Central Project

光对藻类有重要影响：(1)作为光合作用的能量来源；(2)通过光感受器引发光感知介导的行为反应；(3)通过光暗循环携带其生物钟。最近，美国联合基因组研究所（jgi）对莱茵衣藻（Chlamydomonas reinhardtii）和硅藻褐藻（Phaeodactylum tricornutum）的基因组进行了测序，并开展了国际注释工作，从而可以进行比较基因组方法和蛋白质组学分析，例如衣藻（Chlamydomonas）的眼斑器官（一种原始视觉系统）。随着基因组和蛋白质组学方法的发展，在过去的几年里，国际上已经开发了几种针对这两种藻类的分子遗传工具。总之，这些努力提供了新的信息，并代表了一个有效的平台来执行深入表征参与光驱动途径的相关蛋白质。这样的努力需要在生理学、分子生物学和/或生物物理学方面经验丰富的科学家的合作。在这个研究小组的框架内，我们已经组建了这样一个跨学科的团队，并希望专注于光驱动反应的新方面，从光吸收到生理反应，这是两个物种中典型的，关于这一过程的深刻信息仍然缺乏或非常有限。一个重点将是在C. reinhardtii参与光和昼夜节律信号的光感受器的功能和生物物理特性。生理学研究表明，蓝光与衣藻的生物钟有关。潜在的候选物质有植物和动物样隐色素、通道视紫红质2和趋光蛋白。另一个重点将放在莱茵梭菌的光信号级联上，涉及位于眼点装置中的通道视紫红质和Ca2+结合蛋白，它们可以介导光信息的吸收。因此，在眼斑蛋白质组中发现的SOUL血红素结合蛋白（SOUL3）将引起进一步的兴趣。SOUL首先在脊椎动物中被描述，其mRNA在视网膜和松果体中特异性表达（Zylka和Reppert， 1999）。此外，含有his激酶和反应调节结构域的酶样视紫红质，其功能迄今完全未知，将被研究。在三角硅藻中，我们首次分析了隐色素和荧光色素的功能。我们的研究还将包括了解硅藻光合作用在不同水平上的光调节机制，即相关蛋白质的光依赖性合成，以及氧化还原介导的调节过程。尽管硅藻对地球上的初级生产贡献高达20%，但与绿色谱系相比，人们对它们的光合作用知之甚少。这种跨学科的结合方法将详细了解从光的吸收到所涉及的信号级联成员的功能的特定光驱动反应及其在两种选定的模式藻类中不同生物过程中的相关性。

Light has major impacts on algae (i) serving as energy source for photosynthesis, (ii) triggering behavioral responses mediated by light perception via photoreceptors and (iii) entraining their circadian clocks by light-dark cycles. The recent sequencing of the genomes of the green alga Chlamydomonas reinhardtii and of the diatom Phaeodactylum tricornutum by the Joint Genome Institute (JGIDepartment of Energy, USA) and the international annotation effort allowed to perform comparative genome approaches as well as proteomic analysis, e.g. of the eyespot apparatus of Chlamydomonas, a primordial visual system. Along with the genome and proteome approaches, several molecular genetic tools have been developed on an international basis in the past years for these two algae. Altogether, these efforts provide novel information and represent an efficient platform to perform an in-depth characterization of relevant proteins involved in lightdriven pathways. Such an effort requires the collaboration of scientists who are experienced in physiology, molecular biology and/or biophysics. Within the Frame of this research group, we have assembled such an interdisciplinary team and want to focus on novel aspects of light-driven reactions from light absorption to physiological responses that are typical for either of the two species and where profound information about the processes is still lacking or is very limited. One focus will be on the functional and biophysical characterization of photoreceptors in C. reinhardtii that are involved in light- and circadian signaling. Blue light has been shown by physiological studies to be relevant for entraining the clock of Chlamydomonas. Potential candidates are plant- and animal-like cryptochromes, channelrhodopsin 2 and phototropin. Another focus will be on the light-signalingcascade in C. reinhardtii involving channelrhodopsins and Ca2+-binding Proteins located in the eyespot apparatus that can mediate absorbed light information. Thereby, a SOUL heme-binding protein (SOUL3) that was also found in the eyespot proteome will be of further interest. SOUL was first described in vertebrates where its mRNA is specifically expressed in the retina and pineal gland (Zylka and Reppert, 1999). Moreover, enzyme-like rhodopsins containing His-kinase and response regulator domains, whose function is completely unknown so far, will be under investigation. In the diatom P. tricornutum, we will analyze for the first time the function of the cryptochromes as well as of the diatom aureochromes. Our studies will also include an understanding of the mechanism of the light Regulation of diatom photosynthesis on different levels, i.e. the light-dependent synthesis of relevant proteins, as well as redox mediated regulation processes. Albeit diatoms contribute up to 20% to the primary production on Earth, little is known about their photosynthesis in comparison to the green lineage. This combined interdisciplinary approach will give a detailed view about specific light-driven reactions from the absorption of light to the function of the involved signaling cascade members and their relevance in different biological processes in the two chosen model algae.