condition on insulin action (p<0.05, for all tests). RESULTS: Intensity (VO2peak), duration (minutes) and energy expenditure (kcal) were similar between exercise bouts. After exercise, plasma glucose and insulin concentrations were significantly higher following the HIGH-CHO meal compared to the LOW-CHO meal (p<0.001, respectively). The next morning, insulin action was similar between experimental conditions (p=0.30). Non-oxidative glucose disposal was increased during the glucose infusion in Low-CHO compared to BASE (27.2±3.2 vs. 16.9±3.5µM×kg-1×min-1, p<0.05). Carbohydrate oxidation was reduced in Low-CHO (8.6±1.3µM×kg-1×min-1) compared to High-CHO (12.2±1.2µM×kg-1×min-1), and to BASE (17.1 ± 2.2 µM×kg-1×min-1), p<0.05 respectively. Resting fat oxidation was increased in Low-CHO compared to BASE (109.8 ± 10.5 mg×min-1 vs. 80.7 ± 9.6 mg×min-1, p<0.05) and remained elevated during the glucose infusion. CONCLUSION: Limiting carbohydrate, but not energy intake after exercise (carbohydrate deficit) resulted in increased non-oxidative glucose disposal, decreased carbohydrate oxidation and increased fat oxidation during the glucose infusion, compared to baseline, indicating a favorable shift in energy metabolism. Creating a carbohydrate deficit, by withholding expended carbohydrate but not energy following exercise may be a sensible strategy to promote favorable gains in insulin action that requires further evaluation.

<p> Phosphorus (P) is a key element for maize (<em>Zea mays</em> L.) production and plays many important roles in plants. Soil-buffering of P does not allow for precise control of solution concentrations in the field, while greenhouses, growth chambers, and hydroponics provide limiting conditions. Thus, an objective of this study was to develop a practical technique for cultivating several maize plants to physiological maturity (R6) in a growth room environment, with precise control of nutrient availability and timing, and evaluate its utility for the purpose of measuring plant responses to variations in P concentration using a silica-sand-based solution culture technique. A semi-automated growth room for conducting nutrient studies on 96 maize plants was constructed and evaluated to quantify plant growth response to a range of solution P concentrations. Maize yield components were measured and compared to values for field-grown plants. Due to ideal conditions and successful simulation of light intensity, diurnal fluctuations in temperature and relative humidity, and changing photoperiod, grain yield and tissue nutrient concentrations were comparable to field-grown maize, although with greater shoot biomass. The second objective was to quantify the uptake and partitioning of nutrients as affected by P concentration at various maize growth stages. Thus, two maize hybrids were grown under both sufficient and insufficient P fertility rates using the silica-sand-based solution culture technique. Throughout the growth stages, sufficient-P plants had more than double the biomass compared to insufficient-P plants. At R1, N partitioning followed a similar pattern in both treatments, while P remobilization differed, with insufficient-P plants relying on stem tissue and sufficient-P plants remobilizing P from leaf and root tissue for grain production. Plants grown under sufficient-P fertility matured more rapidly and reached physiological maturity (R6) sooner. Sufficient-P fertility resulted in 2- to 3-fold greater grain, leaf, stem, and root biomass at R6 than insufficient-P. Nutrient partitioning patterns to plant tissues between P treatments were generally similar, except for insufficient-P plants allocating more nutrients to root tissues than sufficient-P plants. Partitioning patterns for B and Cu indicated that the high demand of maize reproductive structures for these nutrients may justify a foliar application of B and/or Cu at vegetative growth stages in some cases. The results of these studies suggests that there is great utility in further utilizing this silica-sand-based solution culture technique for more complex plant nutrient studies. </p>

No description available.