Melanophore Response to Light and Melatonin

9319344非洲爪哇养殖的尾鳍黑素细胞受光照射后，细胞内的色素颗粒从均匀的细胞质分布迁移到核周聚集体。这种独立于视觉系统的直接光反应，为研究光直接改变细胞功能的机制提供了一个方便的模型系统。这项拟议的研究将确定培养的黑素细胞中光传导途径的分子组成，比较光和褪黑素(一种导致相似形态变化的激素)诱导的分子级联，并确定诱导光敏表型的实验范式。将采用免疫细胞化学、分子生物学、放射免疫化学和视频显微镜技术。预计这项研究将1)为理解脊椎动物细胞视网膜外接受光的分子机制提供重要的先例，(这种生物反应不仅用于伪装，而且还用于调节各种脊椎动物的季节性繁殖现象)，2)扩大两栖黑素载体作为研究褪黑素和光信号转导的分子机制的模式系统的使用，3)提供一种可靠地诱导非光敏黑素细胞的光敏表型的方法(这是试图确定光敏诱导因子的化学同一性及其作用机制的研究的必要的基础研究)。***

9319344 Rollag Exposure of cultured Xenopus tailfin melanophores to light causes intracellular pigment granules to migrate from a homogeneous cytoplasmic distribution to a perinuclear aggregate. This direct photic response, which is independent of the visual system, provides a convenient model system for study of the mechanisms by which light directly modifies cellular function. The proposed research will identify molecular components of the phototransduction pathway in cultured melanophores, compare the molecular cascades elicited by light and melatonin (a hormone which causes similar morphological changes), and define experimental paradigms that induce the photosensitive phenotype. Immunocytochemical, molecular biological, radioimmunochemical, and videomicroscopic techniques will be employed. It is expected that this research will 1) provide an important precedent for understanding the molecular mechanisms underlying extra-retinal photoreception in vertebrate cells (a biological response that is not only used during camouflage, but also for regulation of seasonal reproductive phenomena in a variety of vertebrate species), 2) expand upon the use of the amphibian melanophore as a model system for study of the molecular mechanism of both melatonin and light signal transduction, and 3) provide a method for reliably inducing the photosensitive phenotype in nonphotosensitive melanophores (a necessary preliminary to studies that seek to determine the chemical identity of photosensitizing inductive factors and their mechanisms of action). ***