京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第20281号 / 医博第4240号 / 新制||医||1021(附属図書館) / 京都大学大学院医学研究科医学専攻 / (主査)教授 髙折 晃史, 教授 岩田 想, 教授 萩原 正敏 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第20421号 / 農博第2206号 / 新制||農||1047(附属図書館) / 学位論文||H29||N5042(農学部図書室) / 京都大学大学院農学研究科森林科学専攻 / (主査)教授 吉村 剛, 教授 梅澤 俊明, 教授 本田 与一 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第21733号 / 工博第4550号 / 新制||工||1709(附属図書館) / 京都大学大学院工学研究科材料化学専攻 / (主査)教授 木村 俊作, 教授 瀧川 敏算, 教授 秋吉 一成 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

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Delivery of photoassimilate, mainly sucrose (Suc) from photoautotrophic source leaves provides the substrate for the growth and maintenance of sink tissues such as roots, storage tissues, flowers and fruits, juvenile organs, and seeds. Phloem loading is the energized process of accumulating solute in the sieve element/companion cell complex of source leaf phloem to generate the hydrostatic pressure that drives long-distance transport. In many plants this is catalyzed by Suc/Proton (H+) symporters (SUTs) which are energized by the proton motive force (PMF). Overexpression of SUTs was tested as means to enhance phloem transport and plant productivity. Phloem specific overexpression of AtSUC2 in wild type (WT) tobacco resulted in enhanced Suc loading and transport, but against the hypothesis, plants were stunted and accumulated carbohydrates in the leaves, possibly due to lack of sufficient energy to support enhanced phloem transport. The energy for SUT mediated phloem loading is provided from the PMF, which is ultimately supplied by the oxidation of a small proportion of the loaded photoassimilates. It was previously shown that inorganic pyrophosphate (PPi) is necessary for this oxidation and overexpressing a proton-pumping pyrophosphatase (AVP1) enhanced both shoot and root growth, and augmented several energized processes like nutrient acquisition and stress responses. We propose that AVP1 localizes to the PM of phloem cells and uses PMF to synthesize PPi rather than hydrolyze it, and in doing so, maintains PPi levels for efficient Suc oxidation and ATP production. Enhanced ATP production in turn strengthens the PMF via plasma membrane (PM) ATPase, increasing phloem energization and phloem transport. Phloem-specific and constitutive AVP1 overexpressing lines showed increased growth and more efficiently moved carbohydrates to sink organs compared to WT. This suggested changes in metabolic flux but diagnostic metabolites of central metabolism did not show changes in steady state levels. This research focuses on fundamental aspects of carbon utilization and transport, and has a strong applied component, since increased H+-PPase activity enhances plant biomass, nutrient up-take capacities, and stress tolerance for as yet not fully characterized reasons.

Encore azaleas are popular ornamental plants for their full sun tolerance, coldhardiness, low maintenance requirements, and reblooming habit in spring, summer, and fall. With their varying growth rates and multiple blooms during a growing season, there is limited information on the nutrient and irrigation requirements of Encore azalea cultivars. The objectives of this study were to investigate the optimum nitrogen (N) requirement of Encore azalea ‘Chiffon’ during a growing season and determine how irrigation frequency and fertilization practices (rates, methods, and timing) affect plant growth and nutrient uptake using both a traditional plastic container and a paper biocontainer. One-year-old liners of Encore azalea ‘Chiffon’ were treated with different N fertigation rates, irrigation frequencies, and sprayed with 3% urea or water in late fall. Plants were investigated for their growth responses and flower production, and analyzed for nutrient and carbohydrate status in different studies when they were grown in both a traditional plastic container and a biodegradable container made from a mix of recycled paper. The biocontainers increased plant growth index, plant dry weight, leaf area, root growth, and uptake of both macro- and micronutrients using N rates of 10, 15, and 20 mM. During a growing season, the biocontainer-grown plants had three flushes of growth while the plastic container-grown plants had only two. The third flush of growth on the biocontainer-grown plants occurred in mid-September, resulting in greater dry weight and N uptake than with plants grown in plastic containers. One irrigation per day resulted in higher flower count and greater root length and surface area. Foliar urea application in late fall was effective in improving plant N status by increasing plant N concentration and content without affecting plant dry weight, but decreased tissue concentrations of glucose, fructose, sucrose, and starch to varying degrees.

