3-D STRUCTURE OF GRANUM-STROMA THYLAKOID ASSEMBLIES IN HIGHER

这个子项目是许多研究子项目中的一个 由NIH/NCRR资助的中心赠款提供的资源。子项目和 研究者（PI）可能从另一个NIH来源获得了主要资金， 因此可在其他CRISP条目中表示。所列机构为 研究中心，而研究中心不一定是研究者所在的机构。 摘要： 螺旋排列的基粒类囊体系统是显而易见的，主要是从连续切片EM研究化学固定标本上的单个基粒或对基粒。这些没有揭示与基质类囊体互连的基粒的3D排列（网络）。基粒的个体发育、大小的变化、在不同环境条件下（强光）的灵活性  低光、短期适应、长期驯化）、膜磷酸化的结构后果以及物理化学环境（渗透压、离子强度）的作用也不清楚。 此外，由于化学固定可能产生伪影，因此存在一些不确定性。 还没有用电子层析技术研究过粒叶绿体  这可能是因为完整成熟的叶绿体体积大，结构致密。 因此，我们计划，此外，试图成像完整的叶绿体（和类囊体膜，即质体没有他们的包膜膜和可溶性成分），通过使用质体与小尺寸的基粒，和基粒基质组件通过超声处理和/或洗涤剂裂解分离。 我们有详细的知识有关组织的复合物和lameprazole在颗粒基质组件的丰富的其他技术，如圆二色光谱，揭示macrodomain组织（直径300-400纳米）和小角X射线和中子散射，提供信息的变化周期性的超微结构，以及它们的光合功能。还已经确定，这些结构能够通过生物学中以前未知的物理机制（热光效应）进行光诱导的可逆结构组织。 在上一个报告期内，进行了几次断层重建。Must UNK rdy和Garab博士访问了RVBC一周。 他们观察并参与了数据收集和断层重建。 一张断层照片显示了基粒是如何在类囊体内连接的，这是他们一直希望澄清的一点。 他们做了一个讲座，展示了各种各样的技术来理解叶绿体的结构/功能。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. ABSTRACT: The helical arrangement of the granal thylakoidal system is evident mostly from serial section EM studies on chemically fixed specimens on single granum or on a pair of grana. These do not reveal the 3D arrangement (network) of grana that interconnects with stroma thylakoids. The ontogeny of grana, the variation of its size, its flexibility under various environmental conditions (high light  low light, short term adaptation, long-term acclimation), structural consequences of the phosophorylation of membranes, and the role of the physico-chemical environment (osmolality, ionic strength) are also poorly undrestood. Futher, there are some uncertainties because of possible artifacts due to the chemical fixation. Granal chloroplasts have not been studied by electron tomographic techniques  perhaps because of the large size and dense structure of whole, mature chloroplasts. Thus we plan, in addition, to attempt the imaging of intact chloroplasts (and thylakoid membranes, i.e. plastids without their envelope membranes and soluble components), by the use of plastids with small-sized grana, and granum stroma assemblies isolated by sonication and/or cleaved by detergents. We have detailed knowledge concerning the organization of complexes and lamellae in the granum-stroma assemblies by a wealth of other techniques, such as circular dichroism spectroscopy that reveals the macrodomain organization (300-400 nm in diameter) and small angle X-ray and neutron scattering which provide information on the variations in the periodic ultrastructure, as well as their photosynthetic functions. It has also been established that these structures are capable of undergoing light-induced reversible structural organization by a previously unknown physical mechanism in biology, the thermo-optic effect. In the previous reporting period, several tomographic reconstructions were made. Drs. Must¿rdy and Garab visited the RVBC for one week. They observed and participated in data collection and tomographic reconstruction. A tomogram was made showing how the grana are linked within the thylakoid, a point they had been hoping to clarify. They presented a lecture showing a variety of techniques brought to bear on understanding structure/function of the chloroplast.