A Study of a Fatty Acid-Binding Protein and Uric Acid Granules in the Light Organ of Taiwanese Firefly, Luciola cerata

• Main Authors: GOH KING SIANG, 吳欽翔
• Other Authors: 李家維
• Format: Others
• Language: en_US
• Published: 2012
• Online Access: http://ndltd.ncl.edu.tw/handle/29728327585299537684

博士 === 國立清華大學 === 分子與細胞生物研究所 === 100 === The light organ of adult fireflies is specialized for producing bioluminescence. In this dissertation, two important studies regarding to the light organ of firefly, Luciola cerata were described. First, the discovery and characterization of a novel firefly protein, fatty acid-binding protein (lcFABP) in the light organ. Second, the study of the morphology and crystal property of uric acid granules in the reflector layer. lcFABP was identified in a search for light organ-specific protein. The cDNA of lcFABP was successfully cloned, and the recombinant lcFABP from E. coli expression binds strongly to long chain fatty acids. Some similarities in structural features were found in the analysis of amino acid sequence of lcFABP with other reported FABPs. In light organ, lcFABP was abundantly expressed in the light-producing cells, photocytes. In addition, biochemical assay demonstrated that the white opaque matter filling in the reflector layer is uric acid. Electron microscopy studies showed that the uric acid is stored in spherical intracellular vesicles that are highly uniform in size. A unique single peak X-ray diffraction (XRD) pattern detected in the XRD analysis of spherical uric acid granules from firefly light organ, is highly similar to those of spherical uric acid crystals found in the dropping of birds and reptiles, and the skin of silkworm larvae. Considering FABPs in other animals tissues are thought to be an energy source supplier, it is believed that lcFABP might be play a key role in supply energy source for continuous bioluminescent flashes in the light organ. The high similarity in morphology and crystal property between uric acid granules from fireflies and those from other animals suggested that the formation of the spherical uric acid crystals in firefly reflector layer and in other animal tissues might be highly similar.