The cell biology of dynamic and stable intercellular bridges in situ

地球上的每一种动物都是细胞的集合。我们的人体含有数万亿个细胞。这些细胞组成块非常小，1500多个细胞就能填满这句话末尾句号那么大的一层。然而，地球上的每一种动物都是从一个特别大的细胞——卵子进化而来的。这种大尺寸对于早期发育的正常进行很重要。我们正在研究动物母亲的身体是如何产生如此大的细胞的。我们已经知道，这需要辅助细胞通过稳定的连接将它们的内容物捐献给正在生长的卵子。我们正在进行的研究是关于维持辅助细胞和卵子之间的窗口状连接的稳定性。我们也在研究这些连接是如何在正确的时间关闭的，从而使卵子最终自主。教育和推广活动将包括对K12教师的指导，二年级学生在发展中的发展和参与，为本科生提供数学-生物学动手实验室，以及为实习生与科学家和工程师进行匹配的新方法。还包括扩大大学学生和妇女参与科学的努力。典型的动物细胞只有一个细胞核。然而，在不同的生物体中，这一规则被合胞体等组织打破。合胞体是一种特殊的组织，由多个细胞核通过细胞间桥连接到一个共同的细胞质上。合胞体存在于多种环境中，如果蝇卵室、丝状真菌、哺乳动物肌管和植物种子。在许多动物中，产生卵子和精子的器官是合胞的，维持细胞间的联系对生育是必不可少的。我们的主要目的是确定连接发育中的卵母细胞（卵细胞）和共同的合胞细胞质的细胞间桥的组成、动力学和调节。对于提出的研究，模型系统将是微小的自由生活的线虫的产卵合胞体，秀丽隐杆线虫。秀丽隐杆线虫合胞生殖系的卵子产生在遗传学和发育上都有很好的描述，但在细胞生物学上才刚刚开始探索。秀丽隐杆线虫的小尺寸和透明度使其适合于定量高分辨率的体内成像。此外，定量图像分析，照片和显微操作，生物化学，反向遗传学和确证建模将结合来研究细胞间的联系。秀丽隐杆线虫具有良好的基因组注释和易于蛋白质缺失，以及基因组编辑用于荧光蛋白标记，因此非常适合解剖分子机制。合胞细胞间桥可以被认为是细胞分裂失败，其中细胞动力学环未能分离子细胞。因此，我们对细胞在细胞分裂过程中如何夹成两半的大量知识，为有关细胞间桥的结构和功能的假设提供了信息。细胞分裂机制的高度保守性预示着我们的发现将适用于整个系统发育。此外，从性腺远端到性腺近端卵母细胞发育的传送带状排列将揭示预测因果关系的时空相关性。

Every animal living on Earth is a collection of cells. Our human bodies contain trillions of cells. These cell building blocks are so tiny that over 1500 of them would fill a layer the size of the period at the end of this sentence. However, every animal living on Earth has developed from a single, exceptionally large cell, the egg. This large size is important for early development to proceed properly. We are studying the way in which the mother animal's body creates such big cells. We already know that this requires helper cells to donate their contents to the growing egg, via stable connections. Our ongoing research is on the maintenance of the stability of the window-like connections between helper cells and the egg. We are also studying how the connections are closed at the right time, so that the egg is finally autonomous. Education and outreach activities will include mentoring of K12 teachers, development and engagement of 2nd grade students in development, a math-biology hands on lab for undergraduates, and a novel approach for matching trainees with scientists and engineers. Also included are efforts to broaden participation of URM students and women in science.The archetypical animal cell has one nucleus. However, in diverse organisms, this rule is broken by tissues such as syncytia. Syncytia are specialized tissues that contain multiple nuclei connected to a common cytoplasm via intercellular bridges. Syncytia are found in diverse contexts such as fruit fly egg chambers, filamentous fungi, mammalian muscle myotubes and plant seeds. In many animals, the egg- and sperm-producing organs are syncytial, and the maintenance of intercellular connections is essential for fertility. Our central aims are to determine the composition, dynamics and regulation of intercellular bridges that connect developing oocytes (egg cells) to a common syncytial cytoplasm. For the propose studies, the model system will be the egg-producing syncytium of the tiny free-living nematod worm, C. elegans. Egg production in the C. elegans syncytial germline is well described genetically and developmentally but has only begun to be explored with cell biology. The small size and transparency of C. elegans make it amenable to quantitative high-resolution in vivo imaging. In addition, quantitative image analysis, photo- and micro-manipulation, biochemistry, reverse genetics and corroborative modeling will be combined to study intercellular connections. C. elegans is highly suitable for dissecting molecular mechanism due to its well-annotated genome and the ease of protein depletion, and genome editing for fluorescent protein tagging. Syncytial intercellular bridges can be thought of as abortive cell division, wherein the cytokinetic ring failed to separate the daughter cells. Therefore, our vast knowledge about how cells pinch in half during cytokinesis has informed hypotheses about the structure and function of intercellular bridges. The high conservation of cell division machinery predicts our findings will be applicable across phylogeny. Furthermore, the conveyor belt-like arrangement of oocyte development from the distal to the proximal gonad will reveal spatio-temporal correlations that predict causal relationships.