Spectral and Metabolic Basis of Visual Responses

视色素再生是维持哺乳动物视觉敏感性的绝对必要条件 视网膜。然而，色素再生和敏感性恢复之间的关系， 暴露于强光（暗适应）目前知之甚少。这些基本原理的阐明 机制是非常重要的，因为色素再生的损害和由此导致的色素再生的减缓， 感光细胞的暗适应是许多致盲眼病的标志，包括Oguchi的 疾病，Stargardt病，Leber先天性黑蒙，眼底白斑，和年龄相关性 黄斑病变总体目标是确定分离的视杆细胞内的细胞机制 从视网膜色素上皮细胞，调节色素再生和暗适应的速度， 哺乳动物的视杆细胞，其过程比哺乳动物的视锥细胞慢得多。灵敏度恢复 将测量电生理学，减少全反式视网膜全反式视黄醇后，色素 漂白将用显微荧光法测量，色素再生的速率将被测量 显微镜下这种多学科的方法将应用于野生型（WT）和转基因 在色素漂白前后以及用11-顺式视黄醇外源性处理后， 再生视觉色素。提出了两个目标：在目标I中，我们将确定细胞机制， 调节分离自视网膜色素的视杆光感受器中的视色素再生速率 上皮细胞暴露在强光下。我们将检验长寿命的衰变 漂白的光产物（Meta III）限制了色素再生的速率，在再生期间11-顺式 视网膜从细胞外间隙中的脂质结合伴侣分配到漂白杆的细胞内盘中 通过被动扩散包围视杆，视蛋白在视杆细胞内盘中的驻留减慢 与视蛋白位于质膜中的视锥细胞相比，色素再生速率。在Aim II中， 将确定和表征再生的视觉色素导致 视杆光感受器视觉敏感性的恢复我们将与我们的合作者Jeannie Chen博士一起 测试漂白和再生的小鼠视杆细胞中敏感性的恢复在时间上发生的假设， 和机械上不同的阶段，与C-末端残基的去磷酸化有关， 再生视紫红质和/或转导素易位。我们将获得的知识是 了解正常和疾病相关条件下的暗适应，这是发展所必需的 治疗致盲眼病的新疗法。

Visual pigment regeneration is an absolute requirement for maintenance of visual sensitivity in the mammalian retina. However, the relationship between pigment regeneration and the recovery of sensitivity following exposure to bright light (dark adaptation) is presently poorly understood. The elucidation of these fundamental mechanisms is of great importance, as the impairment of pigment regeneration and the resulting slowing of dark-adaptation in photoreceptor cells are hallmarks of a number of blinding eye diseases, including Oguchi's disease, Stargardt's disease, Leber's congential amaurosis, fundus albipunctatis, and age-related maculopathy. The overall aims are to determine the cellular mechanism(s) within rod photoreceptors isolated from the retinal pigment epithelium that regulate the rate of pigment regeneration and dark adaptation in mammalian rods, processes that are substantially slower than in mammalian cones. Recovery of sensitivity will be measured electrophysiologically, the reduction of all-trans retinal to all-trans retinol following pigment bleaching will be measured microfluorometrically, the rate of pigment regeneration will be measured microspectrophotometrically. This multidisciplinary approach will be applied to wild-type (WT) and transgenic mouse rods before and following pigment bleaching, and after exogenous treatment with 11-cis retinal to regenerate visual pigment. Two Aims are proposed: In Aim I we will determine the cellular mechanisms that regulate the rate of visual pigment regeneration in rod photoreceptors isolated from the retinal pigment epithelium following their exposure to bright light. We will test the hypotheses that the decay of long-lived photoproducts of bleaching (Meta III) limits the rate of pigment regeneration, that during regeneration 11-cis retinal partitions into intracellular disks of bleached rods from lipid binding partners in the extracellular space surrounding rods by a passive diffusion, and that the residence of opsin in intracellular disks in rods slows pigment regeneration rate compared to cones in which opsin is located in the plasma membrane. In Aim II we will determine and characterize the time course of mechanisms by which regenerated visual pigment leads to recovery of visual sensitivity in rod photoreceptors Together with our collaborator, Dr. Jeannie Chen,we will test the hypotheses that recovery of sensitivity in bleached and regenerated mouse rods occurs in temporally and mechanistically distinct stages that are associated with dephosphorylation of C-terminal residues on regenerated rhodopsin and/or transducin translocation. The knowledge we will gain is prerequisite for understanding dark adaptation under normal and disease-related conditions, and is required for development of novel therapies to treat blinding eye conditions.