Non-consumptive effects that predators have on prey are important to ecosystems. The perceived risk of predation can alter feeding behavior. Giving-up density (GUD) experiments have been a foundational method to evaluate perceived predation risk, but rely on the assumption that food preferences are absolute. However, nutritional preferences are context dependent and can change with risk. In my first chapter, I used spiders and grasshoppers to test the hypothesis that covariance in nutritional preferences and risk may confound the interpretation of GUD experiments. My results demonstrate that predation risk and nutritional preferences covary and can confound interpretation of GUD experiments. In my second chapter, I use a behavioral observation experiment to further explore non-consumptive effects, as well as the movement of prey in response to predation risk.

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.

Background: This study was conducted to determine the association between fiber intake and insulin resistance in 264 women using a cross-sectional design. Methods: Insulin resistance was indexed using HOMA-IR (fasting insulin (μU/mL)×fasting glucose (mg/dL)/405). HOMA-IR values were log transformed. Fiber and energy consumption were assessed using 7-day weighed food records. Fiber was expressed as grams per 1000 kilocalories. Body fat percentage (BF%) was measured using the BOD POD and physical activity (PA) was ascertained using Actigraph accelerometers worn for 7 consecutive days. Results: (Mean±SD) age: 40.1±3.0 years, glucose: 86.7±5.9 mg/dL; insulin: 7.1±4.3 μU/mL; HOMA-IR: 1.5±1.0; fiber intake (g/1000 kcal), total: 9.3±2.9; soluble: 1.7±0.9; insoluble: 3.8±1.9; physical activity: 2.7044 ±0.7842 million counts; BF%: 31.7±6.9; weight (kg): 66.1±10.1; total caloric intake per day (kcal): 2054.1±320.9; and dietary fat intake (% of total kcal): 30.5±0.5. Women with high total fiber intakes had significantly less insulin resistance than their counterparts (F=4.58, p=0.0332), and women with high soluble fiber intakes had significantly lower levels of insulin resistance than other women (F=7.97, p=0.0051). Participants with high insoluble fiber intakes did not differ from their counterparts (F=0.7, p=0.6875). Adjusting for either PA or BF% weakened the relationships significantly. Controlling for BF% nullified the total fiber-HOMA-IR link (F=1.96, p=0.1631), and attenuated the association between soluble fiber and HOMA-IR by 32% (F = 6.86, p=0.0094). To facilitate interpretation of the results, odds ratios were calculated to determine the association between fiber intake and HOMA-IR with both variables treated as categorical. To create dichotomous variables, fiber intake and HOMA-IR were each divided into two categories using the median (Low and High). In women who had high soluble fiber intake (upper 50%), the odds of having an elevated HOMA-IR level was 0.58 (95% CI: 0.36-0.94) times that of women with low soluble fiber intake (lower 50%). And after controlling for all of the potential confounding factors simultaneously, the odds ratio was 0.52 (95% CI: 0.29-0.93). Conclusion: High fiber intake, particularly soluble fiber, is strongly related to lower levels of insulin resistance in women. Part of this association is a function of differences in PA and BF%.

The purpose of the immune system is to protect our bodies from infection. One way it accomplishes this task is through the presentation of foreign pathogens to NKT cells. After an antigen is presented to the T cell receptor, activated NKT cells quickly release soluble chemical signals, termed chemokines and cytokines, that modulate the response of the immune system. Due to the immunological relevance of NKT cell activation, we developed and synthesised non-natural analogs of immunostimulatory type I, II, and gamma delta NKT cell antigens. The immunological evaluations of these analogs resulted in identification of sulfatide as a gamma delta NKT cell antigen, along with the characterization of these newly discovered sulfatide-reactive gamma delta NKT cell line. During sulfatide structure activity relationship studies, a novel azido-sulfatide analog was synthesized to traffick and image sulfatide in vivo. These studies demonstrated that sulfatide accumulated in the late endosome/lysosome. In conjunction with previous studies, this observation explains the persistence of CD1d-restricted T cells with high affinity for this antigen in healthy individuals. Finally, stimulatory assays were performed on a panel of synthesized lyso-glycosylceramides. This led to the discovery of stimulatory type I NKT cell antigens, alpha-psychosine and alpha-glucopsychosine.