Plastid Extensions and Connections in Vascular Plants

9808101汉森体体在维管植物的不同组织中发育成各种形式，反映了这些细胞器发挥的各种重要功能。叶绿体通过分裂进行复制，并在教科书中以离散的、自主的形式出现。然而，文献中零星的报告描述了叶绿体被膜的细丝状突起，有时它与其他叶绿体相连。这些结构在光学显微镜下很少被观察到，几乎没有人注意到，它们的存在有时被认为是一种人工制品。这个项目利用了这样的观察：当绿色荧光蛋白(GFP)作为基质蛋白在叶绿体中表达时，这些结构很容易被检测到。初步实验表明，GFP可以通过质体之间的管状连接进行移动。这增加了这样一种可能性，即这些含有间质的结构，即“间质”，允许交换其他具有重要功能的分子。该项目的总体目标是进一步确定这些种球的特征，并探索它们在叶绿体功能和植物细胞生物学中的未知作用。在模式植物拟南芥中，将通过光学和电子显微镜对不同类型细胞在其细胞周期和发育过程中以及在环境胁迫下的相互连接的丰度、大小和程度进行彻底的表征。转基因植物将在其叶绿体基因组中编码GFP或蓝色荧光蛋白，用于未来的研究，以监测杂交细胞中不同类别蛋白质在叶绿体之间的转移程度。此外，还将研究球茎与其他亚细胞结构在体内的相互作用。

9808101HansonPlastids develop into a variety of forms in different tissues of the vascular plant, reflecting the variety of important functions these organelles perform. Plastids replicate by division and appear in textbooks as discrete, autonomous bodies. However, sporadic reports in the literature have described thin filamentous projections of the plastid envelope which sometimes connect with other plastids. These structures, rarely observable under the light microscope, have received little attention, and their very existence has sometimes been dismissed as an artifact. This project capitalizes on the observation that when green fluorescent protein (GFP) is expressed as a stromal protein in plastids, the structures are readily detected. Preliminary experiments have demonstrated that GFP can move through the tubular interconnections between plastids. This raises the possibility that these stroma-containing structures, denoted "stromules", permit exchange of other, functionally significant molecules. The general aim of this project is to characterize the stromules further and to probe their as yet unknown role in plastid function and plant cell biology. A thorough characterization of the stromules with regard to abundance, size, and degree of interconnections in different cell types during their cell cycle and development and under environmental stress will be carried out in the model plant Arabidopsis by light and electron microscopy. Transgenic plants will be produced that encode either GFP or blue fluorescent protein in their plastid genomes for future studies that will be undertaken to monitor the degree of transfer of different classes of proteins between plastids in hybrid cells. The interaction in vivo of stromules with other subcellular structures will also be examined.