京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第21163号 / 農博第2289号 / 新制||農||1060(附属図書館) / 学位論文||H30||N5137(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 大澤 晃, 教授 北島 薫, 教授 神﨑 護 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DGAM

No description available.

Bacterial membranes act as protective barriers and help to regulate molecular interactions between a cell and its surrounding environment. External chemical and physical influences have the potential to alter the properties of bacterial membranes and therefore impact the viability of the cell. This can stem from natural or seasonal changes to the local environment (e.g., temperature, pH, and salinity), or even deliberate application of an antimicrobial agent. Regardless, understanding exactly how such external stimuli influence bacterial membrane properties is of fundamental importance, both in terms of basic microbiology as well as for designing pharmaceutical interventions. Experimentally, this is a non-trivial task as this requires selective isolation of a signal arising from the membrane, which is typically buried in the overwhelming background response of the surrounding bulk environment. In particular, our lab has previously developed the surface-sensitive nonlinear optical method, second harmonic light scattering (SHS), as a means of interrogating molecular interactions at the membrane surfaces of living cells, even for multimembrane systems (e.g., Gram-negative bacteria). In this dissertation, time-resolved SHS was employed to study a variety of membrane properties across two separate projects, including 1) chemical and physical induced changes in membrane permeability and 2) temperature-induced membrane permeability changes. Specifically, in the first project (Chapter 4), the influence of the signaling molecule, indole, on the permeability of the bacterial cytoplasmic membrane was quantified. It was revealed that the interaction of indole with the tryptophan specific transporting protein, Mtr permease, resulted in enhanced passive diffusion across the membrane. For the second project (Chapter 5), we examined the influence of temperature on the rate of passive diffusion across a membrane, both in model systems (liposomes) and in living cells (E. coli). For both bacterial and liposome systems, increasing temperatures resulted in a modest increase in passive diffusion rates across the membrane. However, when the temperature range included a phase transition, passive diffusion increased by an order of magnitude. Therefore, by monitoring transport rate in relation to temperature, membrane phase transitions can be quantitatively determined based on the characteristic discontinuities in the measured trend. / Chemistry

Parrotfeather [Myriophyllum aquaticum (Vellozo) Verdecourt] is a non-native aquatic plant from South America that was introduced into the United States in the 1890's. Research was conducted to elucidate seasonal life history, starch allocation patterns, and key environmental factors that may affect plant growth. Environmental factors identified in field studies were used to develop a conceptual model to display relationships between growth and environmental factors. The conceptual model served as a broad-based hypothesis to parameterize growth limiting factors as it related to M. aquaticum growth. Mesocosm experiments were then conducted to test relationships depicted in the model and define the growth requirements of this species. Emergent shoot biomass, submersed shoot biomass, and sediment root biomass were related to light transmittance. Submersed shoot biomass was also related to water temperature. Stolons accounted for 40-95% of total biomass. Starch allocation was also greatest in stolons (78.1 g m-2); where up to 16.3% of total starch was stored. Low points in biomass and starch occurred from October to March. Biomass was greater when plants were grown in 30% shade, whereas plant length was greatest when plants were grown in 50% shade, with reductions observed in full sunlight. Biomass increased by 53% when nitrogen and phosphorus were added to the water column at 1.80 and 0.01 mg L-1, respectively. Myriophyllum aquaticum yield response was positively related (r2 = 0.82) to increasing nitrogen content and a critical concentration of 1.80% nitrogen and 0.20% phosphorus was identified for M. aquaticum growth. Plants grown at 0 cm water depth had 96% greater biomass than plants grown at water depths of 137 cm. Total length was 25% greater when plants were grown at water levels from 0-77 cm. Winter drawdowns reduced biomass by 99% at 4 weeks when compared to pre drawdown biomass. Summer drawdown efficacy was more rapid where biomass was reduced by 98% at 2 weeks when compared to pre drawdown biomass. Subsurface herbicide applications were not more efficacious than herbicides applied to the foliage. The foliar application of 2,4-D was the only herbicide and application method that resulted in ¡Ý90% biomass reduction of M. aquaticum.

