RHODOPSIN-MODULATED IONIC CONDUCTANCES IN CHLAMYDOMONAS

采用膜片钳方法对离子电导进行了表征 趋光信号处理的单细胞衣原体， 纤毛真核生物。 这种生物对光线的反应是 超极化受体电位表现出同源形式， 在脊椎动物和其他“修饰纤毛”中发现的 光感受器 感觉处理操作的输入是 信号（？cGMP）从牛样视紫红质中分离，所述视紫红质由具有 与牛视紫红质cDNA保守序列同源。 功能 衣原体中的光耦合离子电导与 已经在杆或锥中研究过的电导将决定 是否存在于受体水平的相同同源性也 延伸到视紫红质在信号中与之偶联的蛋白质 处理，以及这些信号处理通道元件是否 在功能上与杆内节中的那些同源 （RIS）。 中信号处理环境的同源性证明 衣原体对脊椎动物光感受器的作用将引起广泛的兴趣。 视觉生理学家和遗传学家的观众，因为 生理、生物化学和遗传可及性。 一个关键 衣原体系统优于脊椎动物 光感受器是它的遗传学是很好地建立与 在整个输入中可用（或容易产生）的突变体- 输出路径 披衣菌可能允许基因解剖 类似于草履虫神经发生研究的感觉处理 和果蝇。 在一个同源的感觉处理环境中 cDNA技术可以用来克隆通道的基因 或者控制单细胞视觉的酶，这些探针可以 用于绘制人类基因组中类似功能的位点。 相反，cDNA探针被认为是负责人类 光感受器处理缺陷（例如视网膜色素变性（RP）） 或先天性夜盲症（CN）可以筛选生理 或结构影响的一个可访问的同源系统。 另一 衣原体相对于杆状或圆锥体的优势在于它是自由的- 没有与其他细胞的连接， 杆或锥中输入-输出关系的复杂研究 在完整的视网膜上。

Patch clamping method are used to characterize ionic conductances of phototactic signal processing in Chlamydomonas, a unicellular ciliated eukaryote. The response to light in this organism is a hyperpolarizing receptor potential exhibiting homologous form to that found in the vertebrate and other "modified cilium" photoreceptors. The input to sensory processing operations is a signal (?cGMP) from a bovine-like rhodopsin coded by a gene with conserved sequence homology to bovine rhodopsin cDNA. Functional comparison of light-coupled ionic conductances in Chlamydomonas to conductances already studied in rods or cones would determine whether the same homology that exists at the receptor level also extends to the proteins which rhodopsin couples to in signal processing, and whether these signal processing channel elements are functionally homologous to those in the rod inner segment (RIS). Proof of homology of signal processing environments in Chlamydomonas to vertebrate photoreceptors would interest a wide audience of visual physiologists and geneticists because of physiologic, biochemical, and genetic accessibility. A critical advantage of the Chlamydomonas system over vertebrate photoreceptors is that its genetics is well established with mutants available (or readily generated) along the entire input- output pathway. Chlamydomonas may then permit a genetic dissection of sensory processing similar to neurogenetic studies in paramecium and Drosophila. In a homologous sensory processing environment cDNA technology could be exploited to clone genes for the channels or enzymes governing unicellular vision and these probes could be used to map sites for similar functions in the human genome. Conversely, cDNA probes believed to be responsible for human photoreceptor processing defects (e.g. in retinitis pigmentosa (RP) or congenital nyctalopia (CN)) could be screened for physiological or structural effects in an accessible homologous system. Another advantage of Chlamydomonas over rods or cones is that it is freely- behaving organism without the connections to other cells that complicate studies of input-output relationships in rods or cones in the intact retina.