Butterfly wing color patterns are produced by the placement of monochromatic scales that have specific colors due to pigmentation, nanostructures, or a combination of both. Structural coloration results from the interference of light from the architecture of the nanostructures. Structural coloration in butterfly scales has been studied optically, but little is known about the mechanisms used to create these scales compared to scales without structural coloration. Light, scanning, and transmission electron microscopy were used to determine underlying morphological, pigmentation, and developmental differences between blue (i.e., structural) and black (i.e., nonstructural) wing scales of Vanessa cardui. Differences in scale size, pigmentation, nanostructure spacing, and cuticle deposition were identified as contributors to structural coloration in mature scales. Differences in cuticle deposition, trabeculae formation, and longitudinal ridge spacing were identified during development. Differences in cuticle deposition during scale development were implicated as an influential factor for the production of structural coloration.

Mercury levels in the environment have been increasing steadily since the industrial age. Mercury can have deleterious effects on a variety of types of tissue in vertebrates; however, effects of mercury in some animals and/or tissues may be masked by animal's compensatory mechanisms. It is still widely unknown how these rising levels are affecting wildlife, specifically Eastern Bluebirds (Sialia sialis). The goal of this research was to explore a novel method through which mercury may be affecting the fitness of Eastern Bluebirds exposed to varying levels of environmental mercury. Birds on contaminated and reference sites were monitored for two years and various fitness measures were recorded. Four different feather types were also taken to measure mercury's effects on structural coloration. This is the first study to show that mercury in feathers may impact plumage coloration through three possible mechanisms: (1) binding to the sulfide bonds in keratin causing a change in the regular spacing that produces the blue color, (2) inhibition of melanin synthesis, or (3) impacts on the overall health of individuals resulting in lower investment in color production. The overall effects of mercury on bluebirds' fitness and their offspring varied based on adult sex; females with high feather mercury had fewer eggs, and males with high blood mercury fledged fewer offspring. In conclusion, these studies showed a novel way in which mercury may impact birds in an exposed environment as well as ways in which mercury may affect fitness based on sex of the individual and time of exposure. / Master of Science

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24310号 / 理博第4880号 / 新制||理||1698(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 曽田 貞滋, 准教授 渡辺 勝敏, 教授 中務 真人 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Natural precious opals consist of silica nanoparticles of uniform diameter organised in a periodic three-dimensional structure. The physical structure of the material produces the perceived colour by a process of light diffraction. The modification of light by the physical structure of the material is also known as structural colour. This is a different process from how most surface colours are produced where light is more usually absorbed by dye and/or pigment molecules. Desirable aesthetic qualities could be achieved if the structural colours produced by natural opals could be replicated in the form of a film or a coating on textile substrates. The work presented investigates how to produce structurally coloured textiles using surface applications of uniform spherical silica nanoparticles (USSNPs). A novel one-step solvent varying (SV) technique has been developed to synthesise USSNPs with particle diameters in a controlled size range. Using suspensions containing USSNPs, structurally coloured artificial opal (AO) films have been fabricated by self-assembly using a process of natural gravity sedimentation. The sedimentation of a particular particle size range of USSNPs (from which a coloured film was produced), onto the surface of fabrics, produced a structurally coloured fabric. By controlling the mean particle diameter a wide range of spectral colours from red to blue was obtained. The light fastness properties of the coloured textiles were investigated. A further surface modification of USSNPs was performed by adding vinyl functional groups to improve the mechanical strength of the structural colour. This work suggested a novel approach to colouring textile materials without using traditional dyes and/or pigments.

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