<p>  </p> <p>Maternal smoking during pregnancy (MSDP) is still occurring in the United States, as of 2021, at an average rate of 6% (CDC, WONDER). This proximal exposure to MSDP has been associated with decreased fetal head size, increased risk of SIDS, and increased risk for low birthweight (Abraham et al., 2017, Avsar et al., 2021; Knopik et al., 2016b) in infants exposed to MSDP compared to infants not exposed to MSDP. Additionally, MSDP has been associated with epigenetics in the form of differential DNA methylation (DNAm) in children and adolescents who were exposed to MSDP. Among these studies, there has been consistency in gene-specific findings of differential methylation in global DNAm (across the genome), <em>AHRR, CYP1A1, CNTNAP2, MYOIG, </em>and<em> GFI1 </em>(Ladd-Acosta et al., 2015; Lee et al., 2015; Richmond et al., 2015; Rzehak et al., 2016)<em>.</em> Using the frameworks of the Developmental Origins of Health and Disease, as well as Ecological Systems Theory, the current study aims to (1) test the effect of MSDP on global DNAm (across the genome) cross-sectionally in 8-17 y/o children and adolescents, (2) attempt to replicate and analyze the MSDP impacts on <em>AHRR, CYP1A1, CNTNAP2, MYOIG, </em>and<em> GFI1, </em>and (3) adjust for several prenatal and postnatal covariates (second-hand smoke and particulate matter (PM2.5), specifically) in an attempt to isolate the MSDP exposure on DNAm analysis. In a sample of 325 8-17 y/o children whose sibling was exposed to more or less MSDP compared to them, it was found that higher child-specific MSDP was associated with more global methylation and less <em>CNTNAP2</em> methylation, possibly suggesting evidence for a partially causal pathway between MSDP and DNAm for these genetic outcomes. Both child-specific and family-average MSDP were associated with<em> CYP1A1</em> and <em>MYO1G</em> methylation. There were also various findings related to child sex and age covariates, as well as postnatal PM2.5. Future studies focused on replication of these findings in a longitudinal genetic design could further confirm the associations found in the current study.</p>

<p> The vegetational colonization and development preceding the establishment of lichen-heath was examined on a Hudson Bay coastal raised-beach system. A continuous and directional developmental sequence of approximately 200 years was quantified on both a coastal intraridge sample sequence and on an inland interridge sample sequence. Increasing gradients of elevation, soil peat thickness and soil organic matter coincide with the vegetational development, however no appreciable changes in soil pH or concentrations of available nutrients were detected and it is concluded that these parameters have little influence on the development of lichen-heath at this site. Community composition over the ridge profile forms a second major vegetational gradient which appears to be affected primarily by environmental factors related to ridge morphology and orientation. The interactions of environmental factors in the development of lichen-heath are discussed.</p> / Thesis / Master of Science (MSc)

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Structural Health Monitoring (SHM) is the implementation of damage detection and characterization algorithms using in vitro sensing and actuation for rapidly determining faults in structural systems before the damage leads to catastrophic failure. SHM systems provide near real time information on the state of the integrity of civil, mechanical and aerospace structures. A roadblock in implementing SHM systems in practice is the possibility of false positives introduced by environmental changes. In particular, temperature changes can cause many SHM algorithms to indicate damage when no damage exists. While several experimentally based efforts have been attempted to alleviate temperature effects on SHM algorithms, fundamental research on the effects of temperature on SHM has not been investigated. The work presented in this dissertation composes of two main parts: the first part focuses on the experimental studies of different mechanical structures of aluminum beams, lug samples and railroad switch bolts. The experimental study of the aluminum lug samples and beams is done to propose and examine methods and models for in situ interrogation and detection of damage (in the form of a fatigue crack) in these specimen and to quantify the smallest detectable crack size in aluminum structures. This is done by applying the electrical impedance-based SHM method and using piezoceramic sensors and actuators. Moreover, in order to better extract the damage features from the measured electrical impedance, the ARX non-linear feature extraction is employed. This non-linear feature extraction, compared to the linear one, results in detection of damages in the micro-level size and improves the early detection of fatigue cracks in structures. Experimental results also show that the temperature variation is an important factor in the structural health monitoring applications and its effect on the impedance-based monitoring of the initiation and growth of fatigue cracks in the lug samples is experimentally investigated. The electrical impedance-based SHM technique is also applied in monitoring the loosening of bolted joints in a full-scale railroad switch and the sensitivity of this technique to different levels of loosening of the bolts is investigated. The second part of the work presented here focuses on the analytical study and better understanding of the effect of temperature on the vibration-based SHM. This is done by analytical modeling of the vibratory response of an Euler-Bernoulli beam with two different support conditions of simply supported and clamped-clamped and with a single, non-breathing fatigue crack at different locations along the length of the beam. The effect of temperature variations on the vibratory response of the beam structure is modeled by considering the two effects of temperature-dependent material properties and thermal stress formations inside the structure. The inclusion of thermal effects from both of these points of view (i.e. material properties variations and generation of thermal stresses) as independent factors is investigated and justified by studying the formulations of Helmholtz free energy and stresses inside a body. The effect of temperature variations on the vibratory response of the cracked beam are then studied by integrating these two temperature-related effects into the analytical modeling. The effect of a growing fatigue crack as well as temperature variations and thermal loadings is then numerically studied on the deflection of the beam and the output voltage of a surface-bonded piezoceramic sensor. / Ph. D.