ANEURAL PHOTOSENSORY TRANSDUCTION IN STENTOR COERULEUS

蓝花的神经光感传导

• 批准号: 3396242
• 负责人: Pill-Soon Song
• 金额: $ 9.9万
• 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/3396242
• 关键词: Ciliophora; acidity /alkalinity; adenosine triphosphate; adenosinetriphosphatase; bioenergetics; biological signal transduction; biological transport; calcium channel; 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; visual phototransduction

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.

Stentor coeruleus 是一种单细胞异毛虫，具有两种光 强度和颜色（波长）感官“视觉”，代表第一个 以 stentorin 为基础的清晰可辨的“视觉感觉系统” 光感受器，作为成熟的基于视紫红质的替代品 高等动物的视觉感觉系统。 这种神经生物也是 能够感知光的传播方向。 光感应是 表现为生物体纤毛搏动逆转的形式。 这 该细胞中的光传感过程可以示意性地描述为 如下： 光信号到光感受器吸收到信号产生和 反应放大（睫状行程逆转） 我们建议研究光诱导质子的可能参与 从感光体释放（pH 值变化）作为主要机制 光信号的产生。 质子形式的初始信号 有人建议从光感受器复合物中释放 随后的转导步骤包括钙离子从 细胞外介质，从而放大初始光信号。 这是 提出钙离子流入导致支架细胞逆转 纤毛跳动方向并随后避开有害光线 来源。 具体来说，我们计划阐明关键感官的机制 转导步骤。 光感受器 stentorin 将被分离并 进一步表征，及其在溶液中和在中的主要光过程 光感受器细胞器（色素颗粒）以及完整的 细胞将被研究。质子从激发态释放出来的作用 Stentorin 的状态作为初始感觉信号（pH 值变化诱发 受体电位）将通过使用色素中的 ph 探针来说明 颗粒包埋的脂质体和体内。 我们建议暂时 色素释放质子导致细胞内 ph 值下降 颗粒作为电信号打开钙 细胞/睫状膜。 钙离子的流入然后触发纤毛 击败逆转。 这一假设将在目前得到进一步检验 学习。