POWRE: Eyespot Assembly in Chlamydomonas

POWRE：衣藻眼斑组装

• 批准号: 9806135
• 负责人: Carol Dieckmann
• 金额: $ 8万
• 依托单位: University of Arizona
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-15 至 2000-02-29
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9806135&HistoricalAwards=false
• 关键词: POWRE; Eyespot; Assembly; Chlamydomonas

The project is a study of the assembly and organization of the eyespot of the unicellular alga, Chlamydomonas. The eyespot is a light-sensing organelle which gives rise to characteristic phototactic behavior through control of the flagella which this organism has. Several features of the eyespot make it an extremely interesting system. It includes components of both the plasma membrane and a portion of the underlying, closely apposed membranes of the chloroplast. Associated with this region of the chloroplast membranes are layers of carotenoid pigment granules which reflect light to the apposed rhodopsin light-sensing region of the plasma membrane. Light activation of the rhodopsin leads to gated entry into the cell of calcium which initiates a signal transduction pathway that culminates in patterned flagellar movements to move the organism toward or away from the light source. The calcium channel has not been characterized and may in fact be the Chlamydomonas rhodopsin. Also fascinating is the fact that the eyespot is precisely positioned on the surface of the cell with respect to the complex rootlet structures of the flagella. During cell division, the eyespot first disappears. Then two new eyespots form, each 90 degrees from the division plane and 180 degrees from each other. The system poses numerous interesting questions of how expression of individual components is regulated and how these components are assembled into the highly ordered, functional structures. In this sabbatical study, three specific aims will be pursued. The aims are (1) to use biophysical techniques to analyze the physiology and behavior of eyespot-assembly mutants, (2) to analyze multi-eye mutants which presumably have defects in the positioning system for eyespot assembly during cell division, and (3) to use immunofluorescence light microscopy, GFP-protein techniques and immunoelectron microscopy to determine the organization of some of the major components in the eyespot structure of both normal and mutant organisms. This is a POWRE project which will significantly enhance the scientific training and expertise of the investigator.

该项目是对单细胞藻类衣藻眼点的组装和组织的研究。眼点是一种光敏细胞器，它通过控制鞭毛产生特有的趋光行为。眼点的几个特点使它成为一个非常有趣的系统。它既包括质膜的成分，也包括叶绿体下部紧密相对的膜的一部分成分。与叶绿体膜的这一区域相关的是类胡萝卜素色素颗粒层，它们将光反射到质膜的视紫红质感光区域。光激活视紫红质导致门控进入钙细胞，启动信号转导途径，最终形成鞭毛运动，使生物体靠近或远离光源。钙通道尚未被表征，实际上可能是衣藻的视紫红质。另一个令人着迷的事实是，眼点精确地定位在细胞表面，相对于鞭毛复杂的根状结构。在细胞分裂过程中，眼斑首先消失。然后形成两个新的眼点，每个眼点与分割平面成90度，彼此成180度。该系统提出了许多有趣的问题，如如何调节单个组件的表达，以及这些组件如何组装成高度有序的功能结构。在这项休假研究中，将追求三个具体目标。目的是：(1)利用生物物理技术分析眼点组装突变体的生理和行为；(2)分析可能在细胞分裂过程中眼点组装定位系统存在缺陷的多眼突变体；(3)利用免疫荧光显微镜、gfp蛋白技术和免疫电子显微镜确定正常和突变生物的眼点结构中一些主要成分的组织。这是一个power项目，将大大提高科研人员的科学培训和专业知识。