THREE DIMENSIONAL RECONSTRUCTIONS OF THE CLEAVAGE FURROW

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， 因此可以在其他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。 在分裂后期早期开始的胞质分裂代表有丝分裂的最后阶段，其中两个子细胞通过称为分裂的事件而分离。随着子细胞通过胞质分裂的进展，它们形成一个卵裂沟，通过肌动球蛋白收缩环的作用进入。这形成了一个狭窄的细胞质桥，需要分解以产生两个独立的子细胞。此外，研究表明，成功的胞质分裂和脱落需要回收内体。不幸的是，内体在卵裂沟的机制和功能仍不清楚。有两种假说试图解释内体在胞质分裂中的作用。第一个假设，管腔填充模型，表明同步内体融合在沟介导的子细胞的断裂。第二个假设，一个交付模型，提出了一个功能的内体在调节肌动蛋白细胞骨架的动力学和/或脂质组成的犁沟通过交付内体囊泡。我们实验室和其他实验室的先前工作已经确立了内体再循环在介导晚期胞质分裂中的作用。Rab 11和FIP 3已被证明参与胞质分裂过程中内体再循环至卵裂沟的靶向。为了确定卵裂沟内Rab 11/FIP 3相关内体的时空动态，我们将使用电子断层扫描来三维重建卵裂沟。早期和晚期分裂末期沟断层图像的比较将产生什么细胞器填充沟在末期的感觉。此外，免疫电镜的使用将提供用于鉴定细胞器填充的卵裂沟。

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. Cytokinesis beginning in early anaphase represents the last stages of mitosis where two daughter cells become separated via an event termed abscission. As the daughter cells progress through cytokinesis they form a cleavage furrow that ingresses by the action of an actomyosin contractile ring. This forms a narrow cytoplasmic bridge that needs to be resolved to produce two separate daughter cells. Additionally, it has been shown that recycling endosomes are required for successful cytokinesis and abscission. Unfortunately, the mechanism and function of endosomes at the cleavage furrow remain unclear. Two hypotheses have been proposed that try to explain the role of endosomes during cytokinesis. The first hypothesis, a luminal filling model, suggests synchronized endosome fusion at the furrow mediates the scission of daughter cells. The second hypothesis, a delivery model, proposes a function for endosomes in the regulation of actin cytoskeleton dynamics and/or lipid composition at the furrow through the delivery of endosomal vesicles. Previous work from our laboratory and others have established a role for recycling endosomes in mediating late stage cytokinesis. Rab11 and FIP3 have been shown to be involved in targeting of recycling endosomes to the cleavage furrow during cytokinesis . To determine the spatiotemporal dynamics of Rab11/FIP3 associated endosomes within the cleavage furrow, we will use electron tomography to three dimensionally reconstruct the cleavage furrow. Comparison of early and late telophase cleavage furrow tomograms will yield a sense of what organelles populate the furrow during telophase. Additionally the use of immunoEM will provide for the identification of organelles populating the cleavage furrow.