ANEURAL PHOTOSENSORY TRANSDUCTION IN STENTOR COERULEUS

蓝花的神经光感传导

• 批准号: 3396240
• 负责人: Pill-Soon Song
• 金额: $ 8.74万
• 依托单位: UNIVERSITY OF NEBRASKA LINCOLN
• 依托单位国家: 美国
• 财政年份: 1987
• 资助国家: 美国
• 起止时间: 1987-12-01 至 1994-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/3396240
• 关键词: Ciliophora; acidity /alkalinity; adenosine triphosphate; adenosinetriphosphatase; biological signal transduction; calcium channel; calcium transporting ATPase; chemical structure function; chromophore; circular dichroism; electron microscopy; electrophoresis; electrophysiology; fluorescence spectrometry; fluorescent dye /probe; high performance liquid chromatography; infrared spectrometry; liposomes; membrane reconstitution /synthesis; membrane transport proteins; molecular cloning; neural information processing; nonvisual photoreceptor; nonvisual photosensitivity; organelles; photochemistry; sensory feedback; sensory mechanism

Stentor coeruleus, a unicellular hetrotrich,possesses both light intensity-and color (wavelength)-sensory "visions", representing the first clearly identifiable "visual sensory system" based on stentorin as the photoreceptor,as an alternative to the well established rhodospin-based visual sensory system in higher animals. This aneural organism is also able to perceive the direction of light propagation. Light sensing is manifested in the form of ciliary beat reversal by the organism. The photosensory process in this cell can be described schematically as follows: Light signal to Absorption by photoreceptor to Signal generation and amplification to Response (ciliary stroke reversal) We propose to study the possible involvement of a light-induced proton release (ph change) from the photoreceptor as a primary mechanism for the generation of a light signal. The initial signal in the form of proton release from the photoreceptor complexes has been suggested to trigger subsequent transduction steps that include calcium ion influx from the extracellular medium,thus amplifying the initial light signal. It is proposed that the calcium ion influx causes stentor cell to reverse the ciliary beat direction and subsequently steer away from the harmful light source. Specifically, we plan to elucidate the mechanisms of the key sensory transduction steps. The photoreceptor stentorin will be isolated and further characterized,and its primary photoprocesses in solution and in the photoreceptor organelle (pigment granule) as well as in the intact cell will be investigated. The role of proton release from the excited state of stentorin as an initial sensory signal (a ph change-evoked receptor potential) will be illustrated by using ph probes in the pigment granule-entrapped liposomes and in vivo. We propose that a transient intracellular ph drop resulting from the proton release from pigment granules serves as an electrical signal to open calcium in the cell/ciliary membranes. The influx of calcium ions then trigger a ciliary beat reversal. This hypothesis will be further tested in the present study.

支架凝结物是单细胞的hetrotrich，具有两种光 强度和颜色（波长） - 感官“视觉”，代表第一个 基于Stentorin的明确识别的“视觉感觉系统”为 光感受器，作为基于变态的良好的替代品 高等动物的视觉感觉系统。 这种动脉虫也是 能够感知光传播的方向。 光感知是 以有机体的形式表现为睫状跳动的形式。 这 该单元单元中的光感过程可以示意性地描述为 以下内容： 光信号通过光感受器吸收到信号产生和 放大反应（睫状冲逆转） 我们建议研究光诱导的质子的可能参与 从感光器作为主要机制的释放（pH变化） 产生光信号。 质子形式的初始信号 已经建议从光感受器复合物中释放来触发 随后的转导步骤，包括来自钙离子涌入 细胞外培养基，从而扩大初始光信号。 这是 提出钙离子涌入会导致Stentor细胞逆转 睫状跳动方向，随后脱离有害光 来源。 具体而言，我们计划阐明密钥感觉的机制 转移步骤。 光感受器stentorin将被隔离，并 进一步表征，其在溶液和 光感受器细胞器（色素颗粒）以及完整的 将研究细胞。质子释放的作用 Stentorin作为初始感觉信号的状态（pH变化诱发 通过在色素中使用pH探针来说明受体电位） 颗粒结合的脂质体和体内。 我们提出了瞬态 质子从色素释放而产生的细胞内pH下降 颗粒用作电信号，以打开钙 细胞/睫状膜。 然后钙离子的涌入然后触发睫状 击败逆转。 目前将进一步检验该假设 学习。