PHOTORECEPTOR CELL FATE DETERMINATION IN THE RETINA

本研究提案的总体目标是确定 感光细胞命运的分子机制。这 将通过使用分子生物学和 基因技术学习系统将是人类的复眼， 果蝇Drosophila melanogaster 在最近出版的作品中，我们发现并描述了一部小说， 蝇眼视色素基因表达模式。通过操纵 从遗传学上讲，我们已经证明， 一种感光细胞类型的基因。似乎每个细胞中的一个细胞 小眼（R7）在随机的环境中采用两种不同的细胞命运之一， 方式，然后将此决定（感应）传达给相邻的 R8细胞。这些事件有助于协调视觉的表达， 在这两个细胞中的色素，并产生两种类型的光学单位内 具有不同光谱敏感度的眼睛。 在这个建议中，我们提出了一系列的实验，以严格测试 这个模型，通过检查视蛋白基因表达的各个方面， 调节其表达的启动子，并进行遗传筛选 以确定基因所需的规格， 光感受器细胞的命运和视蛋白基因表达的调节。 这些研究对于理解 形成复眼。光感受器分化为 具有不同光谱敏感度的群体是颜色的基础。 歧视整个神经系统内的信号传输也是 依赖于具有不同神经元群体的世代， 不同的敏感性和传递表型。因为蝇眼 已经成为发育生物学中的一个关键模型系统， 该系统中的新信号传导和细胞命运决定途径 将作为一个框架来理解更复杂的发育事件， 在其他生物的神经系统中。

The overall objective of this research proposal is to determine the molecular mechanisms by which photoreceptor cell fate is specified. This will be accomplished by using a combination of molecular biological and genetic techniques. The system of study will be the compound eye of the fruit fly Drosophila melanogaster. In recently published work, we identified and characterized a novel pattern of visual pigment gene expression in the fly eye. By manipulating the eye genetically we have shown that the expression of visual pigment genes in one photoreceptor cell type. It appears that one cell in each ommatidium (R7) adopts one of two different cell fates in a stochastic manner, and then communicates this decision (inductively) to the adjacent R8 cell. These events serve to coordinate the expression of visual pigments in these two cells, and produce two type of optical units within the eye that have distinct spectral sensitivities. In this proposal, we present a series of experiments to rigorously test this model, by examining aspects of opsin gene expression, studying the promoters which regulate their expression, and conducting genetic screens to identify genes which are required for the specification of photoreceptor cell fate and the regulation of opsin gene expression. These studies are of fundamental importance in understanding how the compound eye is formed. The differentiation of photoreceptors into populations having different spectral sensitivities is the basis for color discrimination. Signal trafficking within the nervous as a whole is also dependent upon the generation f diverse neuronal populations having different sensitivities and transmitter phenotypes. Because the fly eye has become a key model system in Developmental Biology, the elucidation of novel signaling and cell-fate determination pathways within this system will serve as a framework to understand more complex developmental events within the nervous system of other organisms.