RHODOPSIN-MODULATED IONIC CONDUCTANCES IN CHLAMYDOMONAS

膜片钳方法用于表征离子电导 单细胞衣藻趋光信号处理的研究 纤毛真核生物。这种有机体对光的反应是一种 超极化受体电位表现为同源形式 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 来自牛样视紫红质的信号(？cGMP) 与牛视紫红质基因的保守序列同源性。功能性 衣藻的光耦合离子电导的比较 已经研究过的杆或锥体中的电导将决定 在受体水平上是否也存在相同的同源性 延伸到视紫红质偶联的蛋白质 处理，以及这些信号处理通道元件 在功能上与棒材内段的功能同源 (RIS)。中信号处理环境同调的证明 衣藻对脊椎动物的光感受器会引起广泛的兴趣 视觉生理学家和遗传学家的受众 生理、生化和遗传可及性。一位批评者 衣藻系统相对于脊椎动物的优势 光感受器是它的遗传学很好地与 沿着整个输入可用的(或容易产生的)突变体- 输出途径。然后衣藻可能会进行基因解剖 感觉处理类似于草履虫的神经遗传学研究 还有果蝇。在同源的感觉处理环境中 可以利用cDNA技术来克隆通道的基因 或控制单细胞视觉的酶，这些探针可能是 用于绘制人类基因组中类似功能的位置图。 相反，被认为与人类 光感受器处理缺陷(如视网膜色素变性(RP)) 或先天性夜视(CN))可以进行生理性筛查 或可接近的同源系统中的结构效应。另一个 衣藻相对于杆状或圆锥体的优势在于，它是自由的- 没有连接到其他细胞的行为有机体 杆状或圆锥体中输入-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.