Melanophore Response to Light and Melatonin

9319344 Rollag将培养的尾爪鱼黑色素细胞暴露在光线下，会导致细胞内色素颗粒从均匀的细胞质分布迁移到核周围聚集。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。拟议的研究将确定培养的黑色素细胞光导通路的分子成分，比较光和褪黑激素（一种引起类似形态变化的激素）引发的分子级联，并定义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。预计本研究将1)为理解脊椎动物细胞视网膜外光接受的分子机制提供一个重要的先例（一种生物反应，不仅用于伪装，而且用于调节各种脊椎动物的季节性生殖现象），2)扩展使用两栖动物黑素细胞作为研究褪黑激素和光信号转导的分子机制的模型系统。3)提供一种可靠地诱导非光敏黑色素细胞光敏表型的方法（这是研究光敏诱导因子的化学特性及其作用机制的必要前提）。＊＊＊

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). ***