Eyespot Placement and Assembly in Chlamydomonas

这项研究使用模式生物莱茵衣藻来了解复杂的分子结构是如何在细胞内的特定位置组装的。衣藻是一种单细胞的光合藻类，在世界各地的淡水栖息地都有发现。衣藻细胞利用细胞前端的两条鞭毛（母鞭毛和子鞭毛）向光或向光游来游去，从而优化光合作用。光的强度和方向由眼斑感知，眼斑是一种复杂的结构，通常位于细胞的外缘，位于细胞的前后两端之间，与子鞭毛位于细胞的同一侧。眼斑含有与哺乳动物眼睛中的视紫红质相似的光感受器蛋白，以及位于眼斑特有的细胞膜层或脂质颗粒中的多种其他蛋白质。这项研究将测试光感受器蛋白是组装和/或放置眼斑所必需的假设，并将识别和表征参与眼斑形成的其他蛋白质。由本研究产生的眼斑组装的分子模型将适用于其他生物系统中各种其他亚细胞结构的研究。长期以来，藻单胞菌一直是研究光合作用和鞭毛组装的模式生物，因此这种光合藻类的生长条件、遗传操作和分子特征已经很好地建立起来。因此，研究衣藻眼点是培养亚利桑那大学攻读学位的不同群体的年轻科学家的一个极好的模式系统。许多本科生和研究生已经完成了他们的高级论文、荣誉论文或博士论文，研究眼斑组装，亚利桑那大学的学生继续从事与眼斑相关的研究。此外，与两位小大学教授和他们的学生建立的关系将继续。因为草绿色的衣藻细胞有亮橙色的眼点和长长的鞭毛，通过光学显微镜很容易观察到，所以参观实验室也受到了小学生的欢迎。作为回应，研究人员开发了以衣原体为基础的生物课，将在课堂上向K-12学生讲授。衣藻只是众多对光有反应的光合微生物中的一种。随着这些微生物成为利用太阳能生产食物和燃料的焦点，学生对衣藻的兴趣正在增加。

INTELLECTUAL MERITThis research uses the model organism Chlamydomonas reinhardtii to understand how complex molecular structures are assembled at specific locations within a cell. Chlamydomonas is a single-celled, photosynthetic alga found in freshwater habitats throughout the world. Chlamydomonas cells optimize photosynthesis by swimming toward or away from light using two flagella (the mother flagellum and the daughter flagellum) at the anterior end of the cell. Light intensity and direction are sensed by the eyespot, a complex structure that is always found at the outer edge of the cell, half way between the anterior and posterior ends of the cell, on the same side of the cell as the daughter flagellum. The eyespot contains photoreceptor proteins that are similar to the rhodopsins in mammalian eyes, and a variety of other proteins that are located in the cell membrane layers or lipid granules that are unique to the eyespot. This research will test the hypothesis that the photoreceptor proteins are required for the assembly and/or placement of the eyespot, and will identify and characterize other proteins involved in eyespot formation. A molecular model of eyespot assembly resulting from this research will be applicable to studies of a wide variety of other sub-cellular structures in other biological systems.BROADER IMPACTSChlamydomonas has long been a model organism for the study of photosynthesis and flagellar assembly, so the conditions for growth, genetic manipulation, and molecular characterization of this photosynthetic alga are well established. Studying the Chlamydomonas eyespot is, therefore, an excellent model system for training the diverse group of young scientists pursuing degrees at the University of Arizona. A number of undergraduate and graduate students have completed their senior, honor, or Ph. D. theses studying eyespot assembly, and University of Arizona students continue to pursue eyespot-related research. Additionally, established relationships with two small college professors and their students will continue. Because the grass-green Chlamydomonas cell with its bright orange eyespot and long flagella is easily viewed through the light microscope, visiting the laboratory has also been popular with grade school students. In response, the researchers have developed Chlamydomonas-based biology lessons that will be presented to K-12 students in their classrooms. Chlamydomonas is only one of a very large number of photosynthetic microorganisms that respond to light. Student interest in Chlamydomonas is increasing as these microorganisms become the focus of efforts to produce food and fuel using energy from the sun.